From: Richard Dumoulin (Richard.Dumoulin@vanco.fr)
Date: Tue Feb 22 2005 - 12:33:52 GMT-3
Taken from the RFC: http://www.faqs.org/rfcs/rfc1793.html
3.2.1. Negotiating Hello suppression
On point-to-point demand circuits, both endpoints must agree to
suppress the sending of Hello Packets. To ensure this
agreement, a router sets the DC-bit in OSPF Hellos and Database
Description Packets sent out the demand interface. Receiving
an Hello or a Database Description Packet with the DC-bit set
indicates agreement. Receiving an Hello with the DC-bit clear
and also listing the router's Router ID in the body of the
Hello message, or a Database Description Packet with the DC-bit
clear (either one indicating bidirectional connectivity)
indicates that the other end refuses to suppress Hellos. In
these latter cases, the router reverts to the normal periodic
sending of Hello Packets out the interface (see Section 9.5 of
[1]).
A demand point-to-point circuit need be configured in only one
of the two endpoints (see Section 4.1). If a router
implementing Sections 2 and 3 of this memo receives an Hello
Packet with the DC-bit set, it should treat the point-to-point
link as a demand circuit, making the appropriate changes to its
Hello Processing (see Section 3.2.2) and flooding (see Section
3.3).
Even if the above negotiation fails, the router should continue
setting the DC-bit in its Hellos and Database Descriptions (the
neighbor will just ignore the bit). The router will then
automatically attempt to renegotiate Hello suppression whenever
the link goes down and comes back up. For example, if the
neighboring router is rebooted with software that is capable of
operating over demand circuits (i.e., implements Sections 2 and
3 of this memo), a future negotiation will succeed.
Also, even if the negotiation to suppress Hellos fails, the
flooding modifications described in Section 3.3 are still
performed over the link.
-- Richard
-----Original Message-----
From: simon hart [mailto:simon.hart@btinternet.com]
Sent: Tuesday, February 22, 2005 3:52 PM
To: ccielab@groupstudy.com
Subject: ip ospf demand circuit
This maybe a bit of a naive question but what the heck.
Which end of an ISDN link would one normally put the ip ospf demand circuit
command?
Thanks
Simon
-- No virus found in this outgoing message. Checked by AVG Anti-Virus. Version: 7.0.300 / Virus Database: 266.3.0 - Release Date: 21/02/2005
This archive was generated by hypermail 2.1.4 : Thu Mar 03 2005 - 08:51:24 GMT-3