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New Member

EIGRP variance load balancing between FR with VOIP and P2P

Current setup : cisco router 3640 connects to a Frame Relay with traffic shapping and VOIP (Hoot N Holler). We need to add a second P2P circuit to the same router for redundancy. We are running Eigrp. If I use the varience to load balance between the two circuits, will it work ? since the voice traffic needs to go through the frame circuit ? I am really not sure how the eigrp load sharing is gonna work for the two pathes to the distination network. Does it do Round robin as if I assign two default gateways ?

Any suggestion is highly appreciated.


  • Other Network Infrastructure Subjects

Re: EIGRP variance load balancing between FR with VOIP and P2P

Eigrp will automatically load balance over, up to four, equal cost paths. You only need to use the varience option if your paths are not equal speed/cost.

Generally however, it is not a good idea to use varience. If you are fast switching, then the load sharing is on a session, rather than on a per packet basis. This means that some sessions will use only the lower speed path.

You can force load sharing on a round robin basis by disabling fast switching, 'no ip route-cache' on the interface, however this is not recommended as it will seriously impact the router's performance. In addition, with varience enabled, some packets will inevitably arrive out of order and require resequencing at the destination. Effectively throttling traffic to the lower speed link and not good for voice traffic.

New Member

Re: EIGRP variance load balancing between FR with VOIP and P2P

Couldn't agree more with the answer provided by the CCIE. May be you can still load balance traffic (by using EIGRP automatic load balance) AND setup your router with "route maps" at the Ethernet interface (ingress interface) to recognise VoIP traffic and route those traffic to the FR interface only. I saw VoIP implementation where the administrator setup VoIP to be on a separate subnet to the data traffic hence recognition of VoIP traffic was pretty simple. Hope this help.

New Member

Re: EIGRP variance load balancing between FR with VOIP and P2P

See this link:

This documents the load balancing in general.

The different from the above posts, is that:

1) You can use per-packet and per-destination load balancing.

2) You can do it not only with route-cache but with CEF&IP.

3) You can find more information on the link above, at the bottom of the


I have tried to run CEF on a 3640, but it loaded my router more than

with ip netflow switching.

What switching method is best for you sometimes is determined best by

experiment, if you can afford this, or by reading some materials on the

My BorderRouter runs CEF and is very much relaxed, because of that.

And about the voice traffice you should consider useing some congestion

avoidance techniques and prioritization of the VoIP traffic. The voice

thing can be done with other methods of queine too. You should go and

check IOS doc for this, as whole chapter on classification and quality of service exist.

This will guarantee the performance of the VoIP and its fast delivery.