AW: ospf p2p network

From: Roger RPF (rpf@bluemail.ch)
Date: Thu Sep 18 2008 - 12:21:04 ART


Well, I'm really not a OSPF Guru but I have the following thoughts about it.

Tien said:" will they get the update as unicast as well?"

To me, with the configuration provided in the initial mail, even if you
specify ip ospf network type point-to-point, the DD, Hello and LSU packets
are being sent to the well know multicast address 224.0.0.5. Sure, with
p-to-p no DR election will be made.

If you really need unicast packets, I think you should do:

SW1:
interface FastEthernet1/0/24

 no switchport
 ip address 10.10.10.2 255.255.255.248
 ip ospf network point-to-multipoint nonbroadcast

router ospf xy
network 10.10.10.2 0.0.0.0 area 0
neighbor 10.10.10.1

SW2:
interface GigabitEthernet1/2

 ip address 10.10.10.1 255.255.255.248
 ip ospf network point-to-multipoint nonbroadcast

I verified that config on my stack, with an incoming access list on one side
denying all multicast. I did not see any multicast packets and neighborship
is still fine.

Maybe one of the OSPF freaks in this forum can comment that :o)

regards

Roger

-----Urspr|ngliche Nachricht-----
Von: nobody@groupstudy.com [mailto:nobody@groupstudy.com] Im Auftrag von
Igor M.
Gesendet: Donnerstag, 18. September 2008 14:24
An: Cisco certification; Tien
Betreff: Re: ospf p2p network

On a p2p ospf network type there is no dr/bdr election, thats the whole
point of it. You should think of a DR function - which is to represent its
connected broadcast domain as a single node, that way DRothers dont have to
form a full mesh but rather neighbor only with the DR. Now on a p2p, there
are only two participants, so there is no need for a full-mesh naturally.

----------------------

I.M., M.Eng. P.Eng.

Network Architect

CI Investments

----------------------

--- On Thu, 9/18/08, Tien <tientien.wang@gmail.com> wrote:
From: Tien <tientien.wang@gmail.com>
Subject: ospf p2p network
To: "Cisco certification" <ccielab@groupstudy.com>
Received: Thursday, September 18, 2008, 3:47 AM

Hi experts,
please help me understand the following configuration,
normally ospf network p2p is for /30, ? is there's anything wrong with this
configuration?
the neighbor peering is up and everything works fine. There's no dr or bdr
election, 10.10.10.3 and 10.10.10.4 is ip for the media converter.
will they get the update as unicast as well?

Thanks

Tien
SW1:
interface FastEthernet1/0/24

 no switchport
 ip address 10.10.10.2 255.255.255.248
 ip access-group 100 out
 ip ospf network point-to-point

SW2:
interface GigabitEthernet1/2

 ip address 10.10.10.1 255.255.255.248
 no ip redirects
 no ip unreachables
 no ip proxy-arp
 ip ospf network point-to-point

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