Behavior Of Flow-Based Monitoring - Dell S4048–ON Configuration Manual

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]]
[order] [fragments] [log [threshold-in-msgs count]] [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 ACL agent whenever the ACL agent is registered with the port
mirroring application or when flow-based monitoring is enabled.
The show monitor session session-id command has been enhanced to display the Type field in the output, which
indicates whether a particular session is enabled for flow-monitoring.
Example Output of the show Command
Dell(conf-mon-sess-0)#do show monitor session 0
SessID Source
------ ------
0 Te 1/1
The show config command has been modified to display monitoring configuration in a particular session.
Example Output of the show Command
(conf-mon-sess-11)#show config
!
monitor session 11
source TenGigabitEthernet 1/1 destination TenGigabitEthernet 1/1 direction both
Destination
-----------
Te 1/2
flow-based enable
Dir Mode Source IP
--- ---- ---------
rx Flow N/A
Dest IP
--------
N/A
Access Control Lists (ACLs)
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