How to aggregate VPN tunnel and frame T1 interface

Answered Question

I appreciate any input for this question, this is the scenario: I have a hub-and-spoke WAN using frame relay fraccional t1's as primary circuits, each branch has the frame relay circuit to headquarters (primary) and there is also a VPN tunnel (DSL circuit) used as back up only, I use EIGRP for the dynamic fail over. We have a need to increase our bandwidth right away, is there a way to aggregate both the frame serial T1 with the VPN tunnel? if so, what is the best way? Thanks in advance.

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Correct Answer by Richard Burts about 8 years 10 months ago

Borman

We could provide better answers if we had a bit more detail about your situation. But based on what we know so far I have a couple of suggestions.

Would I be correct to assume that both the Frame Relay and the VPN are normally both active and that you manipulate the metric in EIGRP so that the Frame Relay is preferred and the VPN has a worse metric and is only used when the Frame Relay goes down? If so, then one alternative would be to manipulate the metric so that both links have equal metric. Then EIGRP will consider both the Frame Relay and the VPN as equally attractive and will load share over both connections.

Or another alternative to consider would be to leave the EIGRP metrics as they are and to maintain the primary/backup relationship as far as the routing protocol is concerned. And then to configure Policy Based Routing so that certain types of traffic were sent over the VPN while most traffic would continue to use the Frame Relay.

HTH

Rick

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Correct Answer
Richard Burts Mon, 02/04/2008 - 08:02

Borman

We could provide better answers if we had a bit more detail about your situation. But based on what we know so far I have a couple of suggestions.

Would I be correct to assume that both the Frame Relay and the VPN are normally both active and that you manipulate the metric in EIGRP so that the Frame Relay is preferred and the VPN has a worse metric and is only used when the Frame Relay goes down? If so, then one alternative would be to manipulate the metric so that both links have equal metric. Then EIGRP will consider both the Frame Relay and the VPN as equally attractive and will load share over both connections.

Or another alternative to consider would be to leave the EIGRP metrics as they are and to maintain the primary/backup relationship as far as the routing protocol is concerned. And then to configure Policy Based Routing so that certain types of traffic were sent over the VPN while most traffic would continue to use the Frame Relay.

HTH

Rick

Richard Burts Mon, 02/04/2008 - 08:51

Borman

While you probably could use variance there is an issue which you need to keep in mind: for variance to work the second path must qualify as a feasible successor. With the metric difference between the Frame Relay and the VPN I wonder if the VPN would qualify as a feasible successor. You might need to manipulate the metric to get them to be feasible successor.

Thank you for using the rating system to indicate that your question was resolved (and thanks for the rating). It makes the forum more useful when people can read a question and can know that they will read responses that resolved the question.

The forum is an excellent place to learn more about Cisco networking. I encourage you to continue your participation in the forum.

HTH

Rick

Richard Burts Mon, 02/04/2008 - 09:01

Borman

If the VPN does qualify as a feasible successor then variance should work ok. If fact if the VPN is a feasible successor then I might think that variance would be better than making the metrics equal.

HTH

Rick

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