Basic L2TPv3 configuration

Posted on April 12, 2010

L2TPv3 in a L2VPN technology, we’re going to have quick look on how to configure it.

For this example I’ll be using the CsC topology to interconnected R1 and R8

To manage this interconnection we’ll be using the interface G1/0 of R2 and G2/0 of R7.

Let’s go, first step configure a pw-class where we’ll set out L2TPv3 options

pseudowire-class L2TPv3
 encapsulation l2tpv3
 ip local interface Loopback0

The commands are pretty much self explanatory, ip local interface is the interface that will source the connection.

Once this is done we’re going to indicate at the interface level how to interconnect the 2 devices using the xconnect command

R2-PE(config-if)#xconnect ?
  A.B.C.D  IP address of peer

R2-PE(config-if)#xconnect 67.99.7.7 ?
  <1-4294967295>  Enter VC ID value

R2-PE(config-if)#xconnect 67.99.7.7 18 ?
  encapsulation  Data encapsulation method
  pw-class       Pseudowire-class to use for encapsulation and protocol
                 configuration

Note that the VC ID needs to match on both side.

This gives us

interface GigabitEthernet1/0
 ip vrf forwarding CustA
 no ip address
 negotiation auto
 xconnect 67.99.7.7 18 pw-class L2TPv3
end

That’s all. Once this is configured on both sides the tunnel will come up.

R7-PE#sh xconnect all
Legend:    XC ST=Xconnect State  S1=Segment1 State  S2=Segment2 State
  UP=Up       DN=Down            AD=Admin Down      IA=Inactive
  SB=Standby  RV=Recovering      NH=No Hardware

XC ST  Segment 1                         S1 Segment 2                         S2
------+---------------------------------+--+---------------------------------+--
UP     ac   Gi2/0(Ethernet)              UP l2tp 23.99.2.2:18                 UP

And your devices are seen as directly connected.

R1-CE(config-router)#do sh cdp neig
Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge
                  S - Switch, H - Host, I - IGMP, r - Repeater, P - Phone

Device ID        Local Intrfce     Holdtme    Capability  Platform  Port ID
R8-CE            Gig 1/0           156            R       7206VXR   Gig 1/0

You have more information on the L2TP session with the command sh l2tp session all

R2-PE#sh l2tp session all

L2TP Session Information Total tunnels 1 sessions 1

Session id 1036085548 is up, tunnel id 1799040119
  Remote session id is 4283795721, remote tunnel id 3157821979
  Remotely initiated session
  Unique ID is 5
Session Layer 2 circuit, type is Ethernet, name is GigabitEthernet1/0
  Session vcid is 18
  Circuit state is UP
    Local circuit state is UP
    Remote circuit state is UP
Call serial number is 2244100008
Remote tunnel name is R7-PE
  Internet address is 67.99.7.7
Local tunnel name is R2-PE
  Internet address is 23.99.2.2
IP protocol 115
  Session is L2TP signaled
  Session state is established, time since change 00:02:43
    61 Packets sent, 64 received
    6633 Bytes sent, 7078 received
  Last clearing of counters never
  Counters, ignoring last clear:
    61 Packets sent, 64 received
    6633 Bytes sent, 7078 received
    Receive packets dropped:
      out-of-order:             0
      total:                    0
    Send packets dropped:
      exceeded session MTU:     0
      total:                    0
  DF bit off, ToS reflect disabled, ToS value 0, TTL value 255
  Sending UDP checksums are disabled
  Received UDP checksums are verified
  No session cookie information available
  FS cached header information:
    encap size = 24 bytes
    45000014 00000000 FF7357A8 17630202
    43630707 FF558909
  Sequencing is off
  Conditional debugging is disabled

2 Replies to "Basic L2TPv3 configuration"

  • Matt Bennett
    November 6, 2012 (16:54)
    Reply

    Hi Remi,

    What version of IOS are you running here, and on which platform?

    I'm trying to emulate your setup, but getting the error “Incompatible with ip vrf command on interface Gi1/0 – command rejected” when adding the xconnect.

    Many thanks,
    Matt.

    • Amir
      March 27, 2015 (01:05)
      Reply

      i get the same error “Incompatible with ip vrf command”


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