Ethernet Switches & Routers

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New Member
Posts: 1
Registered: ‎03-31-2017

Can a Bridge ID (STP) announce a MAC address from a disabled port?

Y have an issue with a MAC Address on an FGS switch with FGS07202k.bin loaded.

 

For... lets say SW-1, I configured spanning-tree and the bridge ID for this switch is 0x80000024380376c0 for VLAN 1. 

 

It has the port eth 0/1/1 disabled and MAC address for that port is 0024.3803.76c0.

 

On switch-2 I had spanning tree configured but then it was choosing as designated bridge 0x80000024380376c0 (SW-1)

 

However when I ran the "Show MAC 0024.3803.76c0" on SW-2 I can see the mac address from SW-1 port 1:

 

Total active entries from all ports = 2854

MAC Address      Port   Age VLAN Type

0024.3803.76c0  5/5       0     1 

 

That port 5/5 its connected to SW-1.

 

Then if I look for that mac on SW-1 it belongs to port 1 which is disabled:

 

Port     Link     State  Dupl  Speed  Trunk  Tag  Pvid Pri    MAC Name
0/1/1 Disable None None None    None   No     1     0     0024.3803.76c0

 

How is that possible? is it because of stp? and the bridge ID?

Brocade Moderator
Posts: 184
Registered: ‎06-30-2010

Re: Can a Bridge ID (STP) announce a MAC address from a disabled port?

Hi,

 

This is normal behaviour, switch will use lowest number port as its Bridge ID which is why you see that MAC as the bridge ID of the root.

 

Whan another switch is conencted it will see that MAC learnt on port connected to root.

 

I have tested this and see same behaviour as you describe.

 

Regards

Mick

 


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