[rbridge] Last Call comments on draft-ietf-trill-rbridge-protocol-13.txt

Radia Perlman Radia.Perlman at sun.com
Thu Jul 16 13:18:14 PDT 2009


Oh right. There was a much simpler reason for asking for a pseudonode to 
optionally be able to have a nickname -- that
was because in some topologies a pseudonode might make a good tree root.

Radia

Radia Perlman wrote:
> It had to do with two RBridges, R1, and R2, connected to the same edge 
> cloud via a bridge B,
> where B has some weird feature where it has 3 ports say, one each to R1 
> and R2, and the other to
> a cloud of endnodes. B forwards traffic from the endnodes to *only one* 
> of R1 and R2.
> B *never* forwards between
> R1 and R2. R1 and R2 know that this is going on (they've been configured).
>
> So the idea is that if the pseudonode associated with that cloud is 
> given a nickname, then both R1
> and R2 can act as encapsulator/decapsulators, and set the ingress 
> nickname as the pseudonode.
> Then return traffic can go shortest path to either R1 or R2 since the 
> actual egress is the LAN itself.
> But even though in the topology both R1 and R2 are connected to that 
> LAN, they can't forward to
> each other, so luckily the IS-IS "overload" feature, which is already 
> there, handles that case perfectly.
>
> There might have been other reasons why someone was asking for it to be 
> optional to ask for
> a nickname for a pseudonode. Certainly seems easy not to go out of our 
> way to preclude it.
>
> Radia
>
>
> Dinesh G Dutt wrote:
>   
>> Radia Perlman wrote:
>>     
>>> Ayan Banerjee wrote:
>>>  
>>>       
>>>> All,
>>>> Please see attached comments on the Last Call for
>>>> draft-ietf-trill-rbridge-protocol-13.txt:
>>>>
>>>> 1. Section 3.7.3
>>>> The last sentence of this section seems to give the impression that
>>>> nicknames are LSP specific and node specific.
>>>>   "If it is desired for a pseudonode to be a tree root, the DRB MAY
>>>>     request one or more nicknames in the pseudonode LSP. "
>>>> Can we please remove this sentence from this section?
>>>>       
>>>>         
>>> Why remove it? There are cases where it is useful for a pseudonode to 
>>> have a nickname.
>>> Are you just objecting to wording?
>>>   
>>>       
>> What cases ?
>>
>> Dinesh
>>
>>     
>
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