Cisco Nexus 3548 - Configuring ERSPAN Truncation

Configuring ERSPAN Truncation
You can configure truncation for local and ERSPAN-source sessions only. SPAN and ERSPAN Truncation,
on page 145 provides more information about truncation.
Procedure
PurposeCommand or Action
Enters global configuration mode.switch# configure terminal
Step 1
Configures an ERSPAN source session.switch(config)# monitor session
{session-number | all} type
erspan-source
Step 2
Configures the MTU size for truncation. Any SPAN packet
that is larger than the configured MTU size is truncated to
the configured size with a 4-byte offset.
switch(config-erspan-src)# mtu
size
Step 3
The MTU truncation size is between 64 bytes and 1518 bytes.
Configures the ERSPAN ID for the ERSPAN source session.
The ERSPAN range is from 1 to 1023. This ID uniquely
switch(config-erspan-src)#
erspan-id erspan-id
Step 4
identifies a source and destination ERSPAN session pair. The
ERSPAN ID configured in the corresponding destination
ERSPAN session must be same as the one configured in the
source session.
Configures the VRF that the ERSPAN source session uses
for traffic forwarding.
switch(config-erspan-src)# vrf
vrf-name
Step 5
Configures the destination IP address in the ERSPAN session.
Only one destination IP address is supported per ERSPAN
source session.
switch(config-erspan-src)#
destination ip ip-address
Step 6
Configures the sources and traffic direction in which to copy
packets. You can enter a range of Ethernet ports, a port
channel, or a range of VLANs.
switch(config-erspan-src)# source
[interface type slot/port |
port-channel channel-number] |
[vlan vlan-range] [rx | tx | both]
Step 7
You can configure one or more sources, as either a series of
comma-separated entries or a range of numbers. You can
specify up to 128 interfaces.
You can specify the traffic direction to copy as ingress, egress,
or both. The default direction is both.
The following example shows how to configure MTU truncation for an ERSPAN-source session:
switch# configure terminal
switch(config)# monitor session 6 type erspan-source
switch(config-erspan-src)# mtu 1096
switch(config-erspan-src)# erspan-id 40
switch(config-erspan-src)# vrf default
switch(config-erspan-src)# destination ip 200.1.1.1
switch(config-erspan-src)# source interface ethernet 1/40
Cisco Nexus 3548 Switch NX-OS System Management Configuration Guide, Release 6.x
174
Configuring ERSPAN
Configuring ERSPAN Truncation