[dev] Issue with route-map on route-reflector?

[Daniel Walton]

Give "bgp route-reflector allow-outbound-policy" a try

Daniel

On Mon, Aug 21, 2017 at 12:54 PM, François Serman <
francois.serman at corp.ovh.com> wrote:

> Hi,
>
> First of all, I hope this is the appropriate ML :)
>
> I have an issue with route-map applied to reflected route, in the
> following scheme:
>
> A [ exaBGP ] --- advertises prefixes ---> B [ FRR ] --- appends attributes
> ----> C [ FRR ]
> 10.1.0.1                                                     10.2.0.1
>                                           10.3.0.254
>
>
> A advertises prefixes (1.1.1.1-24/32 with next hop 1.2.3.4).
> B is supposed to set a community (I've added local-pref and changed the
> next-hop to make for tests purposes).
> C is supposed to have an aggregated view of the prefixes decorated with
> the communities.
>
> My issue is : A's advertised-routes output seems OK (next hop, local pref)
> but only the local network (as in bgp router id block) is actually changed.
>
> I didn't find anything in the documentation about that. I've only found a
> mention in the cisco documentation (https://www.cisco.com/c/en/
> us/td/docs/ios-xml/ios/iproute_bgp/configuration/xe-
> 3s/irg-xe-3s-book/configuring_internal_bgp_features.html) :
>
> "The use of set clauses in outbound route maps can modify attributes and
> possibly create routing loops. To avoid this behavior, most set clauses of
> outbound route maps are ignored for routes reflected to iBGP peers. The
> only set clause of an outbound route map on a route reflector (RR) that is
> acted upon is the set ip next-hop clause. The set ip next-hop clause is
> applied to reflected routes. "
>
> Is there something I'm missing?
> Also, I've been checking who was right using tcmdump, attached to this
> email.
>
> Here is B's config:
>
> router bgp 65001
>  bgp router-id 10.2.0.1
>  bgp log-neighbor-changes
>  neighbor my_route_advertisers peer-group
>  neighbor my_route_reflectors peer-group
>  neighbor my_route_reflectors remote-as internal
>  neighbor my_route_reflectors description route-forwarder
>  neighbor 10.3.0.254 remote-as 65001
>  neighbor 10.3.0.254 peer-group my_route_advertisers
>  neighbor 10.1.0.1 peer-group my_route_reflectors
>  !
>  address-family ipv4 unicast
>   network 192.168.21.0/24
>   neighbor my_route_advertisers route-map deny-in in
>   neighbor my_route_reflectors route-reflector-client
>   neighbor my_route_reflectors route-map deny-out out
>   neighbor 10.3.0.254 route-map apply-community out
>  exit-address-family
>  vnc defaults
>   response-lifetime 3600
>   exit-vnc
> !
> route-map apply-community permit 10
>  set community 65001:1010
>  set ip next-hop 8.8.8.8
>  set local-preference 10
> !
> route-map deny-in deny 5
> !
> route-map deny-out deny 5
>
>
>
> and its advertised routes:
>
> # sh ip bgp neighbors 10.3.0.254 advertised-routes
> BGP table version is 25, local router ID is 10.2.0.1
> Status codes: s suppressed, d damped, h history, * valid, > best, =
> multipath,
>               i internal, r RIB-failure, S Stale, R Removed
> Origin codes: i - IGP, e - EGP, ? - incomplete
>
>    Network          Next Hop            Metric LocPrf Weight Path
> *> 1.1.1.1/32       8.8.8.8                  0     10      0 i
> ....
> *> 1.1.1.24/32      8.8.8.8                  0     10      0 i
> *> 192.168.21.0     8.8.8.8                  0     10  32768 i
>
> Total number of prefixes 25
>
>
> And now, C's config:
>
> router bgp 65001
>  bgp router-id 10.3.0.254
>  bgp log-neighbor-changes
>  neighbor my_route_advertisers peer-group
>  neighbor my_route_reflectors peer-group
>  neighbor my_route_reflectors remote-as internal
>  neighbor my_route_reflectors description route-forwarder
>  neighbor 10.4.0.254 remote-as 65001
>  neighbor 10.4.0.254 peer-group my_route_advertisers
>  neighbor 10.2.0.1 peer-group my_route_reflectors
>  neighbor 10.2.0.2 peer-group my_route_reflectors
>  !
>  address-family ipv4 unicast
>   neighbor my_route_advertisers route-map deny-in in
>   neighbor my_route_reflectors route-reflector-client
>   neighbor my_route_reflectors route-map deny-out out
>   neighbor 10.2.0.1 soft-reconfiguration inbound
>  exit-address-family
>  vnc defaults
>   response-lifetime 3600
>   exit-vnc
> !
> route-map deny-in deny 5
> !
> route-map deny-out deny 5
>
>
> rr# show ip bgp neighbors 10.2.0.1 received-routes
> BGP table version is 0, local router ID is 10.3.0.254
> Status codes: s suppressed, d damped, h history, * valid, > best, =
> multipath,
>               i internal, r RIB-failure, S Stale, R Removed
> Origin codes: i - IGP, e - EGP, ? - incomplete
>
>    Network          Next Hop            Metric LocPrf Weight Path
> *> 1.1.1.1/32       1.2.3.4                  0    100      0 i
> .....
> *> 1.1.1.24/32      1.2.3.4                  0    100      0 i
> *> 192.168.21.0     8.8.8.8                  0     10      0 i
>
> Total number of prefixes 25
>
> Thanks!
>
> François
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