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● Source port (MD) can be a VLAN, where the VLAN traffic received on that port pipe where its members are present is
monitored
● Single MD can be monitored on max. of 4 MG ports.
Examples of Port Monitoring
In the following examples of port monitoring, the four source ports 0/13, 0/14, 0/15, and 0/16 belong to the same port pipe and
mirror traffic to four different destinations (0/1, 0/2, 0/3, and 0/37).
You cannot add another destination on the same port pipe in a monitoring session because a maximum number of four
destination ports are supported on the same port pipe. If you configure another destination port on the same port pipe, a Syslog
message is generated: Unable to create MTP entry for MD interface MG interface in stack-unit stack-num port-pipe port-num.
Example of Changing the Destination Port in a Monitoring Session
Dell(conf)#mon ses 300
Dell(conf-mon-sess-300)#source tengig 0/17 destination tengig 0/4 direction tx
%Unable to create MTP entry for MD tenG 0/17 MG tenG 0/4 in stack-unit 0 port-pipe 0.
Dell(conf-mon-sess-300)#
Dell(conf-mon-sess-300)#source tengig 0/17 destination tengig 0/1 direction tx
Dell(conf-mon-sess-300)#do show mon session
SessionID Source Destination Direction Mode Type
--------- ------ ----------- --------- ---- ----
0 Te 0/13 Te 0/1 rx interface Port-based
10 Te 0/14 Te 0/2 rx interface Port-based
20 Te 0/15 Te 0/3 rx interface Port-based
30 Te 0/16 Te 0/37 rx interface Port-based
300 Te 0/17 Te 0/1 tx interface Port-based
Dell(conf-mon-sess-300)#
Example of Configuring Another Monitoring Session with a Previously Used Destination Port
In the example below, 0/25 and 0/26 belong to port-pipe 1. This port-pipe has the same restriction of only four destination
ports, new or used.
Example of Viewing a Monitoring Session
Dell Networking OS Behavior: All monitored frames are tagged if the configured monitoring direction is egress (TX),
regardless of whether the monitored port (MD) is a Layer 2 or Layer 3 port. If the MD port is a Layer 2 port, the frames
are tagged with the VLAN ID of the VLAN to which the MD belongs. If the MD port is a Layer 3 port, the frames are tagged with
VLAN ID 4095. If the MD port is in a Layer 3 VLAN, the frames are tagged with the respective Layer 3 VLAN ID. For example,
in the configuration source TenGig 6/0 destination TenGig 6/1 direction tx, if the MD port TenGig 6/0 is an untagged member
of any VLAN, all monitored frames that the MG port TenGig 6/1 receives are tagged with the VLAN ID of the MD port. Similarly,
if BPDUs are transmitted, the MG port receives them tagged with the VLAN ID 4095. This behavior might result in a difference
between the number of egress packets on the MD port and monitored packets on the MG port.
Dell Networking OS Behavior: The switch continues to mirror outgoing traffic even after an MD participating in spanning tree
protocol (STP) transitions from the forwarding to blocking.
Configuring Port Monitoring
To configure port monitoring, use the following commands.
1. Verify that the intended monitoring port has no configuration other than no shutdown, as shown in the following example.
EXEC Privilege mode
show interface
2. Create a monitoring session using the command monitor session from CONFIGURATION mode, as shown in the following
example.
CONFIGURATION mode
monitor session
monitor session type rpm/erpm
type is an optional keyword, required only for rpm and erpm
3. Specify the source and destination port and direction of traffic, as shown in the following example.
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Port Monitoring