Dell PowerEdge FN I/O Module Configuration Guide 9.10(0.0)

Flow-based monitoring conserves bandwidth by monitoring only the specified traffic instead of all traffic on the interface. It is available for Layer 2 and Layer 3 ingress traffic. You can specify traffic using standard or extended access-lists. This feature copies all incoming 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).

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 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

#show running-config monitor session
                                 !
                                 monitor session 11
                                 flow-based enable
                                 source GigabitEthernet 13/0 destination GigabitEthernet 13/1 direction both
                                 
                              

The show running-config monitor session command displays whether flow-based monitoring is enabled for a particular session.

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
                                 flow-based enable
                                 	  source GigabitEthernet 13/0 destination GigabitEthernet 13/1 direction both
                                 
                              

The show ip | mac | ipv6 accounting commands have been enhanced to display whether monitoring is enabled for traffic that matches with the rules of the specific ACL.

Example Output of the show Command

Dell# show ip accounting access-list
                                 !
                                 Extended Ingress IP access list kar on GigabitEthernet 10/0
                                 Total cam count 1
                                 seq 5 permit ip 192.168.20.0/24 173.168.20.0/24 monitor
                                 
                                 Dell#show mac accounting access-list kar in gi 10/0 out
                                 Egress Extended mac access-list kar on GigabitEthernet 10/0
                                 seq 5  permit host  11:11:11:11:11:11 host  22:22:22:22:22:22 monitor
                                 	seq 10  permit host  22:22:22:22:22:22 any monitor
                                 	seq 15  permit host  00:0f:fe:1e:de:9b host  0a:0c:fb:1d:fc:aa monitor
                                 
                                 Dell#show ipv6 accounting access-list
                                 	!
                                 	Ingress IPv6 access list kar on GigabitEthernet 10/0
                                 	Total cam count 1
                                 	 seq 5 permit ipv6 22::/24 33::/24 monitor