Configure Packet Truncation

Follow this procedure to truncate a packet to conform to the length required by your analysis tools.

1. Enter the Config mode.
   The command line changes to the configuration mode.

   

   device(config)# 

2. Configure an ACL of type IPv4, IPv6, or MAC and any actions.
   

   device(config)# ip access-list acl3-ipv4
   device(config-ip-acl)# seq 12 permit ip any any count

   The specified ACL and configured actions are bound to a listener policy.
3. Create the listener policy, including the truncate subcommand with any other action subcommands for the policy.
   

   Note

   A listener policy supports only one IPv4 ACL, IPv6 ACL, or MAC ACL.
   

   device(config)# listener-policy lp-3 18
   device(config-listener-policy)# match ip access-list acl3-ipv4
   device(config-listener-policy)# truncate 512
   device(config-listener-policy)# description "truncate ip packets lp"

4. Configure an egress policy and bind the listener policy, specifying any additional egress actions.
   

   Note

   An egress can be associated with only one listener policy.
   

   device(config)# egress e3
   device(config-egress)# set listener-policy lp-3 18
   device(config-egress)# description DirectTool
   device(config-egress)# precedence 1 interface ethernet 2/14

5. Configure an egress group and associate it with the egress policy.
   

   device(config)# egress-group eg_5 
   device(config-egress-group)# description e-group_5
   device(config-egress-group)# set egress e3

6. Configure the route map and set any other parameters, such as forwarding actions, match ip access list, and the egress-group.
   

   Note

   A route-map policy supports only one match-ACL per layer.
   

   device(config)# route-map R2 10 
   device(config-route-map)# match ip access-list acl3-ipv4
   device(config-route-map)# set egress-group eg_5
   device(config-route-map)# forward-action permit

7. Configure an ingress group and associate a route map.
   

   Note

   An ingress group can be associated with only one route map.
   

   device(config)# ingress-group TAP_TRAFFIC
   device(config-ingress-group)# set route-map R2

8. Configure the interface port and channel for ingress traffic.
   

   Note

   In the following example, traffic is coming in on slot/port number 2/3.

   

   interface ethernet 2/3
   description From_TAP
   set ingress-group TAP_TRAFFIC
   no shutdown

9. Configure the interface port and channel for egress traffic.
   

   Note

   In the following example, traffic is leaving on slot/port number 2/14.

   

   interface ethernet 2/14
   speed 40000
   description To_Tool
   no shutdown