North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: FW: TNT issues "workaround"
On Sat, 23 Aug 2003, Ross Chandler wrote: > > I seem to be having the same or similar problems with my Cisco boxes > > also , they either reboot or the pris hang , users get busy's but no > > one is logged in at all , when I do a show isdn status it shows b > > channels in use but no one on, the only way to fix is reboot the box , > > and it seems to be timed , everyday at 1400 and 2200 hours , since > > Monday anybody body heard of ciscos acting funny this week? > > Perhaps your fast switching route cache is filling up memory. If you're > willing to risk it enable CEF on all interfaces. Some of the older cisco access-servers don't even support CEF. The cisco failures seem to be memory starvation/fragmentation issues caused by out of control route-cache growth caused by the nachi worm's attempt to ping so many different hosts so quickly while looking for systems to spread to. You can work around the issue by: a) using policy routing to pass all dialup traffic through a route-map that sends 92 byte echo/echo-reply packets to null0. b) blocking all echo/echo-reply coming in from dial-up users (i.e. apply an input acl to your virtual-template and/or group-async interfaces). c) disabling route caching on the egress interface of the access server. I'm doing a mix of a (on the access-servers that this works on) and b where a doesn't work...and tested c this morning and found it appears to work. ---------------------------------------------------------------------- Jon Lewis *[email protected]*| I route System Administrator | therefore you are Atlantic Net | _________ http://www.lewis.org/~jlewis/pgp for PGP public key_________
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