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homerwsmith
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Putting all routers on lo  [SOLVED]

Wed Apr 10, 2019 9:35 pm

Dear Gentle Folk,

I believe I have seen, but no longer have, an example config on the net connecting multiple mikrotics together in a web/loop with OSPF.

Although each router served different customer subnets from various of their own interfaces, the tiks themselves
were connected via an lo loop-back interface on each router which was assigned on a bridge of its own.

Does this even make sense?

5 routers, each with a loop-back interface, each on a bridge 1, and each interface connected to the network.

Does this bridge all the routers together though their shared lo/bridge?

If so doesn't this create a broadcast loop?

I believe the point was to put all the mikrotics on one single private subnet regardless of where they were in the network, for easy access to them, particularly if one of the many cross connected links went down.

Is there a white paper I can read on this kind of this?

Thank you in advance,

Homer W Smith
CEO Lightlink Internet
 
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Re: Putting all routers on lo

Thu Apr 11, 2019 12:23 am

It would work so long as each router has access to the same L2 broadcast domain. The bridge interface would run STP and would prevent any switching loops, the problem is the OSPF process would need to be a broadcast type which would cause a DR/BDR election. There would be a number of concerns I would have with this design as it is extremely inefficient.

Since you asked I will go ahead and explain the connection type, effectively you would have at least 2 interfaces on each router, one would be north and one would be south (more could exist but for simplicity reason I will leave it there)

In this topology,

A -> B -> C -> A

This would create a ring of sorts, Interfaces on A would face B and C would both be in a bridge, an IP assigned to the bridge and the bridge collectively running OSPF.

I would strongly urge caution in this however, more-so if the paths between routers are radio based.
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homerwsmith
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Re: Putting all routers on lo

Sun Apr 21, 2019 10:11 pm

Thanks your answer, I thought it was too good to be true :).

You mention radio based as a problem for OSPF. Our entire network is multiple mikrotiks in spokes, rings, diamonds and cross connects
all based on ubi wireless in the mountains and surrounding terrain.

OSPF works most of the time, but sometimes it becomes confused, like some kind of out of sync condition throwing
errors into the logs. Restarting the instance usually fixes it. What words of wisdom do you have for this kind of spaghetti
network? Everything is in AREA 0, In theory we would want every mikrotik to be dual homed within the network to provide backup routes within the network
when radio links go down which they do all the time from power out, interference, dead radio, acts of God etc.

Thanks in advance,
Homer W Smith CEO Lightlink

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