Re: [Autoconf] what's a router

Teco Boot <teco@inf-net.nl> Thu, 05 August 2010 12:23 UTC

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From: Teco Boot <teco@inf-net.nl>
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To: Alexandru Petrescu <alexandru.petrescu@gmail.com>
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Subject: Re: [Autoconf] what's a router
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Alex,

Again, I don't think this mail helps.
Nevertheless, another attempt. 


>>> Does a MANET router execute the longest-prefix match algorithm?
>> 
>> Yes. Every router MUST. This is Router Requirement (RFC 1812, page
>> 75) And many other RFCs. Dig yourself.
> >
>> Also applies to hosts.
> 
> Hmmm the rfc1812 title says "Reqs for IPv4 Routers" (not hosts)...

Your question was on routers. So RFC 1812 applies.
Longest match also applies to hosts. RFC 1122 starts with "best next
hop". Then, we had VLSM and CIDR.
All we ask, do a little research yourself and don't bother us.


>>> Does a MANET router select an output interface depending on the
>>> result of that agorithm?  Or is it just doing it with always the
>>> same result?
>> 
>> Also RFC 1812.
> 
> Are MANET Routers referring to RFC1812?  BEcause RFC1812 says:
>> (1) If a host has only a single constituent-network interface, it
>> should not act as a router.
> 
> To me that reads that if a device has a single interface then it can't
> act as a router.

Hmm. You quote from "2.2.8 Notable Oddities".
And it is a "should".
One way to circumvent is sending an icmp redirect, so next packets are send
directly to a better gateway.
More important: ask Fred himself on this. He worked on point-to-multipoint,
which works similar to what MANET routers do.

Appendix C (15) discuss future directions with "Multiple logical (sub)nets 
on the same wire." Thats where we are.

Also, the "lolly-pop router" or "router on a stick" are well known by now.
Isn't MIP HA an example?

So yes, a RFC1812-bis should use other wording.


> Also rfc1812 says:
>> An Internet router performs the following functions:
> [...]
>> (2) Interfaces to two or more packet networks.
> 
> Since MANET is so vaguely defined, because of the undetermined link
> connectivity properties, one wouldn't say that a MANET Router is an
> Internet Router.

See previous remark on future directions.


Regards, Teco


>>>> And you don't need any header files like route.h on a router,
>>>> just on your development system. I don't think you will find
>>>> many embedded routers (DSL, MANET, ...) with header files on
>>>> them.
>>> 
>>> WEll... the /usr/include stuff is there everywhere in the deployed
>>> routers running binaries.  E.g. linux phones.  I think a device
>>> that boots a kernel has a file system and that should have a
>>> /usr/include.
>> 
>> Pure non-info.
> 
> WEll.  There are file systems and dynamically compressed file systems.
> There are off-the-shelf kernels and home-brewed re-compiled kernels.
> 
> Few things are pure :-)
> 
> Alex
> 
>> 
>> 
>> Teco.
>> 
>> 
>>> Alex
>>> 
>>>> 
>>>> Henning Rogge
>>> 
>>> 
>>> _______________________________________________ Autoconf mailing
>>> list Autoconf@ietf.org
>>> https://www.ietf.org/mailman/listinfo/autoconf
>> 
>> 
> 
>