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Netflow problem

  • From: Yannick Le Teigner
  • Date: Thu Apr 13 09:50:50 2000

Hi,

I have a little problem setting up Netflow on routers.
It seems like the timeout to remove unactive flow from the cache is too
low(15"), and I can't set it to a bigger value (say 5 minutes).

A good example is the bgp session. Depending on the time I execute a "show
ip cache flow", the bgp session is seen active or not, although it is always
active!
The problem is that if the router doesn't see any data on a flow during 15
seconds, it considers it unactive.

I included two outputs of "show ip cache flow" to show you the problem.

Thank you for any help!
-Yannick

---------------------------------------------------------------------
without bgp session seen as active (although it is!)
---------------------------------------------------------------------
>#show ip cache flow
IP packet size distribution (89333 total packets):
   1-32   64   96  128  160  192  224  256  288  320  352  384  416  448 
480
   .000 .306 .240 .422 .008 .003 .004 .000 .001 .000 .000 .000 .000 .000
.000

    512  544  576 1024 1536 2048 2560 3072 3584 4096 4608
   .000 .000 .009 .000 .000 .000 .000 .000 .000 .000 .000

IP Flow Switching Cache, 4456704 bytes
  1 active, 65535 inactive, 15172 added
  603804 ager polls, 0 flow alloc failures
  Active flows timeout in 10 minutes
  last clearing of statistics 1w1d
Protocol         Total  Flows   Packets Bytes  Packets Active(Sec) Idle(Sec)
--------         Flows   /Sec     /Flow  /Pkt     /Sec     /Flow     /Flow
TCP-Telnet          33    0.0        68    41      0.0      42.7      13.9
TCP-BGP          15053    0.0         5    93      0.1      23.9      15.4
UDP-other            3    0.0         6    74      0.0       9.9      15.9
ICMP                84    0.0        26    98      0.0       2.6      15.6
Total:           15173    0.0         5    92      0.1      23.9      15.4

SrcIf         SrcIPaddress    DstIf         DstIPaddress    Pr SrcP DstP 
Pkts
Fa1/0/0       ???.7.34.2       Local         ???.0.140.130    06 0CC5 0017  
94


----------------------------------------------------------------------
with bgp session seen as ative
----------------------------------------------------------------------
>#show ip cache flow
IP packet size distribution (89638 total packets):
   1-32   64   96  128  160  192  224  256  288  320  352  384  416  448 
480
   .000 .308 .239 .421 .008 .003 .004 .000 .001 .000 .000 .000 .000 .000
.000

    512  544  576 1024 1536 2048 2560 3072 3584 4096 4608
   .000 .000 .009 .000 .000 .000 .000 .000 .000 .000 .000

IP Flow Switching Cache, 4456704 bytes
  2 active, 65534 inactive, 15179 added
  604112 ager polls, 0 flow alloc failures
  Active flows timeout in 10 minutes
  last clearing of statistics 1w1d
Protocol         Total  Flows   Packets Bytes  Packets Active(Sec) Idle(Sec)
--------         Flows   /Sec     /Flow  /Pkt     /Sec     /Flow     /Flow
TCP-Telnet          35    0.0        72    41      0.0      42.7      14.0
TCP-BGP          15057    0.0         5    93      0.1      23.9      15.4
UDP-other            3    0.0         6    74      0.0       9.9      15.9
ICMP                84    0.0        26    98      0.0       2.6      15.6
Total:           15179    0.0         5    92      0.1      23.9      15.4

SrcIf         SrcIPaddress    DstIf         DstIPaddress    Pr SrcP DstP 
Pkts
Fa1/0/0       ???.7.34.2       Local         ???.0.140.130    06 0CC5 0017  
118
Fa1/0/0       ???.0.140.129    Local         ???.0.140.130    06 A34A 00B3  
2

The flow from the ???.0.140.129 is the bgp session.





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