From: amernas (taloust@gmail.com)
Date: Sun Oct 26 2008 - 18:46:45 ARST
The mask is one of the parameters in the ospf hello packet. in broadcast and NBMA network the mask should match on both sides otherwise the basic connectivity will not work. In point-to-point network the mask does not have to be the same and ospf ignores this check.
*Mar 1 00:09:06.443: OSPF: Dead R 40 C 40, Hello R 10 C 10 Mask R
>> 255.0.0.0 C
>> 255.255.0.0
Fahad Khan wrote:
> hmmm.....well network type is same on both ends that is "broadcast", i set
> it under interface mode. the only different thing is subnet mask. but i
> wonder to see why its prompting as "Mismatched hello parameters"...
>
> On 10/27/08, Jason Madsen <madsen.jason@gmail.com> wrote:
>
>> Fahad,
>>
>> You can mix OSPF types, but NOT if one type requires a DR (broadcast,
>> non-broadcast) with a type that doesn't use a DR (p2p, p2m, and p2m
>> non-broadcast)...it won't work. If mixing compatible types just remember to
>> consider timers...they must match.
>>
>> Jason
>>
>> On Sun, Oct 26, 2008 at 2:24 PM, Fahad Khan <fahad.khan@gmail.com> wrote:
>>
>>
>>> Dear All,
>>>
>>> Have a look to the scenario,
>>>
>>>
>>> R1(s1/0-10.0.0.1/*16*)------------------(10.0.0.2/*8*-s1/0)R2<http://10.0.0.2/*8*-s1/0%29R2>
>>>
>>> *OSPF adj forms* in case if i set the network type "point-to-point" on
>>> both
>>> serial interfaces
>>>
>>> But if I set network type as "Broadcast", *adj is not formed*
>>>
>>> and the "debug ip ospf adj+events+packets" looks like (on R1);
>>>
>>> *Mar 1 00:08:58.783: OSPF: Send with youngest Key 0
>>> *Mar 1 00:08:58.783: OSPF: Send hello to 224.0.0.5 area 0 on Serial1/0
>>> from
>>> 10.
>>> 0.0.1
>>> *Mar 1 00:09:06.431: OSPF: rcv. v:2 t:1 l:44 rid:2.2.2.2
>>> aid:0.0.0.0 chk:0 aut:2 keyid:0 seq:0x3C7EC691 from Serial1/0
>>> *Mar 1 00:09:06.435: OSPF: Rcv hello from 2.2.2.2 area 0 from Serial1/0
>>> 10.0.0.
>>> 2
>>> *Mar 1 00:09:06.439: OSPF: Mismatched hello parameters from 10.0.0.2
>>> *Mar 1 00:09:06.443: OSPF: Dead R 40 C 40, Hello R 10 C 10 Mask R
>>> 255.0.0.0 C
>>> 255.255.0.0
>>>
>>> Can any body shed light on the reason behind all this?
>>> Thanks in advance
>>>
>>> best regards,
>>> --
>>> Fahad Khan
>>>
>>>
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