load balancing between dual links

[moabdallah]

I have a network of Two identical backbone Cat-6513 switches & 30 edge Cat-3560 ( 48 ports ) switches

Each edge switch has dual uplinks connected to backbone layer ( one giga uplink to each backbone switch )

Network contains Voice ( IP Telephony ) & Data traffic

how can I utilize ( load balancing ) the dual uplinks between backbone switches & edge switches ?

Should I configure the edge Cat-3560 as L3 switch & routing will do the load balancing on the dual uplinks ?

OR

Should I configure the edge Cat-3560 as L2 switch & configure Voice VLAN traffic to go though one uplink & the Data VLAN to go though the other uplink ?

Regards

Mohamed

[pflunkert]

Hi,

i would configure layer3 links. The advantage from layer 3 is, that the routing protocol use both link. When you use layer 2, you must configure the spanning tree root on different switches. So half of the traffic will use the first and the other falf will use the second link. Spanning Tree blocks one uplink port. Furthermore you will seperate the broadcast domains. You need more configuration steps. The advantage from the layer 2 configuration would be easier.

You must decide what you want, but i think that layer3 would be better.

Regards

Peter

[raju]

Hi Mohamed,

We have a similar setup with two 6509 acting as backbone configured in such a way to do Load balancing and Redundant. I would prefer to configure the Layer-3 at Core level instead of at edge Level. If you configure Layer-3 at edge level , it will make complicate your Network . As long as your uplink to core is gigabit , you can configure Layer-3 at Core level.

Thanks

[moabdallah]

Hi,

Thanks for your reply

If I configure the edge as L-2 switch, how can get dynamic utilization on the daul uplinks ?

Regards

Mohamed

[pflunkert]

When the uplinks goes to different switche you can configure the root for some vlans on switch 1 and the other half on switch 2. So some vlans use uplink 1 to switch 1 and some vlans uplink 2 to switch 2.

When your uplinks goes to one switch switch you can use a etherchannel. A etherchannel is a logical link which consists up to 8 physical links.

Regards

Peter

[moabdallah]

Hi Peter,

If I configure the edges as L-2 Switches, and some vlans use uplink 1 to switch 1 and some vlans uplink 2 to switch 2.

This is not full utilization ( NOT dynamic utilization ) for the dual uplinks.

Do you think it is better to configure the edges as

L-3 switch ? but it may be more complicated configuration.

What is the advantage and disadvantage of both configuration ( edges as L-2 and edges as L-3 ?

Regards

Mohamed

[gaban]

I would do layer 3 on core and layer 2 on the edge. You want layer 3 on the core 6500 because it will do it faster than your edge equipment. It will also make it easier for configuration changes as you only do it at the core. You want you edge just to pass L2 traffic and not get bog down with routing and such. I would do per vlan spanning tree ( more comlicated) so as peter says you will have one vlan using an uplink and the others on the the other uplink. Unfortunately with you dual core you could not do etherchannel which will use both links the way you like it.

goodluck.

[moabdallah]

Hi,

Someone suggest me to configure L-2 on edge switches & L-3 on backbone switches with GLBP ( Gateway load balancing protocol ), and the GLBP will do the dynamic load balancing on the dual links

Is this correct ?

Regards

Mohamed Abdallah

[nikhilgupta]

but the GLBP is only suuported on sup 720. are you using sup 720?

[moabdallah]

yes, I have Cat-6500 with Sup 720, WS-67xx modules in the backbone and Cat-3560 SMI edge switches

[roadhouse1387]

probably a bit late this but nevermind..

How about connecting your two cores with a routed link between them, then configuring a L3 interface on each core for your edge vlans. Consider using two data vlans and one voice vlan. Now run hsrp between them and make datavlan 'A' core 'A' hsrp active and datavlan 'B' core 'B; hsrp active. You can choose which link you want your voice to run up and use hsrp active for that vlan on the router connected to that uplink for failover.

now configure your edge uplinks to each core as trunks carying all local edge vlans.

This will give you a default gateway for datavlan a on core a and datavlan b on core b (with the stanby routers being the oposite way round) and your voice on one of them also.

put half you users in datavlan A and the other half in Datavlan B. half your traffic will go via uplink one and the other half via uplink 2 with the voice utilising one of them.

In the event of a failure, hsrp will com into play and flip the standby vlan routers into active..all your trafffic will go via the remaining link.

this means no spanning tree as failover is done with routing and a faster recovery.

hope this is of some use.

Cheers

Shaun

[smebbin]

I would use GLBP as suggested before because GLBP will load balance both links and provide fail over. Essentially a Hybrid HSRP. Unless you want to stay away from proprietary protocols on your network.

V/R

brandon