[Diffserv-interest] RE: [Diffserv] [OFFLIST] MPLS+Diffserv(mapping DSCP to EXP)

"Jeff Norman" <jnorman@nortelnetworks.com> Wed, 05 February 2003 17:09 UTC

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Date: Wed, 05 Feb 2003 12:06:17 -0500
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From: Jeff Norman <jnorman@nortelnetworks.com>
Reply-To: Jeff Norman <jnorman@nortelnetworks.com>
To: Shahram Davari <Shahram_Davari@pmc-sierra.com>
cc: nerdboy@rediffmail.com, diffserv-interest@ietf.org
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Subject: [Diffserv-interest] RE: [Diffserv] [OFFLIST] MPLS+Diffserv(mapping DSCP to EXP)
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Shahram,
  You are correct.... i.e. you can use "signalled" E-LSPs
--Jeff

In message "[Diffserv] [OFFLIST] MPLS+Diffserv(mapping DSCP to EXP)", Shahram Davari writes:

>Jeff,
>
>No, I am actually referring to E-LSPs. Each signaled E-LSP can support
>up to 8 PHBs. To support 64 PHBs you need 8 parallel LSPs.
>
>In case of L-LSP, since each L-LSP can support a max of 3 PHBs,
>you would need ~21 parallel LSPs to support the 64 PHBs.
>
>Yours,
>-Shahram
>
>> -----Original Message-----
>> From: Jeff Norman [mailto:jnorman@nortelnetworks.com]
>> Sent: Tuesday, February 04, 2003 5:05 PM
>> To: Shahram Davari
>> Cc: 'Mark Duffy'; nerdboy@rediffmail.com; Diffserv@ietf.org;
>> diffserv-interest@ietf.org
>> Subject: RE: [Diffserv] [OFFLIST] MPLS+Diffserv(mapping DSCP to EXP)
>> 
>> 
>> Shahram,
>>   You are referring to L-LSPs where a one-to-one mapping can
>> be done, where as E-LSPs there isn't, which is what I believe
>> nerdboy is asking about.
>> 
>> Best Regards,
>> --Jeff
>> 
>> In message "[Diffserv] [OFFLIST] MPLS+Diffserv(mapping DSCP 
>> to EXP)", Shahram Davari writes:
>> 
>> >> -----Original Message-----
>> >> From: Mark Duffy [mailto:mduffy@quarrytech.com]
>> >> Sent: Tuesday, February 04, 2003 7:29 AM
>> >> To: nerdboy@rediffmail.com; Diffserv@ietf.org
>> >
>> >> >2. Further, since the DSCP  ( pow(2,8) = 256 combinations ) 
>> >> is 8 bits and
>> >> >provides 22 different PHB's(or roughly 7 different classes),
>> >> >      and the EXP is just 3 bits and therefore can provide 
>> >> only upto 8
>> >> >different classes, wouldnt there be loss of info while 
>> >> mapping DSCP->EXP ?
>> >> >
>> >
>> >No because in MPLS we do DSCP=> PHB translation and PHB=> 
>> EXP+Label encoding. The label gives you the context info, so 
>> each label can support up to 8 PHBs. To support all 64 PHBs 
>> (which are not defined yet) you need 8 parallel LSPs.
>> >
>> >
>> >-Shahram
>> >_______________________________________________
>> >diffserv mailing list
>> >diffserv@ietf.org
>> >https://www1.ietf.org/mailman/listinfo/diffserv
>> >Archive: 
>> http://www.ietf.org/mail-archive/working-groups/diffserv/curre
>nt/maillist.html
>>
>>
>
>


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