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Re: [PWE3] draft-bryant-pwe3-packet-pw-02.txt
Luca, for IP you are right in terms of protocol stack but I have the
impression that the packet-PW draft is more generic and we should be
open minded to other applications apart from IP.
What I propose is to have 1. tunnel label - 2. pw label - 3. a label
which combines the pid label + CW + hash label.
-----Original Message-----
From: Luca Martini [mailto:lmartini at cisco.com]
Sent: woensdag 18 november 2009 23:18
To: HENDERICKX Wim
Cc: stbryant at cisco.com; pwe3 at ietf.org
Subject: Re: [PWE3] draft-bryant-pwe3-packet-pw-02.txt
Wim,
We can , of course , always reduce the label stack depth by merging
labels, but that is usually not a good idea , as it will increase the
number of labels, that that is the most expensive part of MPLS.
Also note that The FAT PW would not be very useful with a packet PW that
contains IP.
Let assume for a moment that 99.9% of traffic in a packet PW will be IP
... ( most likely it's much higher then that )
I do not like the CW much , so let say that we simply encapsulate the IP
packet into a protocol label, a PW label, and a tunnel label.
That's a 3 label stack , with excellent load sharing capabilities. If
you pull the PID out into a CW , for example , you will have to add
another label , and also make the encapsulation process much more
complicated at the PE.
So , for this application it's better to just have 3 labels.
Luca
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
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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