adding port to brifge

RouterOS General
1

Herllo,
when I add port yo my bridge I see that I get 1 port to be root
and all other are designated port.
why is it?
what is the perpuse of this?
how can I change it?

Thanks ,

2

Hi

http://wiki.mikrotik.com/wiki/Manual:Interface/Bridge


(R)STP algorithm assigned role of the port:

Disabled port - not strictly part of STP, a network administrator can manually disable a port
Root port – a forwarding port that is the best port from Nonroot-bridge to Rootbridge
Alternative port – an alternate path to the root bridge. This path is different than using the root port
Designated port – a forwarding port for every LAN segment
Backup port – a backup/redundant path to a segment where another bridge port already connects.

3

can it be change?

also some other strange problem:
I have 2 units with bonding :
10.10.10.1
10.10.10.2
I have ping between the units.
when I put the bonding inside a bridge without any other interface - I don’t have a ping … :confused: :confused: :confused:
(I have change the so now the bridge get 10.10.10.1-10.10.10.2)
when I look in the bridge - I can see that on unit1 the bonding set as root port and in unit2 designated port
this is why I ask

any idea?


Thanks ,

4

Short answer - no you can’t just change it.

Medium answer- these are indications of the state of your spanning tree. Only one switch can be root. If you change which switch is root (lower value in Priority setting) then the ports will change accordingly.

Longer answer-

Suppose you have 3 switches connected like a triangle a-b-c->a and suppose A is the root. The link between b and c will go inactive- so hosts on b can talk to hosts on c but traffic will go through A to get there.

Spanning tree is designed to automatically remove loops from your network. It does this by disabling a port if it’s a second way to reach the root switch. The active path is in the root state, the backup is in the alt state and drops all traffic while in alt state.

You can manipulate which ports enter which state by manipulating switch and port priorities but there will always be exactly one ROOT port with any backup paths to the root in ALT state.

If both were ROOT at the same time, it would cause broadcast storms.

5

Thanks !