Implementation Information; Flow-Based Monitoring Support For Acls; Behavior Of Flow-Based Monitoring - Dell S6100 Configuration Manual

Implementation Information

ACLs and prefix lists can only drop or forward the packet or traffic. Route maps process routes for route redistribution. For example, a route
map can be called to filter only specific routes and to add a metric.
Route maps also have an "implicit deny." Unlike ACLs and prefix lists; however, where the packet or traffic is dropped, in route maps, if a
route does not match any of the route map conditions, the route is not redistributed.
The implementation of route maps allows route maps with the no match or no set commands. When there is no match command, all traffic
matches the route map and the set command applies.

Flow-Based Monitoring Support for ACLs

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 mechanism copies incoming
packets that matches the ACL rules applied on the ingress 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]]
[order] [fragments] [log [threshold-in-msgs count]] [monitor session-ID]
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.
128 Access Control Lists (ACLs)