3640 w/ 3 T1's to same provider Question

[bmshaw]

I am going to be putting in a 3640 with 3 WIC-1DSU-T1 interfaces. Our provider is going to be installing 3 T1 lines as 1 will not be sufficient. These will be Frame Relay connections all being used strictly for internet access to the provider/ISP. What is the best way to handle routing to these interfaces to ensure proper load distribution across all 3?

[rsissons]

The router will automatically load share over, up to 4 equal cost paths so you either need to run a routing protocol or have 3 default static routes, one for each T1, eg

ip route 0.0.0.0 0.0.0.0 serial 1/0

This will load share on a per session, rather than a per packet, basis so you may not see equal utilisation. It is possible to force load sharing on a per packet basis by turning off fast switching, 'no ip route cache' on the interface, but this is NOT recommended as it will significantly degrade the throughput of the router.

[ROBERT WATSON]

Does your provider not offer ATM IMA solutions? 4.5 meg IMA circuits are more common than 3 t1 frame connections and more cost effective. (it's still 3t's just with atm encap to a virtual ima connection instead of frame. ) Static routes of equal cost and destinations will load share.

Bob Watson

SBC Datacomm Implementation Engineer

CCNP, CCDA