[j-nsp] BGP troubleshooting

[Campbell, Alex]

Hi all,

 

We have run into a BGP issue bringing up a new ISP on our J4350s and I
have been struggling to figure out what's going on.  If anyone has any
troubleshooting suggestions or ideas as to what might be doing wrong, I
would be most grateful.

 

We have two border routers, each connected to a separate port with the
same ISPs.  The interface IPs on those ports are

border1: 1.1.1.1.76/29 

border2: 1.1.1.1.77/29

 

border1 is configured to bring up a multihop BGP session with ISP's
router at 2.2.2.2.  We have added a static route on border1 to
2.2.2.2/32 with a next-hop of 1.1.1.1.73.  This works correctly and
border1 receives a full table of around 251,000 routes.

 

border2 is configured to bring up a multihop BGP session with ISP's
router at 3.3.3.3.  We have added a static route on border2 to
3.3.3.3/32 with a next-hop of 1.1.1.1.73.

 

The problem is that when we allow border2 to bring up its BGP session
with the ISP router, the session comes up successfully but the device
receives 0 routes from the ISP router, and we lose complete internet
connectivity.

 

This is what we see on border2 after bringing up the session:

 

=============================================================

 

alex at border2# run show bgp summary

Groups: 2 Peers: 2 Down peers: 0

Table          Tot Paths  Act Paths Suppressed    History Damp State
Pending

inet.0            250985     250972          0          0          0
0

Peer               AS      InPkt     OutPkt    OutQ   Flaps Last Up/Dwn
State|#Active/Received/Damped...

5.5.5.1    24438      67593        103       0       0       43:56
250972/250985/0      0/0/0

3.3.3.3   9443          1          4       0       0          20 0/0/0
0/0/0

=============================================================

 

Here's an example traceroute of what happens from a machine on our
network after we bring up border2's BGP session to ISP:

 

=============================================================

 

C:\Users\a>tracert www.google.com.au

 

Tracing route to www.l.google.com [209.85.171.147]

over a maximum of 30 hops:

 

  1    <1 ms    <1 ms    <1 ms  red2.fw1.mel1.x.com.au [6.6.6.1]

  2    23 ms    28 ms    29 ms  border2 [5.5.5.35]

  3    23 ms    29 ms    29 ms  ge-0-0-2.border1.mel1.x.com.au
[5.5.5.17]

  4     1 ms     1 ms     1 ms  075.196.idc.ourisp.net.au [1.1.1.1.75]

  5     *        *        *     Request timed out.

  6     *        *        *     Request timed out.

  7     *        *        *     Request timed out.

  8     *        *        *     Request timed out.

 

=============================================================

 

Here's an example of what happens from a machine on our network after we
shutdown border2's BGP session to ISP:

 

C:\Users\a>tracert www.google.com.au


 

Tracing route to www.l.google.com [209.85.171.103]

over a maximum of 30 hops:

 

  1    <1 ms    <1 ms    <1 ms  red2.fw1.mel1.x.com.au [6.6.6.1]

 

  2    27 ms    29 ms    29 ms  border2 [5.5.5.35]

  3    25 ms    29 ms    18 ms  ge-0-0-2.border1.mel1.x.com.au
[5.5.5.17]

  4     1 ms     1 ms     1 ms  075.196.idc.ourisp.net.au [1.1.1.1.75]

  5     1 ms     1 ms     1 ms  ge4-15.sw02.mel.ourisp.net.au
[210.50.0.9]

  6   132 ms     2 ms     2 ms  210.50.233.202

  7   170 ms   170 ms   170 ms  p3-0.pr1-lax.primustel.com
[209.227.149.241]

  8   170 ms   173 ms   171 ms  g9-0.pr1-lax.primustel.com
[209.227.129.141]

  9   172 ms   172 ms   172 ms  209.227.129.62

 10   172 ms   174 ms   173 ms  core2-1-1-0.pao.net.google.com
[198.32.176.31]

 11   175 ms   175 ms   174 ms  216.239.49.250

 12   210 ms   198 ms   197 ms  216.239.47.186

 13   205 ms   189 ms   195 ms  216.239.46.211

 14   190 ms   192 ms   194 ms  64.233.174.97

 15   191 ms   200 ms   190 ms  209.85.251.141

 16   189 ms   190 ms   203 ms  74.125.31.134

 17   189 ms   191 ms   190 ms  cg-in-f103.google.com [209.85.171.103]

 

Trace complete.

 

=============================================================