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If ACL logging is stopped because the configured threshold is exceeded, it is re-enabled after the logging
interval period elapses. ACL logging is supported for standard and extended IPv4 ACLs, IPv6 ACLs, and
MAC ACLs. You can configure ACL logging only on ACLs that are applied to ingress interfaces; you
cannot enable logging for ACLs that are associated with egress interfaces.
You can activate flow-based monitoring for a monitoring session by entering the flow-based enable
command in the Monitor Session mode. When you enable this capability, traffic with particular flows
that are traversing through the ingress and egress interfaces are examined and, appropriate ACLs can
be applied in both the ingress and egress direction. Flow-based monitoring conserves bandwidth by
monitoring only specified traffic instead all traffic on the interface. This feature is particularly useful when
looking for malicious traffic. It is available for Layer 2 and Layer 3 ingress and egress traffic. You may
specify traffic using standard or extended access-lists. This mechanism copies all incoming or outgoing
packets on one port and forwards (mirrors) them to another port. The source port is the monitored port
(MD) and the destination port is the monitoring port (MG).
Example
An ACL rule with a TCP port range of 4000–8000 uses eight entries in the CAM.
Dell# Data Mask From To #Covered
1 0000111110100000 1111111111100000 4000 4031 32
2 0000111111000000 1111111111000000 4032 4095 64
3 0001000000000000 1111100000000000 4096 6143 2048
4 0001100000000000 1111110000000000 6144 7167 1024
5 0001110000000000 1111111000000000 7168 7679 512
6 0001111000000000 1111111100000000 7680 7935 256
7 0001111100000000 1111111111000000 7936 7999 64
8 0001111101000000 1111111111111111 8000 8000 1
Total Ports: 4001
Example
An ACL rule with a TCP port lt 1023 uses only one entry in the CAM.
Dell# Data Mask From To #Covered
1 0000000000000000 1111110000000000 0 1023 1024
Total Ports: 1024
Related
Commands
ip access-list extended — creates an extended ACL.
permit — assigns a permit filter for IP packets.
permit tcp — assigns a permit filter for TCP packets.
seq
Assign a sequence number to a deny or permit filter in an extended IP access list while creating the filter.
Syntax
seq sequence-number {deny | permit} {ip-protocol-number | icmp | ip | tcp
| udp} {source mask | any | host ip-address} {destination mask | any |
host ip-address} [operator port [port]] [count [byte]] [dscp value] [order]
[fragments] [log [interval minutes] [threshold-in-msgs [count]] [monitor]
Parameters
sequence-
number
Enter a number from 0 to 4294967290. The range is from 1 to 65534.
deny Enter the keyword deny to configure a filter to drop packets meeting this
condition.
permit Enter the keyword permit to configure a filter to forward packets meeting this
criteria.
ip-protocol-
number
Enter a number from 0 to 255 to filter based on the protocol identified in the IP
protocol header.
Access Control Lists (ACL) 165