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configuring a5120 for redundant bridges

New Member

configuring a5120 for redundant bridges

I have a situation that I need some guidance in configuring.


We have equipment in two buildings (line of site) that are connected via a wireless bridge. They just added a new, faster more stable wireless bridge.  


They want to have all the traffic on the new bridge, and use the old bridge only if there is an issue with the new bridge


I have little information on how the existing network is configured (security reasons), all I know is that it is a flat network and we have to work on layer 2.


They gave me 2 x HP A5120-24G EI Switches (one for each building) and told me use spanning tree.

The plan is to use port 24 to connect to their existing switches, port 1 to the new bridge, port 2 to the old bridge.


I don’t know anything about STP so I RTFpdf and now I know very little more about STP (and the related MSTP) and how it would help in my case. All the examples I’ve seen show 3 or more switches all interlinked. I only have 2 and with 2 bridges.


I also started to read up on Link Aggregation and LACP could that be a solution? Assigning a lower value (1000) on the prime port to keep the traffic on the main bridge?


Any ideas? I could use all the guidance that I can get.





Trusted Contributor

Re: configuring a5120 for redundant bridges

hi gartner

1. your wireless bridge have to support stp/mstp or should forward the bpdu packets (stp control packtes) transparent

2. enable mstp on both 5120

3. rise the stp cost of the link to the old bridge => stp will chose the link with the better cost (the one to the new bridge)

4. if the new bridge fails, stp will chose link to the old bridge


hope thats helps




H3CSE, MASE Network Infrastructure [2011], Switzerland