EIGRP and Port-Channels

Unanswered Question

We used to have our closet switches (routed 3750s) talk OSPF to our 2 core 6509s.. we saw that the 2 port-channels we had configured load balanced the network traffic..


Last weekend, we replaced OSPF with EIGRP and one of our port-channels shows 95% of the traffic..


Regradless of routing protocol (OSPF or EIGRP), etherchannels should load-balance right.. any ideas anyone?

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smitesh kharecha Sat, 05/01/2010 - 00:01
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Hi,


Port Channels will not by default load balance.

Its the member of the port-channels which will load balance by default.

And as you mentioned that you have 2 different port-channels, then definately you need to have some config to get equal or unequal load balancing (Since you using EIGRP, unequal load balancing could be done as well).


Hope that helps.


Regards,

Smitesh Kharecha

Jon Marshall Sat, 05/01/2010 - 05:00
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smitesh.kharecha wrote:


Hi,


Port Channels will not by default load balance.

Its the member of the port-channels which will load balance by default.

And as you mentioned that you have 2 different port-channels, then definately you need to have some config to get equal or unequal load balancing (Since you using EIGRP, unequal load balancing could be done as well).


Hope that helps.


Regards,

Smitesh Kharecha


Smitesh


Port channels are seen as one logical link by the device so it will indeed load-balance across the 2 port-channels or it should do. Within the port-channel you are right that it will use one of the links per destination but a routing protocol should see both links as equal cost paths to destinations beyond the 6500s assuming there is a dynamic routing protocol between the devices.


Jon

Jon Marshall Sat, 05/01/2010 - 00:16
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We used to have our closet switches (routed 3750s) talk OSPF to our 2 core 6509s.. we saw that the 2 port-channels we had configured load balanced the network traffic..


Last weekend, we replaced OSPF with EIGRP and one of our port-channels shows 95% of the traffic..


Regradless of routing protocol (OSPF or EIGRP), etherchannels should load-balance right.. any ideas anyone?


Are they L3 portchannels ? If so then yes the routing protocol should see 2 equal cost paths to destinations on or beyond the 6500 switches. What does your routing table show ie. when you do a "sh ip route" do you see 2 equal cost paths ?


Jon

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