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New Member

T1 load balancing and redundancy

I'm using Csic1721 with 2 WIC-1T connecting to 2 different service provider.I would like to configure load balance and redundancy?Any particular setting or any website to refer such as bgp setting

6 REPLIES
Gold

Re: T1 load balancing and redundancy

IF you're just using static default routes out to the two service providers, the router should load share between the two links.

If you want to route optimally, the best bet, if the router can accept the routes, is to accept a partial feed from each service provider. To do this, just ask the service providers for only those routes which originate in their AS', and then use a static default beyond these routes. You can also accept full routes, and filter out the ones that have an as path of longer than 1 hop, which would filter out those which don't originate in your upstream service provider's network.

ip as-path access-list 1 permit ^[1-9]*$

router bgp xxx

neighbor remote-as

neighbor filter-lilst 1 in

neighbor remote-as

neighbor filter-list 1 in

Note that you'll either need to arrange with both sp's to use a private as number (the same one with both sp's), or you'll need to get a public as number, to do this.

Russ

New Member

Re: T1 load balancing and redundancy

for simple first method,what i need to do is

Ip route 0.0.0.0 0.0.0.0 serial0

ip route 0.0.0.0 0.0.0.0 serial1

correct me again if i'm wrong

thks

Re: T1 load balancing and redundancy

If you want only failover , configure the second route with a higher admin distance, so that that link will be used only when primary link goes down.

Ip route 0.0.0.0 0.0.0.0 serial0

ip route 0.0.0.0 0.0.0.0 serial1 2

here 2 is the admin distance.

Now you want load balancing, you are right in your configs.

Ip route 0.0.0.0 0.0.0.0 serial0

ip route 0.0.0.0 0.0.0.0 serial1

The path taken by packet again depends on what type of switching has been configured on the interface. default is fast switching. so the load balancing would be per-destination.

Gold

Re: T1 load balancing and redundancy

Default should be CEF in almost all newer code, so it should be per source/destination pair.

Russ

New Member

Re: T1 load balancing and redundancy

BTW can serial connection load balance with ISDN connection.

I knew that it can do redundancy?

Gold

Re: T1 load balancing and redundancy

Yes, if you are using static routes, it should be fine. The config you posted earlier should be fine, if you just want 50% of the traffic (more or less) on each link. You probably won't get much more than 60%/40% split, and you need to be careful about the differential in the speeds you are running. It seems like you're talking about a T1 on one side, and an ISDN link on the other, which can cause major problems if you try to shove a malf a T1 down an ISDN link. Consider monitoring the amount of traffic you're sending, and making certain your performance isn't going to be worse load sharing over the second link, if there's really that much difference int eh bandwidths.

Also, for future reference--please note--_never_ use a static route to an interface is the interface is not a point-to-point. This is good:

ip route 0.0.0.0 0.0.0.0 serial0

This is bad:

ip route 0.0.0.0 0.0.0.0 ehternet0

Static routes for large swaths of address space pointing to a broadcast network can cause your router major grief.

Russ

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