Bonded T1 Config

[beatdown]

Hi all,

Our company has a Cisco 1841 Router, and we currently have a single T1 Internet connection. This is the only WAN link attached to the router, and we have a separate firewall that performs NAT, so the router config is very simple and basic.

We need more bandwidth, so our ISP (Qwest) is setting us up with a second T1 line, which will be "bonded" with the original T1. We won't be getting any additional IP Addresses.

I've purchased another T1 WIC card. I asked the ISP for info on how to configure the router for the Bonded T1's, and they said they can't help me, because they don't manage the router.

Can anyone tell me how to do this?

Thanks very much!

 

[JOAMON]

See if this helps.....
Sample of T1 multilink.

interface Multilink1
description connected to ISP
ip address 10.10.10.1 255.255.255.252
ppp multilink
ppp multilink fragment disable
ppp multilink group 1


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


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

1st ip routeable on ethernet interface which should connect to your firewall device which uses the 2nd ip routeable.

 

[JOAMON]

BTW...the 1841 is an awfully nice router to use as just an edge router. You could have done it with a 2620 and saved a ton of money.

 

[BuckWeet]

You need to figure out how the circuit is provisioned on their end.. They might be just doing load balancing over 2 circuits, this is not true bonding. To do this you would just do 2 equal cost static routes to the ISP..

If they're doing PPP multilink to you, you can use the above config..


BuckWeet

 

[beatdown]

Thanks for your help guys. Qwest says it's true "Bonding" so it looks like the multilink config is what I need. It'll be a week or so before the circuit is ready, so I guess we'll find out for sure then.

Yes, the 1841 is a pretty sweet router, and overkill for what we're doing with it. But rather than buying a second firewall for redundancy, I opted to get a decent router that can be quickly reconfigured to do everything our firewall does, if the firewall ever goes down.

Thanks again!

 

[JOAMON]

There is a problem with that in that you cannot do that if the firewall failed. The serial side of the 1841 is to connect to the ist while the ethernet will be the ip routeable port which must then connect to a second router whose second ethernet port will be your lan. You may want to get ahold of a 2621 with 2 older style T1 cards as a cold spare. That way if either device failed you would have a backup. If the firewall fails move the 1841 into a firewall/lan config and put the 2621 as the edge and if the 1841 fails replace it with the 2621.

 

[jeter]

I would ask if they can setup their router using IP CEF and inserting ip load-sharing per packet on the serial interfaces this would bind. Be sure to add the same statment on your serial interfaces.

“Reserve your right to think, for even to think wrongly is better than not to think at all”

CCNA,CCNP,CIPT, Network+
Tek-TIP Member 19,650

 

[JOAMON]

IP CEF is for load balancing only and does not bond them together. It will only use the least congested route for a max speed of 1.5m. His ISP is bonding them together using multilink as he only has one IP address for both T1 circuits. Multilink will give the full 3m of bandwidth.