Hi
How can i setup layer2 failover?
My Network setup:
Distance between Site A and Site B is 2 km. Both sites are connected via wireless link. As a backup line, we also have layer2 fiber link between these two sites.
Primarily I want to transfer all traffic on wireless link only and do not use fiber link at all if wireless link is working well.
Automatically Activate fiber link only if wireless link is down. And when wireless link restored, automatically deactivate fiber link port.
Ether-port A (wireless) needs to continuously ping other side and if no ping reply then activate Ether-port B(Fiber) so all traffic routes without any interference.
When Ether-port A(wireless) ping gets reply, cut off PortB.
If you ask why not to use fiber always when fiber is better then wireless, i says My ISP charges per GB for data traffic. So it is expensive when wireless link is running.
“without any interference”… There is already interference when you don’t get ping back.
If you really insist on l2, you need to use RSTP. Otherwise you can use routing rules on l3. If you have enough MTU on the way, you can use routing over transport network and make eoip tunnel over it to get the l2 transparency regardless the real path…
I won’t suggest bonding over different media as you are facing different latencies.
I’d advise to use RSTP as well.
Enable RSTP on both bridges the links are terminating on and give the fiber bridge ports a lower (i.e. higher number) priority. Probably even a higher path cost.
Give the router with the more resilient power supply (i.e. UPS-backed) a higher (i.e. lower number) bridge priority so it will surely be the master.
User impact during failover, if any, is negligible.
-Chris
From what I understand, both sites are in the same L2 domain, so OSPF can’t do much here. One site would have to be re-addressed and two transport networks would have to be created on the w/l and fiber link.
It might be the ideal solution from an engineer’s point of view but it feels a bit like the sledgehammer for cracking nuts.
I still suggest RSTP with the given parameters - still easily scalable to more links with zero effort.
-Chris
I want to make Port 1 as primary port (root port) and Port 2 as alternate port.
I set Priority of Port2 to 30 and kept Port1 priority to 10.
both ports are part of bridge which is set to RSTP.
So in actual, port1(10 priority) shall be Root and port2(30 priority) shall be alternate in role column.
But problem is when network cable is plugged in port 2, still it act as Root port
and Port1 act as designated port.
why this is happening? how do i force Port2 to be alternate and not as root.
Now this will be complicated w/o BPDUs over the fiber.
As you have routers on both ends, you could try to run a PPPoE tunnel through the fiber and terminate this tunnel on your bridges on both ends.
(means: remove the SFP interface from the bridge, create PPPoE server & client on the fiber interfaces and add those to the bridges). This should enable you to run RSTP over the fiber.
When using RSTP, bare in mind that bridges with higher priorities are disabling downlink ports coming in with lower priority, not local ports having lower priority. So give the fiber port a low port priority on the router with the lower priority.
-Chris
You’re basically right, but in this case with adding the PPPoE interfaces to the bridges, you’re creating a transparent L2 bridge - just cutting MTU a little.
Have a look at this BCP-bridging manual for reference.
-Chris
this topic looks silent since a while but i have been looking to setup similar thing these days. instead of opening a separate thread, i think it would be appropriate that i should get help here.
i want to setup same l2 extension and unable to use stp/rstp because the vendor doesn’t support bpdu. so i want to ask can this PPPoE can have redundancy as well? and can we achieve same thing with EoIP?
I tried with bonding method and used active-backup method.
However this does not work fully.
Reason:
Both router are not connected directly. There are many switches and devices on this fiber link.
So if link fails then MII or ARP does not able to detect down/broken status and keeps primary link up even there is ping from Primary.
It makes primary link down only if cable is removed physically from that primary port.
So bonding is not working in my case. (Let me know if i am wrong in process)
I think now i have to try PPoE as Chris advised. I was avoiding PPoE because
----it may add some latency
----it may slower the bandwidth
----it may change subnet / topology, layer2 to layer 3 and i will not have same subnet at both end
— and also was bit hard to setup for me.
But i think i do not have any option. Have to try PPoE and add it to bridge. Are you sure these 4 worrying points will not give me hard time?
I don’t think that those points would worry you.
I consider the latency and b/w cut negligable - as long as you don’t max out the full gig of the link.
With BCP-bridging, you’re still on a Layer2 connection, no changes in the topology required.
And no, it’s not hard to configure
-Chris
