Making Network Connections

Making Network Connections
CHAPTER
3
Making Network Connections
This chapter provides cabling guidelines for determining how to build networks using
FastHubs and describes how to connect the FastHub to network devices.
Note Before connecting to any network device, you should have performed the
procedures in the “Installing the FastHub” chapter.
Repeater Types
The IEEE 802.3u standard defines two different classes of 100BaseT repeaters, Class I and
Class II. Networks using Class I repeaters are limited to a single repeater (or stack). Class
II repeaters allow networks to be built with more than one repeater (or stack). In addition,
Class II repeaters allow longer cable distances in single repeater configurations than do
Class I repeaters. The FastHub is a Class II repeater. Moreover, the FastHub exceeds the
specifications for Class II repeaters, allowing the use of longer cable lengths than standard
Class II repeaters.
Caution Many switches have “built-in” repeaters or plug-in repeater modules. In these
devices, the switch is actually attached to a port on the internal repeater. When connecting
to a switch, determine if the port is a repeater port or not, and, if so, what type of repeater
is present. If it is not a repeater port, then the switch is treated as an ordinary end-station. If
the port is a Class I repeater port, do not connect a FastHub or any other repeater to the port.
If it is a Class II repeater port, refer to the “Extended and Multivendor Configurations”
section in this chapter for configuration guidelines.
Making Network Connections 3-1
Simple FastHub Configurations
Simple FastHub Configurations
The IEEE 802.3u standard specifies four simple network configurations using Class II
repeaters. These configurations were designed to satisfy the requirements of most networks
that are built to the EIA/TIA-568 wiring standard. This standard specifies 100-meter
Category 5 UTP connections from wiring closets to desktops. If your network requirements
cannot be met with one of these configurations, or if you are building networks mixing
FastHubs with other Class II repeaters, see the “Extended and Multivendor Configurations”
section in this chapter.
Note Because the FastHub exceeds the specifications for Class II repeaters, the cable
distances specified in the following configurations are greater than those specified in the
IEEE 802.3u standard and apply only to networks configured with FastHubs.
In any configuration, the maximum Category 5 UTP cable length (hereafter referred to as
Cat 5 UTP) is 100 meters. Longer segment lengths are possible only when using multimode
fiber-optic cable (hereafter referred to as fiber cable).
Note In the following configurations, each FastHub can be a single unit or a FastHub
stack.
Configuration 1: Single FastHub, Only Cat 5 UTP Cable Segments
With only Cat 5 UTP cable segments, the maximum length for any cable segment is 100
meters, as shown in Figure 3-1.
3-2 FastHub 300 Series Installation and Configuration Guide
Simple FastHub Configurations
Figure 3-1
Single FastHub with Cat 5 UTP Cable Segments
FastHub
1x
100 meters
maximum
2x
3x
4x
5x
6x
18x
7x
19x
8x
20x
9x
21x
10x
22x
11x
23x
12x
24x
13x
25x
14x
26x
15x
27x
16x
28x
29x
30x
31x
32x
NM3324
17x
16
100 meters
maximum
Category 5 UTP straight-through cable
Configuration 2: Single FastHub, Cat 5 UTP Segments and One Fiber-Cable
Segment
The maximum Cat 5 UTP cable segment length is 100 meters (see Figure 3-2).
The maximum fiber-cable segment length is 218 meters.
If all of the Cat 5 UTP-cable segments connected to the FastHub are less than 100 meters,
the length of the fiber cable segment can be increased. See the “Extended and Multivendor
Configurations” section for more information.
Making Network Connections 3-3
Simple FastHub Configurations
Figure 3-2
Single FastHub with Cat 5 UTP Segments and One Fiber-Cable
Segment
FastHub
1x
2x
3x
4x
5x
6x
18x
7x
19x
8x
20x
9x
21x
10x
22x
11x
23x
12x
24x
13x
25x
14x
26x
15x
100 meters
maximum
segment
27x
28x
16
29x
30x
31x
32x
NM3325
17x
218 meters
maximum
Category 5 UTP straight-through cable
Multimode fiber-optic cable
Configuration 3: Two FastHubs, Only Cat 5 UTP Cable Segments
The maximum Cat 5 UTP cable segment length is 100 meters. When stations are connected
to the FastHubs with 100-meter Cat 5 UTP cable segments, the Cat 5 UTP cable connecting
the two FastHubs is limited to a distance of 23 meters, as illustrated in Figure 3-3.
If all of the Cat 5 UTP cable segments connecting stations to one or both of the FastHubs
are less than 100 meters, the length of the Cat 5 UTP cable segment connecting the two
FastHubs can be increased. See the “Extended and Multivendor Configurations” section for
more information.
3-4 FastHub 300 Series Installation and Configuration Guide
Simple FastHub Configurations
Figure 3-3
Two FastHubs with Cat 5 UTP Cable Segments
1x
2x
3x
4x
5x
6x
18x
7x
19x
8x
20x
9x
21x
10x
22x
11x
23x
12x
24x
13x
25x
14x
26x
15x
27x
16x
FastHub
28x
29x
30x
31x
17x
32x
1x
16
100 meters maximum
segment
23 meters
2x
3x
4x
5x
6x
18x
7x
19x
8x
20x
9x
21x
10x
22x
11x
23x
12x
24x
13x
25x
14x
26x
15x
27x
16x
28x
16
29x
30x
31x
32x
NM3326
FastHub
17x
100 meters
maximum
Category 5 UTP straight-through cable
Configuration 4: Two FastHubs, Cat 5 UTP Cable Segments and One
Fiber-Cable Segment
With 100-meter Cat 5 UTP cable segments connecting the stations to the FastHubs and a
5-meter Cat 5 UTP cable connecting the two FastHubs, the maximum length fiber-cable
segment length is 131 meters, as illustrated in Figure 3-4.
If all of the Cat 5 UTP cable segments connecting stations to the FastHub are less than
100 meters, the length of the fiber-cable segment or the length of the Cat 5 UTP cable
segment connecting the two FastHubs can be increased. See the “Extended and
Multivendor Configurations” section for more information.
Making Network Connections 3-5
Extended and Multivendor Configurations
Figure 3-4
Two FastHubs with Cat 5 UTP Cable Segments and One Fiber-Cable
Segment
FastHub
1x
2x
3x
4x
5x
6x
18x
7x
19x
8x
20x
9x
21x
10x
22x
11x
23x
12x
24x
13x
25x
14x
26x
15x
27x
16x
28x
29x
30x
31x
32x
16
1x
100 meters maximum
segment
2x
3x
4x
5 meters
5x
6x
7x
8x
9x
10x
11x
12x
13x
14x
15x
16
NM3327
17x
FastHub
131 meters
maximum
Category 5 UTP straight-through cable
Multimode fiber-optic cable
Extended and Multivendor Configurations
The previous cabling examples applied to configurations of one or two FastHub stacks with
Cat 5 UTP segments assumed to be at their worst case distance, 100 meters. When the
maximum Cat 5 UTP segment length is less than 100 meters, longer fiber segments, longer
inter-repeater links, or more repeaters can be deployed. On the other hand, when FastHubs
are deployed with standard Class II repeaters (Class II repeaters that meet but do not exceed
the IEEE 802.3u specification), the maximum span is decreased.
A specific calculation of maximum cable length is required in the following cases:
•
•
Deploying more than two repeaters
•
•
Providing extended inter-repeater links by reducing other segment lengths
Providing multiple fiber segments or extending fiber segments by reducing Cat 5 UTP
segment lengths
Connecting FastHub stacks with other repeaters
3-6 FastHub 300 Series Installation and Configuration Guide
Extended and Multivendor Configurations
Allowable repeater configurations are determined by the longest path between any two
stations. This path constraint is determined by cable segment lengths, cable types, number
of repeaters, and repeater types. The arithmetic underlying this determination can be
reduced to a constraint on the sum of the segment lengths between the two furthest stations.
The constraint is expressed in total meters and assumes that all segments are Cat 5 UTP.
Therefore, fiber segments must be converted to their Cat 5 UTP equivalents.
Step 1
Confirm that no Cat 5 UTP segment is greater than 100 meters.
Step 2
Convert every fiber segment to its Cat 5 UTP equivalent by multiplying the
fiber-segment length by 0.9 (these segments can be longer than 100 meters).
Step 3
Confirm that the sum of the Cat 5 UTP-equivalent segment lengths between any
two end-stations (including bridges, switches, or routers) is less than the
maximum value specified in Table 3-1. For multirepeater networks, it is critical
to evaluate not just the paths passing through the most repeaters but also the
stations-to-station paths (if applicable) passing through one, two, or three
repeaters.
Step 4
Divide by 0.9 to get fiber segment length.
Note Cat 5 UTP equivalent cable lengths can be converted back to fiber cable lengths by
multiplying the Cat 5 UTP distance by 1.11.
Table 3-1
Determining Cable Lengths
Number and Type of Repeaters
in the Path
Maximum Total Cable Distance in Path
(Cat 5 UTP Equivalents, in Meters)
1 FastHub
296
1 other Class II repeater
287
2 FastHubs
223
1 FastHub and 1 other Class II repeater
214
3 FastHubs
149
2 FastHubs and 1 other Class II repeater
140
1 FastHub and 2 other Class II repeaters
131
Making Network Connections 3-7
Extended and Multivendor Configurations
Example 1: Achieving Longer Fiber Connections
In this example, a 250-meter fiber segment is required to connect a FastHub to a server
located 250 meters away. What are the maximum permissible Cat 5 UTP station
connections in this configuration (see Figure 3-5)?
Figure 3-5
Achieving Longer Fiber Connections
1x
?
2x
?
3x
4x
5x
6x
7x
8x
9x
?
10x
11x
12x
13x
14x
15x
NM3328
FastHub
16
?
250 meters
Category 5 UTP straight-through cable
Multimode fiber-optic cable
Perform the following steps to determine the maximum permissible Cat 5 UTP cable
segment lengths:
Step 1
Convert the fiber distance to its UTP equivalent by multiplying by 0.9. This gives
us a UTP equivalent of 225 meters (250 x 0.9 = 225 meters).
Step 2
Using Table 3-1, we see that the maximum Cat 5 UTP equivalent distance
between any two stations on a single FastHub is 296 meters. Subtracting 225
meters from 296 meters gives us the maximum Cat 5 UTP cable segment length
of 71 meters.
3-8 FastHub 300 Series Installation and Configuration Guide
Extended and Multivendor Configurations
Example 2: Increasing the Distance Between Two FastHubs
It is possible to increase the distance between two FastHubs by reducing the maximum
cable segments connecting stations to the FastHubs. Using Table 3-1, we see that the
maximum Cat 5 UTP equivalent distance between any two stations separated by two
FastHubs is 223 meters.
In the following example, it is necessary to separate the two repeaters by 120 meters (see
Figure 3-6). First, since this distance is greater than 100 meters, we must use fiber cable.
Convert the fiber distance to its UTP equivalent by multiplying by 0.9. This gives us a UTP
equivalent of 108 meters (120 x 0.9 = 108 meters). Using A + B + C = 223 meters and
substituting 108 meters for segment B, we arrive at A + C ≤ 115 meters.
Increasing the Distance Between Two FastHubs
FastHub 1
17x
1x
2x
3x
4x
5x
6x
18x
7x
19x
8x
20x
9x
21x
10x
22x
11x
23x
12x
24x
13x
25x
14x
26x
15x
27x
FastHub 2
28x
29x
30x
31x
17x
32x
1x
16
2x
3x
4x
5x
6x
18x
7x
19x
8x
20x
9x
21x
10x
22x
11x
23x
12x
24x
13x
25x
14x
B
A
26x
15x
27x
28x
29x
30x
31x
32x
NM3329
Figure 3-6
16
C
A + B + C ≤ 223 meters
Where A is longest segment connected to stations on FastHub 1
Where B is longest segment connected to stations on FastHub 2
Category 5 UTP straight-through cable
Multimode fiber-optic cable
Making Network Connections 3-9
Extended and Multivendor Configurations
Example 3: Adding a Third FastHub Stack
It is possible to add a third FastHub stack in the same collision domain to increase the total
number of connected stations to 380. Using Table 3-1, we see that the maximum Cat 5 UTP
equivalent distance between any two stations connected by three FastHubs is 149 meters.
In the following example, all three hub stacks are in the same wiring closet, separated by
1-meter Cat 5 UTP cable segments. Substituting this information into the formula shown in
Figure 3-7, we see that B + D = 2 meters, A + (2 meters) + E ≤ 149 meters, and therefore
A + E ≤ 147 meters. If A is 60 meters, then E would be 87 meters.
Note that after assigning cable lengths to A and E, we must check to see if the configuration
rules for stations separated by two FastHubs have been violated. That is, A + B + C
≤ 223 meters and C + D + E ≤ 223 meters. For the first configuration, we get: A (60 meters)
+ B (1 meter) + C ≤ 223. In this case, C must be ≤ 162. For the second configuration (C +
D + E ≤ 223) we get: D (1 meter) + E (87 meters) + C ≤ 223. In this case, C must be ≤ 135.
To satisfy both paths (A, B, C and C, D, E), C must be less than or equal to 135 meters. Note
that these are Cat 5 UTP equivalent meters. If fiber cable is used, C must be ≤ 135 x 1.11,
or C ≤ 150.
Adding a Third FastHub Stack
FastHub 1
17x
1x
2x
3x
A
4x
5x
6x
18x
7x
19x
8x
20x
9x
21x
10x
22x
11x
23x
12x
24x
13x
25x
14x
26x
15x
27x
16x
28x
FastHub 2
29x
30x
31x
17x
32x
1x
16
B
2x
3x
4x
5x
6x
18x
7x
19x
8x
20x
9x
21x
10x
22x
11x
23x
12x
24x
13x
25x
14x
26x
15x
27x
16x
FastHub 3
28x
29x
30x
31x
17x
32x
1x
16
C
2x
D
A + B + D + E ≤ 149 meters
Where A is longest UTP equivalent segment on FastHub 1
Where C is longest UTP equivalent segment on FastHub 2
Where E is longest UTP equivalent segment on FastHub 3
Category 5 UTP straight-through cable
3-10 FastHub 300 Series Installation and Configuration Guide
3x
4x
5x
6x
18x
7x
19x
8x
20x
9x
21x
10x
22x
11x
23x
12x
24x
13x
25x
14x
26x
15x
27x
16x
28x
16
E
29x
30x
31x
32x
NM3331
Figure 3-7
Making Port Connections
Example 4: One FastHub and One Other Class II Repeater
It is possible to build networks combining FastHubs with other Class II repeaters from
Cisco or other vendors (see Figure 3-8).
Using Table 3-1, we see that A + B + C ≤ 214 meters. Note that these are Cat 5 UTP
equivalent meters.
Figure 3-8
One FastHub and One Other Class II Repeater
FastHub
1x
2x
3x
4x
5x
6x
18x
7x
19x
8x
20x
9x
21x
10x
22x
11x
23x
12x
24x
13x
25x
14x
26x
15x
27x
16x
28x
29x
30x
31x
32x
NM3330
17x
Other Class II repeater
16
B
A
C
A + B + C ≤ 214 meters
(Category 5 UTP equivalent meters)
Making Port Connections
This section provides procedures to connect devices to the 100BaseTX and 100BaseFX
ports.
Note Always observe the following general rules when connecting devices: Use a
straight-through cable to connect two ports when one of the ports is designated with an X;
use a crossover cable to connect two ports when both ports are designated with an X.
Making Network Connections 3-11
Making Port Connections
100BaseTX Ports
Caution Do not connect to both the uplink port (port 16) and port 16x; this disables both
ports.
The 100BaseTX ports are compatible with the 100BaseTX IEEE-802.3u specification and
can connect to any 100BaseTX device.
All FastHub 100BaseTX ports use RJ-45 type connectors and require Cat 5 UTP cable (see
Figure 3-9). The 100BaseTX ports (excluding the uplink port, port 16) are internally
crossed, enabling the use of straight-through cables when connecting to a server or
workstation. Attached servers or workstations must have a 100BaseTX-compatible adapter
installed. When using the 100BaseTX ports (excluding the uplink port) to connect to
another hub, switch, or router, a crossover cable must be used (unless you are connecting
to the uplink port on another FastHub or 100BaseT hub).
The 100BaseTX uplink port is not internally crossed, enabling the use of standard
straight-through cable when connecting to another FastHub 100BaseTX port or to the
100BaseTX port on another hub, switch, or router. Note that the port on the device you are
connecting to must be an X port.
To prevent potential loopback problems when using STP cable in a Token Ring
network environment, make sure media interface connectors (MICs) and baluns are always
connected when they are part of a link connected to a Fast Ethernet repeater.
Caution
Note The status indicator for the uplink port is the port 16x LED.
See “Connectors and Cabling” in Appendix B for connector pinouts.
3-12 FastHub 300 Series Installation and Configuration Guide
Making Port Connections
Figure 3-9
RPS
ACT
H7234
SYSTEM
100BaseTX Port Connections
COL
STAT UTL ID
1x
2x
3x
4x
5x
6x
7x
8x
9x
10x
11x
12x
13x
14x
15x
16x
16
MODE
100BaseFX Port
Warning Avoid exposure to the laser beam.
The 100BaseFX ports are compatible with the 100BaseFX IEEE-802.3u specification and
can connect to any 100BaseFX device.
The FastHub 316C 100BaseFX port uses an SC type connector and requires 62.5/125- or
50/125-micron multimode, fiber cable (see Figure 3-10). The 100BaseFX port can be used
to connect to compatible ports on switches, routers, or other hubs. Attached servers or
workstations must be equipped with a 100BaseFX adapter.
Note SC-to-ST adaptors are available from third-party vendors.
Making Network Connections 3-13
Making Port Connections
Figure 3-10
RPS
ACT
H7233
SYSTEM
100BaseFX Port Connection
COL
STAT UTL ID
1x
2x
3x
4x
5x
6x
7x
8x
9x
10x
11x
12x
13x
14x
15x
16x
MODE
Avoiding Problems with STP Cable
Note Shielded twisted-pair (STP) cable is most commonly used in Token Ring
environments.
The media interface connectors (MICs) and baluns that are used to make
network connections with STP cabling create a loopback when disconnected;
the loopback might cause anomalies with a Fast Ethernet repeater.
To prevent potential loopback problems on your network, make sure that the
MIC connectors and baluns are never left unconnected when they are part of
a link connected to a Fast Ethernet repeater (see Figure 3-11).
3-14 FastHub 300 Series Installation and Configuration Guide
Verifying Port Connections
Figure 3-11
STP Cable Connections
17x
18x
19x
20x
21x
22x
23x
24x
25x
26x
27x
28x
29x
30x
31x
32x
Incorrect
1x
2x
3x
4x
5x
6x
7x
8x
9x
10x
11x
12x
13x
14x
15x
UTP
MIC/Balun
STP
MIC/Balun
UTP
16
16x
NM3516
Fast Ethernet Repeater
17x
18x
19x
20x
21x
22x
23x
24x
25x
26x
27x
28x
Correct
1x
2x
3x
4x
5x
6x
7x
8x
9x
10x
11x
12x
13x
14x
15x
16x
29x
30x
31x
32x
UTP
MIC/Balun
STP
MIC/Balun
UTP
16
NM3517
Fast Ethernet Repeater
Verifying Port Connections
The port LEDs indicate port status as follows:
•
If there is no link activity, the port LEDs are on (solid green). This shows that the
FastHub and the connected devices are turned on and that the link is operational with no
activity.
•
If there is link activity, the port LEDs are on (flashing green). This shows that the
FastHub and the connected devices are turned on and that the link is operational with
activity.
•
•
If the port LEDs are on and alternating green/amber, a reset is in progress.
•
If the port LEDs are on and rapidly alternating green/amber or are solid amber, see the
“Troubleshooting” chapter to determine the source of the problem.
If the port LEDs are off, the FastHub or connected devices are not powered on, or the
cable is incorrectly wired.
Making Network Connections 3-15
Verifying Port Connections
3-16 FastHub 300 Series Installation and Configuration Guide
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