VSS possible problem

[Julio Garcia]

Hi guys,

I have a internal network  with vss running on 2 x 6506 switches

everything works fine , but i noticed something which is a little bit odd  , on the vss i see some port channels with p2p Pre-STD-Rx..

Po61                Desg FWD 10000     128.1693 P2p Pre-STD-Rx
Po62                Desg FWD 10000     128.1694 P2p Pre-STD-Rx
Po63                Desg FWD 10000     128.1695 P2p
Po64                Desg FWD 10000     128.1696 P2p
Po65                Desg FWD 10000     128.1697 P2p Pre-STD-Rx
Po66                Desg FWD 10000     128.1698 P2p Pre-STD-Rx
Po67                Desg FWD 10000     128.1699 P2p
Po68                Desg FWD 10000     128.1700 P2p
Po69                Desg FWD 10000     128.1701 P2p Pre-STD-Rx

the problem is that all the switches on the other end of the etherchannels are all 3560s and all have the same configuration MST configuration on them,

when i check spanning tree on the switches, they all show ..

Po10             Root FWD 10000     128.688  P2p

so i am a little confused why some are showing Pre-STD-Rx, i have cleared spanning tree protocol on the individual portchannels to see if it fixes

Could someone help me please -- im not 100% sure if there is anything to fix but it just seems strange .

[jorge.calvo · Accepted solution]

Hello,

Do not worry about the Pre-STD-Rx message shown on those ports.

That is only informational and it means that the switch showing this message, your Catalyst 6506 is running the IEEE MST standard version whilst the neighboring switch is running the pre-standard MST version so, it automatically sends pre-standard BPDUs on that ports.

There are two ways to hide this message:

1. Install an IOS version with the standard MST on the access switches.

2. Configure the interfaces on the C6506 with the command: spanning-tree mst pre-standard

Hope this helps.

[Julio Garcia]

Hi Jorge

thats brilliant , thanks for explaining.