Frank,
No PPPoE here but you're thinking along the right track. I have about
1200 PVCs configured for RBE DSL termination on the 3660. The best
design I can think of would have been VTIs or some other template
mechanism, one per speed package we offer. Unfortunately this is what I
inherited. ADSL is being phased out and being replaced with FTTH and
ADSL2+ on distributed IP DSLAMs instead of centralized routers in the
core. These routers will breathe easier when the DSL load is taken off
of them.
Slightly off-topic but still related is a problem I first encountered a
couple years ago. RANCID can help alert you to a low memory problem if
you know what signs to look for. This same 3660 started generating
RANCID diffs every day or two. A PVC or 2 would disappear and then
reappear the next time RANCID ran. It was always there when I checked
by hand (sh run int ATMa/b.xyz). I figured it was a fluke, that perhaps
RANCID couldn't handle configs this big. I ignored the diffs for
months, even setting up Outlook to mark diffs related to that router as
read. Over time the number of PVCs disappearing and reappearing grew
larger, up to hundreds at a time. The time between occurences also
shortened until it happened on every RANCID run. The router was running
fine so we never gave it a second thought. One day the router was
reported as down in RANCID. I checked and the router was still up.
However I could not do a sh run; it just returned me to the command
prompt. I figured out then what was going on. The router was running
out of RAM. I tried all sorts of methods of getting the config, dumping
it to tftp, etc before our scheduled maintenance window (just in case).
Nothing worked. About 4 hours before the window the router went
offline. Once onsite I consoled in and found that OSPF had died (not
enough RAM). I rebooted without writing (which I was sure would jack
the config if I wrote it). It came up and ran ok. I diffed the current
config against one a few months back and found I was missing about 12k
lines of config. Woo! I spent the rest of the morning pasting in
config from a RANCID diff over a year old (before the problem first
showed up). It worked but seriously screwed up our carrier system. The
field techs spent most of the day driving around and resetting cards
manually.
I've since seen this exact problem come up twice now with 2 completely
unrelated pieces of equipment. Both had a memory leak. I managed to
reboot them without incident since I caught the problem so quickly. So,
to make a long story short, if you see anything like what I describe
above DO NOT WRITE THE CONFIG and schedule a maintenance window for a
reboot ASAP. Learn from my mistake.
Justin
Post by Frank Bulk - iNAMEI'm guess you're terminating PPPoX on there: have you looked into the range
command to slim down the config a bit? Or is that not possible with your
requirements?
Frank
-----Original Message-----
Sent: Sunday, January 27, 2008 3:11 PM
To: shane Haslem
Subject: [rancid] Re: High CPU Utilization on routers during Rancid capture
Of course. I have 2 3660s and one 7206 (G1) that spike at 100% every
hour on the hour. It's not RANCID's fault. It happens anytime I do a
sh run. The 7206 has about 13k lines in its config. One 3660 has just
under 6k lines. The other 3660 has over 17k config lines. That 3660's
load stays at 100% for well over a minute. A high load is expected
given the sheer size of the config. SSH has a higher load than telnet
of course but that's no reason to not use SSH.
Justin
Post by shane HaslemHi all,
Can anyone advise if they have experienced high CPU Utilization on
routers during config capture, I am using SSH to login, would this be a
factor?
Regards
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