01-06-2009 08:55 AM - edited 03-06-2019 03:16 AM
I have a C2851 facing a private network and behind it a stacked cat3750 (currently there are 2 switches in the stack, but that will grow).
At the moment, the setup is as follows:
cat3750 --> C2851 --> private network
but we wish to add another level of redundancy b/w the 3750 & 2851. Given a HSRP setup will not work on the CAT3750 due to its stacking nature, do you recommend to have two gig ports terminate at each of the switches in the stack with etherchannel?
The idea is if one 3750 fails or one of the gig ports fail on the 2851, the connection will still be maintained (at least to one of the switches).
that is :
cat37500 --> gig0/0 C2851 -->private net
--> gig0/1 C2851
Any thoughts about this?
01-06-2009 09:00 AM
Roni
Yes this seems like a sensible solution to me. Make it a L3 etherchannel rather than a L2 etherchannel and configure it as a P2P link.
This is assuming that the vlans on the 3750 are routed on the 3750 and not the 2800. If the 2800 routes the vlan(s) then L2 etherchannel.
Jon
01-06-2009 09:48 AM
The etherchannel I am familiar with is where I create a portchannel (virtual) interface and then group 2 or multiple physical interface to be part of this etherchannel.
What other options do I have (L2 vs L3).
Can you provide an example?
01-06-2009 10:02 AM
Roni
Attached is paper on 2800 etherchannel - you will need to check the IOS version etc. At the bottom is a configuration example.
Basically L3 etherchannel is configured similarly to L2 etherchannel except that you manually have to create the port-channel interface. So on the 3750
int po1
ip address 192.168.5.1 255.255.255.0
int gi0/1/1
channel-group 1 mode on
no switchport
int gi1/1/1
channel-group 1 mode on
no switchport
Jon
01-06-2009 05:24 PM
I think this might be the reference that Jon meant to attach.
http://www.cisco.com/en/US/prod/collateral/routers/ps5855/prod_white_paper0900aecd806f698a.pdf
01-07-2009 02:59 AM
Thanks Joseph, you are a gentleman !
Belated Happy New Year.
Jon
01-22-2009 11:05 AM
So that's applied to the ISR, what about the CAT3750 stack?
01-22-2009 04:08 PM
See the correct section of the reference manual or guide for your version of 3750 IOS.
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