Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Announcements

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.

New Member

Hub group and core switch

Dear Sir,

We have a pair of WS-C3750G-48TS-S and several groups of 3com Hub for a network of 200 users.

We want to setup 3750 as the resilience core switch and let each groups of hub have dual link connect to them.

But as the hub does not run STP and linking the two 3750 together for resilience will create a loops.

Any idea on this?

Thanks!

6 REPLIES
Cisco Employee

Re: Hub group and core switch

Connecting the hub to the 3750's will work without any configuration as STP by default is turned on

The 3Com hubs should be transparent so the 3750 should see back it's own BPDU's and thus block one of the links towards the hub and breaking the loop

Thanks

/Michel

New Member

Re: Hub group and core switch

Dear Michel,

Thanks for your idea? Did you try it before? We cannot try it now before we purchase the equipment.

Regards.

Cisco Employee

Re: Hub group and core switch

Yes, i've seen this used before and it's working fine.

Thanks

Michel

New Member

Re: Hub group and core switch

This probably goes without saying, but please be sure portfast is disabled on the ports connecting to the hubs.

Jarred

New Member

Re: Hub group and core switch

If there are three groups of hubs, so totally six ports on the switch will be sending BPDU together. Eventually, only one of the ports will be left forwarding PBDU and the other five will be blocked. Am I right?

Cisco Employee

Re: Hub group and core switch

If the hubs group of hubs are connected together directly as well yes.

But probably it makes more sense to link each group of hubs directly to the 3750 (not to the other groups).

Then only one port per group of hubs will be blocked.

In anyway how you do it it will work that only one port connected to the hub (or hubs if they are linked together directly) will be Forwarding, the rest will be Blocked

145
Views
5
Helpful
6
Replies