Hi Young,
Thanks for your answers. Please see inline for further comments.
I have put the "alto" list in Cc rather than "altoext" which will be closed.
Best regards
Sabine
Leeyoung a écrit :
Hi Sabine,
Thanks for providing your comments to our drafts. Please see in-line for my
response.
Best Regards,
Young
-----Original Message-----
From: Sabine Randriamasy [mailto:[email protected]]
Sent: Monday, July 30, 2012 12:14 PM
To: Leeyoung
Cc: [email protected]
Subject: Re: [altoext] FW: New Version Notification for
draft-lee-alto-app-net-info-exchange-00.txt
Hi Young,
I have read your draft and have a couple of comments and questions.
In Section 2 Problem statement, I agree with the need to reduce the
amount of conveyed ALTO information through topology filtering and
constraint-based response filtering. The ALTO base protocol specifies
these features for the Cost Map, Filtered cost map and Endpoint cost
services. I also agree with the necessity to provide several types of
cost information which stresses the necessity of extended filtering
mechanisms. In the Constraints filtering extensions of Section 3, I
didnt' really get how information confidentiality is preserved and the
proposed specification raised the questions detailed below.
YOUNG>> Information confidentiality is a big issue which the current draft has not addressed yet. The current draft was written in the "controlled" or "partially controlled" environments which means there is a trusted relationship amongst the entities involving the exchanges of resource data.
In generic framework where there may be no such trusted relationship amongst the entities, we need to address such issue down the road.
Ok. Indeed, ALTO environment control is introduced in the Introduction.
I was mislead by seing "Such information may be considered sensitive to
the network provider just as..." just before "Section 3 provides ALTO
information model and protocol extensions to support... "
I also agree that detailing end to end path costs at the link level at
some places can be beneficial, especially for local bottlenecks
sometimes with fast changing cost values. Figure 2 shows an example with
Link capacity costs but section 2 uses them rather as capacity, where I
figure the higher the better. Without a hint on how path costs are
calculated it is hard to follow the rationale on the DC choice by ER1.
See also the questions detailed below.
YOUNG>> We actually enhanced this mechanism in section 6 of
draft-bernstein-alto-large-bandwidth-cases-02.txt
where we include path vector along with link b/w. Path vector indicates shared
link information from which
The bottle neck link can be identified.
For instance, consider the following example from the draft.
+----+ L0 Wt=10,BW=50 +----+
| N0 |-----------------------------------------| N3 |
+----+ `. +----+
| `. L4 Wt=7 |
| `-. BW=40 |
| `. +----+ |
| `.| N4 | |
| L1 .' +----+ |
| Wt=10 / L2 |
| BW=45 / Wt=12 |
| /L5 Wt=10 BW=30 |
| .' BW=45 |
| / |
| / |
+----+ .' L3 Wt=15 BW=42 +----+
| N1 |.........................................| N2 |
+----+ +----+
Now suppose the network of Figure 1 is a TDM network controlled by
GMPLS. Once again N0 representing a large data center and nodes N2
and N3 as potential clients. However in this case the network provider
offers an additional path, P3, for getting from N0-N2.
Path Src-Dest Path Vector Path Cost
P1 N0-N2 {L0, L2} 22
P2 N0-N3 {L0} 10
P3 N0-N2 {L1,L3} 25
----------------------------------
Link Bandwidth
L0 50
L1 45
L2 30
L3 42
So the draft now propose that the network can provide abstract path
list along with link bottlenecks. We also provide how this mechanism
works for IP and other types of networks.
I'm fine with the rationale in
draft-bernstein-alto-large-bandwidth-cases-02.txt. It's just that in
draft-lee-alto-app-net-info-exchange-00.txt I missed the relation
between the "LinkCapacity Cost" & ALTO Cost Map in Figure 2 and also the
explanatory text text. Maybe a little clarifying edition can help.
I will provide the responses to your detail questions later.
Thanks.
Young
Thanks,
Sabine
------------------------- Detailed questions -----------------------------
++ Section 3.1 ALTO Query from Application Stratum to Network Stratum
Names used in the list of requested information may be misleading:
- A 'Cost Type' see base protocol (§5.1.1) is expected to indicate an
attribute that has a value such as number, boolean, string... and is is
rather "semantic". 'summary' and 'graph' are cost attributes of
different nature.
- 'Constraints' such as 'min/max metric' look like objectives rather
than expressions such as 'lt. value' as specified in the base protocol
(§ 6.8.2.2.3)
- what kind of information is member 'Parameters' is supposed to carry
and for what use?
- Some members listed here do not appear in the ALTO Query Information
Model of §3.3: 'parameters' 'objective-function'. Neither do they appear
in the example of §3.5
++ Section 3.2 ALTO response from Network ....
- The list of S-D pairs should carry the Cost Type *values* as the
supported Cost Types are expected to be listed and checked in the IRD.
- 'Constraint values': need to be clarified: is it the actual cost
value? then the draft should specifiy that the constraits relate to Cost
Types (as defined in §5.1.1).
- how is the 'Administration Domain ID' of a S-D pair reported and why
is it needed?
++ Section 3.3 Information Model of ALTO Query ...
Looking at the specification here, it is hard to figure out what is
really extended here w.r.t. the Endpoint Cost Service query input
specified in the base protocol.
- A new media type "CsoReqEndpointCostMap" and differs from
"ReqEndpointCostMap" of the base protocol in that the set in member
'contraints' is encoded/interpreted differently, according to example in
§3.5. Then a different member name than 'contraints' should be used.
- As for member 'endpoints': unless you need to specify only 1 src EP,
what is the need to define a new object "EndpointFilterExt" instead of
keeping the "EndpointFilter"?
++ Section 3.4 Information Model of ALTO Response ...
- object CsoInfoResourceEndpointCostMap has the same structure than
InfoResourceEndpointCostMap of base protocol
- what in the list of §3.2 does object 'DstCostsConstraints' refer to?
- this object seem to be encoded like a set of JSONNumbers that are the
values of resp. hopcount, latency and packet loss. So I guess, they
should be arranged in an array.
- why is this set of cost types already set at this level of
specification?
++ Section 3.5 ALTO protocol extension...
I agree with the idea of providing several Cost Type values at a time
but the encoding could be lighter. The draft "Multi-Cost ALTO" proposes
one example.
There is a real need that this section be harmonized with the previous
specification sections, as the encoding provided in the examples are
misleading.
++ Section 4.1 Representing....
- this section is rather about representing links and their attributes,
so could be named accordingly
- the graph specification is curretnly a list of links, do you intend to
extend so that one can infer its structure?
- is there a reason preventing member 'r-cap' to be specified as
JSONNumber capacity?
- what is the usage of wt at this level of a spec ? (could also be
'JSONNumber weight')
Leeyoung a écrit :
Hi All,
We have just published ALTO extension to support application and network
resource information exchange for high bandwidth applications.
This is part of the i2aex initiative.
Thanks in advance for your comment and discussion.
Young
-----Original Message-----
From: [email protected] [mailto:[email protected]]
Sent: Monday, July 09, 2012 11:06 AM
To: Leeyoung
Cc: [email protected]; Sreekanth madhavan; [email protected]; Dhruv
Dhody
Subject: New Version Notification for
draft-lee-alto-app-net-info-exchange-00.txt
A new version of I-D, draft-lee-alto-app-net-info-exchange-00.txt
has been successfully submitted by Young Lee and posted to the
IETF repository.
Filename: draft-lee-alto-app-net-info-exchange
Revision: 00
Title: ALTO Extensions to Support Application and Network Resource
Information Exchange for High Bandwidth Applications
Creation date: 2012-07-09
WG ID: Individual Submission
Number of pages: 14
URL:
http://www.ietf.org/internet-drafts/draft-lee-alto-app-net-info-exchange-00.txt
Status:
http://datatracker.ietf.org/doc/draft-lee-alto-app-net-info-exchange
Htmlized:
http://tools.ietf.org/html/draft-lee-alto-app-net-info-exchange-00
Abstract:
This draft proposes ALTO information model and protocol extensions to
support application and network resource information exchange for high
bandwidth applications in partially controlled and controlled
environments as part of the infrastructure to application information
exposure (i2aex) initiative.
The IETF Secretariat
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