L2 Bridging Across an L3 Network Internet?

[hmc250000]

Is it possible to extend vLANs  over the internet to another site using a 3900 router on one side and ISR4321 on the other side with Layer 2 Tunneling Protocol Version 3 (L2TPv3) and Generic Routing Encapsulation (GRE)?

Has anyone done this? Is it secure?

https://www.cisco.com/c/en/us/support/docs/ip/layer-two-tunnel-protocol-l2tp/116266-configure-l2-00.html

[Georg Pauwen · Accepted solution]

Hello,

if you use it in combination with IPSec, you should be ok. Have a look at the link below:

https://www.softether.org/4-docs/2-howto/9.L2TPIPsec_Setup_Guide_for_SoftEther_VPN_Server/6.Cisco_IOS_L2TPv3%2F%2F%2F%2FIPsec_Edge-VPN_Router_Setup

[hmc250000]

Should the mtu size be adjusted when implementing this?

Can a L2tpv3 trunk link be added to an etherchannel with another WAN metro ethernet trunk? 

[Georg Pauwen]

Hello,

if you use Ethernet interfaces you don't need to adjust the MTU. I am not sure if you can use an existing trunk, I think you do need a layer 3 link...

[hmc250000]

These are both L2, why make it L3? 

Was hoping to bundle these into an etherchannel or make one the primary and the other backup.

SWA L2 trunk -------router A L2TPv3 -----internet------Router B L2TPv3----L2 trunk SWB

SWA L2 trunk ------- WAN metro ethernet 1gbps ---------L2 trunk SWB