02-02-2014 06:20 PM - edited 03-07-2019 05:57 PM
I have this ACL applied to a VLAN interface as follows:
ip access-list extended catch-snmp
permit icmp host 10.83.1.13 host 192.168.60.172
permit ip host 10.83.1.13 host 192.168.60.172
permit udp host 10.83.1.13 eq snmp host 192.168.60.172
permit ip any any
interface Vlan10
ip address 10.83.1.254 255.255.255.0
ip access-group catch-snmp in
I then do a ping from 10.83.1.13 to 192.168.60.172 but I don't get any maches on the ACL.
Is this because the switch (3750X) is doing CEF switching and the ACL on the VLAN doesn't actually get looked at?
02-02-2014 07:10 PM
CEF is enabled globally by default on the 3750X series switches.
Try logging your ACLs.
permit icmp host 10.83.1.13 host 192.168.60.172 log
HTH
02-02-2014 08:31 PM
Logging doesn't help...
I can see the permit ip any any get hits on the counters but not the ones above
02-03-2014 12:05 AM
I just replicated your setup in packet tracer and I get matches on the top line of the ACL:
10 permit icmp host 10.83.1.13 host 192.168.60.172 (16 match(es))
20 permit ip host 10.83.1.13 host 192.168.60.172
30 permit ip any any (3 match(es))
Are there any ACL's on the 192.168.60.* SVI?
Can you do a #show ip access-list catch-snmp and post back the results.
02-03-2014 02:16 AM
Switch acl counters are not reliable because the vast majority of packets are processed in hardware and so they do not increment the hit counters.
Only packets that are sent to the main CPU would register in the hit counters and you generally don't want this on a hardware switch.
If the acl is working ie. allowing and blocking what you want then it is not a problem.
Jon
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