[j-nsp] BGP full mesh or route reflector

[Olivier Benghozi]

In order to avoid this flap, just configure this from scratch on all your
routers during a planned work window:
set protocols bgp advertise-from-main-vpn-tables

https://www.juniper.net/documentation/us/en/software/junos/cli-reference/topics/ref/statement/advertise-from-main-vpn-table-edit-protocols-bgp.html

This way, no risk anymore.


Le sam. 6 déc. 2025 à 12:12, nsp--- via juniper-nsp <
juniper-nsp at puck.nether.net> a écrit :

> Hi,
>
> but please take into consideration that your iBGP Sessions will flap once
> you configure the first rr session on a box if you use vpn families:
>
> https://www.juniper.net/documentation/us/en/software/junos/bgp/topics/topic-map/bgp-session-flaps.html
>
> btw:
> We run 14 routers (MX204-960, peak was 25 devices) with a full table each
> in a full meshed setup (IS-IS/RSVP/MPLS, no SR).
> Works fine since many years and I remember no issue that a rr would have
> avoided.
> On the other side we already had issues (long time ago in an other setup
> with quagga rr and Catalyst 6500 + x86 routers) with a rr setup in which
> router A was not able to reach router B but both reached the RR.
> So I do not think that a full mesh is a no-go for small setups.
>
> kind regards
> Rolf
>
> On 05/12/2025 23:20, Aaron1 via juniper-nsp wrote:
> > Migrating to an RR design later would seem to add RR, full mesh to it,
> then one by one start moving routers to RR-client connections, til complete
> >
> > Aaron
> >
> >> On Dec 5, 2025, at 4:07 PM, Johan Borch via juniper-nsp <
> juniper-nsp at puck.nether.net> wrote:
> >>
> >> Thanks, this is a quite small network at the moment. Three edge routers
> >> (with full tables) and a bunch (9) PE routers (these will be able to
> handle
> >> full table). I guess my only option right now is to run RR on my three
> edge
> >> routers, not sure if that is a good idea.
> >>
> >> A bunch of virtual RRs sound like a good solution. But we can't add more
> >> cost at the moment, is it hard to migrate towards a RR design at a later
> >> stage?
> >>
> >> Johan
> >>
> >>> On Fri, Dec 5, 2025 at 3:39 PM Saku Ytti <saku at ytti.fi> wrote:
> >>>
> >>> I would generally recommend RR on anything more than 2 router setup.
> >>>
> >>> RR gives redundancy on the signalling path, one iBGP flap doesn't
> >>> cause an outage.
> >>>
> >>> With ORR and ADDPATH you're not really losing anything.
> >>>
> >>>> On Fri, 5 Dec 2025 at 14:36, Johan Borch via juniper-nsp
> >>>> <juniper-nsp at puck.nether.net> wrote:
> >>>>
> >>>> Hi!
> >>>>
> >>>> In an SR/MP-BGP underlay, will it have a significant impact on device
> >>>> performance if we use a full iBGP mesh instead of route reflectors or
> >>> other
> >>>> drawbacks? Let’s say we will end up with around 100 PE routers. These
> >>>> routers will not carry an excessive number of prefixes (no full
> tables).
> >>>> We can ignore the configuration part as configuration is
> auto-generated.
> >>>>
> >>>> Br
> >>>> Johan
>

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