jeffreydorn wrote:
We have 10 switches in the datacenter but only have 5 connections back to our 6509 core switches running as a VSS pair. We purchased a couple of 4900M to bring 10G to the datacenter and provide dual uplink on every switch back to the core. I will have dual 10G links on each 4900 back to the 6509 and plan on using a 1G link on each 4900 to each switch. Right now the 6509 does all the VLAN routing.
My question is in the best practice configuration of the 4900. Do I configure this as just a layer 2 switch with every port set as a trunking port? Or should I be moving any layer 3 routing to this switch?
I'm thinking of using it just as a layer 2, but want to make sure I'm doing this right before putting in in production.
Thanks
Jeffrey
There are quite a few discussions in the forum on this ie. L2 vs L3 access-layer. Different people have different views. I have implemented both routed access-layers and L2 access-layers, the routed in a campus environment.
Personally i think routed works well in a campus environment but for a data centre i would still use L2. The reasons are primarily -
1) more flexibility in server placement ie. if you use routed access-layer then if you need to move a switch to another vlan then you may well need to physically move the server depending on your patching
2) just as importantly some services that you want to use in a data centre such as firewalling / load-balancing can be used in either routed or transparent mode. If you deploy a L3 routed access-layer you automatically rule out some deployment options with these services.
Obviously L3 negates the spanning-tree issue but if you are running VSS anyway that should not be an issue for you.
I would still look to deploy L2 in the data centre at the access-layer because it simply gives you more options.
Jon
