Re: OSPF Link State Advertisement

[Acee Lindem <[e-mail]>]

Hi Ameya,

Ameya Pandit wrote:
> Thanks!!  ... the reason i am asking this is because an NMS (Network
> Management Software) uses SNMP queries for getting routing specific
> information. Hence, whenever the NMS receives a 'trap' message from the
> router for a specific LSA (assume an event is configured when an LSA is
> received) then i need to get the neighbor that had forwarded the LSA.

The OSPF MIB doesn't have a trap defined for reception of an LSA. The
OSPF flooding process should be precede very quickly and, IMHO,
it doesn't really make sense to try and monitor it using SNMP.


>
> Using SNMP and OSPF-MIBs, we can query Object Identifiers (OID) for getting
> the details of the LSA. However, I did not find a way of getting the
> neighbor from where the LSA was forwarded. One of the workarounds I was
> thinking for this was to issue a particular command (if any) to get the
> neighbor and thereby the ifIndex. In some manner or the other I need to
> know
> the neighbor that had forwarded the LSA.
>
> Hope i was clear here.
>
> Regards
> Ameya
>
>
>> From: Acee Lindem <[e-mail]>
>> Reply-To: Mailing List <[e-mail]>
>> To: [e-mail]
>> Subject: Re: OSPF Link State Advertisement
>> Date: Tue, 17 Jun 2003 11:09:23 -0400
>>
>> Ameya Pandit wrote:
>>
>>> Thanks for the clarification. I am trying to find out what you ended up
>>> saying. :-). Assume that the network is not Ethernet LAN, but a more
>>> general
>>> case (point to point as an example where in we do not have a DR and a
>>> BDR).
>>>
>>> Is there any user specific table (or any command i can issue) that gives
>>> me
>>> the the interface number on which LS-Ack was sent for a particular LSA?.
>>> LSA
>>> details are available. I need to know the interface on which LS-Ack was
>>> sent. I searched through OSPF-MIBs for the same. However I could not
>>> find
>>> any. Hence my query?
>>
>>
>> Ameya,
>>
>> I'm not sure what you are trying to do but the interface(s) on which a
>> particular LSA was/were ack'ed isn't saved as persistent state
>> informtion.
>> When a packet is sent on an interface, the determination of the ifIndex
>> corresponding to that interface is a platform specific detail.
>>
>> Thanks,
>> Acee
>>
>>
>>
>>
>>>
>>> Any ideas are really welcome.
>>>
>>> Rgds
>>> Ameya
>>>
>>>
>>>> From: Don Goodspeed <[e-mail]>
>>>> Reply-To: Mailing List <[e-mail]>
>>>> To: [e-mail]
>>>> Subject: Re: OSPF Link State Advertisement
>>>> Date: Mon, 16 Jun 2003 14:06:57 -0400
>>>>
>>>> Ameya,
>>>>
>>>> Remember that LSA are global, but a LS-Ack is acknowledging receipt
>>>> from a specific neighbor (or a specific DR on a LAN segment), not
>>>> for the LSA in general.  Therefore, the interface associated with
>>>> that neighbor and/or DR should always be known.
>>>>
>>>> -don
>>>>
>>>> ==========================================
>>>> Hello,
>>>>
>>>> I have a query on link State Acknowledgements (LSAck). We know that
>>>> when a
>>>> router receives a link state advertisement (LSA) it sends a LSAck
>>>> for the
>>>> received LSA. I understand that it is possible to couple different
>>>> acknowledgements together. However, my question is: how do we
>>>> determine the
>>>> 'ifIndex' of the interface on which the router sends the LSAck for the
>>>> currently received LSA.
>>>> Is there any way we can find out the interface on which the LSAck was
>>>> sent
>>>> knowing the details in the
>>>> received LSA (viz. Seq, Checksum et. al.). ?? . In other words, i
>>>> need to
>>>> know the
>>>> interface on which the LSA was received.
>>>>
>>>> More specifically, I have a requirement where in my Network Management
>>>> Software needs to know the ifIndex (and eventually the neighbor that
>>>> sent
>>>> (forwarded) the LSA) of the interface on which the LSAck was generated
>>>> for
>>>> the LSA. I have the details of the LSA. I checked the OSPF MIB however
>>>> there
>>>> was no way to get the ifIndex on which the LSA was received.
>>>>
>>>> Any guidance would be helpful.
>>>>
>>>> Regards
>>>> -Ameya
>>>>
>>>> _______________________________________________
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>>>
>>>
>>>
>>> _________________________________________________________________
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>>
>>
>> --
>> Acee
>
>
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--
Acee