Subject: draft-ietf-mpls-diff-ext-02.txt

From: Rahul Aggarwal <[email-masked]>
Date: Mon, 15 Nov 1999 18:23:17 -0400

Francois,
Here are the issues that I had raised during your presentation of the MPLS
support of diff serv draft at the recent IETF:

1. It is not clear why the DIFFSERV_PSC object should be contained in the
RSVP path message while establishing a E-LSP tunnel for a single ordered
aggregate. The PSC and the drop precedence in this case can be inferred
from the EXP field of the MPLS Shim Header. Hence the use of the
DIFFSERV_PSC object is not clear. Maybe this object is useful for admission
control during tunnel set up. If this is the case perhaps the draft should
be clear about it. 

2. As stated in the draft, the PHB to EXP mapping is considered a local
matter to be defined by the service provider and configured on every LSR.
Have you considered a control plane driven approach for doing this as
opposed to local configuration on each box? I understand that in Diffserv
the PHB to DSCP mapping is also a local matter. However that does not
necessarily mean that the PHB to EXP mapping should be done in the same way. 

Any comments will be appreciated.

Thanks,
rahul

---

From: Juha Heinanen <[email-masked]>
Date: Wed, 17 Nov 1999 23:13:07 +0200 (EET)

> necessarily mean that the PHB to EXP mapping should be done in the

i don't like the idea of manually coordination of the exp-phb mapping in
each mpls switch and end system.  it would be much better, if the "setup
message" would contain the list of phb ids that are going to be carried
over the lsp, and then when the "connect message" comes back, the
downstream box would tell for each phb in the list, which exp value it
expects from the upstream box.

i'll try to find time to check exactly what modifications would be
needed in order to incorporate this into the current text.

-- juha

---

From: Francois Le Faucheur <[email-masked]>
Date: Fri, 19 Nov 1999 10:55:40 +0100

Rahul,

At 18:23 15/11/1999 -0400, Rahul Aggarwal wrote:
>aggregate. 
>The PSC and the drop precedence in this case can be inferred

This is the case and I will make it clear in the draft.

Thanks

Francois

[clip]
>Any comments will be appreciated.
NOTE : New Mobile Number        +33 6 89 10 81 59
_________________________________________________________________
Francois Le Faucheur   
Development Engineer, IOS Layer 3 Services 
Cisco Systems 
Phone Office:   +33 4 92 96 75 64
Phone Home Office:      +33 4 92 94 00 78
Mobile :                +33 6 89 10 81 59
Vmail:                  +33 1 69 18 62 66
Fax:                    +33 4 92 96 79 08
Email:          [email-masked]
_________________________________________________________________
Petra B - Les Lucioles - 291, rue Albert Caquot - 06560 Valbonne - France
_________________________________________________________________

---

From: Francois Le Faucheur <[email-masked]>
Date: Fri, 19 Nov 1999 11:48:06 +0100

Juha, Rahul,

> > necessarily mean that the PHB to EXP mapping should be done in the

Whether you establish the PHB/EXP mapping via signalling or not, the
network administrator has to perform some Diff-Serv PHB configuration for
each and every interface anyway: the network administrator has to allocate
bandwidth to each queue, perhaps has to configure queue parameters, and has
to configure discard profile (eg for AF). Configuring at the same time the
EXP/PHB mapping for each PHB seems fairly straighforward to me.

Also, at least for some time, there may be both IP and MPLS traffic in the
network which need to share the Diff-Serv PHBs. Configuring the EXP-->PHB
mapping at the same time as the DSCP-->PHB mapping seems natural to me to
ensure consitent use of Diff-Serv PHBs across MPLS and non-MPLS IP.

As mentioned in the draft, there are existing implementations of such an
approach already which have returned positive feed-back from early
evaluations.

So, certainly for some time at least, I see a lot of value in the simple
approach with manual configuration of EXP<-->PHB mapping.

>needed in order to incorporate this into the current text.

Do we agree this signalling would be an optional thing?
Would it be possible to group the corresponding text in a standalone
section(s)?

thanks

Francois

---

From: Juha Heinanen <[email-masked]>
Date: Fri, 19 Nov 1999 18:12:25 +0200 (EET)

> EXP/PHB mapping for each PHB seems fairly straighforward to me.

usually i would configure the same wfq weights and red thresholds for
each af class and interface in my network and could thus do it with
global config command.  the phb/exp mapping on the other hand is another
story, since each of my downstream neighbors may ask for different
phb/exp mapping.

 > approach with manual configuration of EXP<-->PHB mapping.

i don't see any value of manually configuring something if it can be
easily automated. 

 > Would it be possible to group the corresponding text in a standalone

sure it could be an option, i.e., the setup message would not be
mandated to  the phb ids and the connect message would not ned to
include the exp values.

-- juha

---

From: Mark Duffy <[email-masked]>
Date: Fri, 19 Nov 1999 11:49:06 -0500

>story, since each of my downstream neighbors may ask for different

Why would there be a different phb/exp mapping to different downstreams?  I
would expect these to be the same throughout the MPLS-DS domain, and only
vary for downstreams in a different domain.  This is the same concept as
DSCP/phb mappings being constant througout a (non-mPLS) DS domain.

Otherwise, you'd need to do remapping of EXP or DS codepoints at every hop,
just to keep the PHB the same.

In my view, it is the phb/exp mapping that would be set globally, and the
queue weights, discard profiles, etc that might be tuned at each interface,
in order to instantiate the same Per Hop Behavior on links having different
characteristics.

Mark

---

From: Juha Heinanen <[email-masked]>
Date: Sat, 20 Nov 1999 06:30:44 +0200 (EET)

Mark Duffy writes:

 > vary for downstreams in a different domain.  

i ment downstream domain (which can be a customer site too).  also, i
need to somehow be able ot tell the upstream domain (e.g. another
customer site), what mapping to use.

-- juha

---

From: Juha Heinanen <[email-masked]>
Date: Sat, 20 Nov 1999 06:35:41 +0200 (EET)

> in order to instantiate the same Per Hop Behavior on links having different

the phb/exp mapping could be set globally within a domain, but between
domains that can't be done, since each domain may support different
possibly overlapping sets of phbs over a single lsp.

-- juha