[rbridge] Consensus Check: Hellos

[Dinesh G Dutt]

Ayan,

Ayan Banerjee (ayabaner) wrote:
> I have a few questions on these: 
>
> Does this mean that there is a single IS-IS adjacency on the LAN among
> all nodes (assuming that K identical VLANs are configured on each node)
> ? 
>   
Yes.
> Alternatively, are there K adjacencies per vlan among the IS-IS members
> on the VLAN? 
>
>   
No.
> Is the DRB being run per VLAN? 
>   
No,

Dinesh
> Thanks,
> Ayan
>
> -----Original Message-----
> From: rbridge-bounces at postel.org [mailto:rbridge-bounces at postel.org] On
> Behalf Of Eric Gray
> Sent: Thursday, April 17, 2008 4:51 PM
> To: Anoop Ghanwani; Eastlake III Donald-LDE008; Rbridge at postel.org
> Subject: Re: [rbridge] Consensus Check: Hellos
>
> Anoop,
>
> 	As I recall, the reason for having this behavior was not at all
> - or at least not primarily - for detecting missing connectivity.
> As I recall, it was (primarily) about preventing looping as a result of
> not detecting that there was more than one designated forwarder.
>
> 	See in particular Radia's discussion on "TRILL things" in the
> minutes at http://www.ietf.org/proceedings/08mar/minutes/trill.txt.
>
> 	Even if your assumption about why we might want to do it was
> correct, I don't see how you could argue that we should have default
> behavior that assumes the existence (and use) of some unspecified
> alternative for detecting connectivity issues.
>
> 	Hence the default should rely on the use of hellos as Donald's
> note suggests.
>
> --
> Eric Gray
> Principal Engineer
> Ericsson  
>
>   
>> -----Original Message-----
>> From: rbridge-bounces at postel.org
>> [mailto:rbridge-bounces at postel.org] On Behalf Of Anoop Ghanwani
>> Sent: Wednesday, April 16, 2008 6:43 PM
>> To: Eastlake III Donald-LDE008; Rbridge at postel.org
>> Subject: Re: [rbridge] Consensus Check: Hellos
>>
>>
>> I had a problem with the general wording and had sent an email to the 
>> list about this a while back.
>>
>> While I think it's OK to have the designated forwarder send hellos on 
>> all VLANs, I would prefer it be worded such that:
>>
>> (a) We clearly state that the intent for this is to detect 
>> connectivity issues.  In other words, this will not be used for 
>> forming adjacencies (and there we will have something in the hello 
>> that distinguishes it from the hellos that are actually used to form 
>> adjacencies).
>>
>> (b) That this behavior is optional because there are other ways to 
>> detect connectivity issues such as 802.1ag.  There is also the L2 
>> Gateway Protocol defined in 802.1ah that we can look into.
>> As such, I prefer that the default be to _not_ send such messages 
>> unless explicitly configured to do so.
>>
>> Anoop
>>
>>     
>>> -----Original Message-----
>>> From: rbridge-bounces at postel.org
>>> [mailto:rbridge-bounces at postel.org] On Behalf Of Eastlake III
>>> Donald-LDE008
>>> Sent: Tuesday, April 15, 2008 10:16 PM
>>> To: Rbridge at postel.org
>>> Subject: [rbridge] Consensus Check: Hellos
>>>
>>> This is the last of the consensus checks via the mailing list to 
>>> confirm or refute an apparent consensus at the Philadelphia meeting.
>>>
>>>
>>> ******* The VLANs on which an Rbridge sends TRILL IS-IS 
>>> Hellos is expanded to include those for which it is an 
>>> appointed forwarder except to the extent that it is 
>>> configured not to send these additional Hellos.
>>>
>>>
>>> If no particular controversy arises over this in the next two 
>>> weeks, we will declare it to be the working group consensus.
>>>
>>> Thanks,
>>> Donald & Erik
>>>
>>> PS: There was not complete agreement on this although there 
>>> did appear to be a rough consensus at the meeting. However, 
>>> in light of the other consensus from that meeting to no 
>>> longer require the "decapsulation check" (see
>>> http://www.postel.org/pipermail/rbridge/2008-April/002939.html
>>>       
>> ) and the discussions of the trade-offs, perhaps the 
>> consensus > should
>> be that, by default, Rbridges MUST either (1) send 
>>     
>>> these additional Hellos if they are an appointed forwarder or 
>>> (2) perform the decapsulation check.
>>>
>>> _______________________________________________
>>> rbridge mailing list
>>> rbridge at postel.org
>>> http://mailman.postel.org/mailman/listinfo/rbridge
>>>
>>>       
>> _______________________________________________
>> rbridge mailing list
>> rbridge at postel.org
>> http://mailman.postel.org/mailman/listinfo/rbridge
>>
>>     
>
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>   

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