David,
It appears you have received conflicting guidance on your
question...I'll throw my 2 cents in but I hope I don't add to the
confusion:
1) RouterDeadInterval is the legth of time a router waits for a Hello
packet from a neighbor before declaring it down...the same timer is used
by the BDR to determine whether the DR is down. The RouterDeadInterval
is recommended by RFC 2328 to be "some multiple of the HelloInterval
(say 4)" With respect to the HelloInterval RFC2328 states "Sample value
for a local area network: 10 seconds." These are the numbers Cisco's
implementation uses : 10 seconds for Hello and 40 seconds for
RouterDead...for NBMA it's 30 and 120 respectively.
2) OSPF enabled routers maintain a data struture for each OSPF enabled
interface. When you type "sh ip ospf int x" the router will disply the
contents of the data structure. Point-to-point interfaces will NOT
display any DR or BDR--because there are none. With only 2 routers on
the segment you don't need 'em.
3) I've never had a need to use 2 OSPF process but Someone already
stated it being used to transition/migrate and that seems
reasonable...but keep in mind you'd have duplicate everything! I would
imagine the strain on resources, say for the network to synchronize,
would be enormous for larger networks.
I hope this helps you out man...aloha, Frank
David Armstrong wrote:
>
> Last night at our BSCN study group meeting in Dallas we had some questions
> about OSPF that we weren't able to resolve. If someone or ones could answer
> these it would clarify some areas we're a little fuzzy on. Also, if you're
> iin the Dallas Ft. Worth area and would like to attend, we'd love to have
> you join us..
>
> Thanks for any help,
>
> David Armstrong
>
> 1) What is the default time period that the BDR waits when listening to
> LSA's from the DR before it decides that the DR is down and promotes itself
> to DR. All the literature we could find simply said that the BDR waits for
> the specified time period but never said what that period is.
>
> 2) In a Point-to-Point network in which the router in Area 0 is connected to
> FR, ISDN, X.25 or ATM branch offices (networks), how does convergence and
> updates take place? From what we've found a DR and BDR is not elected in a
> strictly Point-to-Point network.
>
> I think an example would explain this question better: We have one 3620
> router in our Ft. Worth office connected to an office in Houston (via FR),
> and office in Kansas City (via FR), an office in the DFW area (via ISDN) and
> the owner's home (via ISDN). The 3620 is behind a firewall (Pix 520) and the
> firewall is connected to a 1720 going to the Internet. I'd like to implement
> OSPF on our network simply for the experience. However, I don't have 2
> routers internally on our Ethernet LAN that can be configured for Area 0 and
> elected to DR and BDR. All other routers connected to that router are via
> NBMA Point-to-Point connections. Since I only have one router on the
> Broadcast Multiaccess network (the 3620) and routers connected via PtoP
> don't participate in DR and BDR elections, how would updates occur? Can
> their only be one DR (in this case the 3620)?
>
> 3) The books and tutorials all state that "router ospf 6" defines ospf on
> the router with a process ID of 6. They then all say that you shouldn't
> define more than one process. Does that mean that you can have a router with
> the following:
>
> router ospf 6
> network 10.100.0.0 0.0.255.255
>
> router ospf 7
> network 10.200.0.0 0.0.255.255
>
> If this is an allowed configuration, what kind of instances would it be used
> for? Also, exactly what is the process ID used for?
>
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