[quagga-dev 11697] Re: [PATCH] zebra: Connected route addition shoudn't happen in MRIB

Balaji G balajig81 at gmail.com
Thu Oct 30 07:17:11 GMT 2014


Hi David

On Thu, Oct 30, 2014 at 12:25 PM, David Lamparter <
david at opensourcerouting.org> wrote:

> On Thu, Oct 30, 2014 at 11:55:28AM +0530, Balaji G wrote:
> > On Thu, Oct 30, 2014 at 10:40 AM, David Lamparter <
> > david at opensourcerouting.org> wrote:
> > > This patch was discussed on IRC between Balaji, Everton and me;  the
> > > outcome was that Balaji would resend it with a switch to control the
> > > behaviour.
> > >
> >
> > I would send a V2 with that switch. do you want something "rib-lookup
> > mrib". On executing this the connected routes and the RPF check is made
> in
> > the MRIB and executing "no rib-lookup mrib" would bring it back to URIB
> > lookup and remove the connected routes. Would that be fine ?
>
> Hm, we have 3 cases:
> 1. MRIB only
> 2. MRIB first, then URIB
> 3. URIB only
>
> Options 1. and 3. can be "emulated":
> 1. = use 2. but install add "default unreachable" route to MRIB
>      => URIB lookup never happens
> 3. = use 2. but leave MRIB empty
>      => empty MRIB doesn't get used
>

Thanks for the suggestion but i guess we can have two in terms of CLI.
MRIB-URIB and URIB .

MRIB-URIB Case:This would be with MBGP and Mroute enabled where the look-up
happens at the MRIB first and then URIB. The connected routes would be
installed in MRIB and URIB
URIB Only- No MRIB and No routes get installed in MRIB including Connected
Routes
MRIB Only - Not sure if this is needed in CLI

Thanks,
- Balaji


I still think we should have a switch with all 3 options, so that the
> end user can change his setup (i.e. migrate between MRIB and URIB
> setups) and not need to resort to table-tweaks.
>
> Especially, if we want to support the workflow of "first prepare new
> MRIB, then start using it", then the switch for "connected into MRIB"
> needs to be separate from "use MRIB/URIB for RPF".
>
> (Also, one switch doing multiple things goes against the principle of
> least surprise.)
>
> -David
>
> > > This is particularly relevant in cases where the multicast RIB contains
> > > a default route, such that the fallback to unicast is not triggered.
> > > Such a case would result in local networks not working for RPF checks
> > > because connected routes are not in the MRIB.
> > >
> > > (Of course, all IGPs have essentially the same problem, so we need
> > > controlled RIB<>MRIB route exchange and/or MT support in OSPF & IS-IS.)
>
>
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