Diamond Multimedia HD 4770 PCIE Network Card User Manual

Application Note 34
Configuring ADSL to backup to PSTN/ISDN with
automatic testing and recovery back to ADSL.
UK Support
29 December 2009
1
Contents
1
2
3
Introduction ............................................................................................................................................... 2
1.1
Outline ............................................................................................................................................... 2
1.2
Assumptions ...................................................................................................................................... 2
1.3
Corrections ........................................................................................................................................ 3
1.4
Version ............................................................................................................................................... 3
Configuration ............................................................................................................................................. 4
2.1
Configure PPP 1 (ADSL) ...................................................................................................................... 4
2.2
Configure PPP 4 (PSTN)...................................................................................................................... 6
2.3
Configure the Default Routes ............................................................................................................ 8
2.4
Configure the Firewall ....................................................................................................................... 9
2.5
Save configuration ........................................................................................................................... 10
Testing ..................................................................................................................................................... 11
3.1
4
Simulate a failure ............................................................................................................................. 11
Configuration Files ................................................................................................................................... 11
4.1
Digi Transport Configuration Files ................................................................................................... 11
4.2
Digi Transport Firmware Versions ................................................................................................... 12
1 INTRODUCTION
1.1 Outline
The document describes how to configure a Digi Transport router to fail over to PSTN when there is a
problem with the main ADSL connection. Once the ADSL connection is working again the router will test it
by sending pings and then revert back to ADSL and drop the PSTN connection.
This application note uses PPP 4 (PSTN) as the failover interface, however, if the router being configured
has ISDN, simply configure PPP 2 (ISDN) instead of PPP 4. The same configuration can be applied to the
ISDN interface.
For failover from ADSL to a cellular network, please see Application Note 34a as the configuration is slightly
different.
1.2 Assumptions
This guide has been written for use by technically competent personnel with a good understanding of the
communications technologies used in the product, and of the requirements for their specific application.
Configuration: This application note assumes that the router will be connecting to a cellular network.
This application note applies to;
Models shown: Digi Transport DR64 router with ADSL & PSTN running firmware version 5081.
Other Compatible Models: All Digi Transport products.
Firmware versions: 4905 or later.
2
Configuration: This Application Note assumes that the Digi Transport router is already configured with a
working ADSL connection through PPP 1.
1.3 Corrections
Requests for corrections or amendments to this application note are welcome and should be addressed to:
uksupport@digi.com
Requests for new application notes can be sent to the same address.
1.4 Version
Version Number
Status
1.0
Published
1.1
Re-branded to Digi Transport
3
2 CONFIGURATION
2.1 Configure PPP 1 (ADSL)
This PPP interface should already be configured for use with the ISP. You should confirm that you have a
working ADSL connection before proceeding with this configuration.
The PPP 1 interface needs to be configured to be “always on”.
The inactivity timer should be set to 0.
Configuration - Interfaces > PPP > PPP 0 - 4 > PPP 1 > Standard
Parameter
Setting
Description
Always on mode
ON
Configures interface as always on
Inactivity timeout (s):
0
Interface is always connected and active
Click OK
PPP 1 should be configured to generate ICMP requests that the firewall can monitor and use to detect when
the ADSL connection has a problem.
It is also necessary to configure a settling time on the interface. The settling time is a parameter that
prevents the Digi Transport from using the interface until it has been up for the specified number of seconds.
This delay is required so that any ICMP echo requests (used for testing the interface) are not sent so soon
after the interface has come up that the ISP drops the reply packet. (ISP routing tables are often not updated
within the first few seconds of an interface coming up. Sending packets immediately often causes the reply
to these packets to be dropped.)
Configuration - Interfaces > PPP > PPP 0 - 4 > PPP 1 > Advanced
Parameter
Setting
Description
Ping request interval
Only send PINGs when
interface is in service
10
Send ICMP requests every x seconds
YES
Do not send ICMP requests if using cellular
PING IP address
1.2.3.4
Settling time (*100ms)
100
A public IP address that you can ping to
check connectivity via ADSL
Do not send 1st ping until 10 seconds after
interface has come up
4
Click OK
5
2.2 Configure PPP 4 (PSTN)
It will be necessary to configure PPP 4 as an outbound interface as the default is for the interface to accept
incoming calls. Then ISP configuration will be added.
Navigate to the following location:
Configuration - Interfaces > PPP > PPP 0 - 4 > PPP 4 > Standard
Scroll to the bottom of the page and click “Load dialling defaults”.
The PPP 4 configuration needs to be configured to be “always on” and have a power up delay of 60 seconds
to allow the ADSL connection to come up and be the primary connection. The interface will also be
configured for use with an ISP, enter the details as shown in the tables below.
Parameter
Setting
Description
Dial-out number
0845 1400101
Replace with the number for your ISP
Use GPRS/PSTN/external modem
PSTN
Use internal PSTN modem
**Use W-WAN/external modem
No
Use internal ISDN modem
Username
User
Replace with your dial up username
Password
Pass
Replace with your dial up password
Always on mode
ON
Power up AODI delay (s)
60
Inactivity timeout (s)
0
Local IP address
0.0.0.0
Interface should always be active
Timer to allow main ADSL connection to
come up before this one is activated
Keep interface in service even if no data
passes through interface
Your ISP will normally assign an IP
address automatically
** Only applies if configuring ISDN, not PSTN
6
Click OK
Configuration - Interfaces > PPP > PPP 0 - 4 > PPP 4 > Advanced
The PSTN interface needs to be configured so that if PPP 1 (ADSL) is up and in service (i.e. passing data)
then this interface is not allowed to initiate a connection.
Parameter
Inhibit auto-activation when these
PPPs are active
Inhibit mode
Setting
1
Inhibit if other PPP is
active and not OOS
Description
Inhibit auto-activation of PPP 4 when PPP
1 is active
Only inhibit if PPP 1 is passing data
7
Click OK
2.3 Configure the Default Routes
It is necessary to configure two default routes, one for PPP 1 and one for PPP 4. The PPP 1 default route
needs to be set so PPP 4 is deactivated when PPP 1 returns to service after a successful recovery.
Configuration - Routing > Default Route 0
Parameter
Setting
Interface
PPP
Interface #
1
Deactivate interface
PPP
Deactivate interface #
4
Description
Default route 0 is via PPP 1
PPP 4 will be deactivated when this route
comes back into service after an outage
Click OK
The configuration of default route 1 should be configured as shown.
Configuration - Routing > Default Route 1
Parameter
Setting
Interface
PPP
Interface #
4
Deactivate interface
None
Deactivate interface #
0
Description
Default route 1 is via PPP 4
This will allow for recovery to ADSL
8
Click OK
2.4 Configure the Firewall
The firewall should be configured to monitor the ICMP requests generated by PPP 1. If the firewall detects
that 3 consecutive ICMP echo requests have failed, it will take PPP 1 out of service and deactivated thus
allowing PPP 4 to come up. The IP address in the firewall rule must be the IP address that PPP 1 is sending
pings to.
The recovery code will then test the ADSL connection before bringing it back into service. When the recovery
is successful and PPP 1 comes back into service, PPP 4 will be deactivated.
Configuration – Security > Firewall
Insert the following 2 rules:
Rule 1
pass out break end on ppp 1 proto icmp from any to 1.2.3.4 icmp-type echo
inspect-state oos 10 t=3 c=3 d=3 r=ping,10,5 rd=1 dt=1
Rule 2
Pass break end
Save the firewall rules by clicking the “Save (fw -> fw.txt)” button.
Rule 1 explained:
pass out break end on PPP 1 – allow traffic outbound from PPP 1
proto icmp from any to 1.2.3.4 icmp-type echo – allow pings out to 1.2.3.4
9
inspect-state – monitor the pings for echo replies and allow them back in
oos 10 t=3 c=3 d=3 – if 3 consecutive pings fail, deactivate PPP 1 and start recovery procedures after
10 seconds. This 10 second timer could be increased (by editing the firewall rule) to prevent the Digi
Transport from switching rapdily between PPP 1 and PPP 4 in the case where PPP 1 works intermitantly.
This “oos 10” can be thought of as a de-bounce timer in the context of this application note.
r=ping,10,5 rd=1 dt=1 – during recovery, test the link every 10 seconds with a ping, allow 5
seconds for the response to each ping, if the recovery fails deactivate the interface and deactivate the link
before trying again
Rule 2 then allows all other traffic through.
For a more detailed explanation of the above firewall keywords refer to the Sar/OS reference manual
“ftp://ftp1.digi.com/support/documentation/Digi Transport and Sarian User Guide.pdf”
Finally turn the firewall on for PPP 1 to activate the ICMP monitoring and recovery.
Configuration - Interfaces > PPP > PPP 0 - 4 > PPP 1 > Standard
Parameter
Setting
Description
Firewall
ON
Switches the firewall on for this interface
Click OK
2.5 Save configuration
Save your configuration as the power up configuration.
Administration - Save configuration
Click OK
Reboot the Digi Transport router (or deactivate PPP 1) so the PPP changes take effect.
10
3 TESTING
3.1 Simulate a failure
To test the fail over and recovery you will need to configure the PPP interface to ping a IP address that you
can easily stop responding to ICMP requests (either through the use of a firewall or by physically
disconnecting it from the network). You will also need to alter the firewall rule so it monitors the same IP
address that PPP 1 is pinging.
Once you have the IP address configured and the Digi Transport router is up on the main WAN link, remove
your test device from the network or adjust the firewall so it stops responding to the ICMP requests from the
Digi Transport router.
After approximately 30 seconds the router should bring up PPP 4 (the dial-up connection). To confirm that
PPP 4 is up and being used you can:
• check the entries in Diagnostics - Event Log
• click on Diagnostics - Status > PPP > PPP 0 - 4 > PPP 4 > View and check the link is up and has a
valid IP address
• click on Configuration - Routing > Default Route 0 then scroll to the bottom and click on the button
‘Show IPv4 Routing Table’ to view the routing table which should show PPP 4 with a status of UP
and PPP 1 with a status of OOS.
• Also for dial-up, the routers OH and CD LED’s should be lit.
Once you have confirmed that the router has failed over correctly, re-enable the ICMP response or reconnect the test device to the network. You should notice that after approximately 20 seconds, the router
drops the dial-up connection as the main PPP 1 link becomes available again.
This will again be shown in the event log, the routing table, the PPP 4 status should show Link Inactive, and
the OH & CD LED’s should go out.
4 CONFIGURATION FILES
4.1 Digi Transport Configuration Files
This is the relevant parts of the configuration file:
eth 0 IPaddr "10.1.51.2"
eth 0 mask "255.255.0.0"
def_route
def_route
def_route
def_route
def_route
def_route
def_route
def_route
ppp
ppp
ppp
ppp
ppp
ppp
ppp
ppp
ppp
ppp
ppp
ppp
ppp
ppp
ppp
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
0
0
0
1
1
2
4
ll_ent "PPP"
ll_add 1
deact_ent "PPP"
deact_add 4
ll_ent "PPP"
ll_add 4
ll_add 3
ll_add 4
IPaddr "0.0.0.0"
username "user@isp.com"
epassword "encrypted"
timeout 0
aodion 1
autoassert 1
do_nat 2
firewall ON
pingip "1.2.3.4"
pingint 10
pingis ON
l1iface "AAL"
ipanon ON
pppanon ON
settledly 100
ppp 4 IPaddr "0.0.0.0"
11
ppp
ppp
ppp
ppp
ppp
ppp
ppp
ppp
ppp
ppp
ppp
4
4
4
4
4
4
4
4
4
4
4
username "user@isp.com"
epassword "encrypted"
phonenum " 0845 1400101"
use_modem 3
aodion 1
pwr_dly 60
autoassert 1
ipsec 1
l1iface "Default"
inhibitno "1"
inhmode 1
ana
ana
ana
ana
ana
ana
0
0
0
0
0
0
anon ON
l1on ON
xoton OFF
lapdon 0
lapbon 0
logsize 45
4.2 Digi Transport Firmware Versions
This is the firmware \ hardware information:
Digi TransPort DR6410-HIA DSL2/2+ Router Ser#:60000
Software Build Ver5081. Nov 17 2009 17:49:53 8W
ARM Bios Ver 5.76 v31 197MHz B128-M128-F300-O1841d1,0 MAC:00042d000000
Async Driver
Revision: 1.19 Int clk
Ethernet Hub Driver
Revision: 1.11
ISDN ST 21150 Driver
Revision: 1.7
Firewall
Revision: 1.0
EventEdit
Revision: 1.0
Timer Module
Revision: 1.1
AAL
Revision: 1.0
ADSL
Revision: 1.0
(B)USBHOST
Revision: 1.0
SNA o IP
Revision: 1.02
L2TP
Revision: 1.10
PPTP
Revision: 1.00
TACPLUS
Revision: 1.00
MySQL
Revision: 0.01
LAPB
Revision: 1.12
LAPD
Revision: 1.16
TEI Management
Revision: 1.6
BRI Call Control Layer
Revision: 1.11
X25 Layer
Revision: 1.19
MACRO
Revision: 1.0
PAD
Revision: 1.4
X25 Switch
Revision: 1.7
V120
Revision: 1.16
TPAD Interface
Revision: 1.12
SCRIBATSK
Revision: 1.0
BASTSK
Revision: 1.0
ARM Sync Driver
Revision: 1.18
TCP (HASH mode)
Revision: 1.14
TCP Utils
Revision: 1.13
PPP
Revision: 1.19
WEB
Revision: 1.5
SMTP
Revision: 1.1
FTP Client
Revision: 1.5
FTP
Revision: 1.4
IKE
Revision: 1.0
12
PollANS
PPPOE
BRIDGE
MODEM CC (Option 3G)
FLASH Write
Command Interpreter
SSLCLI
OSPF
BGP
QOS
RADIUS Client
SSH Server
SCP
CERT
LowPrio
Tunnel
TEMPLOG
OK
Revision:
Revision:
Revision:
Revision:
Revision:
Revision:
Revision:
Revision:
Revision:
Revision:
Revision:
Revision:
Revision:
Revision:
Revision:
Revision:
Revision:
1.2
1.0
1.1
1.4
1.2
1.38
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.2
1.0
13