Re: [babel] Restarting nodes and seqno requests

[Toke Høiland-Jørgensen <[e-mail]>]

Juliusz Chroboczek <[e-mail]> writes:

>>> - add an option for picking a different router-id each time (but
>>> don't make it the default, since it makes management more difficult
>>> without stable router-ids);
>
>> Hmm, actually, since Bird sets its router ID from an IPv4 address,
>
> What if there's no IPv4 address? What if two IPv6 routers have the
> same IPv4 address (because they're in different NAT domains)? (FYI,
> babeld uses the first MAC address if finds that has the local bit
> unset, and falls back to random if no such address is found.)

Well, usually the router ID is manually configured. If not, it'll be the
lowest IP on a non-loopback interface. I have no idea what happens if
there are none... There is quite a bit more configuration needed to get
a basic babel node running with bird than with babeld in general; you'll
need a couple dozen lines of config...

>> My implementation of the randomisation only randomises the top 32 bits,
>> so there's still a stable identifier. Maybe it would make sense to
>> default to this behaviour?
>
> That would break the optimisation of using the low bits of the IPv6
> address to encode the router-id.

Bird doesn't do that anyway.

> I'm not sure how you'd avoid router-id collisions, though.

By chance? With 32 bits of randomness, even in a moderately sized
network the chance of collision is quite low (which means that it will
not happen until it is the most inconvenient, of course...) :)

>>> - bug the BIRD guys about implementing persistent storage; two octets is
>>>   all we're asking for.
>
>> Yeah, 16 bits should be enough for everyone, right? ;)
>
> You could always encode it in JSON if you want to use more space.

I was actually thinking I should add JSON support to Bird :D

>>> Should I document the issue in 6126bis?  I'll definitely add a paragraph
>>> in applicability-statement.
>
>> Hmm, documenting it *somewhere* is needed, certainly. Maybe putting it
>> into 6126bis is a good idea,
>
> Yeah. I'll try to find some time to make a new revision tomorrow, if
> you'd like to send me a patch, I'd be grateful. (No promise to keep
> your wording, though.)

No promises to send any either ;)

-Toke