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Re: [PWE3] draft-bryant-pwe3-packet-pw-02.txt
It is a bit counter intuitive to me that the technology that added Penultimate Hop Popping to our venacular as an optimization in minimizing the required egress packet fondling, is now bracing for having to process a plethora of labels...
A variation on the "what Grove giveth, Gates taketh away" theme??
Cheers
D
-----Original Message-----
From: pwe3-bounces at ietf.org [mailto:pwe3-bounces at ietf.org] On Behalf Of Stewart Bryant
Sent: Monday, November 16, 2009 3:08 PM
To: HENDERICKX Wim
Cc: pwe3 at ietf.org
Subject: Re: [PWE3] draft-bryant-pwe3-packet-pw-02.txt
The amount of b/w that you save is completely trivial.
- Stewart
HENDERICKX Wim wrote:
> I would vote for the latter. It is not much about the label uniqueness
> but the depth of the stack since it reduces BW.
>
> If we embed the e-type in the label it becomes more easy as well.
>
> -----Original Message-----
> From: Stewart Bryant [mailto:stbryant at cisco.com]
> Sent: maandag 16 november 2009 18:15
> To: HENDERICKX Wim
> Cc: Andrew G. Malis; pwe3 at ietf.org
> Subject: Re: [PWE3] draft-bryant-pwe3-packet-pw-02.txt
>
> It depends what you mean by optimize.
>
> Say you have 100 PWs and 2 protocols
>
> If you optimize for minimum number of unique labels by separating the
> functions, as per the draft, this takes 102 labels
>
> If you optimize for number of labels in the stack, which is what you
> are
>
> requesting, you need 200 unique labels.
>
> - Stewart
>
>
>
>
> HENDERICKX Wim wrote:
>
>> This is correct but could we not optimize this special mapping ?
>>
>> -----Original Message-----
>> From: Andrew G. Malis [mailto:amalis at gmail.com]
>> Sent: maandag 16 november 2009 15:39
>> To: HENDERICKX Wim
>> Cc: stbryant at cisco.com; pwe3 at ietf.org
>> Subject: Re: [PWE3] draft-bryant-pwe3-packet-pw-02.txt
>>
>> Wim,
>>
>> It's still more efficient on the wire than a simulated Ethernet PW,
>> because you would have one less label (the protocol identifier), but
>> would add the Ethernet MAC header instead.
>>
>> Cheers,
>> Andy
>>
>> On Mon, Nov 16, 2009 at 9:03 AM, HENDERICKX Wim
>> <wim.henderickx at alcatel-lucent.be> wrote:
>>
>>
>>> Ok good, this is what I thought, the client LSP exist in the "client
>>> packet Network layer".
>>>
>>> Don't you think this is a huge stack for such a function. You could
>>>
> have
>
>>> 4-6 LBL(s) + CW (optionally). I understand this proposal re-uses
>>> existing functions defined in MPLS, but there are lot's of
>>>
> optimizations
>
>>> possible here -> we could combine FAT LBL, PID LBL, CW potentially.
>>>
>>> -----Original Message-----
>>> From: Stewart Bryant [mailto:stbryant at cisco.com]
>>> Sent: maandag 16 november 2009 14:49
>>> To: HENDERICKX Wim
>>> Cc: pwe3 at ietf.org
>>> Subject: Re: [PWE3] draft-bryant-pwe3-packet-pw-02.txt
>>>
>>>
>>>
>>>>> WH> what I meant is this:
>>>>>
>>>>> -------- --------
>>>>> PE1-----| | | | --- PE3
>>>>> | LSR |------- PKT PW ------| LSR |
>>>>> | | | |
>>>>> PE2-----| | | |---- PE4
>>>>> -------- --------
>>>>>
>>>>> Assume PE1 has a LSP to PE3 and PE2 has an LSP to PE4, how is this
>>>>> distinguished on the PKT PW ?
>>>>>
>>>>>
>>>>>
>>>>>
>>>> SB> I am not sure what you have drawn there, but it is not what is
>>>>
>>>>
>>> shown
>>>
>>>
>>>> in the draft. The pkt pw run between the PEs and is carried over
>>>>
> the
>
>>>> LSPs. PWs are distinguished from each other at the PE via the PW
>>>>
>>>>
>>> label.
>>>
>>>
>>>> WH> What I tried to draw is PE(s) attached to the device (drawn
>>>> WH> with
>>>>
>>>>
>>> the
>>>
>>>
>>>> box) which is performing the LSR function on a PKT PW to another
>>>>
>>>>
>>> device
>>>
>>>
>>>> (drawn with the box) which attaching PE(s).
>>>>
>>>> The question is if I have multiple LSPs from different PE(s)
>>>> through
>>>>
>>>>
>>> the
>>>
>>>
>>>> PKT PW how are the distinguished. Do I need a separate PID LBL, a
>>>> separate PW, etc such that the LSR can make the correct LBL
>>>>
> mappings.
>
>>>>
>>>>
>>> Wim
>>>
>>> Think of the PW as a point to point link between a pair of PEs. The
>>>
> PE
>
>>> chooses what traffic to sent over a given PW. The PE then pushes an
>>>
> MPLS
>
>>> label to identify the destination. The mid-point LSRs have no clue
>>>
> what
>
>>> is being carried over the LSP. The egress PE unwraps that packet and
>>> figures out what the payload is.
>>>
>>> RFC3985 applies to pkt pw as it does to any other PW.
>>>
>>> - Stewart
>>>
>>>
>>>
>>> _______________________________________________
>>> pwe3 mailing list
>>> pwe3 at ietf.org
>>> https://www.ietf.org/mailman/listinfo/pwe3
>>>
>>>
>>>
>>
>>
>
>
>
>
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