How to test dial backup

[cbeazley]

I have two 2505 routers that I need to communicate with each other via the async backup interface but when I send a ping to initiate the modem the modem doesn't respond. I just get timed out. I have tested reverse telnet and all is good.

Any ideas how to get my modem responding to the ping request ?

 

[svermill]

It would help if you posted your config. The modem doesn't respond to a ping request. The router does if DDR is properly setup.

 

[cbeazley]

I wish I could post it but the config is too sensitive for me to post. I'll look into the DDR. Thanks for your help.

C

 

[cbeazley]

This is the best I can do for the config. Do you see any problems ? I know this works if my frame relay is connected first and then drops but I don't have a frame relay setup in my lab so I need to force the dial back some how.

interface Async1
ip address xxx.xxx.xxx.xxx 255.255.255.0
ip access-group 2 in
encapsulation ppp
keepalive 10
async default routing
async dynamic address
async mode dedicated
no peer default ip address pool
dialer in-band
dialer idle-timeout 2147483
dialer map ip xxx.xxx.xxx.xxx name LVTS2 modem-script dialup broadcast 2363535
dialer-group 3
ppp callback request
ppp authentication chap

 

[svermill]

At quick glance, that looks correct (assuming the dialer-list is set up correctly for your traffic). Did you set up your line also? e.g. 'modem inout' and such.

 

[svermill]

And for the purpose of your test, did you enter a static route pointing out that interface so that the dialer-group command gets tested in the first place? Data has to show up at the interface somehow. Usually that happens via the backup interface command on the primary interface. Since you don't have a primary interface, you need a way to get traffic there.

 

[cbeazley]

It's all setup except for what svermill suggested. I'll try the static route to see if it works. Thanks for your suggestions.

 

[cbeazley]

Uggg. Ok I created a static route from the hub on the router say 10.1.1.0 to my async 1 interface but still no dialout occurs. Man this is frustrating.

Any other ideas ?

 

[svermill]

I would start with 'debug dialer' and 'sh dialer' to get an idea of where to go next. Since you're in a lab environment, you might get away with running quite a number of debug commands. 'debug icmp' also comes to mind. Perhaps even the dreaded 'debug all' if your feeling bold. I'll keep thinking about it and please keep us posted.

I have to admit I'm confused by your statement about the static route you entered. Where does the hub fit in? What you would need is a route (static or otherwise) that points out of your async interface for traffic that is defined as interesting in your dialer-list statement(s). If 10.1.1.0 were interesting, it would have to be reachable via async 1.

 

[cbeazley]

To start, your help is greatly appreciated.

In further detail: I have a 2505 cisco router which has a built-in 8 port hub which (in production) connects a series of pc's (on say a 10.1.1.0 255.255.255.0 subnet), it then would be attached to a frame relay modem through a serial connection. If the serial (frame-relay) drops the async 1 interface (aka the analog modem) would initiate a call. It is the modem dial back I am trying to simmulate but I know this usually only works (on a 2505) only if a frame is first detected then drops. I do not have this problem on a 2600 router but it is the 2505 I'm after.

Given your previous tip on adding a static route I added a static destination of the ip and subnet on the async interface (I think). I then tried to ping the async interface expecting the modem to dial but nothing happened.

I suspect I am setting the static route wrong so I will continue 'playing'.

Thanks again for your time.

 

[svermill]

Glad to help and I hope it eventually gets you somewhere. What I was suggesting was that you look in your dialer-list. That is where "interesting" traffic is defined. Only traffic meeting the criteria of the dialer-list will cause the async interface to dial out. So you need a static route that says, for example, 'ip route 192.100.100.0 255.0.0.0 async 1' where 192.100.100.0 is defined as an interesting outside destination in your dialer-list. Then ping 192.100.100.1. It doesnt' really matter it it's really reachable - if it is defined as interesting, it should cause dialing.

 

[cbeazley]

Now this is a dumb question but I see that 'dialer-list 3 protocol ip permit' in my config but how do I determine who is in the list ?

 

[svermill]

All IP is in the list. So any IP traffic that the router determines should be sent out Async 1 should cause dialing. So I would just make a static route to any old made up address and try to ping it. If that doesn't work, resort to the debug to see why it is failing.

 

[cbeazley]

This must be an IOS problem because nothing is happening. I see no activity when showing the dialer. I have done reverse telnet and can manually run the modem but as for getting the modem to dial out by itself....

I have added the static route exactly as you have said and even removed any acls that may have been causing problems.

I will keep hacking at it. Wish me luck.

 

[svermill]

By the way, I screwed up the route statement. It should have been something more like 'ip route 192.168.100.0 255.255.255.0 async 1'. Having a static route to the 192.0.0.0 network could be dangerous, depending on whether or not you use the private class C address space somewhere else in your network. I must have been typing too fast or talking to someone while I was typing (it freaks people out and lets them know I'm busy).

I'm leaving for the day soon but will keep your problem in mind. Did you run any of the debug? Is a packet being queued up for async 1 when you issue the ping? If not, try again using a better static route than what I first suggested.

 

[cbeazley]

Actually the static route I created is more like the last one you suggested. I knew what you were after so I just modified my statement to resemble your example.

Thanks for your help.

Tomorrow I will modify my config and post a more complete one to see if you can find any other problems.

 

[svermill]

That would be ideal. By the way, I don't think it matters, but as a matter of cleanup, you may want to remove 'async dynamic address' since you are in dedicated mode and have specified an address with the 'ip address' command.

 

[svermill]

I'll leave you with this link for the day. Look towards the bottom of the Table of Contents for some config examples that may somewhat apply to your situation (writing scripts, ddr and ppp, etc).

http://www.cisco.com/univercd/cc/td/doc/product/software/ios102/accscg/63441.htm

 

[cbeazley]

Hi svermill

Well still no luck.

Here is our config (modified a bit). As you can see it is pretty standard but if you see anything let me know.

Note: Out of frustration i removed the dialer-list and added some unnecessary static routes but nothing seemed to work.

******************************************************
Building configuration...

Current configuration:
!
version 11.1
service timestamps log datetime localtime show-timezone
service udp-small-servers
service tcp-small-servers
!
hostname MYROUTER
!
clock timezone EST -5
enable secret xxxxxxxxxxxx
enable password xxxxxxxxxx
!
username CISCO password xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
no ip domain-lookup
chat-script dialup ABORT ERROR "" "AT Z" OK "ATDT\T" TIMEOUT 30 CONNECT
!
hub ether 0 1
link-test
auto-polarity
!
hub ether 0 2
link-test
auto-polarity
!
hub ether 0 3
link-test
auto-polarity
!
hub ether 0 4
link-test
auto-polarity
!
hub ether 0 5
link-test
auto-polarity
!
hub ether 0 6
link-test
auto-polarity
!
hub ether 0 7
link-test
auto-polarity
!
hub ether 0 8
link-test
auto-polarity
!
interface Ethernet0
ip address 10.123.92.1 255.255.255.0
no ip mroute-cache
no ip route-cache
!
interface Serial0
description interface for Frame Relay
no ip address
ip access-group 1 in
no ip mroute-cache
encapsulation frame-relay
no ip route-cache
bandwidth 64
shutdown
no fair-queue
frame-relay lmi-type ansi
!
interface Serial0.1 point-to-point
backup delay 1 120
backup interface Async1
ip address 10.1.1.38 255.255.255.240
ip access-group 1 in
no ip mroute-cache
no ip route-cache
bandwidth 64
frame-relay interface-whatever broadcast
!
interface Serial1
no ip address
shutdown
no cdp enable
!
interface Async1
ip address 10.123.251.1 255.255.255.0
encapsulation ppp
keepalive 10
async default routing
no peer default ip address pool
dialer in-band
ppp authentication chap
!
router eigrp 100
network 10.0.0.0
!
ip http server
no ip classless
ip route 0.0.0.0 0.0.0.0 Async1
ip route 10.123.92.0 255.255.255.0 Async1
ip route 10.123.251.0 255.255.255.0 Ethernet0
logging buffered
logging trap debugging
banner exec ^CCC
Exec level:
^C
banner login ^CCC
Login via Telnet:
^C
banner motd ^CCC

^C
!
line con 0
exec-timeout 30 0
password xxxxxxxxxxxxxxxxxx
line aux 0
exec-timeout 0 0
modem InOut
monitor
transport input all
stopbits 1
rxspeed 38400
txspeed 38400
line vty 0 4
exec-timeout 30 0
password xxxxxxxxxxxxxxxxxx
login
!
end

 

[svermill]

Your static route statement will definitely put your router in a tail spin. I would remove those ASAP.

I'm curious about your config. Are you dialing through the AUX port? If so, is it really Async 1? I don't have any 2500s at the moment so I can't check for myself. It's usually numbered one higher than the highest tty port (i.e. 5 in your case).