Back to Back 2514s over Async Ports and USR Sportster Modems

[jfisher]

I have a couple of 2514 (ios 11.2(18)) routers connected via their asyn ports and a us robotics sportster modems. They are dialing in to each other fine and from inside the router I can ping the other router over this link. The problem is from the ethernet side of router a I can not ping the ethernet side of router b.........unless there is traffic inbound from router b to router a! I can try to telnet to my unix box on the ethernet network of router b and nothing happens.....untill I ping from inside router b to a host on router a's ethernet network. After doing that everything is working "honky-dory". The network works great when running an extended ping but as soon as that ping stops all connections over the async port between the ehternet LANs comes to a "screeching" halt! If anyone would like to give me a hand on this I would surely appreciate it as I am fresh out of ideas! I can forward router configurations to anyone who has the time and inclination to take a look at this problem. Thanks in advance.

Justin

[svermill]

Justin,

I have some recent experience with DDR and aysnc connections (and some problems that went along with it). I'll try to help but I recommend that you post the config here so other folks can pitch in too.

Scott

[jfisher]

Here are the configuration files from the two routers. They were generated by cisco configmaker 2.5 and were modified (slightly) by me to use static routes vice using rip as configmaker had set up. On a side note...what is the deal with a dialer interface and a async interface? Is it one or the other or are they both needed to get things working? Anyhow here are the configurations.

Router 1

ILO

*************************************************

!

version 11.2

service timestamps debug uptime

service timestamps log uptime

service password-encryption

no service udp-small-servers

no service tcp-small-servers

!

hostname ILO

!

enable password 7 XXXXX

!

username Albany password 7 XXXXX

ip subnet-zero

no ip domain-lookup

chat-script default ABORT ERROR ABORT BUSY ABORT "NO ANSWER" "" "ATDT\T" TIMEOUT 60 CONNECT \c

!

interface Ethernet0

description connected to EthernetLAN

ip address 209.22.149.1 255.255.255.0

!

interface Ethernet1

no ip address

shutdown

!

interface Serial0

no ip address

shutdown

!

interface Serial1

no ip address

shutdown

!

interface Async1

description connected to Albany

no ip address

encapsulation ppp

async mode dedicated

dialer in-band

dialer rotary-group 1

no cdp enable

!

interface Dialer1

description connected to Albany

ip address 192.168.1.1 255.255.255.252

encapsulation ppp

dialer in-band

dialer map ip 192.168.1.2 name Albany modem-script default broadcast 9,8361275

dialer hold-queue 10

dialer-group 1

no cdp enable

ppp authentication chap

pulse-time 3

!

ip classless

ip route 138.139.16.0 255.255.255.0 192.168.1.2

snmp-server community public RO

dialer-list 1 protocol ip permit

!

line con 0

exec-timeout 0 0

password 7 XXXXX

login

line aux 0

autoselect ppp

modem InOut

modem autoconfigure type usr_sportster

transport input all

stopbits 1

rxspeed 38400

txspeed 38400

flowcontrol hardware

line vty 0 4

password 7 XXXXX

login

!

end

Router 2

Albany

**************************************************

!

version 11.2

service timestamps debug uptime

service timestamps log uptime

service password-encryption

no service udp-small-servers

no service tcp-small-servers

!

hostname Albany

!

enable password 7 xxxx

!

username ILO password 7 xxxx

ip subnet-zero

no ip domain-lookup

chat-script default ABORT ERROR ABORT BUSY ABORT "NO ANSWER" "" "ATDT\T" TIMEOUT 60 CONNECT \c

!

interface Ethernet0

description connected to EthernetLAN_1

ip address 138.139.16.2 255.255.255.0

!

interface Ethernet1

no ip address

shutdown

!

interface Serial0

no ip address

shutdown

!

interface Serial1

no ip address

shutdown

!

interface Async1

description connected to ILO

no ip address

encapsulation ppp

no ip route-cache

no ip mroute-cache

async mode dedicated

dialer in-band

dialer rotary-group 1

no cdp enable

!

interface Dialer1

description connected to ILO

ip address 192.168.1.2 255.255.255.252

encapsulation ppp

dialer in-band

dialer map ip 192.168.1.1 name ILO modem-script default broadcast 9,8361441

dialer hold-queue 10

dialer-group 1

no cdp enable

ppp authentication chap

pulse-time 3

!

ip classless

ip route 209.22.149.0 255.255.255.0 192.168.1.1

logging buffered 128000 debugging

no logging console

no logging monitor

snmp-server community public RO

dialer-list 1 protocol ip permit

!

line con 0

exec-timeout 0 0

password 7 xxxx

login

line aux 0

autoselect ppp

modem InOut

modem autoconfigure type usr_sportster

transport input all

stopbits 1

rxspeed 38400

txspeed 38400

flowcontrol hardware

line vty 0 4

password 7 xxxx

login

!

end

Thanks again,

Justin

[svermill]

-

[svermill]

The async interface matches to your aux port when used for routing apparently. The dialer interface serves as the logical entity just like on any other type of interface. So I guess you have to have both in this type of setup.

I have never routed via the aux port though so I may not be of much help to you until I can get a chance to do some experimenting in my lab. I would make one wild suggestion though. Replace your static routes with default routes and see what happens. I saw a loosely related example config that involved setting up the static routes out of the dialer interface instead of a physical interface or distant end IP address (as in your case). You may want to try that as well. But like I said, that is more guessing than reasoning.

I’ll see what I can set up later.

Also, is it your intention that this connection be up 24 x 7? Just curious. I didn't see any idle timers set.

Scott

[jfisher]

Yes I am going to leave the interface up all the time. It is a local call and there is no need for them to have the extra line while working on this project. Thanks again for your help, I vaguely remember using default routes but you know how your brain gets after troubleshooting for a couple of hours. ;-) Anyhow this is the wierdest problem I have ever come across. A link that only works when traffic is being generated from one side of the link to the other. One for the record books I guess! I am used to "worky no-worky" problems.....which this is definitely not. Thanks for your time.

Regards,

Justin

[svermill]

I found a better example config than the one I had bookmarked some time ago. Here is the link:

http://www.cisco.com/warp/customer/779/smbiz/service/configs/async/async_ip_static_aux.htm

Maybe you have already seen it. Notice the strange way that the static routes are set up. For your address scheme, it would look like this:

ip route 138.139.16.2 255.255.255.255 Dialer1

ip route 138.139.16.0 255.255.255.0 138.139.16.2

A static to the actual IP of the distant end ethernet interface via the dialer and then a static to the network via the first static to the ethernet.

I’m sure that makes sense somehow.