[c-nsp] IOS XR 3.6.0 BGP next-hop to null 0 bug?

[Zhang Huanjie]

I am writing a simple bgp client and want use this client to send blacklist
prefix to router. My goal it to add and remove blackhole routes automatically.

First, I add static route 192.0.2.1/32 to null 0 in a router. Then
start my simple program
opening a bgp session and sending update to this router. The next hop
of are set
to 192.0.2.1.

My program works very well with cisco 6509 rung IOS 12.2(18)SXD, and
blacklist prefix is added to FIB,
here is the show results under 6509:

#show bgp
BGP table version is 31, local router ID is x.x.x.x
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
              S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete

   Network          Next Hop            Metric LocPrf Weight Path
*> 192.168.100.1/32 192.0.2.1                              0 i
*> 192.168.100.2/32 192.0.2.1                              0 i

#show ip route 192.0.2.1
Routing entry for 192.0.2.1/32
  Known via "static", distance 1, metric 0 (connected)
  Redistributing via ospf xxxx
  Advertised by ospf xxxx subnets
  Routing Descriptor Blocks:
  * directly connected, via Null0
      Route metric is 0, traffic share count is 1

While sending updates to a GSR 12404 running IOS XR 3.6.0, it seems
the router treate 192.0.2.1 always
as inaccessible. None of the prefix is add to FIB. Here is the show:

#show bgp 192.168.100.1
BGP routing table entry for 192.168.100.1/32
Versions:
  Process           bRIB/RIB  SendTblVer
  Speaker                  0           0
Paths: (1 available, no best path)
  Not advertised to any peer
  Path #1: Received by speaker 0
  Local
    192.0.2.1 (inaccessible) from x.x.x.x (x.x.x.x)
      Origin IGP, metric 20, localpref 100, valid, internal

#show ip route 192.0.2.1
Routing entry for 192.0.2.1/32
  Known via "static", distance 1, metric 0 (connected)
  Installed Jul 14 22:07:37.893 for 00:19:32
  Routing Descriptor Blocks
    directly connected, via Null0
      Route metric is 0
  No advertising protos.

#show bgp nexthops

Gateway Address Family: IPv4 Unicast
Table ID: 0xe0000000
Nexthop Count: 4
Critical Trigger Delay: 3000msec
Non-critical Trigger Delay: 10000msec

Nexthop Version: 1, RIB version: 1

Status codes: R/UR Reachable/Unreachable
              C/NC Connected/Not-connected
              L/NL Local/Non-local
              I    Invalid (Policy Match Failed)
Next Hop        Status          Metric        Notf      LastRIBEvent RefCount
192.0.2.1       [UR]        4294967295         1/0    00:19:58 (Cri)       10/19


Is this a bug of IOS XR?


Thanks

-- 
Zhang Huanjie    james at ustc.edu.cn
+86-551-3601897  13505693311
Network Information Center
University of Science and Technology of China