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CEF load-sharing

Hello

I'm not sure about load-sharing by CEF, how it works. Hope somebody can explain it for me:

For example I have two interfaces (f0/0 and f0/1) for equal-cost load-balancing. Now I set cef algorithm for layer4

(config)# ip cef load-sharing algorith include-ports destination

on interface f0/0

(config-if)# ip load-sharing per-packet

on f0/1

(config-if)# ip load-sharing per-destination

What happens now? both interfaces have a route to some host, for example 1.1.1.1. I would like to load-share my http traffic to 1.1.1.1:80.

Global cef config creates one hash for 1.1.1.1:80, so all the traffic to 1.1.1.1:80 should use only one interface, lets say f0/0. But cef config on f0/0 would like to share the traffic per packet, and f0/1 per destination... So I think i do not understand something here.

And one more thing - if i have multiple tunnel interfaces, exiting the same physical interface, so where should i configure load-sharing, on tunnel interfaces or on the physical interface?

Thank you in advice

  • WAN Routing and Switching
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1 REPLY

Re: CEF load-sharing

Hello, Dmytro.

I guess "show ip cef " could reveal you how CEF treats your configuration.

It will show, if it's per-packet.

Please remember, that per-packet sharing could lead to packet reordering that could negativly impact application performance or even lead to crash (in case of UDP or some legacy TCP/IP implementation).

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