Cisco 2620 routers connected via dual T1 lines

[scullen]

scullen (IS/IT--Management) Nov 28, 2005
I am attempting to connect two Cisco 2620 series routers to each other at remote locations. One resides at my office, the other at a colocation. I will be using 2 T1 lines between the devices. Each router has 2 WIC-1DSU-T1 cards.

My problem is, I have 1 line connected but cannot seem to get the other working. The card shows an amber AL light when the data line is connected, but goes green when I plug in a hardware loopback connector. So I'm pretty sure it's not my hardware. I've got loss of frame on each corresponding CSU on each end, but that's to be expected I assume.

I'm pasting my config below (with certain unrelated config items omitted for security reasons). Any help anyone can provide would be greatly appreciated!

2620 #1:
Current configuration : 1286 bytes
!
version 12.1
service timestamps debug uptime
service timestamps log uptime
!
hostname name
!
enable secret
enable password
!
!
!
!
!
ip subnet-zero
no ip finger
ip domain-name
ip name-server
!
!
!
!
interface Loopback0
no ip address
!
interface FastEthernet0/0
description
ip address 172.16.1.1 255.255.255.0
duplex auto
speed auto
!
interface Serial0/0
description
bandwidth 1536
ip address 10.10.10.11 255.255.255.240
encapsulation ppp
no fair-queue
!
interface Serial0/1
description
bandwidth 1536
ip address 10.10.10.13 255.255.255.240
encapsulation ppp
no fair-queue
!
ip nat inside source static 172.16.2.25 xxx.xxx.xxx.xxx
ip classless
ip route 0.0.0.0 0.0.0.0 172.16.1.254
ip route xxx.xxx.xxx.0 255.255.255.224 10.10.10.10
ip route 172.16.2.0 255.255.255.0 10.10.10.10
ip http server
!
!
line con 0
password
login
transport preferred none
transport input none
line aux 0
password
login
modem InOut
transport preferred none
transport input all
transport output pad v120 telnet rlogin udptn
stopbits 1
flowcontrol hardware
line vty 0 4
no login
transport preferred none
!
end


2620 #2:
Current configuration : 1494 bytes
!
version 12.1
service timestamps debug uptime
service timestamps log uptime
!
hostname name
!
enable secret
enable password
!
!
!
!
!
ip subnet-zero
no ip finger
ip domain-name
ip name-server
!
!
!
!
interface FastEthernet0/0
description To Office FastEthernet
ip address xxx.xxx.xxx.xxx 255.255.255.248 secondary
ip address xxx.xxx.xxx.xxx 255.255.255.240 secondary
ip address 172.16.2.1 255.255.255.0
duplex auto
speed auto
!
interface Serial0/0
description
bandwidth 1536
ip address 10.10.10.10 255.255.255.0
encapsulation ppp
no fair-queue
dce-terminal-timing-enable
ppp multilink
!
interface Serial0/1
description
bandwidth 1536
ip address 10.10.10.12 255.255.255.0
encapsulation ppp
no fair-queue
dce-terminal-timing-enable
ppp multilink
!
ip classless
ip route 0.0.0.0 0.0.0.0 172.16.2.254
ip route 172.16.1.0 255.255.255.0 10.10.10.11
ip route xxx.xxx.xxx.xxx 255.255.255.240 xxx.xxx.xxx.xxx
ip route xxx.xxx.xxx.xxx 255.255.255.248 xxx.xxx.xxx.xxx
ip http server
!
!
line con 0
password
login
transport preferred none
transport input none
line aux 0
password
login
modem InOut
transport preferred none
transport input all
transport output pad v120 telnet rlogin udptn
stopbits 1
flowcontrol hardware
line vty 0 4
no login
transport preferred none
!
end

 

[JOAMON]

Here is how I would do this setup:

Router#1

interface Multilink1
description connected to router#2
ip address 10.10.10.1 255.255.255.252
ip nat inside
ppp multilink
ppp multilink fragment disable
ppp multilink group 1

interface Serial0/0
description multilink 1 interface
no ip address
encapsulation ppp
tx-ring-limit 26
tx-queue-limit 26
no keepalive
no fair-queue
service-module t1 clock source internal
ppp multilink
ppp multilink group 1

interface Serial0/1
description multilink 1 interface
no ip address
encapsulation ppp
tx-ring-limit 26
tx-queue-limit 26
no keepalive
no fair-queue
service-module t1 clock source internal
ppp multilink
ppp multilink group 1


Router#2

interface Multilink1
description connected to router#1
ip address 10.10.10.2 255.255.255.252
ip nat inside
ppp multilink
ppp multilink fragment disable
ppp multilink group 1

interface Serial0/0
description multilink 1 interface
no ip address
encapsulation ppp
tx-ring-limit 26
tx-queue-limit 26
no keepalive
no fair-queue
ppp multilink
ppp multilink group 1

interface Serial0/1
description multilink 1 interface
no ip address
encapsulation ppp
tx-ring-limit 26
tx-queue-limit 26
no keepalive
no fair-queue
ppp multilink
ppp multilink group 1


Adjust your IP routes as needed

 

[JOAMON]

Also from global config issue IP CEF and enable it as well.

 

[doohder]

When we had someone come put our T1 lines in they actually physcially wired them wrong. So what I did to make sure it wasn't a hardware problem I made a T1 crossover cable and made sure it worked from there and narrowed it down to being the Qwest fault for wiring it wrong to the Dmark. What happened for me was the AL light would be on then when you plugged it in would show its connected and AL stayed on. Made the crossover cable plugged it in and the AL light would go away. Could ping accross telnet in and everything. So you are also going to be doing load balanced static route? or for back up route?

 

[doohder]

Also another thing is looks like you are going to use PPP. I am using the 2800 series router for a similar setup. I would use HDLC which is setup by default. I believe the same is for 2600 series.

 

[jneiberger]

doohder, I believe scullen is using PPP so that he can take advantage of PPP Multilink to bond the two T1s together. The primary issue that scullen is having--and that JOAMAN corrected--is one of timing. If these are point-to-point T1s, one end needs to provide clocking and the other end needs to derive its clock from the line.

 

[scullen]

Thanks everyone!
jneiberger, you're right. I'm trying to bond the T1s together and double my pipe.
JOAMAN, thanks a ton for the config suggestion. I will save it and perhaps give it a try. My problem right now is I have a working T1 line that I can't interrupt. I have a tech at my colo getting a Cisco guru on site to help with this. I will bring along this config. I just can't have both lines down. One is better than none.

 

[JOAMON]

I am using this config and it works great. Don't forget to enable IP CEF. You can do this without losing connection. When you get the connection problem solved with the second T1 build the multilink interface and put that interface into it. Add a new IP route as secondary route should the primary route go down. Use an extended ping and test connection accross the new path and if looks good then shutdown the other interface and traffic should just switch over to the only available path. Re-configure those interfaces as part of the multilink and bring them back online and remove the old ip route(s). Show interface multilink1 should show you your new connection speed.