Cisco Cisco IOS Software Release 12.0(23)S

To display detailed information about current L2TPv3 sessions on a router, use the show l2tun session 
all command:

Router# show l2tun session all

Tunnel Information Total tunnels 1 sessions 1

Tunnel id 26515 is up, remote id is 41814, 1 active sessions

  Tunnel state is established, time since change 03:11:50

  Tunnel transport is IP (115)

  Remote tunnel name is tun1

    Internet Address 172.18.184.142, port 0

  Local tunnel name is Router

    Internet Address 172.18.184.116, port 0

  Tunnel domain is 

  VPDN group for tunnel is 

  0 packets sent, 0 received

  0 bytes sent, 0 received

  Control Ns 11507, Nr 11506

  Local RWS 2048 (default), Remote RWS 800

  Tunnel PMTU checking disabled

  Retransmission time 1, max 1 seconds

  Unsent queuesize 0, max 0

  Resend queuesize 1, max 1

  Total resends 0, ZLB ACKs sent 11505

  Current nosession queue check 0 of 5

  Retransmit time distribution: 0 0 0 0 0 0 0 0 0 

  Sessions disconnected due to lack of resources 0

Router(config-if-xconn)# l2tp cookie 

size low-value [high-value]

(Optional) Specifies the value that the router includes in the 
cookie field of outgoing (sent) L2TP packets. The size of the 
cookie field can be 4 or 8 bytes. If you do not enter this command, 
no cookie value is included in the header of L2TP packets.

If you configure the cookie length in outgoing packets as 8 bytes, 
you must specify a 4-byte high value and a 4-byte low value.

This command must be configured on the Cisco 12000 
series Internet routers.

Router(config-if-xconn)# l2tp hello 

(Optional) Specifies the L2TP class name to use (see the section 
“

”) for control 

channel configuration parameters, including the interval to use 
between hello keepalive messages. This command assumes that 
there is no control plane to negotiate control channel parameters 
and that a control channel is to be used to provide keepalive 
support through an exchange of L2TP hello messages. By default, 
no hello messages are sent.