Spanning Tree over Access Port

Apr 23, 2005 3 Replies
M

I have what is probably a super simple switching question, but can't seem to find a clear answer. I'm a routing guy who does BGP and MPLS for a living, but am stumped my this switching problem:



I have two switches with many VLans and a VTP domain. I want to connect my two switches to a group of 4 untrusted switches, have one common L3 vlan between my 2 switches and their 4 switches, and have spanning tree be fully functional throughout to provide L2 redundancy..



If I hand off to them as access ports in the one VLAN I want, will spanning tree still function????



OR, If I had off to them as trunk ports and prune all VLANs except the one VLAN I want to talk to them on (and VLAN 1 which I cant prunt), how do I secure my VTP domain so they cant become a VTP server and kill my VTP domain????



Any help would be extremely appreciated.. Thanks much!



Mike



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T

Spanning-tree runs per vlan and is active on access ports as well.

Make sure you configure a root switch for that vlan to increase stability.

/TC

skrev i meddelandet news: snipped-for-privacy@o13g2000cwo.googlegroups.com...

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M

Thanks much for the reply Tony.. I really appreciate it..

I'm just stumped because all I hever hear from people I talk to and see online is "switch to switch, use trunk ports!".

So your say> Spanning-tree runs per vlan and is active on access ports as well. >

stability.

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T

skrev i meddelandet news: snipped-for-privacy@l41g2000cwc.googlegroups.com...

It will work.

The switch run separate instaces of STP for each vlan, and will send and receive BPDUs on access-ports and trunk-ports and caclulate the best path with the lowest cost of all paths available.

Some people disable STP on access-port and say they have no loops in the network, but that can cause big melt-downs when other people connect or rearrange things. It's too easy to have accidents.

Be careful and don't enable spanning-tree portfast on access ports connecting switches!

/TC

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