Drops in the input queue are only for process switched packets (there is
some exceptions, but given the next item it is pertinent). Since at the
snap-shot provided we have 8 packets in the queue, you probably have
something odd going on causing the packets to be punted to the CPU (and
thus high CPU load).
Are you missing a route?
Are the packets going to a local destination that doesn't exist, and you
are ARPing for the MAC address to send them too?
Are the packets destined for the router?
Do you have route-caching disabled on this interface, or the outgoing
interface for the destination traffic?
"ip route-cache same-interface" is only useful if you are on a 7500 with
distributed switching turn on on VIP's. Since this is a 7100 all the
processing is on the central CPU.
David
-----Original Message-----
From: George Robbins [mailto:grr@shandakor.tharsis.com]
Sent: Wednesday, August 01, 2001 7:07 AM
To: cisco-nsp@puck.nether.net; jcv@vbc.net
Subject: Re: [nsp] 7100 and small packets
I'm not sure that the CPU loading is your worst problem.
> Output queue 0/40, 0 drops; input queue 8/75, 1478 drops
The load realated packet loss is .0015% though it will be worse
at peak loading. Since this is input drops, it means packets
coming in more quickly than old ones can be sent out.
> 208760 input errors, 208760 CRC, 0 frame, 0 overrun, 0 ignored
> 0 watchdog, 0 multicast
> 103898 input packets with dribble condition detected
These suggest that you have an ethernet problem, possibly wiring
or perhaps a switch that's not 100% compatible as far as switching
modes or flow control, or is having loading problems on it's own.
In any case, you want to review the setting and error statistics
for the other end of the link.
As far as CPU utilization, if you're not using "ip route cache cef"
plus "ip route-cache same-interface" do it.
Generally if the router has lots of routes, as in an internet gateway,
you need to be using CEF, if it has only a few such as an internal
corporate network, then flow or normal (fast) cache will work about
as well.
George
> Date: Wed, 1 Aug 2001 14:44:14 +0100 (BST)
> From: Jean-Christophe Varaillon <jcv@vbc.net>
> Subject: [nsp] 7100 and small packets
>
> Hi,
>
> On a 100 M Full-duplex interface of a Cisco 7100, I receive some very
> small packet due to Games application and/or VOIP traffic.
>
> Because of this I have an abnormal CPU utilization rate.
> Therefore, I have some packet loss when I run somes ping.
>
> kg6.uk0#sho int fa0/0
> FastEthernet0/0 is up, line protocol is up
> Hardware is DEC21140A, address is 0003.3184.8800 (bia
0003.3184.8800)
> Internet address is 192.168.0.21/25
> MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,
> reliability 255/255, txload 11/255, rxload 13/255
> Encapsulation ARPA, loopback not set
> Keepalive set (10 sec)
> Full-duplex, 100Mb/s, 100BaseTX/FX
> ARP type: ARPA, ARP Timeout 04:00:00
> Last input 00:00:00, output 00:00:00, output hang never
> Last clearing of "show interface" counters 22:17:20
> Queueing strategy: fifo
> Output queue 0/40, 0 drops; input queue 8/75, 1478 drops
> 5 minute input rate 5453000 bits/sec, 1975 packets/sec
> 5 minute output rate 4342000 bits/sec, 1983 packets/sec
> 95383572 packets input, 1399376380 bytes
> Received 162215 broadcasts, 0 runts, 294 giants, 1478 throttles
> 208760 input errors, 208760 CRC, 0 frame, 0 overrun, 0 ignored
> 0 watchdog, 0 multicast
> 103898 input packets with dribble condition detected
> 95244094 packets output, 1975945187 bytes, 0 underruns
> 0 output errors, 0 collisions, 0 interface resets
> 0 babbles, 0 late collision, 0 deferred
> 0 lost carrier, 0 no carrier
> 0 output buffer failures, 0 output buffers swapped out
>
>
> I would like to know what alternative I have to solve this trouble.
>
> Regards,
> Jean-Christophe.
>
>
>
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