Gigabit EtherChannel

[AspenMan]

I am planning to stack 3750G and 3750E cisco switches. I will have two sets of these for our redundant SAN locations. Each location will have a 3750G/3750E switch stack. Redundant fiber connections between these stacks would be ideal for failover purposes. I would like to have a fiber connection for the 3750G switches and the fiber connecting the 3750E switches together. My question is "Can I gigabit channel these two pieces of fiber eventhough they are two different speeds?" One is a 1 gig connection and the other would be a 10gig connection. If I can't Channel these fibers due to speed incompatability "Will spanning-tree protocol take care of data loops between the two switches?"

Rich

 

[vipergg]

Etherchannel must have the same parameters , speed etcc to be in the same group. Spanning tree "should" take care any loop .

 

[AspenMan]

Vipergg -

Thanks for the post. STP "should" take care of it. Here is the configuration we planned for the fiber links between the stacks.

switchport trunk encapsulation isl
switchport mode trunk
flowcontrol receive desired
spanning-tree portfast trunk

Does this look right to you and do we need anything else?

RG

 

[burtsbees]

I would use dot1q, as isl is dead and has a bit more overhead (you may experience giant frames).

/

tim@tim-laptop ~ $ sudo apt-get install windows
Reading package lists... Done
Building dependency tree
Reading state information... Done
E: Couldn't find package windows...Thank Goodness!

 

[AspenMan]

I will take dot1q into condiseration. Thanks for the heads up.

In previous loops I have designated a Root switch from which STP calculates where to block VLANs. Do I need to designate a "root stack" inorder for STP to work with my fiber loop?

 

[VinceWhirlwind]

You should still configure STP because you want to control how it works. Choose your "core" switch and give it priority. That should be enough.

Incidentally, stacking 3750G with 3750E means the 3750E's performance is limited to the 3750G's.
I suppose you are doing what you are doing because it gives you a 10Gb link between switch stacks, but saves the expense of buying all 3750Es.

I can see pros and cons for what you are doing.
cons:
- lose 3750E performance
- no etherchannel split across the stack members
- have to use STP (yuk)

 

[AspenMan]

Vince -

Actually we are making do with what we have. The original switches (G) are from 3 years ago when we put the SAN in originally. Eventually we will replace the G switches with E switches and move the G's to the edge somewhere. Thanks for the tip on STP. I'll make one of the switches the Root (core) switch.

Rich