[rbridge] Back to ND/ARP optimization

[Radia Perlman]

Actually, I'm not sure that's the conclusion that Arien was making (that 
ARP/ND
optimization is not worth it), especially with the comment "peak rates 
much higher".

So Arien...was that actually your conclusion?

I think that ARP/ND optimization could be added in the future as an 
option, or
even that an implementation can do something about it without having the 
spec
saying anything about it. Which would argue for not needing it in the 
spec now.

But just want to verify what Arien's conclusion is from the data 
presented...

Radia


Silvano Gai wrote:
> Arien
>
> Thanks for the real world data, which proves that ARP/ND proxy must not
> be implemented on RBridges.
>
> In fact, since the queries toward unused addresses are dominant, the
> ARP/ND cache will almost always miss and the RBridge CPU will be busy
> trying to remotely resolve queries that will never complete.
>
> -- Silvano
>
>   
>> -----Original Message-----
>> From: Arien Vijn [mailto:arien.vijn at ams-ix.net]
>> Sent: Friday, May 04, 2007 10:04 AM
>> To: Silvano Gai
>> Cc: Arien Vijn; Radia.Perlman at sun.com; rbridge at postel.org
>> Subject: Re: [rbridge] Back to ND/ARP optimization
>>
>> Hi,
>>
>> On May 3, 2007, at 10:55 PM, Silvano Gai wrote:
>>
>> [...]
>>
>>     
>>>> Does anyone have a handle on how much traffic is caused by ARP/ND?
>>>>
>>>>         
>>> With an ARP cache of 30 minutes, typical in hosts today, even with
>>> a 100
>>> K hosts in a VLAN we get at most 55 ARP seconds. Since not all the
>>> hosts
>>> talk with each other, it is more typically like 5 ARP/sec.
>>>
>>> BASICALLY NOTHING.
>>>       
>> Well... that might be the case if all your hosts are actually
>> answering. But query rates are pretty much determined by queries for
>> unused addresses. In other words by the query rates hosts (routers)
>> can achieve for addresses that are not in their caches.
>>
>> For what its worth. I am involved in a real network with 400+ BGP
>> routers in one broadcast domain (/23 IPv4 subnet). The average rate
>> is little over 13 queries/second. That is with ARP mitigation and
>> peak rates are much higher.
>>
>> -- Arien
>>     
>
>
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