On Aug 12, 2010, at 3:55 PM, Brian E Carpenter wrote:

> Isn't this a case where what we really want is MUST implement and SHOULD 
> enable?
> 
> If I bought a router, I would expect it to be capable of redirecting but
> I might want to disable it.

Makes sense to me.

Bob


> 
> Regards
>   Brian
> 
> On 2010-08-13 07:47, Alain Durand wrote:
>> I have a question about draft-ietf-6man-node-req-bis-05.txt.
>> Section 5.2:
>> 
>>   Redirect functionality SHOULD be supported.  If the node is a router,
>>   Redirect functionality MUST be supported.
>> 
>> However, draft-ietf-6man-node-req-bis-05.txt refer to the normative text on 
>> Neighbor Discovery, ie RFC4861 that says:
>> Section 8.2:
>> 
>> 
>> A router SHOULD send a redirect message, subject to rate limiting,
>>   whenever it forwards a packet that is not explicitly addressed to
>>   itself (i.e., a packet that is not source routed through the router)
>>   in which:
>> 
>>      - the Source Address field of the packet identifies a neighbor,
>>        and
>> 
>>      - the router determines (by means outside the scope of this
>>        specification) that a better first-hop node resides on the same
>>        link as the sending node for the Destination Address of the
>>        packet being forwarded, and
>> 
>>      - the Destination Address of the packet is not a multicast
>>        address.
>> 
>> 
>> It seems that the Node requirement text is going above and beyond what is 
>> required by RFC4861, transforming the SHOULD into a MUST.
>> I might have missed (or do not remember) the discussion, is there a reason 
>> for this change? And shouldn't the ND spec have been changed first
>> to allow to upgrade the SHOULD into A MUST?
>> 
>> For the record, I support the SHOULD in RFC4861 and I would rather like to 
>> see the node requirements document say the same thing.
>> 
>>   - Alain.
>> 
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