From: Don Banyong (don_study@xxxxxxxxxxx)
Date: Thu Mar 14 2002 - 23:26:07 GMT-3
Your OSPF network type determines whether a DR/BDR election will be carried
out and also how adjacencies are formed.
In a broadcast networks such as Ethernet, DR/BDR elections are always
created. Use the OSPF Interface priority and loopback address to determine
the DR and BDR.
In Non-Broadcast Multi-Access networks(FR, ATM), OSPF operates in
Non-broadcast, Point-to-Multipoint, and Point-to-Point modes.
In Non-Broadcast mode, DR and BDRs are elected. You must use the NEIGHBOR
command in order for your OSPF nodes to create neighbors (remember you are
in a Non-Broadcast network, broadcast and multicast capabilities are not
possible). Also all the OSPF routers must be in the same subnet. Use the
NEIGHBOR X.X.X.X PRIORITY X command to specify which router becomes the
DR/BDR
In Point-to-Multipoint, OSPF treats the network as physical point-to-point
links. No DR/BDR election occurs. Same as the OSPF Point-to-Point network
type.
Just remember that no matter what, all OSPF routers must agree on the
network type before a NEIGHBORSHIPs can be formed.
Don
CCA, MCSE, CCNP, CCDP, CCIE Written.
----- Original Message -----
From: "Chua, Parry" <Parry.Chua@compaq.com>
To: "Shadi" <ccie@investorsgrp.com>
Cc: "ccielab" <ccielab@groupstudy.com>
Sent: Thursday, March 14, 2002 8:01 PM
Subject: RE: when do we need to nail the DR priority?
> DR is require for any multiaccess network type regardless it is broadcast
or non-broadcast.
> The reason is in ospf, a neigh is require, in a multiaccess network, there
are "n" devices,
> so number of neigh require will be n*(n-1)/2, so with DR/BDR, each DR/BDR
will have (n-1) neigh
> and Dother will have 2 neighs.
>
> > Parry Chua
> >
>
>
> -----Original Message-----
> From: Shadi [mailto:ccie@investorsgrp.com]
> Sent: Thursday, March 14, 2002 10:14 PM
> To: Chua, Parry
> Cc: ccielab
> Subject: Re: when do we need to nail the DR priority?
>
>
> That is always when using Broadcast or non-broadcast networks right?
>
>
>
> ----- Original Message -----
> From: "Chua, Parry" <Parry.Chua@compaq.com>
> To: "Michael C. Popovich" <mpopovich@layer3.biz>; "Bhisham Bajaj"
> <bhishambajaj@yahoo.com>; "Shadi" <ccie@investorsgrp.com>; "ccielab"
> <ccielab@groupstudy.com>
> Sent: Thursday, March 14, 2002 12:23 PM
> Subject: RE: when do we need to nail the DR priority?
>
>
> You must ensure that the spoke's can never be a DR or not even a BDR, set
it
> priority to 0 is the answer.
>
> Regards
> Parry
> -----Original Message-----
> From: Michael C. Popovich [mailto:mpopovich@layer3.biz]
> Sent: Thursday, March 14, 2002 12:08 AM
> To: Bhisham Bajaj; Shadi; ccielab
> Subject: RE: when do we need to nail the DR priority?
>
>
> How would this work in the following scenario.
>
> R1 is hub in a frame network with R2 and R3 the spoke for multipoint
> network.
>
> You have set R1 to be the DR and R2 to be the BDR. R1 goes down so R2 is
> then DR. R1 comes back up. How do we get R1 to become DR again? I
> thought this was discussed a couple of months ago but I can't seem to
> find the answer.
>
> MP
>
>
> -----Original Message-----
> From: Bhisham Bajaj [mailto:bhishambajaj@yahoo.com]
> Sent: Wednesday, March 13, 2002 9:32 AM
> To: Shadi; ccielab
> Subject: Re: when do we need to nail the DR priority?
>
> with Fr the hub has to be the dr
> your network will go for a tos if the spoke becomes
> the Dr
> so it is very Imp in Fr
>
> but in lan there is no problem any roter can be the dr
>
>
>
>
>
> Bajaj
>
>
> > Hi,
> >
> > During my studies, I saw that we should always nail
> > the DR Router by ip ospf
> > priority, so that always that router be the DR when
> > using Frame-relay with
> > broadcast or non broadcast network type.
> >
> > What about Ethernet network why we don't nail it
> > too?
> >
> >
> > Shadi
> >
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