Best Practices - Cisco 3750E's with 2960G's

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Sep 4th, 2008

I have a very simple questions. I'm creating a stack of 2 3750's switches and connecting it to 12 2960G's switches through the copper ports (using etherchannels, one trunk per 3750 switch for redundancy). Should I hardcode duplex/speed on the trunks? I've read so many opinions on this that I am confused. How about the trunks from the 3750 to the 3725 router, Firewall and servers?


I have this problem too.
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glen.grant Thu, 09/04/2008 - 12:36

Really a matter of preference , auto between cisco gear generally works pretty well. If you have a old 3725 router you might want to hardcode that. If your worried about it then hardcode both ends on all connecting links.

farialuism Fri, 09/05/2008 - 04:43

That was my plan, to just hardcode the router trunks since the router is a couple of years old and anyway, that's the way it's set right now. I figure the new equipment, being all Cisco, would autonegotiate pretty well. In any case, I will be monitoring the system for a week. Should I see too many errors, I would change the settings and hardcode them. I'll keep you posted as of the outcome. Thanks.

subharojdahal Thu, 09/04/2008 - 12:58

Hey Far

As far as my understanding, you coulld leave speed as default. Only thing you have to consider for a trunk link is the protocol, that has to be same on either side of trunk. So, if one end of you switch has dot1q then other end must be same.

Same thing applies to router as well, there is no trunk like setting in router but you dont have enough interface then you can make router on stick setting. For that you have to assign the ip address to sub-interface with encapsulation that must match with the trunk port of the switch.

For firewall, I cann't say easily without looking at your network design, but each port you connect to the server or host is access ports. I would suggest you to enable portfast on those ports to avoid delays while STP topology changes.

Please rate if it helps


farialuism Fri, 09/05/2008 - 04:45

I definitely agree with you and all the trunks are set to dot1q since it's the only protocol that the 2960's support. Most likely I will hardcode the servers and the firewall trunks, together with the router connection. Fastport and BPDU guard is enabled already. Thanks for your response.


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