[c-nsp] 7304-NSE100, 12.2(28), duplicated BGP paths

[Jakob Borg]

Hi all,

We have an issue I wonder if any of you recognize. It's hitting us on
peering routers (7304) running 12.2(27)SBC3 through 12.2(28)SB1 at least and
has to do with BGP paths.

These routers receive one or more full feeds and a number of peering feeds.
The problem is that BGP memory usage is continously increasing, until a
reload is necessary once every one or two months. The memory seems to be
allocated in the form of BGP paths that shouldn't be duplicated; a quick
"show ip bgp paths" and scroll down shows:

mlmo-krvg-pr0#sh ip bgp paths
Address    Hash Refcount Metric Path
...
0x567708E8    1        1      0 16150 12989 19151 23342 30686 2013 i
0x560A0B28    1        1      0 16150 12989 19151 23342 30686 2013 i
0x560A15D0    1        1      0 16150 12989 19151 23342 30686 2013 i
0x560A4D84    1        1      0 16150 12989 19151 23342 30686 2013 i
0x560A0C9C    1        1      0 16150 12989 19151 23342 30686 2013 i
0x560A3A24    1        1      0 16150 12989 19151 23342 30686 2013 i
...

which to my mind should be just one line with a refcount of 6. All external
connections are configured to set MED and local preference, to avoid any
possible reason there would be multiple similar paths. A summary shows the
path count slowly increasing, from somewhere around 200K to start with to
over 750K now:

  mlmo-krvg-pr0#sh ip bgp sum
  BGP router identifier 172.16.16.31, local AS number 15782
  BGP table version is 16071189, main routing table version 16071189
  194477 network entries using 21975901 bytes of memory
  572830 path entries using 29787160 bytes of memory
--> 753729/35019 BGP path/bestpath attribute entries using 81402732 bytes of
memory
  20 BGP rrinfo entries using 480 bytes of memory
  438821 BGP AS-PATH entries using 15757724 bytes of memory
  6965 BGP community entries using 394456 bytes of memory
  0 BGP route-map cache entries using 0 bytes of memory
  0 BGP filter-list cache entries using 0 bytes of memory
  BGP using 149318453 total bytes of memory
  BGP activity 590692/396214 prefixes, 8390049/7817218 paths, scan interval
60 secs

Any ideas why this is happening?

MVH,
Jakob, Perspektiv Bredband AB