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Port-channel - type Peer STP


We have two Catalyst 4006 as core switchs in our network. Other access layer and server layer switchs (also Catalyst 4006) connect to the two core switchs; two Gigabit Ethernet links between one layer switch and one core switch form a port channel.

Now I add one Catalyst 4507 switch in the backbone, Il connects to each core switch by two GE links formed a port channel. The show spanning-tree command presente different port-channel type for the older(P2P Peer STP and the new port-channel (PO31, only P2P, not peer STP).

CDP-CO-SW-S17-01#sh spanning-tree vlan 2


Spanning tree enabled protocol rstp

Root ID Priority 8192

Address 000a.418b.0401

This bridge is the root

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 8192

Address 000a.418b.0401

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Aging Time 300

Interface Role Sts Cost Prio.Nbr Type

---------------- ---- --- --------- -------- --------------------------------

Po21 Desg FWD 3 128.661 P2p Peer(STP)

Po22 Desg FWD 3 128.662 P2p Peer(STP)

Po23 Desg FWD 3 128.663 P2p Peer(STP)

Po24 Desg FWD 3 128.664 P2p Peer(STP)

Po25 Desg FWD 3 128.665 P2p Peer(STP)

Po26 Desg FWD 3 128.666 P2p Peer(STP)

Po31 Desg FWD 3 128.671 P2p

Po44 Desg FWD 3 128.684 P2p Peer(STP)

Po45 Desg FWD 3 128.685 P2p Peer(STP)

What does the type Peer STP means? I made the same configuration for PO31 like the other port-channel, why it is not in Peer STP type?

Thank you.

Jessie Dong


Re: Port-channel - type Peer STP

Hi Jessie,

You are running RSTP, which sends version 2 BPDUs. If the switch receives on a port version 0 BPDU (i.e. regular STP BPDUs), it will go to an STP compatibility mode and will start sending version 0 BPDUs on this port.

So basically, what you are seeing is that all your neighbors are running STP, except the one connected to Po31 who is running RSTP.



New Member

Re: Port-channel - type Peer STP

That is right. The two core switchs and the new Catalyst 4507 runs RSTP and the other Catalyst 4006 runs regulier STP.

Thank you for your explication.


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