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Comments on CDN Peering Architectural Overview
- To: firstname.lastname@example.org, Gary Tomlinson <email@example.com>
- Subject: Comments on CDN Peering Architectural Overview
- From: Barron Housel <firstname.lastname@example.org>
- Date: Fri, 03 Nov 2000 01:27:36 -0500
- Delivery-date: Thu, 02 Nov 2000 22:29:07 -0800
- Envelope-to: email@example.com
These comments are based on the version dated 10/20.
Exellent start, very packed with insights and articulates the relationships
well for the level of maturity we're at.
As I commented on the model doc, I'd fold in the Model material here to
make the document more complete and simplify life for the reader.
5th para typo: "itself, is the it be able" ->"itself, is that
it be able"
Item 3 under the fundamental assumptions: This is not clear. Is this
a new proposal for structuring URLs to include meta data? Can you
give an example?
On Figure 1 and the example flow: The flow of the request is not
clear. Does the URI travel: client->direction peering system->surrogate?
or client->direction peering system->(address of surrogate)->client->surrogate?
I assumed the latter from looking at the figure; this would be analogous
to the way DNS works. Maybe reworking steps 3. and 4. would help.
Also, it would be most clear if you labeled the lines (arrows) in the figure
and then referenced them in the example.
Are we constraining the content to be location to be a function of domain
name only -- which, in general, can map to multiple locations? Does
this relate to the URL meta-data you mentioned earlier?
In the paragraph: "The DIRECTION PEERING systems is hierarchical ..." should
PUBLISHER URI really be PUBLISHER domain? (related to previous comment)
An 8th problem you could mention here: How do we choose among multiple
You broach the question of policy distribution in 5. What is the
relationship between CDN policy distribution and the other policy work
going on in IETF? Is COPS relevant? Maybe a footnote is appropriate
to acknowledge a "to do" to look into it.
Sections 184.108.40.206 and 220.127.116.11
1st para: can you give an example of information DIRECTION SYSTEMs may
2nd para: Are we really going to require exchanging potentially a huge
number of client addresses? or perhaps subnets? Are there ambiguities
introduced via DHCP and NAT in some cases? Isn't the issue whether
or not a client can get to content published to the CDN by a presumably
paying content provider? Does the content provider provide a list
of the clients that can access the content? (doubtful)
Item 2 under Request Direction Requirements: Is URI name space really the
DNS name space?
I have a little trouble with "virtual SURROGATE". Thus far SURROGATES
deliver content. The virtual SURROGATE seems to process the request
to derive a real SURROGATE. I presume that the real SURROGATE delivers
content directly to the client without having to revisit the virtual SURROGATE.
How about just calling it a "content-aware redirection network element"
or DIRECTION EXTENSION ELEMENT and avoid the confusion. Also, the
virtual SURROGATE seems to be outside the DIRECTION system but it is in
fact doing request directing.
A general comment on advertising. I expected to see some relationship
between the DISTRIBUTION CPG and the DIRECTING CPG. i.e., When content
is replicated (distributed) in another CDN, doesn't the location of the
content and its URI have to be passed to the DIRECTION CPG in the receiving
CDN so the client can locate the surrogate more efficiently? Or does
the URI visit the owning CDN's CPG to determine where all the surrogates