<div dir="ltr"><div>Yep, you're right, Alexander. Thanks a lot for your feedback!</div><div><br></div><div>- <br></div><div>Roman.<br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Mon, Jan 21, 2019 at 2:16 PM Alexander Zubkov <<a href="mailto:green@qrator.net">green@qrator.net</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">But than it'll be replaced on the router1 and it will withdraw the<br>
announce, and so on...<br>
<br>
On Mon, Jan 21, 2019 at 7:38 PM Roman Romanyak <<a href="mailto:roman.romanyak@gmail.com" target="_blank">roman.romanyak@gmail.com</a>> wrote:<br>
><br>
> I'd like to do a route manipulation on the route server and send a route back also to router1 with a local pref via ISP1.<br>
><br>
> On Sat, Jan 19, 2019 at 2:43 AM Alexander Zubkov <<a href="mailto:green@qrator.net" target="_blank">green@qrator.net</a>> wrote:<br>
>><br>
>> Hi,<br>
>><br>
>> Thank you for a good description. But what's your problem there now?<br>
>> You receive x.y.z.0/24 from Router1 and send it to Router2. What do<br>
>> you want to achive and are missing?<br>
>><br>
>> On Fri, Jan 18, 2019 at 9:13 PM Roman Romanyak <<a href="mailto:roman.romanyak@gmail.com" target="_blank">roman.romanyak@gmail.com</a>> wrote:<br>
>> ><br>
>> > Alexander, thank you for your feedback.<br>
>> ><br>
>> > Here is a diagram:<br>
>> ><br>
>> > [ ISP1 ] [ ISP2 ] [ ISP3 ] [ ISP4 ]<br>
>> > | | | |<br>
>> > | | | |<br>
>> > [ Router 1 ] [ Router 2 ]<br>
>> > | |<br>
>> > | |<br>
>> > [ Layer 2 Switch ]<br>
>> > |<br>
>> > |<br>
>> > [ Bird Route Server ]<br>
>> ><br>
>> ><br>
>> > Router 1 and 2 do not peer directly. There is OSPF running, so all nodes learn a route to other nodes connected interfaces.<br>
>> > Both routers peer to route-server and are route reflection clients.<br>
>> ><br>
>> > There is a route x.y.z.0/24 coming from from each ISP. Router 1 chooses ISP2 (because of as-path), what path Router 2 is choosing doesn't matter.<br>
>> ><br>
>> > I need to force traffic to x.y.z.0/24 via ISP1.<br>
>> > In order to do that, I'm matching the route x.y.z.0/24 in the import filter on the route-server (maching a route itself and also ISP1 ASN in the path) and setting the local preference to 150.<br>
>> > Then this route is re-advertised to Router 2, which will select it as best, because of iBGP and high local-preference. The route is not announced back to Router 1, because it came from there.<br>
>> ><br>
>> > An alternative way, to do that is to mach a route on Router 1, increase a local-pref there and that route will be leared by router 2 through the route-server. But I'd like to do that on route-server to use a centralized place for these kinds of things.<br>
>> ><br>
>> > Here is a show route output from a route server:<br>
>> ><br>
>> ><br>
>> > bird> show route for x.y.z.0/24 all<br>
>> > x.y.z.0/24 via 10.1.1.65 on em2 [edge_r1 18:25:09] * (100/11) [AS123i]<br>
>> > Type: BGP unicast univ<br>
>> > BGP.origin: IGP<br>
>> > BGP.as_path: 111 888 333 999<br>
>> > BGP.next_hop: 1.1.1.1<br>
>> > BGP.med: 0<br>
>> > BGP.local_pref: 150<br>
>> > via 10.1.1.65 on em2 [edge_r1 2019-01-17] (100/11) [AS123i]<br>
>> > Type: BGP unicast univ<br>
>> > BGP.origin: IGP<br>
>> > BGP.as_path: 222 777 999<br>
>> > BGP.next_hop: 2.2.2.2<br>
>> > BGP.med: 0<br>
>> > BGP.local_pref: 100<br>
>> > via 10.1.1.66 on em2 [edge_r2 2019-01-16] (100/11) [AS123i]<br>
>> > Type: BGP unicast univ<br>
>> > BGP.origin: IGP<br>
>> > BGP.as_path: 333 666 999<br>
>> > BGP.next_hop: 3.3.3.3<br>
>> > BGP.med: 0<br>
>> > BGP.local_pref: 100<br>
>> > via 10.1.1.67 on em2 [edge_r2 2019-01-17] (100/11) [AS123i]<br>
>> > Type: BGP unicast univ<br>
>> > BGP.origin: IGP<br>
>> > BGP.as_path: 444 555 999<br>
>> > BGP.next_hop: 4.4.4.4<br>
>> > BGP.med: 0<br>
>> > BGP.local_pref: 100<br>
>> ><br>
>> > bird><br>
>> ><br>
>> ><br>
>> ><br>
>> ><br>
>> ><br>
>> ><br>
>> > On Fri, Jan 18, 2019 at 2:17 PM Alexander Zubkov <<a href="mailto:green@qrator.net" target="_blank">green@qrator.net</a>> wrote:<br>
>> >><br>
>> >> Hi,<br>
>> >><br>
>> >> I do not completely understand your setup. You better show route<br>
>> >> tables from all the routers and what is announced in which direction.<br>
>> >><br>
>> >> > So I get the desired effect on the second router, it will learn and install a route with high local pref. The first router where the desired transit link is connected by default selects another transit link because of the shorter as-path.<br>
>> >><br>
>> >> How this could happen? If you got this route on the route reflector<br>
>> >> from the first router, than it should have this route in the required<br>
>> >> direction. If it had this route to another transit link, it would<br>
>> >> announce this to the route reflector. There is no reason to propagate<br>
>> >> the routes back to the peer, because they are already there.I think<br>
>> >> you can do some tricks, but first we need to understand what do you<br>
>> >> want to achieve.<br>
>> >><br>
>> >> On Fri, Jan 18, 2019 at 7:23 PM Roman Romanyak <<a href="mailto:roman.romanyak@gmail.com" target="_blank">roman.romanyak@gmail.com</a>> wrote:<br>
>> >> ><br>
>> >> > Hello Bird users,<br>
>> >> ><br>
>> >> > Does anyone know if there is a way to announce a BGP route back to the router it was received from.<br>
>> >> > I need to do this for the following scenario.<br>
>> >> > Lets say there are two routers with 2 transit links on each with full view tables and Bird server as a route-reflector. There is a need to force traffic to a specific destination via one of the ISPs, so I match the route in the import filter and set a local pref on it. But that will only make the route server announce the route with a high local pref to a second router, where the desired transit isn't directly connected. So I get the desired effect on the second router, it will learn and install a route with high local pref. The first router where the desired transit link is connected by default selects another transit link because of the shorter as-path.<br>
>> >> ><br>
>> >> > Here is the import filter snippet (x.y.z.0/24 is a dest route, as-path 1234 is a directly connected ISP on router-1:<br>
>> >> ><br>
>> >> > if source = RTS_BGP && net = x.y.z.0/24 && bgp_path.first = 1234 then {<br>
>> >> > bgp_local_pref = 150;<br>
>> >> > accept;<br>
>> >> > }<br>
>> >> ><br>
>> >> > I think that bird doesn't do that because the protocol matches on the peer and on the route.<br>
>> >> ><br>
>> >> ><br>
>> >> > Thanks!<br>
</blockquote></div>