two unequal circuit

[mohammedrafiq]

Hi,

We have two WAN layer 2 ccts in our datacentres,one cct is 10gig and other is 5gig.We are planning to installed both cct into pair of Cisco 6500-VSS switches in each datacentre and bundle together as etherchannel to utilise both links, but I am not sure that we will achieve 15gig total bandwidth.My views are that , we might only get 5gig each, 10gig in toatal,then its mean we should leave etherchannel and use links in active/passive.

Any sugesstins please.

Regards.

[Collin Clark]

You can not bundle those two links. They must be the same speed.

http://www.cisco.com/en/US/docs/switches/lan/catalyst6500/ios/12.1E/native/configuration/guide/channel.html#wp1020420

If possible you could use them as layer 3 links and load balance using your routing protocol. Regular old STP would work too, but no load balancing available.

Hope that helps.

[mohammedrafiq]

Thanks Colin,

Though the 2nd 10gig link has been capped by provided as 5 gig as b/w, our switch will still see as 10gig.

Regards.

[Collin Clark]

OK, that will work then. You can set the load balance to a couple of different modes.

With a PFC2:
–src-port—Source Layer 4 port
–dst-port—Destination Layer 4 port
–src-dst-port—Source and destination Layer 4 port

•With a PFC or PFC2:
–src-ip—Source IP addresses

–dst-ip—Destination IP addresses

–src-dst-ip—Source and destination IP addresses

–src-mac—Source MAC addresses

–dst-mac—Destination MAC addresses

–src-dst-mac—Source and destination MAC addresses

Depending on your traffic flows and the amount of traffic, you could possibly get the bundle to load balance effectively, assuming the amount of traffic rarely if ever hits 5GB. It's safe to assume that if you will get that much traffic, not to use etherchannel. Again P2P links or STP will probably be better, but you know your network best.

[Giuseppe Larosa]

Hello Mohammed,

given the scenario I would suggest the following:

use full 10 G link as L2 trunk with two SVIs over it

use 5 Gbps limited link as L2 trunk with a third SVI over it.

use a routing protocol of your choice (OSPF or EIGRP can be good choices) to use the three SVI/vlans as three equal cost paths

this should allow you to take in account the different speads and to use the three logical links

Hope to help

Giuseppe