Re: OSPF virtual-link-

oo IPX,

The only area that can not be fragmented is area 0.

On Thu, Oct 4, 2012 at 5:15 PM, oo IPX <oispxl_at_gmail.com> wrote:

> Thanks for quick answers. In-fact I was trying a virtual-link over an area
> 0, while trying making non-backbone area contiguous over a V-link (just for
> curiosity), and got this error into debug that 'source ip address don't
> match'. I guess over area 0 either its not supported or it behaves
> differently, AS for sure the ios allows to use area 0 in the command
> syntax, but how it deals with it later, i don't know :-)
>
> And an interesting thing i noted, when using virtual link over a link in
> area 0 with both endpoint on common sub-net is -- as soon as
> one side is configured for the virtual link it starts sending hello packets
> that don't contain the neighbor router-id, and as the source of the hello
> packet is same over which the underlying peering is built on, the other
> router jumps to INIT as soon as the hello packet that don't recognize this
> router arrives.
> But, I didn't notice this problem in same setup with non-backbone area.
> I know its silly and not required, ( using a v link over backbone)
>
> Can we source the hello packets from different address, not by using the
> tunnels.
>
> Thanks
>
> On Fri, Oct 5, 2012 at 5:22 AM, Adam Booth <adam.booth_at_gmail.com> wrote:
>
> > Even though the Cisco documentation is generally good , when it comes to
> > base protocol operation, it's better to look at the RFC for the protocol,
> > http://www.ietf.org/rfc/rfc2328.txt
> >
> > Section 15 second paragraph
> >
> > The virtual link is treated as if it were an unnumbered point-to-
> > point network belonging to the backbone and joining the two area
> > border routers. An attempt is made to establish an adjacency over
> > the virtual link. When this adjacency is established, the virtual
> > link will be included in backbone router-LSAs, and OSPF packets
> > pertaining to the backbone area will flow over the adjacency
> >
> >
> > virtual-links are configured on a router with the peer being the
> > router-id, which is not necessarily an active IP address
> >
> >
> >
> >
> > On Fri, Oct 5, 2012 at 9:16 AM, oo IPX <oispxl_at_gmail.com> wrote:
> >
> >> Hello,
> >>
> >> how the ospf peering comes up over a virtual link even when the source
> ip
> >> address of the uni-cast hello are not on the same subnet ?
> >>
> >> Thanks.
> >>
> >>
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>

-- 
*Narbik Kocharians
*CCSI#30832, CCIE# 12410 (R&S, SP, Security)
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