From: Nnanna Obuba (obuba@xxxxxxxxx)
Date: Tue Oct 17 2000 - 13:11:47 GMT-3
'ip ospf brodacast ' works just fine even on FR
networks, you do have to remember to ensure that the
spoke router becomes the DR and if there's going to be
a BDR then it should be reachable by all the other
routers...the problem with the config below is the
fact that u did not set 'ip ospf priority' to 0 on the
spoke routers.
Nnanna
www.nantech.com
CCIE Preparation lab
--- Sam Munzani <sam@munzani.com> wrote:
> Comments inline.
>
> > Hi,
> > I was playing in ospf over FR lab and came across
> an interesting problem(I
> > was trying to simulate the problem we had in our
> client production
> network).
> > I configured R1 as hub (sub-ifs) and R2 and R3 as
> spoke (physical
> > interface). Here the config,
> >
> > R1 :
> > interface Serial0.1 point-to-point
> > ip address 10.1.0.1 255.255.0.0
> > ip ospf network broadcast
> > frame-relay interface-dlci 100
>
> Why are you using "ip ospf network broadcast" on a
> point-to-point link?
> Specially in NBMA it's not a good idea. Leave it to
> default Point-to-Point.
> and it will form adjecency with remote end.
>
> > !
> > interface Serial0.2 point-to-point
> > ip address 10.2.0.1 255.255.0.0
> > ip ospf network Point-to-multipoint
> > frame-relay interface-dlci 103
>
> Again,
> If your interface is Point-to-Point why are you
> using Point-to-Multipoint in
> here? Use point-to-point at both ends.
>
> > router ospf 10
> > network 10.0.0.0 0.255.255.255 area 0
> >
> > R2 :
> > interface Serial0
> > ip address 10.1.0.2 255.255.0.0
> > encapsulation frame-relay
> > ip ospf network Point-to-multipoint
> > frame-relay map ip 10.1.0.1 106
> >
> > router ospf 10
> > network 10.0.0.0 0.255.255.255 area 0
> >
> > R3:
> > interface Serial0
> > ip address 10.2.0.2 255.255.0.0
> > encapsulation frame-relay
> > ip ospf network Point-to-multipoint
> > frame-relay map ip 10.2.0.1 106
> >
> > router ospf 10
> > network 10.0.0.0 0.255.255.255 area 0
> >
> > It worked fine with this config. Then I changed
> OSPF network type to
> > "Broadcast" in s0 of R3 and s0.2 of R1. R3 became
> DR and R1 became BDR.
> > After I changed OSPF network type to "Broadcast"
> in s0.1 of R1 and s0 of
> R2.
> > As soon as I entered network type 'broadcast' in
> R2, the network broke. I
> > couldn't access any of the routers for 5 minutes.
> >
> > Now 'sh ip ospf nei' command shows,
> >
> > R1:
> > Neighbor ID Pri State Dead Time
> Address
> Interface
> > 10.1.0.2 1 FULL/BDR 00:00:39
> 10.1.0.2
> Serial0.1
> > 10.2.0.2 1 FULL/BDR 00:00:37
> 10.2.0.2
> Serial0.2
> >
> > R2:
> > Neighbor ID Pri State Dead Time
> Address
> Interface
> > 10.2.0.1 1 FULL/DR 00:00:31
> 10.1.0.1 Serial0
> >
> > R3:
> > Neighbor ID Pri State Dead Time
> Address
> Interface
> > 10.2.0.1 1 FULL/DR 00:00:39
> 10.2.0.1 Serial0
> >
> > I know DR and BDR election was going on, but why
> the network broke? During
> > election, routers multicast packets and we have
> only 3 routers. So, what
> > traffic did the routers send here? Can I have
> multiple OSPF network in one
> > broadcast medium? Can someone clarify my
> questions? Think I am missing
> > something here.
> >
> > Thanks,
> > Mannan Venkatesan
> >
> >
> >
>
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