LAN RSTP bridge

[geryperisic]

Hi,

I have two routers with two links between them. Ether1 on both router is Prmary link, ether2 on both router is Backup link, and Ether3 on both router is Customer.
I created bridge on both routers and put all port in them(ether1, ether2, ether3) and set protocol RSTP(master rouer set priority 7000). I also set up port cost(20) for backup ports cost and port priority(90).
Now primary link is root port and backup link is alternate port. When i shuttown primary link, backup link then changes to root port and everything works fine, but when is my primary link full of capacity and lossing packet, then RSTP protocol wont change backup link like root port. Why?

BR,
Milan

[tdw]

STP/RSTP/MSTP were designed to reorganise networks when links failed, not provide bandwidth sharing.If you wish to use both links at the same time see https://wiki.mikrotik.com/wiki/Manual:Interface/Bonding

[sindy]

when is my primary link full of capacity and lossing packet, then RSTP protocol wont change backup link like root port. Why?

As said above by @tdw, with STP, a “backup” is a backup against a complete failure, not against exhaustion of capacity.

But in your simple case, you may create a bond of ether1 and ether2 and make the bond a member port of the bridge, and it will work both ways - as long as both paths are working, the load will be distributed between them (unless all the traffic goes between just two IP addresses), and if one of them fails, all traffic will take the remaining one.

[ste]

when is my primary link full of capacity and lossing packet, then RSTP protocol wont change backup link like root port. Why?

As said above by @tdw, with STP, a “backup” is a backup against a complete failure, not against exhaustion of capacity.

But in your simple case, you may create a bond of ether1 and ether2 and make the bond a member port of the bridge, and it will work both ways - as long as both paths are working, the load will be distributed between them (unless all the traffic goes between just two IP addresses), and if one of them fails, all traffic will take the remaining one.

Looking into MSTP now. If read correctly it should be possible to spread vlans over links on a per vlan basis.

[sindy]

I’m afraid that while each MST instance does build its individual topology (it’s the essence of MST functionality), you cannot set different priority/cost to a single port in each instance. So if your idea was to say that port A has lower cost than port B for MSTI 0 and port B has lower cost than port A for MSTI1, and thus make member VLANs of MSTI 0 use port A and member VLANs of MSTI 1 use port B if both ports are working, and only send member VLANs of both via one of the ports if the other one is down, it won’t work.

[xvo]

I’m afraid that while each MST instance does build its individual topology (it’s the essence of MST functionality), you cannot set different priority/cost to a single port in each instance. So if your idea was to say that port A has lower cost than port B for MSTI 0 and port B has lower cost than port A for MSTI1, and thus make member VLANs of MSTI 0 use port A and member VLANs of MSTI 1 use port B if both ports are working, and only send member VLANs of both via one of the ports if the other one is down, it won’t work.

Actually, you can do this, and that is one of the advantages of MSTP:
https://wiki.mikrotik.com/wiki/Manual:Spanning_Tree_Protocol#MST_Override

[ste]

I’m afraid that while each MST instance does build its individual topology (it’s the essence of MST functionality), you cannot set different priority/cost to a single port in each instance. So if your idea was to say that port A has lower cost than port B for MSTI 0 and port B has lower cost than port A for MSTI1, and thus make member VLANs of MSTI 0 use port A and member VLANs of MSTI 1 use port B if both ports are working, and only send member VLANs of both via one of the ports if the other one is down, it won’t work.

Actually, you can do this, and that is one of the advantages of MSTP:
https://wiki.mikrotik.com/wiki/Manual:Spanning_Tree_Protocol#MST_Override

Thanks for clarification. Was wondering what it should be all about with MSTP if this wasn’t possible. I will test this with a 317 and 2x305 in lab before rolling it out. They should do it in HW.

[pranoy1083]

Hello…
I have created a bridge with my 2 WAN links for auto redundancy. Enable rstp as protocol mode. Fiber link is connected on ether11 and Radio link is on ether12. I want to make fiber link as root port. But Radio link goes to be a root port. As radio link is backup, i am getting the full bandwidth. How can i set the fiber port as root port?