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● The order option works across ACL groups that have been applied on an interface via the QoS policy
framework.
● The order option takes precedence over seq sequence-number.
● If sequence-number is not configured, the rules with the same order value are ordered according to
their configuration order.
● If sequence-number is configured, the sequence-number is used as a tie breaker for rules with the
same order.
When you use the log option, the CP processor logs details about the packets that match. Depending on
how many packets match the log entry and at what rate, the CP may become busy as it has to log these
packets’ details.
You cannot include IP, TCP, or UDP (Layer 3) filters in an ACL configured with ARP or Ether-type (Layer
2) filters. Apply Layer 2 ACLs to interfaces in Layer 2 mode.
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).
NOTE:
When ACL logging and byte counters are configured simultaneously, byte counters may
display an incorrect value. Configure packet counters with logging instead.
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} {source [mask] | any | host ip-
address}} [count [byte] [dscp value] [order] [fragments] [threshold-in-msgs
[count]
Parameters
sequence-
number
Enter a number from 0 to 4294967290. The range is from 0 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.
source Enter an IP address in dotted decimal format of the network from which the packet
was received.
mask (OPTIONAL) Enter a network mask in /prefix format (/x) or A.B.C.D. The mask,
when specified in A.B.C.D format, may be either contiguous or non-contiguous.
any Enter the keyword any to specify that all routes are subject to the filter.
count (OPTIONAL) Enter the keyword count to count packets the filter processes.
byte (OPTIONAL) Enter the keyword byte to count bytes the filter processes.
224 Access Control Lists (ACL)