Concept Guide

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 is 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 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.
You cannot apply the same ACL to an interface or a monitoring session context simultaneously.
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 displays the Type field in the output, which indicates whether a
particular session is enabled for flow-monitoring.
Example Output of the show Command
DellEMC# show monitor session 1
SessID Source Destination Dir Mode Source IP Dest IP
DSCP TTL Drop Rate Gre-Protocol FcMonitor
------ ------ ----------- --- ---- --------- --------
---- --- ---- ---- ----------- ---------
1 Tf 1/2 remote-ip rx Port 0.0.0.0 0.0.0.0 0
0 No N/A N/A yes
DellEMC#
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 TwentyfiveGigE 1/1 destination TwentyfiveGigE 1/22 direction both
The show ip 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
DellEMC# show ip accounting access-list
!
Extended Ingress IP access list kar on twentyFiveGigE 1/1
Total cam count 1
seq 5 permit ip 192.168.20.0/24 173.168.20.0/24 monitor
DellEMC#show ipv6 accounting access-list
!
Ingress IPv6 access list kar on twentyFiveGigE 1/1
Total cam count 1
seq 5 permit ipv6 22::/24 33::/24 monitor
Enabling Flow-Based Monitoring
Flow-based monitoring conserves bandwidth by monitoring only specified traffic instead of all traffic on the interface. This
feature is particularly useful when looking for malicious traffic. It is available for Layer 3 ingress traffic. You can specify traffic
using standard or extended access-lists.
NOTE: Flow-based monitoring is supported for known unicast egress traffic.
1. Create a monitoring session.
CONFIGURATION mode
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Port Monitoring