Subject: Loop Prevention in RSVP LSP Tunnels

From: Geping Chen <[email-masked]>
Date: Mon, 25 Oct 1999 11:14:46 -0400

Hi, Lou,

The RSVP LSP Tunnel spec says we can use
RECORD_ROUTE object in PATH meesage
to do loop prevention.

When each router records the IP interface
address in the RECORD_ROUTE object, is
this IP address the outgoing IP interface address
or the least one of all the IP interface addresses
in this router?  For loop prevention, the latter
seems more reasonable to me.

Thanks,

Geping

---

From: "Finn, Rob" <[email-masked]>
Date: Mon, 25 Oct 1999 13:19:50 -0400

Geping,

If I understand the problem you have solved,  the problem where if the
routing layer was not totally stable ( waffling routes etc.)   a packet
could pass through a router/node that had multiple IP interfaces, multiple
times until finally being stopped by a record route mechanism?  Your choice
of  using the router ID/IP address helps with this problem.   I hope at a
future date we could firm up the concept of "least IP address" and revisit
the concept of "node ID/IP address" ( RFC 2500 ).  A manufacturer ID is
pretty stable.   As you are aware some nodes do have unnumbered IP
interfaces with IP addresses of 0.0.0.0  and to further complicate the
problem some routers have  dynamic interface/circuit combination
configurations which get their IP address from external IP Address
repositories via protocols such as DHCP.  

Thank you for bringing up this issue.

Robert A. Finn
Manager Software Development
Harris & Jeffries

888 Washington Street
Dedham, Massachusetts
02026-6031 USA

Phone: 781-329-3200
Fax: 781-329-4148
e-mail: [email-masked]

-----Original Message-----
From: Geping Chen [mailto:[email-masked]]
Sent: Monday, October 25, 1999 11:15 AM
To: [email-masked]; [email-masked]
Subject: Loop Prevention in RSVP LSP Tunnels

Hi, Lou,

Thanks,

Geping