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Strange results

Phil.Storey
Occasional Contributor

Strange results

Hello all again, I'm trying to sort out a 12 switch network using 2524 units,

When I run the sh sy command it show the Base Mac address, which I noted. I then run the sh sp and it outputs the info on the ports, forwarding / blocking etc.

In the first location there are 3 switches with the stack modules in.
so port 25 / 26 on sw1 show as stk 1000 forwarding all looks ok until you look at the MAC addresses and it is somthing like this:
Commander:
Base Mac Address 000f20-b4da40

Port 25 ( STK ) forwarding to 000f20-b4da40
Port 25 ( STK ) Forwarding to 000f20-b27300
Switch 2 in the Stack
Base Mac Address 000f20-b27300
Port 25 (100FX) Forwarding to 001ffe-223f80
Port 25 (STK) Forwarding to 000f20-b27300
This strange reporting is happening on all switches where one port is forwaring to the next switch but one port is forwarding to itself, with the exception on one switch

Building 3 Ra
Base MAC address 000f20-b1ca40

port 25 (100FX) forwarding to 000f20-b1ca40
port 26 (100FX) forwarding to 000f20-b1ca40
this is the output from one switch:
Port Type Cost Priority State | Designated Bridge
---- --------- --------- -------- ---------- + -----------------
1 10/100TX 200000 128 Forwarding | 000f20-b43a00
2 10/100TX 200000 128 Disabled |
3 10/100TX 200000 128 Disabled |
4 10/100TX 200000 128 Disabled |
5 10/100TX 200000 128 Disabled |
6 10/100TX 200000 128 Disabled |
7 10/100TX 200000 128 Forwarding | 000f20-b43a00
8 10/100TX 200000 128 Forwarding | 000f20-b43a00
9 10/100TX 200000 128 Forwarding | 000f20-b43a00
10 10/100TX 200000 128 Disabled |
11 10/100TX 200000 128 Disabled |
12 10/100TX 200000 128 Disabled |
13 10/100TX 200000 128 Disabled |
14 10/100TX 200000 128 Forwarding | 000f20-b43a00
15 10/100TX 200000 128 Forwarding | 000f20-b43a00
As you can see all connected devices are seeing the base MAC address of the switch they are connected as the designated bridge.

I can connect to all the switches, via telnet or HTTP, all devices that are attached are working. All the switches except for 2 are at FW 5.017, all swithes have STP ( RSTP ) enabled
at switch level not port level.

I think this could be down to the FW level and maybe some misconfiguration by myself.
any help would be appreciated
Regards
1 REPLY
Richard Brodie_1
Honored Contributor

Re: Strange results

The designated bridge for a link is the bridge nearest the root bridge. Ports with end systems on will always show the local bridge as designated.

For links with bridges as both ends, the designated bridge gives you a 'compass arrow' showing you which bridge is the next hop towards the root bridge. The root bridge itself will be the designated bridge for all its ports - any direction you go will be away from the root.

Conversely, in the antipodes, there'll be a spot where it is roughly the same distance in either direction round the ring to the root. That's where the blocking port will be.