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RSTP: Port status?!


RSTP: Port status?!

i have 4 3500s, they are meshed together in a full mesh, they are in two stack of two, each stack also have a number of 2810s that are in pairs.

2810 #01 has a 4gb trunk to 3500 #01
2810 #02 has a 4gb trunk to 3500 #02

now for redundancy there is a 1gb connection between the two swithes. (both on port 44)

2810 #2 - port state is blocking on port 44 and forward on trk1
2810 #1 - port state is forwaring on both on port 44 and trk1 - this isnt right is it?

3500 #01 is the root bridge.

please can someone confirm that it should be blocking both ends and that im not loosing my marbles.

all switches running latest firmware.
Matt Hobbs
Honored Contributor

Re: RSTP: Port status?!

On your Mesh switches, have you set them to be a higher priority for spanning-tree?

e.g. spanning-tree priority 1

With the scenario you've described it sounds like 2810 #1 has become the root bridge which will put all of it's ports into forwarding. If you check what port 44 is connected to on the 3500's you should see it has been blocked from the 3500's side.

Re: RSTP: Port status?!

i set the 3500s to be highest priority in spanning tree, 3500-01 & 3500-02 have priority 1 & 2 respectively.

when i do the show spanning-tree on 2800-01 it says the STP root is on trk1 so i dont think its become roor bridge.

will check that the 3500s say though on monday.

if i understand correctly, on the root bridge all interfaces should show as forwarding, the switches they are connected to should show blocked, now when i have two non root switches connected they should both say blocked? or should one end say forwarding and one end say blocking?

it seems to be working properly though, if i run Iperf i can see the traffic going over the trunks, not the redundant link that uses port 44, if i pull out the trunk ports i see it swap over to the redundant link and out through the trunk on the other switch in the pair, plug trunks back in and it switches back, when i do this with a ping i get one packet lost on each cutover but thats an acceptable level for us.

just wanting to clarify if both ends should be blocking or not.

Trusted Contributor

Re: RSTP: Port status?!

you should be happy it works as expected, as shown by your trials :-)
Occasional Visitor

Re: RSTP: Port status?!

We have 5 3Com Switches 4200. We install Zabbix on our server, which query Switches via SNMP. Zabbix reported this text:

Trigger: Port 16 on 3com Status Change
Trigger status: PROBLEM
Trigger severity: Average
Trigger URL:

Item values:

1. Port 16 Status (3com 5

Trigger: Port 22 on Status ChangeTrigger status: OKTrigger severity: AverageTrigger URL: Item values:1. Port 22 Status ( 22. *UNKNOWN* (*UNKNOWN*:*UNKNOWN*): *UNKNOWN*3. *UNKNOWN* (*UNKNOWN*:*UNKNOWN*): *UNKNOWN*

Trigger: Port 22 on Status Change
Trigger status: PROBLEM
Trigger severity: Average
Trigger URL:

Item values:

1. Port 22 Status ( 2

What does it mean "Port Status: 1(2,3,4,5...X)" and "ifOperStatus.122"???

John Gelten
Regular Advisor

Re: RSTP: Port status?!

Next time, don't reuse a five-year-old completely non-related discussion, but open a new one.


I don't really know what the status-numbers mean exactly. The refer to the different states a port is in. I guess that you haven't configured Zabbix to use the MIB for this switch, otherwise Zabbix would probably not show this number, but the corresponding text.


You might have more luck asking this in the Network Management section of this forum.


As to the original question: it is completely conform specifications (RFC's) that only one side of the link will be blocking.