A SLR (Service Level Requirements) based footprint for CDNI
draft-song-cdni-slr-based-footprint-00

CDNI                                                             H. Song
Internet-Draft                                                    Huawei
Intended status: Standards Track                           July 09, 2012
Expires: January 10, 2013

      A SLR (Service Level Requirements) based footprint for CDNI
                 draft-song-cdni-slr-based-footprint-00

Abstract

   Footprint advertisement is a very important step for CDN
   interconnection and generates a lot of discussion.  Actually, each
   CDN can serve the whole world if its surrogates are publicly
   reachable by IP addresses.  But if a CDN does that, it can not
   satisfy the requirements from the applications.  So CDNs deliver
   contents for applications, and the basic requirements should be from
   the applications, but there is rare discussion on service level
   requirements based footprint.  This document is used to generate the
   discussion on this aspect.

Status of this Memo

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Table of Contents

   1.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3
   2.  Why SLR Based Footprint . . . . . . . . . . . . . . . . . . . . 3
   3.  What are the parameters for SLR . . . . . . . . . . . . . . . . 4
     3.1.  Up-time . . . . . . . . . . . . . . . . . . . . . . . . . . 4
     3.2.  Average Response Time . . . . . . . . . . . . . . . . . . . 4
     3.3.  Hit Ratio . . . . . . . . . . . . . . . . . . . . . . . . . 4
     3.4.  Capability  . . . . . . . . . . . . . . . . . . . . . . . . 4
     3.5.  Throughput  . . . . . . . . . . . . . . . . . . . . . . . . 4
     3.6.  Discussion  . . . . . . . . . . . . . . . . . . . . . . . . 4
   4.  Message Flows . . . . . . . . . . . . . . . . . . . . . . . . . 5
   5.  Security Considerations . . . . . . . . . . . . . . . . . . . . 5
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
   7.  Normative References  . . . . . . . . . . . . . . . . . . . . . 5
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . . . 5

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1.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

2.  Why SLR Based Footprint

   Each CDN's footprint can be worldwide, if its surrogates' IP
   addresses are publicly reachable.  However, not every CDN can serve
   the applications for worldwide distribution because it can not
   satisfy the serverice level required by those applications.  So what
   an application basically needs is a CDN to satisfy its service level,
   and distribute the contents to certain areas.  If a CDN or together
   with its downstream CDNs, cannot meet the SLR (service level
   requirements) in an area from an application, then we can say this
   upstream CDN is not competent for this content distribution task.
   This document specifies how the parameters of SLR impact a CDN's
   footprint.  There is other draft [I-D.he-cdni-cap-info-advertising]
   mentioned capability advertisement, please note that capability
   advertisement is also very important and footprint is impacted by
   capability of a CDN.  While each CDN serve many tasks concurrently,
   the dynamic resources that it can allocate is also variable at
   different time.

   The physical deployment area of a CDN might be small, but it can have
   larger footprint area where it can satisfy an application's SLR.  The
   footprint area might be even larger than a CDN that has larger
   physical deployment area.  Choosing SLR as the basis for footprint
   can avoid some CDN magnifying its service level and service area on
   purpose, and also make some other "small" but powerful CDN be treated
   with justness.

   We think that applications should participate in the CDN
   interconnection process implicitly, i.e. its requirements for service
   level should be transmitted between upstream and downstream CNDs
   (message protection is required due to the privacy).  A downstream
   CDN should notify its capability information to its upstream CDN as
   well when notifying its footprint that satisfies certain SLR, which
   will allow a upstream CDN to choose multiple downstream CDN to
   fullfill a task even in a same area.

   In general, service level is the main driver for the definition of
   footprint, and applications do not care about the locations where a
   CDN's surrogates are deployed while it can satisfy its service
   requirements.  And topologically, ALTO [I-D.ietf-alto-protocol] is
   used for the appropriate surrogate selection after the footprints are

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   defined.  And ALTO network map information can also be used for the
   footprint description to upstream CDN .

3.  What are the parameters for SLR

   The general principal for SLR is fast, scalable, secure and reliable.
   But it needs detailed measurement metrics for it.  Here we put the
   capability requirements as one parameter for SLR, as one upstream CDN
   can choose multiple downstream CDNs to satisfy an customer
   application's requirements.  This section lists the possible
   parameters for SLR.  However, this document is not going to define
   the specifics for the measurement methods.

3.1.  Up-time

   Uptime is a measure of the time a machine has been up without any
   downtime.  For a CDN system, it usually needs to guarantee a 100% up-
   time for system (not for each host).

3.2.  Average Response Time

   This value is to refelct the average response time in normal network
   condition.  This value impacts the footprint a lot.

3.3.  Hit Ratio

   This is about the content availability.  (TBD)

3.4.  Capability

   Please refer other documents for the CDN capability advertisement in
   CDNI WG.

3.5.  Throughput

   This parameter will also impact the footprint.  If a CDN's available
   throughput is very big then it can serve more than its deployment
   area.

3.6.  Discussion

   Not all parameters required for a certain service level are listed.
   Some parameters might impact a CDN's footprint, and some will not.
   Should all of them be conveyed in the same way among CDNs or just a
   portion of them that affect the footprint?

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4.  Message Flows

   TBD.

5.  Security Considerations

   TBD.

6.  IANA Considerations

   There is no IANA consideration for this document.

7.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [I-D.he-cdni-cap-info-advertising]
              He, X., Dawkins, S., Chen, G., Zhang, Y., and W. Ni,
              "Capability Information Advertising for CDN
              Interconnection", draft-he-cdni-cap-info-advertising-01
              (work in progress), March 2012.

   [I-D.seedorf-cdni-request-routing-alto]
              Seedorf, J., "CDNI Request Routing with ALTO",
              draft-seedorf-cdni-request-routing-alto-01 (work in
              progress), March 2012.

   [I-D.ietf-alto-protocol]
              Alimi, R., Penno, R., and Y. Yang, "ALTO Protocol",
              draft-ietf-alto-protocol-11 (work in progress),
              March 2012.

Author's Address

   Haibin Song
   Huawei

   Email: haibin.song@huawei.com

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