From: Andres Zeller (azeller@xxxxxxxxxx)
Date: Tue Oct 17 2000 - 13:17:03 GMT-3
The OSPF network type is only significant, in that it must be the same
for all routers participating on a particular link, Whether it is a p2p
or p2multip.
Andres
Sam Munzani 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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