3750 Stack... connecting to access switches

I'm ordering a couple 3750s to use in the core of our network.

I plan on creating etherchannels between each access and core switch.

Should I connect 2 cables from the access switch - one to each 3750? Or would it be more advisable to connect 4 cables to the access switch - 2 to each 3750?

Are both of those frequently used setups? Or is having a 4port etherchannel just excessive?

The reason I ask is I'm debating between 24 port and 48 port 3750s so I want to know how many ports I "need".

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Comments

jason_lunde

I would do some monitoring and see what my bandwidth baselines were. Its always easier to defend facts to management...and nothing is much more factual than real numbers.

xxdrexx

I would do 2 cables from each access switch.

So let's say your 3750 stack is 2 switches, with ports ranging from gi1/0/1-28 and gi2/0/28. Access switch 1 would connect its gi1/0/25 port to the core's gi1/0/25 and its gi1/0/26 port to the core's gi2/0/26. Access switch 2 connects its gi1/0/25 to the core's gi2/0/25 and its gi1/0/26 port to gi1/0/26.

That way if one 3750 fails completely, your network stays up. Make sense?

bmauro

I'm no design guru - but I've always thought that it would be best to have the links between your access and core/distribution be L3 links. EIGRP will handle failures quicker than STP/RSTP and like I just mentioned - no STP (even though you really don't have STP issues with port channeling).

mikej412

bmauro wrote: »

I'm no design guru - but I've always thought that it would be best to have the links between your access and core/distribution be L3 links.

Yep -- Routed Access Designs are popular.

xxdrexx

I guess I assumed the OP's access switches are not layer 3. If you've got layer 3 capability on those, routed links are definitely the way to go.

mikej412

xxdrexx wrote: »

I guess I assumed the OP's access switches are not layer 3. If you've got layer 3 capability on those, routed links are definitely the way to go.

Single subnet on your layer 2 switch and uplink to routed port(s) on your layer 3 distribution switch.