[cisco-bba] cpu load due to PPP IPCP (Add Route)

[Tassos Chatzithomaoglou]

Today we had the cpu of one of our 7200's reaching 100%. We found that this was due to the "IPCP 
Skipped - Add Route:" which was constantly increasing (we supply routes per user through radius). 
After we did a "clear ppp queue", it returned to normal.

Any idea what might have happened?

router#sh proc cpu sorted | e 0.00
CPU utilization for five seconds: 99%/70%; one minute: 99%; five minutes: 99%
  PID Runtime(ms)   Invoked      uSecs   5Sec   1Min   5Min TTY Process
   77    14284408   3108213       4595 20.47% 21.03% 21.11%   0 PPP IPCP         <---
  163    84786456   2270413      37344  1.86%  0.79%  0.64%   0 VTEMPLATE Backgr
  148    75342260   4779805      15762  1.19%  0.76%  0.76%   0 IGMP Input
  150    92048440  14330863       6423  1.12%  1.02%  1.00%   0 PIM Process
   31    42891736   4708264       9109  1.12%  0.42%  0.38%   0 Per-Second Jobs
  156    32672884 184875306        176  1.04%  1.03%  1.04%   0 PPP Events
   79    84550988   7024517      12036  0.97%  0.69%  0.67%   0 CEF process
  129    48902960    889685      54966  0.59%  0.53%  0.53%   0 Compute load avg
   50    56443568 247614090        227  0.29%  0.38%  0.37%   0 IP Input
    5    32496292   1692766      19197  0.22%  0.17%  0.22%   0 Check heaps
  167    18315212  18625936        983  0.22%  0.21%  0.24%   0 OSPF Router
   63     4082388   5244432        778  0.14%  0.12%  0.11%   0 IP Background
  160     1580920 997329231          1  0.14%  0.04%  0.01%   0 SAA Event Proces
   76     9643460   1590124       6064  0.07%  1.58%  1.62%   0 PPP IP Route


router#sh ppp queues

5 Event Queues
                  size   max      kicks     starts    false   suspends ticks(ms)
  1 PPP Events       0     9      27514      27512        7          0        20
  5 PPP Bind         0     2        445        445        0          0        20
  3 PPP IPCP         0     0          0          0        0          0        20
  2 PPP IP Route     0     3        226        226        0          0       100
  4 PPP Hooks        0     1          1          1        0          0        20

  30 Events
  #  Q Name                 Events   Queued  MaxQueued Suspends  usec/evt max/evt
  1  1 Setup                     1        0        1        0       654       654
  2  1 Free PPP                661        0        3        0       111      3172
  3* 1 Timer                 28072 4294967290 4294967295        1      1047      9575
  4  1 Cstate                   18        0        3        0      1041      4249
  5  1 Restart CP                0        0        0        0         0         0
  6    UNREGISTERED
  7  1 Hard Disc               409        0        2        0       893      2466
  8  1 Soft Disc                77        0        2        2      3174      9366
  9  1 Packet                    2 4294967294 4294967295        0       380       475
10  1 Auth Packet               0        0        0        0         0         0
11* 3 IPCP Packet               0        0        0        0         0         0
12* 2 Add Route                 0        0        0        0         0         0
13* 2 Remove Route            247        0        3        0       293      1358
14* 2 Remove Top                0        0        0        0         0         0
15* 2 Remove Flag               0        0        0        0         0         0
16* 2 Neg Addr Add              0        0        0        0         0         0
17* 2 Neg Addr Remov            0        0        0        0         0         0
18* 2 DHCP Opt Add              0        0        0        0         0         0
19* 2 DHCP Opt Del              0        0        0        0         0         0
20* 2 IPCP UP                   0        0        0        0         0         0
21  1 Set LCP Open            448        0        2        0       497      1794
22  1 Virtualize                0        0        0        0         0         0
23  1 Redirect                  0        0        0        0         0         0
24  1 Forwarded                 1        0        1        0       317       317
25  4 Hook                      1        0        1        0        17        17
26  1 AAA Response              3        0        2        0       994      1568
27  1 Static Bind               1        0        1        0       379       379
28  5 Dynamic Bind            448        0        2        0       585      1893
29  1 Bound                     0        0        0        0         0         0
30  1 Virtual Profil            0        0        0        0         0         0

Pre-processed Requests  LCP:         0  IPCP:         0
PPP Request Failures: 0
PPP Hold Queue Drops: 14248
IPCP Skipped - Add Route:         545  AddrAdd:         0  AddrRem:         0
PPP Handles:  alloc[5719489] free[5717015] outstanding[2474]