Weird ping times

[Karan Gupta]

Hi
   I have a router setup with fBSD
#### uname output ########
FreeBSD aaa.xxx.com 5.4-RELEASE FreeBSD 5.4-RELEASE #0: Wed May 25 
15:08:04 PDT 2005     root@:/usr/src/sys/i386/compile/EFKERNEL  i386

When i ping this machine from different networks i get the following timings

Reply from xxx.aaa.bbb.ccc: bytes=32 time=187ms TTL=49
Reply from xxx.aaa.bbb.ccc: bytes=32 time=1688ms TTL=49
Reply from xxx.aaa.bbb.ccc: bytes=32 time=251ms TTL=49
Reply from xxx.aaa.bbb.ccc bytes=32 time=1696ms TTL=49
Reply from xxx.aaa.bbb.ccc: bytes=32 time=181ms TTL=49
Reply from xxx.aaa.bbb.ccc: bytes=32 time=1626ms TTL=49
Reply from xxx.aaa.bbb.ccc: bytes=32 time=93ms TTL=49
Reply from xxx.aaa.bbb.ccc: bytes=32 time=1474ms TTL=49
Reply from xxx.aaa.bbb.ccc: bytes=32 time=82ms TTL=49
Reply from xxx.aaa.bbb.ccc: bytes=32 time=1504ms TTL=49
Reply from xxx.aaa.bbb.ccc: bytes=32 time=92ms TTL=49
Reply from xxx.aaa.bbb.ccc: bytes=32 time=1544ms TTL=49
Reply from xxx.aaa.bbb.ccc: bytes=32 time=97ms TTL=49
Reply from xxx.aaa.bbb.ccc: bytes=32 time=1033ms TTL=49
Reply from xxx.aaa.bbb.ccc: bytes=32 time=79ms TTL=49
Reply from xxx.aaa.bbb.ccc: bytes=32 time=1593ms TTL=49
Reply from xxx.aaa.bbb.ccc: bytes=32 time=188ms TTL=49
Reply from xxx.aaa.bbb.ccc: bytes=32 time=1766ms TTL=49
Reply from xxx.aaa.bbb.ccc: bytes=32 time=207ms TTL=49
Reply from xxx.aaa.bbb.ccc: bytes=32 time=1464ms TTL=49
Reply from xxx.aaa.bbb.ccc: bytes=32 time=91ms TTL=49
Reply from xxx.aaa.bbb.ccc: bytes=32 time=1678ms TTL=49
Reply from xxx.aaa.bbb.ccc: bytes=32 time=137ms TTL=49

Alternate good and bad times!!! I rebooted the machine to no effect. The 
problem seems to go away on its own for a few hours & then comes back. I 
ran tcpdump & saw nothing different between the times this behaviour was 
seen & the times it wasnt.

The machine is running IPFW, isc-dhcp server and nat.


Any thoughts??