Hello,
I am a little late on this one, but is R1E2 and R2E2 on the same Lan?
(10.2.0.0).
If so any device on that lan with the correct IP will be able to ping any
other device with the correct IP. I think a simple ARP will allow that. No
Router needed for the ping to succeed.
Even if I have missed the gist of the story, please don't stop. I love this
OSPF stuff. And the next time I will read all 400 of my emails before I jump
in.
Winston.
> -----Original Message-----
> From: Chuck Larrieu [SMTP:[EMAIL PROTECTED]]
> Sent: Thursday, November 30, 2000 5:47 AM
> To: Howard C. Berkowitz; [EMAIL PROTECTED]
> Subject: RE: About OSPF and Loopback port
>
> OK Howard. I'm not afraid to look foolish in front of everyone.
>
> -----------------------
> Howard's scenario:
>
> Scenario 1 (R1 is initially misconfigured)
> R1 E0: 10.6.0.1 DOWN R2 E0: 10.1.0.1 UP/UP
> E1: 10.5.0.2 UP/UP E1: 10.5.0.2 UP/UP
> E2: 10.2.0.1 UP/UP E2: 10.2.0.2 UP/UP
>
> Admin discovers that R1 E1 is misconfigured and should have been
> 10.5.0.1.
> Our Heroine corrects that interface to 10.5.0.1.
>
> Assuming both routers had OSPF configured with
> network 10.0.0.0 0.255.255.255 area 0.0.0.1
>
> Will a device on R1 E2 be able to ping a host on R2 E2?
> ----------------------
>
> My feeble attempt at cleverness:
>
> Assuming that there is no typo in your addressing scheme, I say you have a
> real mess here and that the answer is no.
>
> 1) you have the same subnet appearing on two different routers
> 10.0.5.0/whatever on R1E1 and R2E1 While OSPF can handle discontiguous
> subnets, I would be surprised if it can handle duplicate subnets with any
> aplomb
>
> 2) on R1 the interface with the address of 10.0.5.2 has been placed into
> area 0.0.0.1. when the ip address for that interface is changed, without
> either reloading the router or performing a clear ip ospf process the
> interface with the address 10.5.0.1 will NOT have been placed into the
> OSPF
> process.
>
> 3) I have not done this on my routers yet. I want to see if I am in the
> right ballpark so far. ( well, to be honest, as soon as I send this
> message
> I am setting up a scenario, upon which I will report subsequently )
>
> Well, gang - am I wise or still a fool?
>
> Chuck
>
>
>
> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of
> Howard C. Berkowitz
> Sent: Wednesday, November 29, 2000 12:37 PM
> To: [EMAIL PROTECTED]
> Subject: RE: About OSPF and Loopback port
>
> At 10:45 AM -0800 11/29/2000, Healis, Jim wrote:
> >Use loopback ports in OSPF so you can set the Router OSPF ID, otherwise
> it
> >will take the highest IP address.
> >
> >Jim Healis CCNP, CCDP
> >Senior Network Administrator
> >Virata
>
> Unless there have been recent IOS changes (I'm really most current in
> 11-something), it's even more unpredictable than just the highest IP
> address:
>
> At the time of OSPF initialization, the router ID is:
>
> if there are multiple loopback interfaces, the highest IP address on
> any
> loopback (i.e., not highest loopback interface number)
> if there is a single loopback interface, use its address
> if there are no loopback interfaces, use the highest IP address on any
> active interface (i.e., if all interfaces are in shutdown, OSPF
> can't initialize. Using loopbacks avoids this because a loopback
> cannot be down.)
>
> A fiendish troubleshooting scenario:
>
> R1 comes up first, then R2. They share an Ethernet. Neither has
> any loopbacks.
>
> Scenario 1 (R1 is initially misconfigured)
> R1 E0: 10.6.0.1 DOWN R2 E0: 10.1.0.1 UP/UP
> E1: 10.5.0.2 UP/UP E1: 10.5.0.2 UP/UP
> E2: 10.2.0.1 UP/UP E2: 10.2.0.2 UP/UP
>
> Admin discovers that R1 E1 is misconfigured and should have been
> 10.5.0.1.
> Our Heroine corrects that interface to 10.5.0.1.
>
> Assuming both routers had OSPF configured with
> network 10.0.0.0 0.255.255.255 area 0.0.0.1
>
> Will a device on R1 E2 be able to ping a host on R2 E2?
>
>
> >
> >
> > -----Original Message-----
> >From: Moerdo [mailto:[EMAIL PROTECTED]]
> >Sent: Wednesday, November 29, 2000 8:26 AM
> >To: [EMAIL PROTECTED]
> >Subject: About OSPF and Loopback port
> >
> >Does anyone here can explain to me, why me must use loopback port for
> OSPF
> >configuration. Thank you for the answer for this stupid question. Thank
> you.
> >
> >moerdo.
> >
>
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