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New Member

L2TPv3 on 2851 routers with switch modules

Hi.

Can I configure L2TPv3 between two 2851 Routers, when the Vlan I want to pass (Vlan 22) from site to site is configured on HWIC 4 port FastEthernet on one Router and a 23 Port FastEthernet on the second Router?

The two sites are connected between then via IP over Ethernet (FastEthernet 0/1 on each Router).

My problen is the switch modules on each side.

Any idea?

Danny.

  • WAN Routing and Switching
1 ACCEPTED SOLUTION

Accepted Solutions
Hall of Fame Super Bronze

Re: L2TPv3 on 2851 routers with switch modules

If you have access-vlan 18 on both F0/3 and F0/23, you aren't sending a dot1q vlan header, the frame is untagged.

The only way to send dot1q vlan headers is to configure dot1q trunking on both F0/3 and F0/23.

Both routers in the L2TPv3 configuration will forward these frames but you need to make sure both end devices (the laptops on this case) support dot1q.

__

Edison.

17 REPLIES
Hall of Fame Super Bronze

Re: L2TPv3 on 2851 routers with switch modules

HWIC won't support the xconnect command under its fastethernet interface nor there is support for the SVI

http://www.cisco.com/en/US/prod/collateral/routers/ps5853/prod_white_paper0900aecd8064c9f4_ps5855_Products_White_Paper.html

You can attach the routed fastethernet port on the router to Vlan 22 and configure the xconnect there on each router.

With this configuration, L2/L3 traffic will transparently be sent/received between these 2 routers.

HTH,

__

Edison.

New Member

Re: L2TPv3 on 2851 routers with switch modules

Hi Edison

do you mean:

interface FastEthernet 0/1.22 (interface that connects between the Rs)

no ip address

dot1q tunneling ethertype 0x9100

xconnect A.B.C.D 1 pw-class CLASS1

???

danny.

Hall of Fame Super Bronze

Re: L2TPv3 on 2851 routers with switch modules

You don't need the 'dot1q' command, all you need is the xconnect.

HTH,

__

Edison.

New Member

Re: L2TPv3 on 2851 routers with switch modules

Thank you.

I will try it.

Danny.

New Member

Re: L2TPv3 on 2851 routers with switch modules

Hi Edison.

NOT working with my configuration.

See attached files with configurations (very simple) and a drawing of the setup.

interfaces FastEthernet 0/0 on both Routers can NOT be used, in production they are connecting other LANs.

Thank U for your help.

Danny.

Hall of Fame Super Bronze

Re: L2TPv3 on 2851 routers with switch modules

The xconnect is up and running. Per your configuration, the problem is on the switch side where you are connecting from access-vlan 18 while the router is expecting a tagged dot1q header of Vlan 18.

You need to create a trunk on the router facing interface at the switches.

New Member

Re: L2TPv3 on 2851 routers with switch modules

On the 3750 inter fast 0/1 facing the router, it was configured as a trunk.

On the MATE router fast 0/2/0 was configured as trunk.

No changes were done on the ELTA router side becouse a laptop is connected directly to the switching module.

Still no connctivity between the two laptops.

What am I missing?

See drawing.

danny.

Hall of Fame Super Bronze

Re: L2TPv3 on 2851 routers with switch modules

You only posted one switch config and it has this:

interface FastEthernet0/1

description CONNECTION TO ROUTER MATE

switchport access vlan 18

switchport mode access

speed 100

duplex full

spanning-tree portfast

!

I don't see any trunk configured on any of the ports.

The question is; why did you configure the xconnect under a subinterface? Make this simple, and configure the xconnect under the physical interface. It will forward all the Vlans for you end-to-end.

PS: Just looked at your diagram, you need to connect the 3750 on the MATE site directly to Port F0/1 on the router - same on the ELTA site. While the L2 Tunnel is up, your physical connection is not correct. You have to think of this as a wire between the devices and the routers are transparent. When you enable xconnect on an interface, a directly connected device on that interface will see the remote end as if they were directly connected. You can't do what you intend to do here as connecting the CE device in other ports.

___

Edison.

New Member

Re: L2TPv3 on 2851 routers with switch modules

See attached files after changes.

I configured loobback on both sides according to cisco recommendation on a document I have.

With the running configuration, can you see the problem?

I will also try to change configuration, working without loobback interfaces.

Danny.

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