[rbridge] Max Network size

[Guillermo Ibáñez]

Guillermo Ibáñez wrote:

Joe Touch wrote:

>Guillermo Ibáñez wrote:
>...
>  
>
>>I agree with your view, except about ARP. 
>>Is there any estimation on the ARP load expected on Rbridges as ARP 
>>proxies and hosts in general (ARPs unsolved by proxies)?
>>I wonder whether the Rbridges are the most suited devices to handle many 
>>ARP requests. For big networks like this it might be worth to consider 
>>the use of separate ARP servers distributed over the subnetwork instead 
>>of ARP proxies at Rbridges.
>>    
>>
>
>I am anticipating that RBridges should handle ARPs via broadcast as a
>default; we're looking into proxy-ARP based on knowledge of ingress
>locations, to reduce ARP load. That solution would need to be fault
>tolerant to loss of the proxy mechanism, whether distributed or at a server.
>
>Joe
>
>  
>
Right. Default must always be ARP broadcast.  I understand that in this 
case the frame is not encapsulated,  just forwarded by Rbridge.
 ARP load is somewhat reduced in the core  by diffusing ARP to Rbridges 
via a specific multicast address iso broadcast address . But still the 
cost of local ARPs issued by each Rbridge at the ends may be significative.
I wonder if an ARP server/registrar approach can be foreseen as an 
alternative or complementary strategy.  The Designated Rbridge registers 
each host, when an ARP is received, at a (distributed) ARP server. This 
can help to enforce security (like preventing MAC spoofing) and  also 
ensure ARP resolution in one step without broadcast. The point is to 
distribute the load of ARP registry and queries between multiple ARP 
servers. This may be based on IP hashing.
Regards
Guillermo

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