11-28-2006 07:36 AM - edited 03-05-2019 01:04 PM
Please could someone tell me whether this is what you would expect to see on a 3750 running CEF:
On each of the SVIs:
#show int vlan 2 stats
Vlan2
Switch path Pkts In Chars In Pkts Out Chars Out
Processor 5826 471156 92287 9831437
Route cache 65 5005 0 0
Total 5891 476161 92287 9831437
I would expect to see far fewer packets process switched...(ACLs are not being used on the above int, there's no NAT, tunneling, ICMP redirect etc, that I'm aware of)
On each of the L2 ints:
FastEthernet2/0/1
Switch path Pkts In Chars In Pkts Out Chars Out
Processor 0 0 305587 22393864
Route cache 0 0 0 0
Total 0 0 305587 22393864
Surely none of them should be process switched??? I'm confused.
Not cef switched:
show ip cef switching stat
show ip cef switching stat
Reason Drop Punt Punt2Host
RP RIB Packet destined for us 0 1077419198 0
RP RIB Total 0 1077419198 0
RP LES No route 2094 0 1188
RP LES No adjacency 504 0 626
RP LES TTL expired 0 0 39
RP LES Unclassified reason 0 1023819519 0
RP LES Total 2598 1023819519 1853
All Total 2598 2101238717 1853
Seems like a huge amount to be punting, we have an ACL on a tunnel int - could this be the reason why?
I just want to verify that all is working OK before I get started on QoS.
Also here's the show cef state output:
CEF Status:
RP instance
common CEF enabled
IPv4 CEF Status:
CEF enabled/running
dCEF enabled/running
CEF switching enabled/running
universal per-destination load sharing algorithm, id xxxxxxx
Any help appreciated.
Thanks,
J
12-04-2006 04:01 AM
Hello,
What does your CPU utilisation look like?
The Catalyst 3750 Switch can be configured with the tunnel interface. However, because of a hardware limitation, it cannot switch those packets in hardware. This causes all the packets routed through this tunnel to be switched via software.
This would explain why you are seeing punts. A punt is basically where the hardware cannot process the frame, so it 'punts' the frame to the CPU for further inspection.
Below is a link where I sourced the above information about gre tunnels:
Hope this helps,
Michael
TAC LAN Switching
12-06-2006 06:14 AM
Hi Michael,
Many thanks for the link, I think that must explain it. CPU utilisation is around 60%.
Regards,
J
12-06-2006 07:27 AM
Also Michael, can I please ask (sorry a bit off the topic but still cef):
I have a input service policy on my vlan interfaces as follows:
class-map match-any critical
match ip dscp ef
class-map match-any priority
match access-group 181
policy-map classify-traffic
class critical
trust dscp
class priority
set dscp af31
From looking at the hits in access-list 181, it appears that only software-switched packets are being marked - is this actually the case? Or is it that hardware-switched packets don't show as hits on the access-list but still are marked?
From the output of show policy-map int, it appears that nothing is being seen:
Service-policy input: classify-traffic
Class-map: critical (match-any)
0 packets, 0 bytes
offered rate 0 bps, drop rate 0 bps
Match: ip dscp ef
0 packets, 0 bytes
rate 0 bps
Class-map: priority (match-any)
0 packets, 0 bytes
offered rate 0 bps, drop rate 0 bps
Match: access-group 181
0 packets, 0 bytes
rate 0 bps
Class-map: class-default (match-any)
0 packets, 0 bytes
offered rate 0 bps, drop rate 0 bps
Match: any
0 packets, 0 bytes
rate 0 bps
But this is not true as I can see dscp26(af31) appearing on the physical interface (actually more packets than hits on the ACL).
Any help would be much appreciated!
Many thanks,
J
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