From: kym blair (kymblair@xxxxxxxxxxx)
Date: Sat Aug 03 2002 - 17:36:26 GMT-3
Malcolm,
As you know, the important thing is that the interface types on the hub and
spokes match so the hello/dead intervals match and the election of DR/BDR
matches:
(1) Serial physical = type non-broadcast = hello 30 dead 120 = Elects DR/BDR
(2) Serial multipoint subint = type point-multipoint = hello 30 dead 120 =
no DR/BDR
(3) Serial pt-pt subint = type point-to-point = hello 10 dead 40 = no DR/BDR
(4) Ethernet = type broadcast = hello 10 dead 40 = Elects DR/BDR.
In your example, the hub router is programmed on a physical interface
(non-broadcast), so if the spoke routers are also physical serial interface
(i.e., also non-broadcast), you do not need to change the network type. But
you will need to set the priority of the Hub higher (in fact, recommend
setting spoke priorities to zero) so the hub is elected as DR, and you must
install neighbor statements on the hub.
I have difficulties with non-broadcast, especially when ospf authentication
is required, so I always prefer to change the ospf network type to
multipoint or broadcast. Those work well for me. I've spend several
weekends trying to get non-broadcast working and only have intermittent
success. Setting priority before ospf network type and neighbor statements
seems to help. People on GroupStudy have told me what to do, but I still
have problems ... and hope the real lab doesn't force me to stay with
non-broadcast!
HTH, Kym
>From: "Malcolm Price" <malcolm@lanbase.com>
>Reply-To: "Malcolm Price" <malcolm@lanbase.com>
>To: <ccielab@groupstudy.com>
>Subject: OSPF over Frame Relay
>Date: Sat, 3 Aug 2002 20:03:39 +0100
>
>Hi Group,
>
>This is probably a simple question which really I should know, but I was
>wondering if someone could clarify the need for the following:
>
>When using OSPF over NBMA Frame Relay, given the following 4 router
>multipoint scenario:
>
>interface serial0
>encapsulation frame-relay
>ip address 172.16.2.1 255.255.255.0
>frame-relay map ip 172.16.2.4 200 broadcast
>frame-relay map ip 172.16.2.5 200 broadcast
>frame-relay map ip 172.16.2.6 200 broadcast
>!
>router ospf 100
>network 172.16.0.0 0.0.255.255 area 0
>
>
>As I understand, using the command "frame-relay map ip 172.16.2.4 200
>broadcast" would forward "broadcast" and multicast packets across the NBMA
>network.
>
>Given this useage, why would we need to use the following command to
>forward
>ospf multicasts/broadcasts:
>
>ip ospf network broadcast
>
>if the purpose of these commands is to broadcast forward ospf info..?
>
>
>I understand what the ip ospf network commands represent and their
>function,
>it's clarification of the broadcast option of the frame-relay map command I
>was looking for?.
>
>Many thanks,
>Malcolm
>
>
>
>Malcolm Price M.Phil. MBCS C.Eng.
>Technical Director
>LanBase Technologies
>www.lanbase.com
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