Re: [v6ops] [Idr] BGP Identifier

Christopher Morrow <> Sat, 15 February 2014 18:37 UTC

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From: Christopher Morrow <>
To: Shane Amante <>
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Subject: Re: [v6ops] [Idr] BGP Identifier
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On Sat, Feb 15, 2014 at 10:53 AM, Shane Amante <> wrote:
>> And what does an integer called ROUTER_ID tell you about that?
> In my past experience, I have found that -- particularly in new networks that I'm unfamiliar with -- looking at the output of "show (ospf|isis) database extensive", finding a ROUTER_ID that originated the LSA/LSPDU and performing a ping and/or traceroute to it to verify the sanity of where in the topology that ROUTER_ID is located has been helpful in rapidly diagnosing and fixing brokenness.  Yes, I will admit that it is not a panacea (i.e.: it does not help in the case of duplicate ROUTER_ID's), but 99% of the time it's often using that information to figure out where traffic is, or is not, going to.

for isis I think unique router-id is important (at least inside the
same level? or perhaps I'm just thinking that changing the router-id
is a ted update event.) but for bgp it seems less important (aside
from the troubleshooting you outline). I imagine it'd actually be nice
to be able to set a router-id externally and a different one
internally actually. This could have some fun implications really...
'my router-id everywhere is 1!' (or zero)

>> And hey, you can always create records like
> And, when your DNS server is unreachable because you've got a network issue, what then?

you could, of course, replace 'dns' with any other separated mapping
system (say a text file in the least complex setup). This does add
more work for O&M though, which is probably bad :( extra record
keeping isn't particularly good...

I wonder though what's going to happen if you don't have ipv4 on the
network anylonger, and have no need for ipv4 identifiers? do you just
keep numbering the router-id from "some ipv4 space" or do we have to
look at updating bgp to have a router-id (and isis and ospf and...)
that's more than just 32 random bits that happen to look like an ip