Re: OSPF virtual-link-

*discontiguous

On 5 Oct 2012, at 12:02, Imran Ali <immrccie_at_gmail.com> wrote:

> Narbik , i have never heard of area fragmentation. what does it mean?
>
> On Fri, Oct 5, 2012 at 6:25 AM, Narbik Kocharians <narbikk_at_gmail.com> wrote:
>
>> 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)
>> *www.MicronicsTraining.com* <http://www.micronicstraining.com/>
>> Sr. Technical Instructor
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Received on Fri Oct 05 2012 - 12:05:17 ART