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Spanning-tree edge ports

chris99099
Occasional Contributor

Spanning-tree edge ports

I have this network with phones connected to the switch and a pc connected to the phone. The phone is tagged in vlan 5 the pc connected to the phone is untagged in 6. My question is: should I configure the phone as a spanning-tree edge-port.

Also I have wireless-accesspoints connected to the switches on some ports, the same question goes here.

Johnny99
3 REPLIES
chris99099
Occasional Contributor

Re: Spanning-tree edge ports

I wrote "should I configure the phone as a spanning-tree edge-port." I meant "should I configure the switchport on which the phone is connected as a spanning-tree edge port."

Mohieddin Kharnoub
Honored Contributor

Re: Spanning-tree edge ports

Hi

Why you would configure this port as an edge port, are you sure that no one can connect a small hub or switch one day to the phone (say for testing).

This feature is for protection, and if you are sure that its not going to cause any problem for you in the future then do it,

I don't think that the edge port feature is causing any problem.

I did a test once, and connect a PC and it started looking for an IP from a DHCP and it got it in about 25-30 seconds.

After enabling the edge port and bpdu filter, it got it within 5 seconds , its pretty fast but without any protection.

Good Luck !!!
Science for Everyone
Matt Hobbs
Honored Contributor

Re: Spanning-tree edge ports

Even if you set a port's edge-status to yes, there is still spanning-tree protection, but you may get a small amount of flooding until spanning-tree detects the loop and blocks it.

The other reason you need to set the edge-port status is so that when a port comes online it does not trigger a topology change. In a large enough network with ports going online/offlne fairly regularly this can be a real problem.

RSTP on ProCurve switches defaults the edge-port status to yes.

MSTP is going through a bit of a transition at the moment, previously it defaulted edge-port no - but new firmware releases now will use auto-edge-port as default.

The other feature I would consider enabling is the loop-protect feature, as some phones do not forward spanning-tree BPDU's - so a loop could be created and not detected. Some switches also 'eat' BPDU's - the 1800 currently does but I believe this will be changed in a future firmware release.

For your AP's, since they are part of the infrastructure it's not so important to set the edge-port status since they will always be up.