Subject: L2TP Queries.

From: [email-masked]
Date: Wed, 4 Apr 2001 19:54:03 +0530

Hello,
I am Narendra Kumar from Hughes Software Systems
in Gurgaon, Haryana, India.

I am not sure whether it is correct to write to you w.r.t
queries about L2TP. But the RFC( 2661) dosen't mention
any email address to which the reader( of rfc) can send his queries to.
But your email address is mentioned in the RFC as one of the authors.

If you are not supposed to reply such emails(  because typically for such
queries there is a common mailing addres) please atleast forward this
query to the right email address.

1) Can there be scenarios in which a single LAC is having tunnels
to multiple LNS(s)? If this is true then how does the remote pots user
( incoming call) convey to LAC as to which LNS he wants to contact?
The most basic question which arises on reading rfc 2661 is :
How does a LAC know a LNS ? OR How does a LNS know about a LAC ?
If the packet switched network is IP then LAC and LNS identify each other
by a IP adress. But based on an incoming call how does the LAC decide
which LNS( ip address) to contact, to establish a tunnel for entertaining the
incoming call ??

2) Can there be mulitiple tunnels between a given LAC -LNS pair ? As far
as i see the protocol does allow this to happen. But if multiple tunnels
can exist then what could be the use of this ? Is it possible for you
to give a real life example where multiple tunnels could be useful between
a LAC-LNS pair?

Any inputs from you would be a great help.
thanks,
--narendra.

---

From: [email-masked]
Date: Wed, 04 Apr 2001 08:03:41 -0700

Greetings,

> Hello,

hi

> queries about L2TP. But the RFC( 2661) dosen't mention

you've the right place

> ( incoming call) convey to LAC as to which LNS he wants to contact?

Imagine a dial-in connection. User dials into an LNS. During the PPP
negotiation, the user name is [email-masked]''; the LNS creates
a tunnel to ``somecompany.com'' and either modifies the username to
``dummy'' or passes the whole thing unchanged.

> How does a LAC know a LNS ? OR How does a LNS know about a LAC ?

This is mutually agreed on. If you're tunneling into your company, it's
assumed that you know the address of the LAC and have the proper
credentials to get in.

> to give a real life example where multiple tunnels could be useful between

Different QOS might be a valid reason. Imagine a VoIP tunnel and a
telnet tunnel.

-- 
Kyle A. York
Sr. Subordinate Grunt

---

From: [email-masked]
Date: Wed, 04 Apr 2001 08:51:13 -0700

Greetings,

In my last message, reverse ``LAC'' and ``LNS''. I invariably get these
backwards. Sorry.

-- 
Kyle A. York
Sr. Subordinate Grunt