Administrator Guide

The port mirroring application maintains and performs all the monitoring operations on the chassis. ACL
information is sent to the ACL manager, which in turn notifies the ACL agent to add entries in the CAM area.
Duplicate entries in the ACL are not saved.
When a packet arrives at a port that is being monitored, the packet is validated against the configured ACL
rules. If the packet matches an ACL rule, the system examines the corresponding flow processor to perform
the action specified for that port. If the mirroring action is set in the flow processor entry, the destination port
details, to which the mirrored information must be sent, are sent to the destination port.
When a stack unit is reset or a stack unit undergoes a failure, the ACL agent registers with the port mirroring
application. The port mirroring utility downloads the monitoring configuration to the ACL agent. The interface
manager notifies the port mirroring application about the removal of an interface when an ACL entry
associated with that interface to is deleted.
Behavior of Flow-Based Monitoring
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 interfaces are examined, and appropriate ACLs can be applied in the ingress direction. By
default, flow-based monitoring is not enabled.
You must specify the monitor option with the permit, deny, or seq command for ACLs that are assigned to
the source or the monitored port (MD) to enable the evaluation and replication of traffic that is traversing to
the destination port. Enter the keyword
monitor with the seq, permit, or deny command for the ACL rules
to allow or drop IPv4, IPv6, ARP, UDP, EtherType, ICMP, and TCP packets. The ACL rule describes the traffic
that you want to monitor, and the ACL in which you are creating the rule will be applied to the monitored
interface. Flow monitoring is supported for standard and extended IPv4 ACLs, standard and extended IPv6
ACLs, and standard and extended MAC ACLs.
CONFIG-STD-NACL mode
seq sequence-number {deny | permit} {source [mask] | any | host ip-address} [count
[byte]] [monitor]
If the number of monitoring sessions increases, inter-process communication (IPC) bandwidth utilization will
be high. The ACL manager might require a large bandwidth when you assign an ACL, with many entries, to an
interface.
The ACL agent module saves monitoring details in its local database and also in the CAM region to monitor
packets that match the specified criterion. The ACL agent maintains data on the source port, the destination
port, and the endpoint to which the packet must be forwarded when a match occurs with the ACL entry.
If you configure the flow-based enable command and do not apply an ACL on the source port or the
monitored port, both flow-based monitoring and port mirroring do not function. Flow-based monitoring is
supported only for ingress traffic and not for egress packets.
The port mirroring application maintains a database that contains all monitoring sessions (including port
monitor sessions). It has information regarding the sessions that are enabled for flow-based monitoring and
those sessions that are not enabled for flow-based monitoring. It downloads monitoring configuration to the
Access Control Lists (ACLs) 157