[rbridge] ARP proxying

[Guillermo Ibáñez]

Joe,

Joe Touch wrote:

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>Radia Perlman wrote:
>  
>
>>I'm changing the subject line to make it easier, as least for me, to
>>find mail on specific issues.
>>
>>I remember writing up alternatives for ARP/ND proxying and
>>sending the choices and pros and cons to the list, and I'm not sure there
>>was ever strong opinions voiced on any of them.
>>However, I am quite sure the WG did not rule
>>out ARP proxying.
>>
>>I prefer ARP proxying, rather than treating ARP like any other L2 traffic.
>>We could make things a bit fancier, for instance,
>>a) further cutting down on
>>traffic by having an RBridge suppress an ARP request to a particular 
>>target if
>>it knows that another one has occurred recently (either because it
>>iniated it as ingress RBridge or because it forwarded the encapsulated ARP
>>query)
>>b) getting rid of stale ARP caches faster by sometimes (we'd have to decide
>>under what circumstances) sending the ARP query directly to the
>>assumed target's link, and making the target respond.
>>
>>Joe...you seem to be definitively stating that the WG has ruled out 
>>ARP/ND proxy.
>>    
>>
>
>We need to be clear about the difference between ARP Proxy and ARP
>Replay. Replay is closer to what we have always been talking about. We
>never talked about proxying.
>
>For proxying to work:
>
>	1- a designated rbridge would intercept an ARP
> 	and reply with its own MAC address
>  
>
This seems to be right for the term "proxying"

>2- the rbridge would need to know to which egress to forward
>	the packet
>

>3- the egress would need to know the MAC on the destination LAN
>  
>
>steps 2 and 3 involve a new set of state in the rbridge campus that we
>haven't talked about.
>
>  
>
To provide some ideas on 2 and 3  you mention, in the Abridges draft  
recently submitted, determination
of destination host MAC address (ARP  resolution) and destination 
Rbridge (Abridge) are performed
simultaneously by the ARP/AB server (they were registered together by 
the host Agent Bridge).

>My impression is thus that we've been talking about replay more than
>proxy. Correct me (anyone) if that's not accurate...
>
>  
>
I do not know if "replay" is the best suited term, but I agree that 
proxying is not accurate.

Guillermo

>Joe
>
>  
>
>>I may have missed some of the emails on the list (it's *really* hard
>>to keep up with the volume of traffic). Was this debated and concluded 
>>somehow?
>>Or were you just misremembering? Ruling proxy out is definitely a change 
>>from
>>the original intent, and changes such as this should not be done 
>>arbitrarily.
>>
>>Radia
>>
>>
>>
>>
>>Guillermo Ibáñez wrote:
>>
>>
>>    
>>
>>>ARP Proxying by the Designated Rbridge was considered an acceptable 
>>>optimization,  right?
>>>GI
>>>Joe Touch wrote:
>>>
>>>
>>>
>>>
>>>      
>>>
>>>>Guillermo Ibáñez wrote:
>>>>
>>>>
>>>>  
>>>>
>>>>
>>>>        
>>>>
>>>>>>My understanding was that Rbridges would do ARP proxying and would 
>>>>>>forward ARP requests to other Rbridges. Am I still right?.
>>>>>>   
>>>>>>
>>>>>>      
>>>>>>
>>>>>>            
>>>>>>
>>>>Not proxying; they forward ARPs like all other L2 traffic. They don't
>>>>generate ARPs directed at their own L2 addresses in response to seeing
>>>>other ARPs (proxying).
>>>>
>>>>Joe
>>>>
>>>>
>>>>
>>>>------------------------------------------------------------------------
>>>>
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>>>>
>>>>
>>>>  
>>>>
>>>>        
>>>>
>>>
>>>      
>>>
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>>
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-- 
Guillermo Ibáñez
Departamento de Ingeniería Telemática
Universidad Carlos III de Madrid
1.1.B.11 Colmenarejo 91-6241393
4.1.F.13 Leganés 91-6248794