Multiple T1 lines in one cisco router

[kjanakiraman]

We have four T1 Lines terminated at four serial interface on one cisco router from a single service provider. We have a /24 ethernet subnet. i have 4 default ip route pointing towards the ISP with equal cost. How can i make sure that the traffic is equally distributed among the four T1 lines?

Thanks in Advance

[amit-singh]

Hi,

I am not sure how the load-balancing will occur using the default routes. I would say in that case it would be per-destination base which is default on cisco interfaces, i.e the traffic for a particular destination the traffic will take only one link. For load balancing over the parallel links from the same ISP You can use the following options :

1. You can use any routing protocol like EIGRP or OSPF for load-balancing depending on per-destination or per-packet based.

2. You can use Multilink PPP to do the load-balancing and have one default route ponining towards the ISP.

3. You can use the CEF to do the load-balancing depending upon per-destination or per-packet.

I would suggest you to use the CEF do to the load-balncing on per-packet basis. Caution should be taken If you are using these links for VOIP as the packets may arrive out of order.

Please use the following link:

http://www.cisco.com/en/US/products/hw/modules/ps2033/products_white_paper09186a0080091d4b.shtml

HTH,

-amit singh

[sdoremus33]

Right on Amit, if U R using an app like VOIP or anything that is TCP gauranteed or driven, From the examples CEF would be your choice because it works on a per destination basis which gaurantees all packets trhat are traversed are sequential