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vpdn failures

Hi all,

I have a LAC which forwards ppp sessions of pppoe users to a LNS through a l2tp.The pppoe implementation is pppoe over ethernet.

A 7300 acts as the LAC while a 7206 as LNS.

By default, the LAC works as a PPP LCP and authentication proxy.Based on the domain name of the username forwards ppp sessions to the LNS through the l2tp.

While this initialy worked fine, after some user calls the LNS did not accept from the LAC the proxy parameters of LCP. The error appeared to be on the MRU of PPP LCP negotiated, which LAC negotiated with the user:LAC negotiates a MRU of 1492(since it is pppoe) which has been configured on the virtual template of a vpdn accept dialin group.

LNS does not accept this MRU.Even when "ip mtu 1492" configured on the v.template of LNS or other values, LNS does not accept them(t.e same error). Only when "lcp renegotiate on-mismatch" added to the configuration of LNS, LNS renegotiates PPP and negotiates the standard value 1500 for mtu.(when no "ip mtu" command exist on LNS).

All calls come from users using same hardware platforms.

Any suggestion for avoiding the renegotiation of PPP?

Thanks in advance.

1 REPLY
Silver

Re: vpdn failures

This document discusses the L2TP tunnel setup and teardown, and also gives a summary of Point-to-Point Protocol (PPP) and L2TP.

http://www.cisco.com/en/US/tech/tk801/tk703/technologies_tech_note09186a0080204aef.shtml

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