OSPF: A series of hopefully easy questions

RouterOS Forwarding Protocols
1

I have a wireless network with a lot of nbma ospf links. All works well really. I just had a few questions on everything that I’ve been wondering about.

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  1. What’s the recommended polling-time setting for NBMA? By default it is set to 2minutes. Is there some con to changing that to 20seconds or even less?

  2. Is there any reason to change priority? Honestly I don’t understand how priority/designated routers work and when I would need to make changes to that.



    Thanks!

2

The defaults were chosen well over time. I would leave settings you don’t understand alone until you have issues which you can directly attribute to those settings.

  1. The default is the recommended value, by definition. :slight_smile: It could use more CPU time to lower the setting. Theoretically, the neighbor associations will begin trying to rebuild faster after an event if you lower the setting.

  2. You would change priority to get your most stable router, without the highest RouterID, to always be the DR. Or, you leave it alone and probably be in good shape.

It sounds like you could benefit from some reading material… http://www.cisco.com/c/en/us/support/docs/ip/open-shortest-path-first-ospf/7039-1.html

I recommend against changing anything you don’t understand, in general. In the lab you need to break things to have learning opportunities, so change away. On the production network, don’t touch if you don’t understand.

3

All good points, thanks, I really do need to sit down and read the OSPF docs with the aide of a test environment.

4

I went looking for OSPF videos after seeing your question. I should be training the other guys here, but I don’t have time to train them. Isn’t that always the problem…

I like this video so far, I have not watched the whole thing yet. So far he’s covering theory without Cisco specifics (except NBMA hello intervals). Once you understand the theory, it doesn’t matter what product you are using so it should be good for MikroTik networks.

https://www.youtube.com/watch?v=1Qc2GHHuAzE 45 Minutes

He also has a part 2 but I have not gotten close to checking it out yet.