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L2TP Client: Cisco

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Cisco Routers

Cisco routers running IOS 12.3(2)T and later support L2TP client initiated tunneling which allows the router to establish an L2TP tunnel to A&A's L2TP server.

Most of the information required was gleaned from here: [1] plus a bit of trial and error and some packet capturing of good and bad L2TP sessions.

I have tested this on a Cisco 837 router running 12.3(11)YZ2, a 2821 running 12.4(15)T10 SPServices and a 2801 running 12.4(24)T3 ADVIPServices

Caveats:

- You will need to sanity check routing in your particular environment. This is especially important if you choose to use ppp ipcp route default on the l2tp tunnel. It's safest to make sure that you have a static route set to the L2TP server.

- I haven't tested this for IPV6 yet.

- This is "early release" information - I haven't yet used this in anger over a long period of time but will try to remember to come back and update if I find any major issues.

- This config snippet contains no security settings - be sure to configure some!

- I've used the IP address of the L2TP server rather than the DNS address - this is obviously at risk of change .

- You need to be running IP CEF on the router

Config:

Replace <whatever> with the appropriate information for your connection

ip cef
l2tp-class lc-aaisp

pseudowire-class pc-aaisp
 encapsulation l2tpv2
 protocol l2tpv2 lc-aaisp
 ip local interface <interface that l2tp connection should go out from>

interface Virtual-PPP9797
 shutdown
 ip address negotiated
 no cdp enable
 ppp authentication chap callin
 ppp chap hostname <l2tp line login eg stzzz@a.2>
 ppp chap password 0 <site password>
 ppp direction callout
 ppp pap refuse
 pseudowire 90.155.53.19 10 pw-class pc-aaisp
 

Once the interface is configured you can issue a no shut on it to bring it up.

Debugging:

debug ppp authentication and debug ppp negotiation are your friends... In particular if you see "Circuit ID not set - contact support" in the authentication debug, contact A&A support to get them to fix your L2TP login.

Once the connection is up, you should see the virtual PPP interface configured with the static IP that is assigned to it in clueless.

If you get stuck, pop into the IRC channel and see if I'm around (basil_uk) and I'll help if possible.