Re: OSPF hello question?

From: alsontra@hotmail.com
Date: Sun Feb 29 2004 - 22:11:37 GMT-3


RE: OSPF hello question?RFC 2338 say's

1. OSPF type-1 hello packets transmitted on a P2P links should have
destination address of 0.0.0.0, which means no DR.

This is most likely a bug in IOS 12.2T for P2P non_broadcast links. 0.0.0.6
is not referenced any with respect to OSPF on Cisco's website. I'm almost
positive that the address should be 0.0.0.0 for P2P links and 224.0.0.6 for
P2M links.

moving on.....

<rfc 2328>

Section 9.5

        The format of an Hello packet is detailed in Section A.3.2. The
        Hello Packet contains the router's Router Priority (used in
        choosing the Designated Router), and the interval between Hello
        Packets sent out the interface (HelloInterval). The Hello
        Packet also indicates how often a neighbor must be heard from to
        remain active (RouterDeadInterval). Both HelloInterval and
        RouterDeadInterval must be the same for all routers attached to
        a common network. The Hello packet also contains the IP address
        mask of the attached network (Network Mask). On unnumbered
        point-to-point networks and on virtual links this field should
        be set to 0.0.0.0.

+++++++++++++++++++++++++++++++++

Section A.3.2

Designated Router
        The identity of the Designated Router for this network, in the
        view of the sending router. The Designated Router is identified
        here by its IP interface address on the network. Set to 0.0.0.0
        if there is no Designated Router.
</rfc2328>

  ----- Original Message -----
  From: Richard Dumoulin
  To: Scott, Tyson C ; alsontra@hotmail.com ; ccielab@groupstudy.com
  Sent: Sunday, February 29, 2004 10:55 AM
  Subject: RE: OSPF hello question?

  Alsontra, I also saw this on lab 4 of IExpert but did not take the time to
research --Richard

  -----Mensaje original-----
  De: Scott, Tyson C [mailto:tyson.scott@hp.com]
  Enviado el: domingo, 29 de febrero de 2004 5:55
  Para: alsontra@hotmail.com; ccielab@groupstudy.com
  Asunto: RE: OSPF hello question?

  If it was 224.0.0.6 it would match OSPF designated router advertisement?
  Could it be a bug in the output?

  Regards,

  Tyson Scott
  Agilent Problem Management Team
  Managed Network Services
  Phone: 313-583-5812
  Pager: 877-997-0811

  -----Original Message-----
  From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
  alsontra@hotmail.com
  Sent: Saturday, February 28, 2004 6:13 PM
  To: ccielab@groupstudy.com
  Subject: OSPF hello question?

  Group,

  Topology is simply, R2 is the hub, R1 and R3 are spokes. The spoke
  routers are
  configured on p2p subifs with ip ospf network type broadcast specified.
  Network type is non_broadcast on R2's multi-point physical interface. R2
  has
  neighbor statements pointing toward the hubs, so R1and R3 become
  adjacent with
  R2. My question is this is a follows: When I do a debug ip ospf hello
  on the
  hubs, why is the destination of the hello packets 0.0.0.6? I understand
  that
  the network type is non_broadcast and hello packets are replicated as
  unicasts
  to the Hub router, but what is this 0.0.0.6 address? Is it irrelevant?

  debug ip ospf hello

  <output on R3, makes no since to me>
  *Mar 1 01:12:31.907: OSPF: Send hello to 0.0.0.6 area 0 on Serial1/0.1
  from
  141.1.123.3

  Alsontra

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