From: Matthew Poole (matthew.poole@blueyonder.co.uk)
Date: Tue Apr 08 2003 - 14:52:10 GMT-3
That would be true on a broadcast medium, but were discussing NBMA, in a FR
cloud with PVC's which are P-P. If the hub goes down then the spokes don't
form a relationship with any of the other spokes. Considering this would it
be perfectly valid in the lab to configure it this way?
Both methods nail it down - Although what happens if we add a router with a
higher router ID later?? Or forget to set the priority to 0 when adding a
new spoke?? As far as I can see they both have the same gotchas, the
priority method requires extra config (assuming everybody fixes router ID's
routinely??).
Up until yesterday I would have done it using the priority of 0 on the
spokes, the book I referred to earlier got me thinking.
I'm glad this thread has come up again, I hadn't considered Peters original
point of the difference between configuring non-broadcast and leaving it as
default.
Any thoughts on this anybody?
----- Original Message -----
From: "OhioHondo" <ohiohondo@columbus.rr.com>
To: "Matthew Poole" <matthew.poole@blueyonder.co.uk>; "OhioHondo"
<ohiohondo@columbus.rr.com>; "ccie_studying" <ccie_studying@hotmail.com>;
"Brian Dennis" <brian@labforge.com>; "'Scot Peter'"
<scotsman@rediffmail.com>; <ccielab@groupstudy.com>
Sent: Tuesday, April 08, 2003 6:13 PM
Subject: RE: A question on OSPF for NBMA Networks
> Matthew
>
> The highest router ID only works when the router that you want to be DR
> comes up and negotiates with other routers BEFORE a DR and BDR are
elected.
> If you want something to work all of the time, set all non-DR routers to
an
> OSPF priority of 0 and then the desired router will become DR with a
> priority of 1.
>
> -----Original Message-----
> From: Matthew Poole [mailto:matthew.poole@blueyonder.co.uk]
> Sent: Tuesday, April 08, 2003 12:57 PM
> To: OhioHondo; ccie_studying; Brian Dennis; 'Scot Peter';
> ccielab@groupstudy.com
> Subject: Re: A question on OSPF for NBMA Networks
>
>
> Agreed, although another method is to fix the router ID's so that the
> highest router ID is on the hub.
>
> This is discussed in Parkhursts OSPF command and config handbook (P406)-
> Using this method there is no need to set OSPF priority.
>
> Does anybody know any situations where this wouldn't be valid.
>
> ----- Original Message -----
> From: "OhioHondo" <ohiohondo@columbus.rr.com>
> To: "ccie_studying" <ccie_studying@hotmail.com>; "Brian Dennis"
> <brian@labforge.com>; "'Scot Peter'" <scotsman@rediffmail.com>;
> <ccielab@groupstudy.com>
> Sent: Tuesday, April 08, 2003 4:12 PM
> Subject: RE: A question on OSPF for NBMA Networks
>
>
> > You do not have to set the priority on the desired DR to 255. If you set
> the
> > priority of all other routers to 0, this will suffice. The desired DR
will
> > then have the default priority of 1 -- and it will get selected.
> >
> > I suggest using the "ip ospf priority" command on the interfaces of the
> > routers to set each routers priority.
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
> > ccie_studying
> > Sent: Tuesday, April 08, 2003 9:50 AM
> > To: Brian Dennis; 'Scot Peter'; ccielab@groupstudy.com
> > Subject: Re: A question on OSPF for NBMA Networks
> >
> >
> > A question regarding DR selection :-).
> >
> > I learned that if you want one router be hundred percent sure as DR, you
> can
> > configure this router as "priority 255" and configure other routers
> > "priority 0".
> >
> > Scenario: FR cloud, neighbour command only:
> >
> > But when I check router configuration, in the one with "priority 0",
> > "neighbour xxxxx" command doesn't show up in running configuration at
all.
> > Is this normal?
> >
> > And just to confirm, do you need two neighbour statement in DR-other
> router
> > (spoke) pointing to both hub and other spoke?
> >
> > Thanks!
> >
> > ----- Original Message -----
> > From: "Brian Dennis" <brian@labforge.com>
> > To: "'Scot Peter'" <scotsman@rediffmail.com>; <ccielab@groupstudy.com>
> > Sent: Thursday, March 06, 2003 2:32 PM
> > Subject: RE: A question on OSPF for NBMA Networks
> >
> >
> > > Well putting my CCIE lab thinking cap on ;-) the task states "don't
> > > configure network type broadcast or non-broadcast" but the default
will
> > > be non-broadcast since we are using physical interfaces and multipoint
> > > subinterfaces. Here are my preferred solutions in order of preference.
> > >
> > > 1) All interfaces point-to-multipoint. Note: Creates /32 host routes
for
> > > the end points but doesn't need frame-relay mappings between the
spokes.
> > >
> > >
> > > 2) Point-to-multipoint on R1 and point-to-point on R2 and R3. The
> > > hello/dead timers need to be set on R1 or R2/R3 to match. Note:
Creates
> > > /32 host route for only R1 so frame-relay mappings would be needed
> > > between the spokes.
> > >
> > > 3) Unicast neighbors on R1 and set the OSPF priority to "0" on R2 and
> > > R3. But first I would clarify with the proctor the wording of the
"don't
> > > configure" part of the task and ensure "don't configure network type
> > > non-broadcast" doesn't also mean "don't use non-broadcast network
type"
> > > (you've got to love the CCIE lab ;-) If the wording means "don't
> > > configure network type non-broadcast" then this solution is okay but
if
> > > the wording means "don't use network type non-broadcast" then I would
> > > scrap this solution. Note: Frame-relay mappings would be needed
between
> > > the spokes.
> > >
> > > Brian Dennis, CCIE #2210 (R&S/ISP Dial/Security)
> > > brian@labforge.com
> > > http://www.labforge.com
> > >
> > >
> > > -----Original Message-----
> > > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
Of
> > > Scot Peter
> > > Sent: Thursday, March 06, 2003 8:39 AM
> > > To: ccielab@groupstudy.com
> > > Subject: A question on OSPF for NBMA Networks
> > >
> > > Hi Group,
> > >
> > > If we need to configure OSPF on a Multipoint interface with the
> > > following condition,
> > > - R1 should use Multipoint interfaces,
> > > - R2, R3 should not use subinterfaces,
> > > - All three routers should be in the same Network.
> > > - Don't configure Network type Broadcast or non-broadcast.
> > >
> > > R1
> > > / \
> > > R2 R3
> > >
> > > I am not sure about configuring "ip ospf network
> > > point-to-multipoint" (as it is mentioned not to configure
> > > non-broadcast) or do we need to configure using "neighbor"
> > > command? Please advice me on this.
> > >
> > > Thanks
> > > Peter
This archive was generated by hypermail 2.1.4 : Thu May 01 2003 - 13:35:49 GMT-3