Re: Best way to have redundancy announcing on separate routers

[Tom Beecher <beecher () beecher cc>]

Jean-

Thanks. Many BGP implementations have the ability to do conditional
advertisements, where you announce (or don't) a set of prefixes based on
the presents (or absence) of other routes. I don't think quagga does
natively, and not sure if VyOS has added that on.

Conceptually, you want to be doing "announce these prefixes from this
router only if I don't see routes from the upstream on the other router".
The 'safest' way is probably to just monitor default, but it depends on
your environment.




On Fri, Dec 27, 2024 at 6:09 PM Jean Franco <jfranco () maila inf br> wrote:

> Hi Tom,
> This is exactly what I was planning.
> I'm announcing a block via ISP1 and another set of blocks via ISP2, and
> have iBGP running between them.
>
> Thanks a lot!!
>
> Best regards,
>
>
>
>
>
>
>
> On Fri, Dec 27, 2024 at 1:00 PM Tom Beecher <beecher () beecher cc> wrote:
>
> > Jean-
> >
> > Yeah, don't worry about people complaining.
> >
> > Is this an accurate description of what you are trying to achieve?
> >
> > - Have 2 different sets of prefixes that you announce. Set A via
> > router1/ISP1 , Set B via router2/ISP2
> > - If BGP to one of your ISPs goes down, start announcing those prefixes
> > to the other ISP. ( Example, if ISP2 goes down, start announcing prefix Set
> > B over ISP1 )
> >
> > On Thu, Dec 26, 2024 at 8:16 AM Jean Franco <jfranco () maila inf br> wrote:
> >
> > > Hi guys,
> > > I've been on the list for as long as I cannot even remember.
> > > So just you know, I'm not new at this.
> > >
> > > This is no easy task, that's why I came here looking for help.
> > > I'm sorry if I brought anguish to the experts on the list!
> > > I thought I could bring something that someone may have
> > > experienced before.
> > >
> > > I haven't solved this yet, but at least I've received some
> > > valuable suggestions and I Thank you!
> > >
> > > About all the details of the connections, numbers of peerings, PNI's and
> > > IXP's I have left them out, since I figured this additional information
> > > could make things worse.
> > >
> > > ISP 1 <router01> ====20KM====<Router>====20KM====<router02> ISP2
> > >
> > > The ISP connections are all 10G.
> > > I don't believe these routers are DFZ capable.
> > > All the routers are well capable and already receive the full routes.
> > > The connections between these routers are 40G.
> > >
> > > Best regards,
> > >
> > >
> > > On Thu, Dec 26, 2024 at 12:53 AM Bryan Fields <Bryan () bryanfields net>
> > > wrote:
> > >
> > > > On 12/25/24 6:18 PM, Randy Bush wrote:
> > > > > where does one go for is-is help?  the mtu issie can be painful!!!
> > > >
> > > > I think here would be good too.  I recently had to do this between a
> > > > Cisco
> > > > 3945e and a Juniper, and from my unrevised notes:
> > > >
> > > > vlan {
> > > >   unit 405 {
> > > >     family iso {
> > > >     # holy shit this is important.  CISCO and Juniper will not talk
> > > > unless the
> > > > MTU is set
> > > >         mtu 1492;
> > > >       }
> > > >    }
> > > > }
> > > >
> > > > :-)
> > > >
> > > > --
> > > > Bryan Fields
> > > >
> > > > 727-409-1194 - Voice
> > > > http://bryanfields.net