[c-nsp] High CPU due to BGP Router process after changing BGP neighbor descriptions

[Clinton Work]

Has anyone seen the following behavior before?

Updated the BGP neighbor descriptions for roughly 25 peers at once:
conf t
router bgp NNNN
neighbor x.x.x.x description ...
neighbor y.y.y.y description ...
... (other 23)
end
write

After making the description changes the CPU on the GRP was pegged at 99% 
for over 15 minutes. The GSR is running 12.0(25)S3.

router# show proc cpu | BGP Router|1Min
PID Runtime(ms)   Invoked      uSecs   5Sec   1Min   5Min      TTY Process
163    67304608  48727901       1381  95.24% 95.20% 70.34%   0 BGP Router

Looks like updating the BGP neighbor descriptions caused IOS to flush
the BGP tables for each peer and rebuild them. Notice how the table version
for many of the peers is zero. The router worked through all the peers
until the table versions returned to normal. After the table version
updates were complete the BGP Router CPU utilization returned to normal as well.


"show ip bgp sum" output during high CPU utilization:

Neighbor        V    AS MsgRcvd MsgSent   TblVer  InQ OutQ Up/Down  State/PfxRcd
x.x.x.x         4 NNNNN  112815  122506        0    1    0 2d12h          23
x.x.x.x         4 NNNNN  227004  234546        0    0    0 2w3d          129
x.x.x.x         4 NNNNN  178672  122095        0    0    0 10w4d        6030
x.x.x.x         4 NNNNN  187098  122206        0    0    0 5w4d         2450
x.x.x.x         4 NNNNN 7712421  594845        0   15    0 10w6d      132384
x.x.x.x         4 NNNNN 7600928  581011        0   20    0 10w6d      132384
x.x.x.x         4 NNNNN  112409  594096        0    0    0 3w4d            0
x.x.x.x         4 NNNNN       0       0        0    0    0 never    Idle
x.x.x.x         4 NNNNN  446905  121754        0    1    0 11w1d       16860
x.x.x.x         4 NNNNN   84950   79027        0    0    0 3d16h        2437
x.x.x.x         4 NNNNN  225290  234390        0    1    0 11w1d          24
x.x.x.x         4 NNNNN  249884  234537        0    0    0 1w4d         3686
x.x.x.x         4 NNNNN  114817  122002        0    1    0 8w3d          459
x.x.x.x         4 NNNNN  268480  234147        0    1    0 11w1d        1209
x.x.x.x         4 NNNNN  322976  234559 33385307    2    0 1w2d         7508
x.x.x.x         4 NNNNN  125838  122059 33385307    0    0 8w4d         1373
x.x.x.x         4 NNNNN  114889  122184 33385307    1    0 11w1d         977
x.x.x.x         4 NNNNN       0       0        0    0    0 never    Idle 
x.x.x.x         4 NNNNN  141576  122079 33385307    0    0 11w1d        3160
x.x.x.x         4 NNNNN  377547  125053 33385307    0    0 2d17h        3281
x.x.x.x         4 NNNNN       0       0        0    0    0 never    Idle 
x.x.x.x         4 NNNNN  244772  122013 33385307   14    0 11w1d        8567
x.x.x.x         4 NNNNN  225580  234830 33385307    1    0 8w3d           80
x.x.x.x         4 NNNNN  128156  121825 33385307    1    0 1w5d         2453
x.x.x.x         4 NNNNN  225327  234871 33385307    1    0 1w4d           17
x.x.x.x         4 NNNNN  225310  234870 33385307    1    0 1w4d           17
x.x.x.x         4 NNNNN  230653  234431 33385307    1    0 11w1d        1409


-- 
===================================================
Clinton Work	clinton at scripty.com
Calgary, AB