User manual | IP Networking for Broadcast Engineers

IP Networking for Broadcast Engineers
SBE Chapter 53 – Miami, FL
March 30, 2012
Wayne M. Pecena
Texas A&M University
IP Networking for Broadcast Engineers
Advertised Presentation Scope:
Course Level: Intermediate to Advanced Level
IP Networking for Broadcast Engineers is an intensive instructor-led class focused on major IP networking topics. The goal is
to equip the broadcast engineer with the knowledge and understanding of IP networking fundamentals. The morning will
focus on the principals of IP networking including the OSI and TCP models, physical layer technologies, IP addressing, IP
subnetting, and applying best practices in the design of an IP address plan.
The afternoon will focus on applying the morning fundamentals to the understanding of routing protocols, switching
fundamentals, VLAN implementation, and security best practices in network design.
The lecture will be supplemented with network design examples presented by virtual demonstration and class exercises
designed to apply learned concepts in a practical manner. Students will receive a complete set of class notes, class
exercises, and reference materials.
My Goals & Deliverables:
‐ Awareness of Major IP Networking Topics (broadcast application focused)
‐ Understanding of Topic Fundamentals & Practical Application Principals
‐ Where to Obtain Further Knowledge
‐ Foundation for CBNE Certification Exam
2
SBE Networking Certifications
CBNT
CBNE (coming in 2012)
Certified Broadcast Networking Technician
Certified Broadcast Networking Engineer
•
This certification is designed for persons who wish to demonstrate a basic familiarity with networking hardware as utilized in business and audio/video applications in broadcast facilities.
•
Exam Focus:
– Network topologies and layouts
– Common network protocols
– Wiring standards and practices
– Maintenance, troubleshooting and connectivity issues
– Challenges unique to broadcast‐
based networks
•
This certification is an “Advanced” level that reflects the skill and knowledge that will be required in today's world of converged IT and broadcast engineering.
•
Exam Focus:
–
–
–
–
–
Audio/Video over IP
Digital Content management
Video Systems in an IT World
Data Transmission Systems
General IT Hardware 3
SBE CBNE
SBE SIGNAL – February 2012
4
Certification Exams
MY DISCLAIMER
This class should not be considered a certification preparation class.
However the material presented will provide an excellent background in IP networking
technology for those pursuing the SBE Certified Broadcast Networking Technologist
(CBNT) or the Certified Broadcast Networking Engineer (CBNE) certifications.
Why Is This NOT a Preparation Class?
1. I have no personal knowledge of the certification exam question pools.
2. The published exam scope covers more than just IP networking.
What I Will Do With Regards to the CBNE:
1. Cover IP Networking Technology fundamentals and focus on topics which
represents 60-70% of published exam content scope
2. Tailor network design examples towards possible CBNE “essay” questions
3. Provide suggested self-study material sources to address missing exam content
5
IP Networking for Broadcast Engineers
Course Outline
• 1. Introduction & Standards Organization Overview
• 2. OSI Reference Model
• 3. TCP Reference Model
• 4. TCP/IP Protocols
• 5. TCP and UDP Fundamentals
• 6. IP Addressing (IPv4)
• 7. IP Addressing (IPv6)
6
IP Networking for Broadcast Engineers
Course Outline ‐ continued
•
•
•
•
•
8. Switching & Routing Fundamentals
9. QoS Basics
10. Controlling Network Traffic & Security
11. Network Design Practical
12. Additional CBNE Topics:
– Broadcast Digital Content Management & Workflow
– General Server Hardware
– Wireless Networking
7
1. Introduction & Standards Organization Overview
8
What is a Network?
• The foundation for human interaction.
• A group of computers that are interconnected to share resources and information.
• A group of hosts that share a common address scheme.
• Networks are often defined by their geographic reach:
–
–
–
–
Local Area Network ‐ LAN
Wide Area Network ‐ WAN
Metropolitan Area Network ‐ MAN
Campus Area Network ‐ CAN
9
5 Things Required To Build a Network
•
•
•
•
•
Send Host
Receive Host
Message or Data to Send Between Hosts
Media to Interconnect Hosts
Protocol to Define How Data is Transferred
10
Network Device Evolution
11
Network Topologies
Bus Topology
Ring Topology
Mesh Topology
StarBus Topology
12
Introduction
• IP Networking – A Brief History:
– Development Began in the Early 70’s
– Goal ‐ Vendor Independent & Survivable Networking for DoD ARPAnet
– The Name “internet” Came into Use for “Interconnecting ARPANet Sites” – Internet Protocol Version 4 Completed in 1978 – IPv4
• Nomenclature Clarification:
– “internet” or “internetwork” means to interconnect networks
– “Internet” refers to a specific global network of TCP/IP based systems
13
The Early Days
•
•
•
•
•
14
First “Router” Was the “Interface Message Processor – IMP”
Developed in the Late‐60’s for ARPANET
First Message “lo” Was Sent on October 29, 1969 from
UCLA to the Stanford Research Institute
After Recovery From a System Crash, the Word “login”
Was Successfully Transmitted
Life Has Never Been the Same Since!
Standards Organizations
De Jure & De Facto
• IETF – Internet Engineering Task Force
– The Internet Standard RFC’s Originate Here
• IEEE‐ Institute of Electrical & Electronic Engineers
– Ethernet & Wireless LAN Standards
• EIA – Electronic Industries Association
– Focused on Physical Layer Standards
• ISO – International Standards Organization
– OSI Reference Model Creation
• ITU – International Telecommunications Union
– Global Telecommunications Standards (ie PSTN)
15
IETF – Internet Engineering Task Force
•
•
Request for Comments – RFC’s
– The “Standards Bible” of the Internet
– Used to Explain All Aspects of IP Networking
– Nomenclature “RFC xxxx”
Requirement Levels:
– Required
– Recommended
– Elective
– Limited Use
– Not Recommended
www.rfc-editor.org/rfc.html
16
IEEE‐ Institute of Electrical & Electronic Engineers
• Project 802
Ethernet Standards:
– 802.1
– 802.3 – 802.11
Bridging
Ethernet
Wireless
http://standards.ieee.org/about/get/
17
ITU – International Telecommunications Union
• ITU‐T Sector:
– ITU‐T G‐Series TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS
– ITU‐T H‐Series AUDIOVISUAL AND MULTIMEDIA SYSTEMS – ITU‐T I‐Series INTEGRATED SERVICES DIGITAL NETWORK – ITU‐T X‐Series DATA NETWORKS, OPEN SYSTEM COMMUNICATIONS AND SECURITY http://www.itu.int/ITU-T/info/structure.html
18
2. OSI Reference Model
Opens Systems Interconnection Reference Model (OSI stack)
19
OSI Model
The TCP/IP Architecture Begins Here
•
•
•
•
•
International Standards Organization (ISO) ‐ Open Systems Interconnection Model
– Layered Model to Standardize the Networking Process
– Guidelines to Provide Vendor‐Independent Interoperability
– Detailed by ITU‐T X.200 Series of Recommendation
Provides an “abstract description of the network communications process”
Serves as a “Reference Model” + Associated Protocols
Layers also reference to by numbers 1 – 7
– Each Layer Relies on the Previous Layer and is Transparent to the Next Higher Level
• A Layer Only Interacts With the Layer Below It
• A Layer Only Provides Capability for the Layer Above to Interact With It
Data is “Encapsulated” As It Travels Through the Model
20
OSI Model
Open Systems Interconnection (OSI) Model
Developed by the International Organization for Standardization (ISO)
Networking
Focus
21
OSI Model Expanded
Protocol
Data
Unit
PDU
“All People
Seem To Need
Data
Processing”
OR
“Please Do Not
Throw
Sausage Pizza
Away”
“Some People
Fear
Birthdays”
22
Encapsulation
Data is “Encapsulated” As It Travels Through the Model
23
Encapsulation & De‐Encapsulation
Application
Upper Level Data
Session
TCP Header
MAC Header
Presentation
PDU
Upper Level Data
Session
Upper Level Data
IP Header
LLC Header
Application
Presentation
Transport
Segment
Transport
Network
Packet
Network
Data Link
Frame
Data Link
Bits
Physical
Data
Data
Data
CS
CS
Physical
0110010111001000111000111010
24
Real – World OSI Model
RFC 2321
Important to Recognize During Troubleshooting
ID10T Errors Occur Here
25
The Physical Layer ‐ 1
Receives frames from the Data Link layer
Places bits onto the physical network medium
Controls the signaling
Takes bits off the physical network medium
Sends constructed frames to the Data Link Layer
26
Ethernet Media Evolution
Thinnet
Thicknet Vampire
Tap
Topology Also Migrates from “Bus” to “Star” Based
27
Ethernet Cable Wiring ‐ Straight
28
Ethernet Cable Wiring ‐ Cross
29
Ethernet Cable Types
Router 1
Router 3
Router 2
Ethernet 1
Ethernet 3
Ethernet 0
Ethernet 0
Ethernet 0
MDI
MDI
Ethernet 1
Ethernet 1
MDIX
MDIX
MDIX
MDI
MDI
Cable Type Legend
EIA/TIA-568B
EIA/TIA-568B
Straight-Through
EIA/TIA-568A
EIA/TIA-568B
Cross-Over
30
Ethernet Auto‐Negotiation
• Auto Configuration of Port Duplex & Speed
– Utilizes Ethernet FLP & NLP Bursts
• Duplex – Half Duplex or Full Duplex
• Speed ‐ 100 / 1000 Mbps
• Be Careful With Depending Upon Auto‐Negotiation
– 10 Mbps Full Duplex is Not a Valid Mode
– 100 Mbps Half Duplex Indicates Auto‐Negotiation Failure
– Duplex Mismatch = Poor Performance = CRC Errors
• Best Practice – Static Configure Infrastructure
31
Duplex Mismatch Result
When Duplex Mismatch Occurs:
High Collision Rate Results, thus Performance Reduced
32
Ethernet
Physical Medium
IEEE
Cable Designation
Topology Speed / Duplex / Media
802.3
10-Base-5
Bus
10Mbps / Half / Thicknet
802.3
10-Base-2
Bus
10Mbps / Half / Thinnet
802.3
10/100-Base-T
Star
10/100 Mbps / Half-Full / UTP
802.3u
100-Base-T
Star
100 Mbps / Half-Full / UTP (Cat 5)
802.3u
100-Base-FX
Star
100 Mbps / Full / MM Fiber
802.3ab
1000-Base-T
Star
1000 Mbps / Full / UTP (Cat 6)
802.3z
1000-Base-SX
Star
1000 Mbps / Full / MM Fiber
802.3z
1000-Base-LX
Star
1000 Mbps / Full / SM Fiber 1310nm
802.3z
1000-Base-ZX
Star
1000 Mbps / Full / SM Fiber 1550nm
and 20 Gigabit, 40 Gigabit, & 100 Gigabit Ethernet are emerging ……
33
FDDI
Token Ring
802.6
Ethernet
802.3ab
Gigabit Ethernet
(copper)
Ethernet
802.3z
Gigabit Ethernet
Ethernet
802.3u
Fast Ethernet
Ethernet
802.3
Ethernet
The OSI Model & Ethernet Types
34
Ethernet GBIC & SFP Modules
“Giga-Bit Interface Converter” - GBIC Transceiver
SC Fiber Connector
“Single Form-factor Pluggable” – SFP (mini GBIC) Transceiver
LC Fiber Connector
Copper or Optical Based Transceiver to Provide Flexible
Physical Interface
-1000Base-T (some support 100/100-Base-T as well)
- 1000Base-SX / LX / ZX - Multi-Mode / Single-Mode Fiber
35
Fiber Optic Connector Types
36
Power Over Ethernet – “POE”
37
WAN Technology
•
•
Generally Categorized as Dedicated, Circuit Switched , or Packet Switched:
Dedicated
– T‐Carrier (data)
– Optical Carrier
•
•
Circuit Switched
– ISDN – BRI
– ISDN – PRI
– T‐Carrier (voice)
Packet Switched
– X.25
– Frame Relay
– ATM
– ADSL / HDSL
– Metro Ethernet Offerings
38
WAN Component Example
Point – Point T‐1 or DS‐1
Possible Interfaces That Might Be Found
39
WAN Link Types
Line Type:
Signaling Type:
Bit Rate
64
DS0
64 kbps
T1 or DS1
DS1
1.544 Mbps
T3 or DS3
DS3
44.735 Mbps
SONET OC:
SONET STS:
Bit Rate
OC‐1
STS‐1
52 Mbps
OC‐3
STS‐3
155 Mbps
OC‐12
STS‐12
622 Mbps
OC‐48
STS‐48
2400 Mbps
OC‐96
STS‐96
5000 Mbps
40
DS1 Configuration
•
•
•
DS1 or T1 Types:
– Channelized (voice)
– PRI (ISDN)
(voice or data)
– Clear Channel
(data)
Encoding
– AMI (voice)
– B8ZS (data)
Framing
– D4 Super Frame (voice)
– Extended Super Frame (data)
• Timing
– Must specify source
41
The Data Link Layer ‐ 2
Unique
Network Layer Packets Encapsulated into Frames
Hardware Addressing Scheme Implementation
Unique Sub-Layers: LLC & MAC
42
The Data Link Sub‐Layers:
Data Link Functions:
LLC Sublayer
Package Frames
- Flow Control
- Error Control (CRC)
- Synchronization
Transmit Frames
Control Flow
Error Correction
MAC Sublayer
- Physical Addressing (MAC Address)
- Transmitting On The Media
Network ID
Data Link Frames:
Are Likely Ethernet Layer 2 Protocol Data Units
But, they could be:
Token Ring Layer 2 Protocol Data Units
Frame Relay Layer 2 Protocol Data Units
43
Ethernet Basics
IEEE 802.3
•
•
•
The “de facto Standard” of Networking Today!
Based Upon Contention‐Access to the Wire
4 Basic Building Blocks of the Ethernet System
– The Ethernet Frame
•
•
•
•
–
–
–
–
802.3 Raw
802.2 LLC
Ethernet II (DIX)
Ethernet SNAP
Early Novell Netware IPX
Current Novell NetWare IPX TCP/IP
IPX, AppleTalk v2
The Ethernet Frame
Media Access Control Protocol
Signaling Components
Physical Medium
44
Ethernet Frame – Layer 2
Preamble
Destination
Address
8
BYTES
6
BYTES
Source
Address
Data
CRC
46 – 1500 BYTES
VARIABLE
4
BYTES
Type
6
2
BYTES BYTES
Invalid FRAME Lengths:
< 64 BYTES = “RUNT” FRAME
> 1518 BYTES = “GIANT” FRAME
Note – Preamble Not Used in Frame Length Calculation
Destination
Address
Source
Address
Type
Data
CRC
64 Byte Minimum
45
MAC Address
“Media Access Control” Address
•
•
•
•
•
•
Known as Hardware Address or Physical Address
48 bit / 6 Byte Unique Address in Hardware
Expressed as 6 Groups of 2 Hex Characters
00:A0:C9:14:C8:29
1st 3 Bytes = Organizational Unit Identifier “OUI”
00:A0:C9 OUI Assigned to Intel
2nd 3 Bytes = Network Interface Controller “NIC”
14:C8:29 is Unique to Hardware
Also Expressed as: 00‐A0‐C9‐14‐C8‐29
00A0.C914.C829 MAC Lookup:
http://hwaddress.com/
46
Ethernet Media Access Control Protocol
Carrier Sense Multiple Access with Collision Detection – “CSMA/CD”
• CSMA/CD Process:
– Listen Before Sending
– Detect Collisions
– Jam Signal &
Random Backoff
47
Some Ethernet Trivia
•
Conceptually Based Upon “ALOHA NET”
– Developed as a “Wireless” Network by
Norman Abramson & colleagues
– Deployed at the University of Hawaii in 1971
•
Later Refined at Xerox PARC in 1973
– Bob Metcalf & David Boggs “Fathers of Ethernet”
•
More Ethernet History:
http://ethernethistory.typepad.com/
48
The Network Layer ‐ 3
Internetwork Communications Focused:
Packet Delivery from Source Host
To Destination Host
Logical Addressing Scheme
Implementation
Routing Decisions via Routing Protocols
49
IP Packet – Layer 3
RFC 791
50
Ethernet Frame In More Detail
51
The Transport Layer ‐ 4
Send Host
Receive Host
Implements Reliable End-End Data Transport
Implements Error Detection / Correction
Establishes Virtual Connect Between Hosts
Provides Segmentation, Sequencing, Flow Control
52
Ports
RFC 1700
• Applications Are Indexed by a “Port Number”
• Allows Datagrams to be Multiplexed Between Applications
• Port Numbers Can Be Between 0 ‐ 65535
– 0–1023 Are Considered Reserved
– 1024–49151 Can Be Registered
– 49152–65535 Are Considered Dynamic or Private
• TCP and UDP Port Numbers Are Independent
53
Common Port Numbers
• RESERVED PORTS
“System Port Numbers”
•
•
•
•
•
•
•
•
Port 20 / 21 – FTP “File Transfer Protocol”
Port 23 – TELNET
Port 53 – DNS “Domain Name Service”
Port 80 – HTTP
Port 110 – POP3 “Post Office Protocol”
Port 123 – NTP “Network Time Protocol”
Port 161 – SNMP “Simple Network Management Protocol” (UDP)
Port 443 ‐ HTTPS
• REGISTERED PORTS
“User Port Numbers”
•
•
•
•
•
•
•
•
•
Port 1720 – H.323 Video Call Setup
Port 1812 – RADIUS Authentication
Port 2000 – CISCO “Skinny”
Port 3074 – “X‐Box” Live
Port 4664 – Google Desktop
Port 5004 – RTP “Real Time Transport Protocol”
Port 5060 – SIP “Session Initiation Protocol
Port 5631 – PC Anywhere
Port 8080 – Alternate HTTP
http://www.iana.org/assignments/port‐numbers
54
Sockets
• A “Socket” Is a Combination of an IP Address & A Port Number
• Used for Client‐Server Application Interaction
• IP Address + Port Number = Socket
IP Address: 10.10.10.10
Port Number: 80
Socket: 10.10.10.10:80
55
Ports & Sockets
Ports
RFC 1700
•
•
•
Allows Datagram Multiplexing Between Applications
Port Numbers Can Be Between 0 ‐
65535
– 0–1023 Are Considered Reserved
– 1024–49151 Can Be Registered
– 49152–65535 Are Considered Dynamic or Private
TCP and UDP Port Numbers Are Independent
Sockets
•
•
•
A “Socket” Is a Combination of an IP Address & A Port Number
Used for Client‐Server Application Interaction
IP Address + Port Number = Socket
Socket: 10.10.10.10:80
56
3. TCP Reference Model
An Implementation of the OSI Model
57
TCP/IP Model
DOD Model Stack or TCP/IP Model Stack Focused on IP
58
The Models in Comparison
59
4. TCP/IP Protocols
(TCP/IP Application Layer Protocols)
ARP, DNS, DHCP
HTTP, SMTP, FTP, Telnet, and the list goes on……
60
Primary TCP/IP System Protocols:
• ARP – Address Resolution Protocol
• DHCP – Dynamic Host Configuration Protocol
• DNS – Domain Name System
• ICMP – Internet Control Message Protocol
61
ARP Operation
Host 1:
192.168.1.10
00:07:E9:D4:EC:9A
Host 4:
192.168.1.40
00:07:E9:D4:EC:9D
Host 2:
192.168.1.20
00:07:E9:D4:EC:9B
Host 3:
192.168.1.30
00:07:E9:D4:EC:9C
Host 5:
192.168.1.50
00:07:E9:D4:EC:9E
62
DHCP Operation
DHCP Server
Client
DHCP Discover – IP Address Request
DHCP Offer – IP Address Offer
DHCP Request – Select IP Address
DHCP ACK – Ack IP Address
63
DNS Operation
• DNS Provided:
– Manual Configuration (Hosts file)
– Dynamic Configuration via DNS Server
• Primary Server – Authoritative Server – Master Zone File
• Secondary Slave Server
• Caching Server
DNS Record Types:
DNS Record
-----------------A
AAAA
CNAME
MX
Record Description
-------------------------------------Address Record – Host IPv4
Address Record – Host IPv6
Canonical Host Name
Domain E-Mail Server Exchange Record
64
DNS Hierarchy
Root DNS Servers
www.root-servers.org
.com
.edu
.org
Top Level Domain Servers
Secondary – Level
Domain Servers
SBE.org
ClearChannel.com
DNS
Client
DNS
Client
TAMU.edu
DNS
Client
65
DNS Example
66
ICMP
• Sends Error & Control Messages Between Hosts – Common Messages Include:
– Echo
– Echo Reply
– Destination Unreachable
– Time Exceeded
– Source Quench
– And Others ……
67
ICMP
Messages:
• Platform Utilized by Ping & Traceroute Utilities
68
Noteworthy TCP/IP System Protocols:
FTP “File Transfer Protocol”
TELNET
HTTP
POP3 “Post Office Protocol”
NTP “Network Time Protocol”
SNMP “Simple Network Management • HTTPS
•
•
•
•
•
•
69
5. TCP and UDP Fundamentals
TCP Fundamentals & Operation
UDP Fundamentals & Operation
TCP vs UDP Comparision
Unicast & Multicast
70
TCP / UDP
TCP ‐ RFC 793
•
•
Referred to as a “Connection –
Oriented” Protocol
Guaranteed Or Reliable Data Delivery
– Acknowledgment of Packet Receipt
– Retransmission Occurs if Packet Not Received or Error Occurs
•
•
High Overhead thus Slow
A TCP Conversation Requires Establishment of a 2‐Way “Session” Between Hosts
UDP ‐ RFC 768
•
•
•
•
A “Simple” Protocol or “Lightweight”
Low Overhead = Fast
“Best Effort” – Non‐Guaranteed Data Delivery
Why Use?
– Required for Real‐Time Applications ‐ VoIP or Video Transmission”
– Latency More Detrimental Than Data Loss
71
TCP Handshake / UDP Data Flow
72
TCP vs UDP
73
TCP Basics
RFC 793
•
•
Referred to as a “Connection – Oriented” Protocol
Guaranteed Or Reliable Data Delivery
– Acknowledgment of Packet Receipt
– Retransmission Occurs if Packet Not Received or Error Occurs
•
•
High Overhead thus Slow
A TCP Conversation Requires Establishment of a 2‐Way “Session” Between Hosts
•
TCP Windowing
– Segment Acknowledgement
– Dynamic Window Sizing
– “Slow‐Start”
74
TCP Session
Segment
Acknowledgment
TCP Connection
Established
75
TCP 3‐Way Handshake
Send Host
I Want to Connect. My
Sequence Number is 100
SEQ = 1
ACK=100
CONTROL = SYN, ACK
I Received Your
Sequence 1 & Ready for
Sequence 2
Receive Host
SEQ = 100
CONTROL = SYN
I Received Your
Sequence 100! My
Sequence Number is 1 &
Ready for 101
SEQ = 101
ACK=2
CONTROL = ACK
76
Handshake in More Detail:
77
TCP Dynamic Window
Receive Host
Send Host
17
16
15
14
13
12
11
SEQ = 200
ACK=13
Window Size = 3
10
Window=8
Window Size = 3
All Packets Dropped Past 12
17
16
15
14
13
Window=8
78
TCP “Slow‐Start”
RFC 1122
•
•
•
Determines How Reliable a Connection Path is Between Two Hosts
Transmit Larger and Larger Blocks of Data Until Path is Deemed “Reliable” or Receiver Window Size is Reached
Window Size is Usually Based Upon Network Connection Bandwidth
– Windows XP Default:
•
•
•
< 1 Mbps
<100 Mbps >100 Mbps 8 Kb 17 Kb
64 Kb
79
UDP Basics
RFC 768
•
•
•
•
•
A “Simple” Protocol or “Lightweight”
Low Overhead = Fast
“Best Effort” – Non‐Guaranteed Data Delivery
Why Use?
– Required for Real‐Time Applications ‐ VoIP or Video Transmission”
– Latency More Detrimental Than Data Loss
Used By:
– DNS
– SNMP
– DHCP
– TFTP
– And others …..
80
UDP Session
81
Practical Protocol Analysis
“Visualization of Network Activity”
http://www.wiresharktraining.com/
www.wireshark.org
82
6. IP Addressing (IPv4)
Classful IP Addressing
Classless IP Addressing
Private vs Public IP Addresses
Private – Public Address Integration
IP Subnetting
Subnetting Basics
The Subnet Calculation Process
83
IP Address Classes
• Class A – 126 Networks / 16,777,214 Hosts
– 1.0.0.0 to 126.0.0.0
• Class B – 16,384 Networks / 65,534 Hosts
– 128.0.0.0 to 191.255.0.0
• Class C – 2,097,152 Networks / 254 Hosts
– 192.0.0.0 to 192.255.255.0
• Class D – Multicast
– 224.0.0.0 to 239.255.255.255
• Class E – Reserved
– 240.0.0.0 to 255.255.255.255
84
IP Address Classes
“Classful” Public & Private
• Class A – 126 Networks / 16,777,214 Hosts
– 1.0.0.0 to 126.0.0.0
– PRIVATE ‐ 10.0.0.0 to 10.255.255.255
• Class B – 16,384 Networks / 65,534 Hosts
– 128.0.0.0 to 191.255.0.0
– PRIVATE ‐ 172.16.0.0 to 172.31.255.255
• Class C – 2,097,152 Networks / 254 Hosts
– 192.0.0.0 to 192.255.255.0
– PRIVATE ‐ 192.168.0.0 to 192.168.255.255
85
IP Address Classes
“32 Bit Doted Decimal Notation”
IPv4 Provides 232 or 4,294,967,296 IP Addresses
86
Classful vs Classless IP Address Subnetting
•
•
•
Classful Environment IP Address Allocation:
– /8 address blocks
– /16 address blocks
– /24 address blocks
Classless Environment IP Address Allocation:
– Can Be Customized to Fit Environment
Benefits:
– Flexible Network Design
– Allow Room For Growth
– Efficient Use of Resources
87
VLSM & CIDR
VLSM
RFC 1009
•
CIDR
RFC 1517, 1518, 1519, 1520
Variable Length Subnet Masking (VLSM)
– Host Addressing & Routing Inside a Routing Domain
– Allowed “Classless” Subnetting
• Mask Information is Explicit
– Allows More Efficient Use of Address Space – Taylor Address Space to Fit Network Needs
– Allows You to Subnet a Subnet
Example:
Classful Addressing
VLSM Addressing
CIDR Notation
•
Classless Interdomain Routing (CIDR)
– Class System No Longer Applies
– Routing Between Routing Domains
– Allows “Supernets” To Be Created
• Combining a Group of Class C Addresses Into a Single Block
– CIDR Notation (slanted notation):
172.16.1.1 /16
165.95.240.136 Implied Mask 255.255.0.0
165.95.240.136 Explicit Mask 255.255.255.192
165.95.240.136/26
88
VLSM
RFC 1009
• Variable Length Subnet Masking (VLSM)
– Host Addressing & Routing Inside a Routing Domain
– “Classful” Subnetting
• Mask Was Assumed Based Upon Class
– “Classless” Subnetting
• Mask Information is Explicit
– Allows More Efficient Use of Address Space
– Allows You to Subnet a Subnet
89
CIDR
RFC 1517, 1518, 1519, 1520
• Classless Interdomain Routing (CIDR)
Class System No Longer Applies
Routing Between Routing Domains
Class A & B IP Address Exhaustion Pressured Class C Address Space
Allows “Routing Tables” To Be Reduced by Grouping Contiguous Class C Addresses into One Network
– Allows “Supernets” To Be Created
• Combining a Group of Class C Addresses Into a Single Block
– CIDR Notation (slanted notation): 172.16.1.1 /16
–
–
–
–
90
IP Address Formats
Classful Addressing:
165.95.240.136
(Implied Mask 255.255.0.0)
VLSM Addressing:
165.95.240.136 255.255.255.192
(Explicit Mask 255.255.255.192)
CIDR Notation :
165.95.240.136/26
91
Private vs Public IP Addresses
• RFC 1918 Established “Private” Address Space
– Class A: 10.0.0.0 to 10.255.255.255
– Class B: 172.16.0.0 to 172.31.255.255
– Class C: 192.168.0.0 to 192.168.255.255
• Key Points:
– Private IP Addresses Are NOT Routable Outside the Local Network
– Widely Used in Home & Industry Networks
– May Be Translated With NAT At An Edge Router
• Map Private Address Space to Public Address Space
92
NAT & PAT
NAT
• Translates IP Addresses
– Limited IP Address Space
– Security
• Static NAT
PAT
• Always Used with NAT
• Allows 65,536 “Inside” Hosts To Be Identified by a Socket Address
– 1 to 1 Translation
– Hides Real Host IP Address
• Dynamic NAT (PAT)
– 1 to Many Translation
93
Network Address Translation – NAT
RFC 1631
•
94
Allows Mapping Internal (private) Address Space to External (public) Address Space
– Allows Internal IP Addresses to be Hid (Security)
– Can Conserve IP Address Space
Port‐Based Network Address Translation – PAT
or “NAT Overload”
•
Allows Mapping Internal (private) Address Space to a Single External (public) Address or Small Address Pool
– Allows Multiple Internal Addresses to Share a Single Public Address
– Translation In Place for Duration of Connection
– Outside Users CANNOT Establish A Connection to an Internal Host
95
Why Do We Subnet?
•
Exact Reason Varies Based Upon Deployment:
– Efficient Use of IP Address Space
• Dividing Networks Into the “Right” Size
– Performance
• Create Broadcast Domains
– Enhance Routing Efficiency – Reduce Routing Table Size
– Network Management Policy and Segmentation
• Grouping Hosts by Function or Purpose
• Grouping Hosts by Ownership
• Grouping Hosts Geographically
– Job Security for Network Engineers!
96
Subnetting
• What is a Subnet?
– Logical Subdivision of a Larger Network
• Why Do We Subnet?
• Efficient Use of IP Address Space
• Enhance Routing Efficiency – Reduce Routing Table Size
• Network Management Policy and Segmentation
• Job Security for Network Engineers!
97
Classful IP Address Subnetting
98
Classless IP Address Subnetting
Provided IP Address Space: 200.25.0.0./16
Represents 4,096 IP Addresses
Goal:
Allocate Smaller Address Blocks Across Organization
To Suite Environment
200.25.30.0/23
D
200.25.28.0/23
C
A
200.25.16.0/21
B
200.25.24.0/22
99
Subnetting Basics
• Identifies the Boundary Between Network and Hosts
• “Subnetting” Simply Moves the Boundary!
– Moves Boundary to the Right
– IP Address Subnetting Applies to All Classes
– Boundary Position Determined by the Subnet “Netmask”
• Expressed in Several Forms:
– Doted Decimal Notation (same as IP address)
– Slash Notation (also known as CIDR notation)
IP Address 165.95.240.100 with Netmask of 255.255.255.0
OR
165.95.240.100 /24
100
IP Subnetting Example
/24 = 254 hosts
/27 = 30 hosts
/28 = 14 hosts
101
Required Host IP Configuration Information
•
•
•
•
IP Address
Address Mask
Gateway Address
DNS Server Address(s)
Where Do We Get This Information?
102
Implied Subnet Mask Exercise
10.1.1.100
Class A
Class B Class C ?
191.18.10.1
Class A
Class B Class C ?
128.194.247.55
Class A
Class B Class C ?
192.95.240.135
Class A
Class B Class C ?
100.100.100.100
Class A
Class B Class C ?
103
Decimal to Binary Conversion
104
What Must Be Known About a Subnet?
IP Address and Mask
Provides:
First Network Address
First Network Address Assignable to a Host
Last Network Address Assignable to a Host
Broadcast Address
192.0.0.0 /24
Provides: 254 useable IP addresses
Mask: 255.255.255.0
Network Address (Wire Address)
First Network Address Assignable to a Host
Last Network Address Assignable to a Host
Broadcast Address
192.0.0.0
192.0.0.1
192.0.0.254
192.0.0.255
105
Subnet Calculation Examples
192.0.0.0 /20
Provides: 4094 useable IP addresses
Mask: 255.255.240.0
Network Address (Wire Address)
192.0.0.0
First Network Address Assignable to a Host 192.0.0.1
Last Network Address Assignable to a Host 192.0.15.254
Broadcast Address
192.0.15.255
192.168.1.0 /28
Provides: 14 useable IP addresses
Mask: 255.255.255.240
Network Address (Wire Address)
First Network Address Assignable to a Host
Last Network Address Assignable to a Host
Broadcast Address
192.168.1.0
192.168.1.1
192.168.1.14
192.168.1.15
106
IP Addressing Reverse Engineering
“A Useful Troubleshooting Tool”
• Verifying Proper Subnet Configuration When Given an IP Address and Subnet Mask
– Determine Subnet Address Range
– Determine “Assignable” IP Addresses
– Determine Broadcast Address
• Subnetting When Given A Network Requirement
• Subnetting When Given A Host Requirement
You Are Provided:
IP Address / IP Mask
107
Subnetting Tutorial
“The Magic Box” Approach
The Complete Tutorial:
https://learningnetwork.cisco.com/docs/DOC-2413#comment-7559
108
Exercise #1
26
64
258
128
32
248
128
16
238
128
8
10101100
00010000
00000000 00000001
255.255.255.0
11111111
11111111
11111111 00000000
Subnet Number:
172.16.0.0
10101100
00010000
00000000 00000000
First IP Address:
172.16.0.1
10101100
00010000
00000000 00000001
22
4
Broadcast IP Address:
172.16.0.255
10101100
00010000
00000000 11111111
21
2
Last IP Address:
172.16.0.254
10101100
00010000
00000000 11111110
208
128
1
OP
AND
AND
AND
AND
Bit 2
0
1
0
1
Subnet Mask:
128
64
32
16
8
4
2
1
172.16.0.1
IP Address:
128
64
32
16
8
4
2
1
128
64
32
16
8
4
2
1
128
128
64
32
16
8
4
2
1
27
Bit 1
0
0
1
1
Yields
0
0
0
1
109
Exercise #2 & #3
IP Address:
128
64
32
16
8
4
2
1
128
64
32
16
8
4
2
1
128
64
32
16
8
4
2
1
You Are Provided – 192.168.12.0 Mask 255.255.255.224.
128
64
32
16
8
4
2
1
Exercise 2:
192.168.12.0
Subnet Mask:
255.255.255.224
Subnet Number:
27
128
First IP Address:
26
64
258
128
32
248
128
16
238
128
8
22
4
21
2
208
128
1
OP
AND
AND
AND
AND
Bit 2
0
1
0
1
Broadcast IP Address:
Last IP Address:
IP Address:
192.168.100.0
Subnet Mask:
255.255.254.0
Subnet Number:
First IP Address:
128
64
32
16
8
4
2
1
128
64
32
16
8
4
2
1
128
64
32
16
8
4
2
1
You Are Provided – 192.168.100.0 Mask 255.255.254.0
128
64
32
16
8
4
2
1
Exercise 3:
Bit 1
0
0
1
1
Yields
0
0
0
1
Broadcast IP Address:
Last IP Address:
110
Subnet Calculation Tools
111
IP Addressing
CIDR Conversion
Reference
112
Special Use Address
RFC 5735
•
•
•
•
•
•
•
•
0.0.0.0/8
10.0.0.0/8
127.0.0.0/8
169.254.0.0/16
172.16.0.0/16
192.168.0.0/16
224.0.0.0/4
255.255.255.255/32
Network Address “Wire Address”
Private IP Address Space (RFC 1918)
Loopback Address
IETF Zero Configuration Address Space (RFC 3927)
Private IP Address Space (RFC 1918)
Private IP Address Space (RFC 1918)
Multicast Address Space
Broadcast Address
And many more special use cases………..
113
IP Address Trivia
•
•
•
What is Special About 127.0.0.1 ?
– Actually Any Address Works in Range of
127.0.0.1 to 127.255.255.255
Known as a “Loop‐Back” Address
Useful For:
– Test Local IP Stack and Network Adapter Test
– May Be Used by Client‐Server Ap on Host
114
7. IP Addressing (IPv6)
IPv6 Terminology & Fundamentals
Addressing Concepts
IPv4 to IPv6 Migration & Integration Strategies
115
IP Address Distribution
•
•
•
Assigned Internationally by “Internet Corporation for Assigned Names and Numbers (ICANN)” to One of 5 Regional Internet Registries (RIR)
Allocated in North & South America by “American Registry for Internet Numbers (ARIN)”
– US
– Canada
– South America
– Caribbean
Most User IP Addresses Obtained from an Internet Service Provider ‐ ISP
– Exceptions: Large Companies / Organizations, Higher Education, Federal & State Government, etc.
5 Regional Internet Registries (RIR)
ICANN Available IPv4 Space IPv4 Address Depletion
•
•
•
Recent Press About IP Address Depletion
As of February 2011 ALL ICANN IPv4 Address Space Assigned!
Regional Registries Now Have Their Last Allocation!
IPv4 Run Down Model
Source:
http://www.potaroo.net/
tools/ipv4/plotvar.png
IPv6 Address Space
IETF ‐ RFC 2460
IPv6 Provides Expanded IP Address Space
2128 =
340,282,366,920,938,463,463,374,607,431,768,211,456
(three hundred forty UNDECILLION addresses)
3.4 x 1038
•
But, IPv6 is More Than Expanded Address Space:
– An Opportunity to Re‐Engineer IPv4
•
•
•
•
•
•
Improved Support for Multicasting, Security, & Mobile Aps
Multiple Addresses per Interface
Host Auto‐Configuration Capability
Security Incorporated
MTU Discovery Incorporated
Traffic Engineering Provisions Incorporate
The IPv6 Address
128‐Bit Address Binary Format:
001001100000011110111000000000001111101010100000000000110010000110010101100110001000011110111100010010000010100011110001
Subdivide Into Eight (8) 16‐bit Groups:
0010011000000111 1011100000000000 0000111110101010 0000000000000011 0010000110010101 1001100010000111 1011110001001000 0010100011110001
Convert Each 16‐bit Group to Hexadecimal:
(separate with a colon)
2607:b800:0faa:0003:2195:9887:bc48:28f1
2607:b800:faa:3:2195:9887:bc48:28f1
Address Summarization
128‐Bit Address Represented as a 32 Hexadecimal Digits
Subdivided Into Eight Groups (Chunks, Quads, Quartets) of Four Hexadecimal Digits
(separated by colon)
2001:0000:0000:0000:0DB8:8000:200C:417A
or
2001:0:0:0:DB8:8000:200C:417A or
2001::DB8:8000:200C:417A IPv6 Representation
• IPv6 Address in a URL:
In IPv4: https://192.168.1.1:8080
In IPv6: Address 2001::0DB8:8:200C:417A
Entered in URL within [Brackets]
as: https://[2001::0DB8:8:200C:417A]:8080
IPv6 Is More Than Address Space
“An Opportunity to Re‐Engineer IPv4”
• Improved Authentication and Security
• Host Auto‐Configuration
• Mobility Incorporated
125
IPv6 Header Simplification
Ipv4
32 bits
Version
(4)
Header
(4)
Precedence / Type
(8)
Identification
(16)
Time to Live
(8)
Length
(16)
Flag
(3)
Protocol
(8)
Offset
(13)
Header Checksum
(16)
Source IP Address
(32)
Destination IP Address
(32)
Options & Padding
(0 or 32)
Packet Payload
(Transport Layer Data)
Fewer Fields & Fixed Header Size Result in Faster Packet Processing Providing Enhanced Routing Efficiency
20
Bytes
Improved Authentication and Security
• IPsec is Mandatory in IPv6
– IPv6 Is Not Necessarily More Secure Than IPv4
• Mandatory Implementation Ensures Enhanced Security:
– Data Integrity
– Authentication
– Confidentiality
127
Host Auto‐Configuration
•
•
•
•
Simply Saves Network Administrators Work!
Stateless Auto‐Configuration
Stateful Auto‐Configuration
Auto‐Configuration Process:
Host ID Generated from MAC Address:
Generated IPv6 Address: 2002:80c2:f737::80c2:f737
For Host with MAC Address: 80:C2:F7:37
128
Mobility Incorporated
• Provides Roaming Service Without Interrupting Connectivity
– Ability to Move Between Networks
– Maintains Home IP Address Regardless of Location
– Establishes Care‐Of IP Address When In a “Foreign” Network
• Similar in Concept to IPv4 Mobile IP
129
IPv6 Address Types
• Unicast – One‐to‐One Mapping
– Global Unicast Address
– Unique‐Local Unicast Address (non‐Routable or Private)
– Link‐Local Unicast
• Multicast – One‐to Many Mapping
– Multicast Groups Established
• Anycast – One‐to‐Nearest Mapping
– Packets Are Delivered to the “Closest, Nearest, or Lowest‐Cost” Interface
• Global Anycast
• Site‐Local Anycast
• Link‐Local Anycast
130
ARIN IPv6 Address Allocation Policies
•
End‐User / Enterprise Network
– Qualify by Meeting IPv4 Qualifications
– /48 Minimum Allocated
• 65,536 subnets
• Qualify for Larger Blocks by Justification of Proposed Use
– Allocation Guideline – Large Sites: /48
– Allocation Guideline – Small Sites: /56
131
IPv6 Address Assignment
•
•
•
•
Service Provider:
Large End User:
Small End User:
SOHO:
/32
/48
/56
/64
232 /64 subnets
65,536 /64 subnets
256 /64 subnets
1 /64 subnets
A /64 IPv6 subnet = 18,446,744,073,709,552,000
hosts
Routed vs Host portion
• Every IPv6 Address is Divided Into:
– Routed Portion – Host Portion
• The Block Size To‐Be‐Routed Specified by the Mask
• The Host Portion is the Interface Identifier
128 bits
Network Portion
Provider
0x001
IANA Allocated Global Routing
Prefix
3 bits
45 bits
Host Portion
Site
SLA
(Subnet ID)
16 bits
Interface ID
64 bits
EXAMPLE: Global Unicast Address Format (Aggregatable & Routable)
Address Mask
•
•
Every IPv6 Address is Divided Into Routed Portion & Host Portion
Mask Specifies the Block Size To‐Be‐Routed
128 bits
Network Portion
Provider
0x001
IANA Allocated Global Routing
Prefix
3 bits
45 bits
Host Portion
Site
SLA
(Subnet ID)
16 bits
Interface ID
64 bits
EXAMPLE: Global Unicast Address Format (Aggregatable & Routable)
IPv4 and IPv6
Comparison Summary
IPv4
IPv6
Developed: 1973-1977
Deployed: 1981
232 or 4.3 Billion Addresses
Developed: mid 1990’s
Deployed: 1999
2128 or 340 Undecillion Addresses
“More Than Anyone Could Possibly
Use”
“More Than Anyone Could Possibly
Use”
Address Based Assignment Unit /32
Network Based Assignment Unit /64
Why Slow IPv6 Implementation?
• FUD Principal
• “Does Not Apply to Me” – I Have adequate IP Address Space
• Another IT Industry “Crying Wolf” Event
• Low Priority – No “ROI” Seen
Where is IPv6 Growth?
• Internationally:
‐ Developing Countries
‐ Asian‐Pacific Region
• In US, Those Needing for Large Quantities of IP Address Space:
‐ Broadband Access Providers
‐ Wireless Access Providers
Is the Year of IPv6 Here?
• Major Broadband Providers Now Deploying:
– ‐ Comcast
– ‐ Time Warner Cable
– ‐ AT&T
• Consumer Electronics Association predicts emergence of IPv6 enabled TVs, Blu‐Ray Players, and related consumer devices in 2013
Migration Strategies
This Can Have Different Impact for:
• Broadband Access Providers
• Internet Service Providers
• Content Providers (The Broadcaster)
• Enterprise Customers
• Equipment Vendors
• Government Organizations
Migration
• Call to Action – Content Providers or “Broadcasters”
‐
Provide “Outward” Facing Services in IPv4 and IPv6
Be Reachable By New IPv6 Only Internet Customers
– ‐ Be Reachable Without Translation Solutions
– ‐ Provide the “Best Quality” Experience to Content Consumer
‐
Viewing the Network
“Content
Consumer”
Your Network
“Content Provider”
IPv6 Implementation Techniques
• Tunnel
• Native
– ‐ IPv4 and IPv6 “Dual Stack”
• Translation Based
– ‐ Multiple Layer NAT – CGN
– ‐ NAT64
– ‐ NAT44
Migration Techniques
“Tunnel”
Migration Techniques
“Native or Dual‐Stack”
Hosts Run IPv4 and IPv6 Simultaneously, But Independently
Advantages:
Gradual IPv6 Host Implementation
No Translation Devices – No Added Latency
Migration Techniques
“Translation”
Translation
But, Translation Is Bad for Real-Time Traffic!
Why IPv6?
• Reduction of Dependency Upon IPv4 Address Space for Growth
• Restores the End‐End Communications Path Model of the Global Internet
• Enhances Overall Routing Efficiency
• Improved Security Increases Security and Confidentially
Takeaway Summary
•
•
•
•
•
•
•
•
•
The Industry is Predominantly IPv4 Based Today
IPv4 Demand Continues, But IPv4 Availability Pool Decreasing
IPv6 Adoption is the Solution for Continued Growth
A Growing IPv6 Only Environment Exists
As a Content Provider, Focus on the “Content Consumer” to Guide Your Migration
Focus on Outward Facing Services
Translation is Not the Solution – Especially With Real-Time Media
IPv6 Is Still IP, but IPv6 is NOT Backward Compatible With IPv4
Expect IPv4 and IPv6 To Be Maintained for Many Years to Come
An Ipv6 Address You Can Remember
The IPv6 Loopback Address
::1
Summarized from:
0:0:0:0:0:0:0:1
Equivalent of the IPv4 Loopback Address: 127.0.0.1
Learn More:
IPv6 Enable Your Home Network
But, My Provider is Not IPv6 Enabled!
Then “Tunnel” to an IPv6 Provider:
http://www.tunnelbroker.net/
IPv6 Test Sites
http://ipv6‐test.com/
http://v6.testmyipv6.com/
www.ARIN.net
World IPv6 Day
June 6, 2012
http://isoc.org/wp/worldipv6day/
Vinton Cerf
“One of the Fathers of the Internet”
"Who the hell knew how much address space we needed for an experiment?“
“The experiment has not ended”
“Vint” Cerf comments on his & colleagues 1977 decision to use 32‐bit IP Numbers
Some Final Trivia
What Happened to Version 5 or IPv5 of the Internet Protocol?
“IPv5 Simply Does Not Exist!
Version 5 was intentionally skipped to avoid confusion, or at least to rectify it. The problem with version 5 relates to an experimental TCP/IP protocol called the Internet Stream Protocol, Version 2, originally defined in RFC 1190. This protocol was originally seen by some as being a peer of IP at the Internet Layer in the TCP/IP architecture and these packets were assigned IP version 5 to differentiate them from “normal” IPv4 packets. This protocol never went anywhere, but to be absolutely sure that there would be no confusion, version 5 was skipped over in favor of version 6.”
8. Switching & Routing Fundamentals
Switching Fundamentals
MAC Addresses
VLANS
Routing Fundamentals
Routing Protocols
Routing Metrics
Which Routing Protocols Do I Use?
155
Switching vs Routing
When to Switch? ‐‐ When to Route?
Broadcast Domain
Collision
Domain
Collision
Domain
Router
Collision
Domain
Collision
Domain
Broadcast Domain
156
Switching Fundamentals
•
Legacy Ethernet Used Hubs
– An “Ethernet DA” of sorts – All Bits Go to All Ports
– High Collision Level Due to Shared Media
(40‐50% of Bandwidth Consumed by Collision Recovery)
– High Collision Level Yields High Latency
•
Switches Allow Segmentation of Network
–
–
–
–
•
157
Allows Dedicated Bandwidth and Point‐Point Communications
Increased Throughput Due to Zero or Minimal Collisions
Allows Full‐Duplex Operation
Increased Security Capability
Switches Selectively Forward Individual “Frames” from a Receiving Port to a Destination Port
Switching Fundamentals
•
Switches Allow Segmentation of Network
–
–
–
–
•
Allows Dedicated Bandwidth and Creates Point‐Point Communication
Increased Throughput Due to Zero or Minimal Collisions
Provides Full‐Duplex Operation
Increased Security Capability
Switches Selectively Forward Individual “Frames” from a Receiving Port to a Destination Port
– Builds Internal Table of Destination Address on each Port
– Forwards Ethernet Frame if in Table
– Floods Ports if Broadcast Frame
158
Ethernet Review
IEEE 802.3
159
MAC Addresses
•
•
Layer 2 Media Access Control “MAC” Address
Unique Hardware Encoded Address
– Burned In Address
– Physical Address
– But Cab Be “Spoofed”
•
Hexadecimal Format: 12:3A:4D:66:3A:1C or FF‐FF‐FF‐FF‐FF‐FF
•
Switches “Learn” a Table of MAC Addresses
– MAC Table – Maps Destination MAC Addresses to a Port
160
Ethernet Switch Function
• 5 Basic Functions of an Ethernet Switch:
–
–
–
–
–
Learning MAC Addresses
Aging – How Long is a MAC Address Maintained?
Flooding
Selective Forwarding
Filtering
161
A Simple MAC Table Example
162
How is the MAC Table Populated?
Host A
172.15.2.2
00:12:3F:8D:4D:A7
frame
FF:FF:FF:FF:FF:FF
Destination
MAC
00:12:3F:8D:4D:A7
Source
MAC
172.15.1.1
172.15.2.2
Destination
IP
Source
IP
DATA
Trailer
IP Packet
Ethernet Frame
163
Simplified Ethernet Switch Internals
164
Switching Types
“Forwarding Method”
•
Store – and – Forward
– Receives the Entire Frame Then Makes Decision
– Drops Any Errored Frame Based Upon CRC
– SLOW! (but insures no frame errors)
•
Cut – Through
– Look Only @ Destination Address in Header of the Frame
– FAST! (but no error checking)
•
Fragment Free (modified Cut‐Through)
– Known as “Runt Free” Switching
165
VLANS
IEEE 802.1Q •
Virtual Local Area Network – VLAN
– Logical Network of a Physical Network
•
Allows Separation of Networks Across a Common Physical Media
–
–
–
–
•
Creates Subset of Larger Network
Control Broadcast Domains – Each VLAN is a Broadcast Domain
Architecture Flexibility
Security
Static Port Based VLAN(s)
– Most Popular
– Manual Configuration
•
Dynamic Port Based
– MAC‐Based VLAN(s)
•
Assignment Based Upon MAC Address
– Protocol‐Based VLAN(s)
•
166
Assignment Based Upon Protocol
VLAN Trunking
Public
Internet
Sub-Interfaces:
eth0/1.1 VLAN 1
eth0/1.2 VLAN 2
eth0/1.3 VLAN 3
Router
Switch 2
Switch 1
VLAN VLAN VLAN VLAN
1
2
3
4
Switch 3
VLAN VLAN
2
3
VLAN VLAN VLAN VLAN
1
2
3
4
167
VLAN Example
Switch Port Type Configuration:
Access Link – Member of One VLAN Only Connects to a Host
Trunk Link – Carries Traffic From Multiple VLANS Between Switches
168
Spanning Tree Protocol “STP”
Prevents a “Broadcast Storm”
Switch A
Switch A
Switch C
Switch B
Switch B
Switch C
Switch D
Switch D
STP Operation:
Switch E
Switched Topology Example
1 - Determine Root Bridge
2 - Select Root Port
3 - Select Designated Ports
4 - Block Ports with Loops
Switch E
Active Topology After
Spanning Tree Example
169
Another Look at Spanning Tree
Elected ROOT
Switch 1
E0
E0
1. Root Bridge Elected:
-
First Powered On
Priority Configuration
Lowest MAC Address
Switch 2
E2
E1
Root Port
E1
Designated
E2 Designated
Ports
Port
2. Root Ports Identified
Based Upon Path Cost
3. Designated Ports Identified
Root Port
E0
BLOCKED
E1
Switch 3
Lowest Path Cost to Root
E2
4. Port Blocked
Designated Port with Highest Cost
In The End:
1 Root per Network / 1 Designated Port per Segment / 1 Root Port per Non-Root Switch
170
Port Mirroring
Analyze “Sniff” Data Flow Between Two Hosts
171
Managed vs Un‐Managed Ethernet Switches
• Managed Switch
– User Configurable
– Provides Ability to Control & Monitor Host Communications
– Port Configuration , Security, & Monitoring
– VLAN Implementation
– Redundancy Supported (STP)
– QoS (Prioritization) Implementation
– Port Mirroring
• Un‐Managed Switch
– Fixed Configuration
– “Plug & Play”
– Provides Basic Host Communications
– Cheaper
172
Routing
•
•
•
Routing is Simply the Moving of Data Between Networks OSI Model Layer 3 Process
Routing Involves Two Processes:
– Determining the Best Path
– Actually Sending of the Data
•
Routing Types:
– Static Routing
– Dynamic Routing
•
Routing Protocols:
– Interior Gateway Protocol
• Distance‐Vector
• Link‐State
– Exterior Gateway Protocols (BGP)
173
Routing Fundamentals
•
Routing is Simply Moving Data From One Network to Another Network
174
Static Routing
• Static Routing Can Be Appropriate:
– Small Networks – Stable Network
– When an Isolated Network is Connected to a Single ISP
– When an Isolated Network is Connected to a Hub‐Spoke Network (single exit point)
• Advantages:
– Absolute Control
– Minimal Router CPU Demand
– No Bandwidth Utilized for Router Communications
• Disadvantages:
– Any Infrastructure Changes Must Be Manually Entered
– No Fault Tolerance
– Impossible to Manage in a Large Network Environment
175
Dynamic Routing
Determine the Best Path
• The “Best” Path Between Networks is Determined By Routing Algorithm Metrics Maintained in a Routing Table.
– Administrative Distance (AD) – Trustworthiness of the Routing Information
Route Source:
Administrative Distance (default)
Direct
0
Static
1
EIGRP
90
OSPF
110
RIP
120
Unknown
255
Highest
Reliability
176
Routing Metric Factors
•
•
•
•
•
•
Hop Count
Bandwidth
Load
Delay
Reliability
Cost
The Number of Routers in a Path
Throughput (bps)
Traffic Flowing Through a Router
Network Latency (distance or congestion)
Amount of Downtime of a Network Path
Administrator Assigned
Smaller Metrics = Best Route
177
Routing Type Applications:
• Static Routing
–
–
–
–
Appropriate for Small Networks
Appropriate for Stable Networks
Use in “Stub” Networks
Minimal Hardware / Easy Administration
• Dynamic Routing
–
–
–
–
Appropriate for Changing Topology Environments
Desirable When Multiple Paths Exist
More Scalable
Less Configuration Error Prone
178
Static vs Dynamic Routing
STATIC ROUTING
DYNAMIC ROUTING
Complexity Increases With
Network Size
Network Complexity Independent
Human Intervention Required
Automatically Adapts to Topology
Simple Topology Suited
Complex Topology Suited
Secure
Less Secure
Routing Predictable
Topology
Routing Dependant Upon Current
Less Skill Required
Higher Skill Level Required
Reduced Hardware Requirements
Increased Hardware Requirements
179
Routing Protocols:
• Routing Protocols:
– Interior Gateway Protocols (IGP)
Used With Routers Under the Same Organizational Control
• Distance‐Vector
• Link‐State
– Exterior Gateway Protocol (EGP)
The Routing Protocol of the Internet (between ISP’s)
Interior Gateway Protocol Sample:
RIP v1 & RIP v2
IGRP
EIGRP
OSPF
Exterior Gateway Protocol Sample:
IS-IS
BGP v4 (BGP4)
180
Routing Protocol Choices
Interior Distance Vector
Interior Link State
Exterior Path Vector
Classful
RIP IGRP
Classless
RIP v2 EIGRP
OSPF v2 IS‐IS
BGP v4
IPv6
RIPng
OSPF v3 IS‐IS v6
BGP v4
EIGRP v6
EGP
Our Focus
181
Distance‐Vector Routing Protocols
•
•
“Routing by Rumor” – The Overall Network is Unknown, Only Directly Connected Neighbors Are Known by Each Router
Routing Decision Based Upon a “Distance” or Metric and “Direction” or Vector to Describe the “Next‐Hop”
182
Simplified Distance Vector Routing Example:
Router A
Router C
Network 1
Network
Metric
Network 4
Next Node
Network 1
0
-
Network 2
0
-
Network
Network 2
Metric
Next Node
Network 3
0
-
Network 4
0
-
Metric
Next Node
Network 3
Router B
Network
Metric
Next Node
Network 2
0
-
Network 3
0
-
After Convergence:
Network
Metric
Next Node
Network
Network 1
0
-
Network 3
0
-
Network 2
0
-
Network 2
0
-
Network 4
0
-
Network 3
1
B
Network 3
0
-
Network 2
1
B
Network 4
2
B
Network 1
1
A
Network 1
2
B
Network 4
1
C
Network
Metric
Next Node
183
Link‐State Routing Protocols
•
•
Network Topology Information is Flooded Throughout the Network
Each Router Determines its Own “Best Path”
184
Link – State Algorithms
• More Efficient for Large Networks
• Maintains Topology of the Entire Network
• Only Forwards Updates When Changes Occur
(OSPF “Paranoia” Updates Every 30 Minutes)
•
•
•
•
Classless IP Addressing Supported
Metrics More Complex – Thus More CPU Overhead
Fast Convergence
No Hop Count Limits
185
Routing Protocols:
Which One is Best?
“It Depends”
186
“Practical” Routing Protocol Comparison
“Common” Interior Protocols – VLSM Support
RIP v2
EIGRP (Cisco)
OSPF v2
Type:
Distance Vector
Hybird
Link‐State
Metric:
Hop Count
Bandwidth/Delay
Cost
Administrative Distance:
120
90
110
Hop Count Limit:
15
224
None
Convergence:
Slow
Fast
Fast
Updates:
Full Table Every 30 Seconds
Send Only Changes When Change Occurs
Send Only When Change Occurs, But Refreshed Every 30m
RFC Reference:
RFC 1388
N/A
RFC 2328
187
RIP v2
Routing Information Protocol
RFC 1388 • Advantages:
– Simple – Easy to Configure
– Low Maintenance
– General Understanding Of
• Disadvantages:
–
–
–
–
–
Higher Router CPU Utilization
High Bandwidth Use for Routing Updates
No Knowledge of Link Bandwidth
Slow Convergence
Limited Network Size (hop count = 15)
188
OSPF v2
Open Shortest Path First
RFC 2328
• Advantages:
–
–
–
–
Fast Convergence
Routing Updates Are Small
Scales to Varying Network Sizes
Considers Link Bandwidth Into Metric Calculation
• Disadvantages:
– More Knowledge Required – A lot of Options
– Complex to Configure
189
When to Route – When to Switch?
Broadcast Domain
When to ROUTE?
“Breaks the Broadcast Domain”
Collision
Domain
Collision
Domain
Router
Collision
Domain
Collision
Domain
When to SWITCH?
“Breaks the Collision Domain”
Broadcast Domain
Routing & Switching Summary
191
What Is A “Layer 3” Switch?
•
“Marketing Terminology” Applied to a One Box Solution:
– Layer 2 Switching or Forwarding
• Traditionally Performed in Hardware
– Layer 3 Routing or Forwarding
• Traditionally Performed in Software
•
Layer 3 Switch Performs Both
•
Eliminates Use of VLAN(s) – Each Port Can Be Assigned to a Subnet
•
Not for All Environments
–
–
–
192
Typically Found in Workgroup Environment
Limited to Ethernet
Limited to OSPF and RIP Protocols
Layer 3 “Routing Switch”
• Performs Layer 2 & Layer 3 Functions:
– Layer 2 Forwarding Performed:
• Destination MAC Address is different from the switch MAC Address
– Layer 3 Forwarding Performed:
• Destination MAC Address is the same as the switch MAC Address
• Remember – No WAN Ports (Ethernet Only)
193
Multi‐Layer Switch Summary
• Layer 1 Switch = Really Does Not Exist ‐ Often a Simple “Hub”
• Layer 2 Switch = Traditional Data‐Link Layer Switching
• Layer 3 Switch = Performs Layer 3 Forwarding Decisions
• Layer 4 Switch = Implements Transport‐Layer Flow Decisions
– Firewall
– VPN Concentrator
• Layer 7 Switch = Provides Applications Level Functionality
– Often Based Upon a Uniform Resource Locator (URL):
• Load Balancing
• Content Management
194
9. Q0S Basics
Why is QoS Needed?
QoS Fundamentals
Implementing QoS
195
Quality of Service – “QoS”
•
Why QoS?
– Allows Network Traffic to Be Prioritized Based Upon Application
•
•
•
•
Streaming Media
IP Telephony
Real‐Time Control (automation)
Mission Critical Applications
– Network Factors Impacting Quality:
• Throughput
• Dropped Packets
• Errors
• Latency
• Jitter
• Packet Delivery Out‐of‐Order
196
QoS continued…..
•
Implementing QoS
– VLAN Implementation
– Bandwidth Over Provisioning
– Traffic Shaping
– DiffServ Implementation
• Mark Packets According to Type of Service
• Assigned to Multiple Queues
– Queue Scheduling Algorithms:
• Techniques Raise or Lower Queue Priority
– WFQ ‐ Weighted Fair Queuing
– Class Based Weighted Fair Queuing
– WRR – Weighted Round Robin
– HFSC – Hierarchical Fair Service Curve
197
QoS continued…..
•
QoS Implementation Architecture
– Packet Identification & Marking
– Network Element Provisioning
– End‐End Policy Management
198
Controlling Network Traffic
•
•
•
•
Traffic Shaping (packet shaping) is Generally Achieved by Delaying Packets
Used to Optimize or Guarantee Performance
Control Volume of Traffic Placed on A Network Segment (ingress)
Traffic Classification:
– Sensitive
– Best‐Effort
– Undesired Traffic
– File Sharing (P2P Traffic)
199
Packet Filtering & Shaping
•
Packet Filtering
– A Firewall is Used to Create a “Trusted” Network Segment by Permitting or Denying Network Packets
– Can Be Implemented in Router with Access Control Lists (ACL)
– Ingress Filtering
– Egress Filtering
– Types of Firewalls:
• Packet Filtering:
– Stateless – Filters Solely on Packet Info
– Statefull – Identifies as Packet Stream Component
• NextGen – Provide Application Awareness
•
Packet Shaping
– A Traffic Shaper is Used to Control the Volume of Traffic on a Network Segment
– Generally Achieved by Delaying Packets
– Traffic is Classified – Rules Applied Based Upon Classification
200
10. Controlling Network Traffic & Security
201
The Challenge
SECURITY
USEABILITY
202
Goals of Network Security
• Confidentiality
“Keeping Data Private”
• Integrity
“Insuring Data Has Not Been Modified”
• Availability
“Insuring Data is Available to the Intended User”
203
IT Infrastructure Threats
•
•
•
•
•
Viruses
Worms
Trojan Horse
Spyware & Adware
Botnets “Zombie Computer”
• Operating Systems
• File System / Media
• Application
– Web Services
– Email Services
– P2P
• Wireless / Mobile Environment
• Social Engineering
• And the list goes on & on…..
204
Network Infrastructure Threats
Denial of Service “DoS”
Spoofing
Hijacking
Authentication Bypass or “Back Door” Access
• Physical Access
• And the list goes on & on…..
•
•
•
•
205
Network Security – The First Step
• Control Access to the Network
– Open or Available LAN Switch Ports?
– Can I get an IP Address?
– If I get an IP Address, can I get Network Access?
• First Step:
– Lock down all LAN switch ports
– Require Users & Devices to Authenticate (802.1xX)
206
Switch Port Security
“Port Lockdown”
• An Important Feature of Implementing Switch Infrastructure
• Port Security Aspects:
– One MAC Address Per Port
• Dynamic
• Static
– n MAC Addresses Per Port
– Unused Ports Disabled
– MAC Violation Action
– VLAN Specified Per Port
207
Network Security Concerns
•
•
Focused on Protecting the Network Infrastructure
Common Threats:
–
–
–
–
–
•
DHCP Snooping
ARP Spoofing (IP Spoofing)
Rogue Routers Advertisements
Denial of Service Attacks
Application Layer Attacks
Implementation Considerations:
–
–
–
–
–
–
Know Your Enemy
Cost
Human Factors
Understand Your Network
Limit Scope of Access
Don’t Overlook Physical Security
208
Network Security Tools
• Firewall
– Used to Create a “Trusted” Network Segment by Permitting or Denying Network Packets
– Types of Firewalls:
• Packet Filtering
– Stateless
– Stateful
• Detection Tools
– Intrusion Detection Systems (IDS)
• Signature Based
• Anomaly Based
– Intrusion Prevention Systems (IPS)
• Combine Firewall & IDS Functions
209
Firewalls
• Firewall
– Defines Traffic Types That Can Enter or Exit a Network
– Can Be Software Based
• Access Control List “ACL” Applied to Router or Switch Interface – Ingress or Egress Filtering:
– IP Address Filtering
– Port Number Filtering
– MAC Address Filtering
– May Be Hardware Based “Appliance”
210
Firewall Types:
Packet Filtering - “Stateless”
Packet Filtering - “Stateful”
211
Layered Network Design
• Separate Network in “Layers” or Zones
– External or Public Network
– “DMZ” or Demilitarized Zone or Perimeter Network
– Internal or Private Network(s)
Non‐Secure
Secure
212
Firewall Implementation
213
VPN Implementation
“Virtual Private Network”
214
Don Not Confuse VLAN’s and VPN’s
Essence of a VPN is a Tunnel Through a Network Infrastructure
Virtual Private Network – VPN Protocols
- IPsec with Encryption
- L2TP inside of IPsec
- SSL with Encryption
215
Some Best Practices to Consider
•
•
•
•
•
•
•
•
•
•
•
Recognize Physical Security
Change Default Logins
Utilize Strong Passwords
Disable Services Not Required
Adopt a Layered Design Approach
Segregate Network(s)
Separate Networks via VLANS
Implement Switch Port Security
Utilize Packet Filtering in Routers & Firewalls
Do Not Overlook Egress Traffic
Deny All Traffic – Then Permit Only Required
•
•
•
•
•
•
•
•
•
Keep Up With Equipment “Patches”
Utilize Access Logging on Key Network Devices
Utilize Session Timeout Features
Encrypt Any Critical Data
Restrict Remote Access Source
Understand & Know Your Network Baseline
Actively Monitor and Look for Abnormalities
Limit “Need‐to‐Know”
Disable External “ICMP” Access
216
Can You Balance Your Network Infrastructure?
“DoS”
Spoofing
Hijacking
“Back Door” Access
Viruses
Physical Access
Worms
Trojan Horse Social Engineering
Phishing
Spyware
And more …..
Adware
Botnets
USEABLE
The Goal – “Create a Secure But Useable Network”
217
11. Network Design Practical
Refer to Separate Handout Documents
218
IP
Address
Allocation
219
12. Additional CBNE Topics:
Highlights:
Broadcast Digital Content Management & Workflow
General Server Hardware
Wireless Networking
220
Broadcast Digital Content Management & Workflow
Acquisition
Production
Asset
Management
Record
Log
QC
Ingest
Encoder
Add Metadata
QC
Catalog
Search
Archive
Store
Distribution
Encode
Transcode
Digital Rights Mgmt
Brand
Stream
Transfer
Tutorial:
http://www.sbe.org/sections/IPandFileBasedArchitecture.php
221
Content Management & Workflow
•
Workflow:
The decisions and processes that occur in the broadcast plant when a Media Asset enters the system to the distribution of the Media Asset at the output of the system.
•
Media Asset (SMPTE definition):
Essence
Metadata
Content
Rights
Media Asset
222
General Server Hardware
• Hard Disk Interface Types
– SCSI
– IDE
– SATA
– Fiber Channel (FC)
• RAID Basics
• NAS Fundamentals
• SAN Architecture
www.TomsHardware.com
223
Hard Disk Interface Types
Data Transfer Rate (maximum)
•
•
•
•
SCSI
IDE/ATA
SATA
FC
160 MBps – 320 MBps
100 MBps – 133 Mbps
150 MBps – 300 Mbps
400 MBps
Reference:
http://www.intel.com/technology/serialata/pdf/np2108.pdf
224
RAID Level Basics
Redundant Array of Independent Disks
• Choosing a RAID Level:
– Cost
– Data Availability (protection)
– Performance (read/write)
• Levels:
–
–
–
–
–
RAID 0
RAID 1
RAID 5
RAID 10 (RAID 1 + 0)
And many more……….
225
RAID Level Overview:
RAID Level 0
RAID Level 1
Data Blocks Stripped
No Redundancy
High Performance
Data Blocks Mirrored
High Redundancy
Good Performance
A
B
A
A
C
D
B
B
E
F
C
C
2 disks minimum
Usable Capacity = 100%
2 disks minimum
Usable Capacity = 50%
226
RAID Level Overview:
227
NAS & SAN Architecture
Similar, But Different!
•
Network Attached Storage
NAS – Provides File System & Storage (stand alone)
Shared Storage Over Shared Network
•
Storage Area Network
SAN – Provides Storage Only
Shared Storage Over Dedicated Network
Workstation Clients
Workstation Clients
NAS
Server
File
Server
Application
Server
File
Server
SAN
Archive
Tape
RAID
Subsystem
Tape
Robot
228
Wireless Fidelity Networking
• 802.11 Standards
–
–
–
–
802.11a
802.11b
802.11g
802.11n
5 Ghz
2.4 Ghz
2.4 Ghz
2.4/5 Ghz
54 Mbps (maximum)
11 Mbps
54 Mbps
600 Mbps
• Frequency Bands (ISM):
– 2.4 Ghz – 5 Ghz 2.4‐2.497 Ghz
5.15 – 5.875 Ghz
• Wireless Security
– WEP
– WPA
– WPA2 (802.11i)
Tutorial:
http://www.radio-electronics.com/info/wireless/wi-fi/ieee-802-11-standards-tutorial.php
229
CBNE Recommended Study:
230
My Favorites:
231
“The TCP/IP Bible”
For any detail I might
have over-looked today
or not fully covered, you
will find it in 1537 pages!
☺
232
Web Reference Sources:
•
Subnet Calculation Tools:
– www.subnet-calculator.com
– www.solarwinds.com/products/freetools/free_subnet_calculator.aspx
– iPhone / iPad Ap: (iTunes Store): The MASK
•
RFC Documents:
– www.rfc-editor.org
•
IP Subnetting References:
– http://www.scribd.com/doc/7833118/CCNA-Prep-IP-Subnetting-fromNetworkers
•
IP Address Subnet Block Size Chart:
– https://www.arin.net/knowledge/cidr.pdf
– http://img.docstoccdn.com/thumb/orig/14990233.png
233
Web IPv6 Reference Sources:
•
IPv6 Reference Texts:
– Deploying IPv6 Networks – Ciprian Popoviciu
– Deploying IPv6 In Broadband Access Networks – Adeel Ahmed &
Salman Asadullah
– IP Address Management Principals & Practice – Timothy Rooney
– Migrating to IPv6 – Marc Blanchet
•
IPv6 Reference Websites:
– www.getipv6.info
– www.ipv6forum.com
– www.GoGo6.com
– http://www.6diss.org/e-learning/index.html
Internet Cleaning Day
Yearly Internet Maintenance Announcement
It is URGENT that you do not connect to the Internet from March 31st 23:59 GMT
(11:59 PM) until 00:01 GMT (12:01 AM) April 2nd
It's that time again. As many of you know, each year the Internet must be closed down for a 24-hour period of time in order
to receive maintenance, or a "Tune Up" if you will. Many dead links on the World Wide Web will be removed, as well as
FTP links that are no longer used. Lost e-mail will also be removed from the system at this time.
In addition to the normal maintenance to be completed this year, we will also be using new high-pressure information jets
to clear out the bottlenecks that have plagued the Internet so greatly this past year. Although the down time for
maintenance will be an inconvenience for many people, you will find this will allow for a much more efficient and faster
responding Internet. This year, the "Tune Up" will occur from 23:59 GMT (11:59 PM) on March 31st until 00:01 GMT (12:01
AM) on April 2nd. During that 24 hour period, dozens of powerful Internet bots at key locations around the globe will
simultaneously scan the Internet and complete the desired maintenance jobs wherever they may be required.
To help protect any valuable data you may have on the Internet from possible corruption, we highly recommend you take
the following steps before this 24 hour maintenance period begins:
Disconnect all terminals and LANs from the Internet.
Disconnect all Internet servers from the Internet.
Refrain from connecting any computer, or any other Internet connection device, to the Internet in any way.
Again, we understand the inconvenience this will cause many people. And for that, we apologize. However, the great
increase in Internet performance you will experience after this short period of maintenance will far outweigh any problems it
will cause.
Thank you in advance for your cooperation.
Mr. Yuben T. Ricked
Global Internet Maintenance Organization
235
Upcoming Webinars
TV White Space Devices & Wireless Microphones with Joe Snelson, CPBE, 8‐VSB May 2 ∙ 2‐3 p.m. Eastern AM Directional Antenna Modeling with Cris Alexander, CPBE, AMD, DRB
May 10 ∙ 2‐5 p.m. Eastern SBE RF Safety Course
with Richard Strickland
May 24 ∙ 2:30‐5:45 p.m. Eastern IPv6 for Broadcasters with Wayne Pecena, CPBE, 8‐VSB, AMD, DRB, CBNT
July 11 ∙ 2‐3:30 p.m. Eastern www.sbe.org
With these online, self‐study courses, you pick the date, time and location to learn. Now that’s convenience! The cost for these courses varies from $65 to $99 for SBE Members. Once you register, you immediately receive a link to the course where you can access it again and again as your schedule permits. More Information: www.sbe.org Preparing you for SBE Certification More Information: www.sbe.org Webinars by SBE addresses specific subjects of interest to broadcast engineers. You can view the webinars live, or choose to view the recording on our website. More Information: www.sbe.org The Ennes Workshops, presented by SBE, were created in an effort to bring affordable education to members locally. These one‐day workshops are presented around the United States. Presentations are non‐commercial and focus on technology.
More Information: www.sbe.org ? Questions ?
Thank You for Attending!
Wayne M. Pecena
Texas A&M University
[email protected]
[email protected]
979.845.5662
241

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