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based on bit mask boundaries; the space required depends on exactly what ports are included in the
range.
When the configured maximum threshold is exceeded, generation of logs is stopped. When the interval
at which ACL logs are configured to be recorded expires, the subsequent, fresh interval timer is started
and the packet count for that new interval commences from zero. If ACL logging was stopped previously
because the configured threshold is exceeded, it is re-enabled for this new interval.
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 udp — assigns a permit filter for UDP packets.
permit udp
To pass UDP packets meeting the filter criteria, configure a filter.
Syntax
permit udp {source mask | any | host ip-address} [operator port [port]]
{destination mask | any | host ip-address} [dscp] [operator port [port]]
[count [byte]] [order] [fragments] [threshold-in-msgs [count]]
To remove this filter, you have two choices:
● Use the no seq sequence-number command if you know the filter’s sequence number.
● Use the no permit udp {source mask | any | host ip-address} {destination
mask | any | host ip-address command.
Access Control Lists (ACL) 163