IP everywhere does not mean that the difference between the network and the
inter-network goes away. Making
QoS happen inside a network and across an Inter-network are two very
different problems.
I agree - https://datatracker.ietf.org/doc/draft-ietf-tsvwg-diffserv-intercon/
recognizes this, and cleanly separates QoS within a network from what happens
at network boundaries, as does ...
Forgetting the distinction between the network and the inter-network gives us
a choice between only network layer everywhere or only packet layer
everywhere.
If we recognize the border, we might end up with a stack something like this:
ZServ:
A A
T Q <-|-> Q T
N <--> N <--> N <-|-> N <--> N <--> N
P <--> P <--> P <-|-> P <--> P <--> P
Gee, this looks familiar - see RFC 2475 on DiffServ architecture, and in
particular the difference that it draws between classification functionality
that is appropriate within a network vs. at its edges (i.e., DiffServ
recognizes that border). The DiffServ Intercon draft is trying to iterate
across networks, because DiffServ differentiation as currently deployed tends
not to cross network boundaries well.
Thanks,
--David
From: tsvwg [mailto:tsvwg-bounces(_at_)ietf(_dot_)org] On Behalf Of Phillip
Hallam-Baker
Sent: Monday, February 09, 2015 11:07 AM
To: Ruediger(_dot_)Geib(_at_)telekom(_dot_)de
Cc: IETF Discussion Mailing List; Jim Gettys; Richard Shockey;
tsvwg(_at_)ietf(_dot_)org; Michael Richardson
Subject: [tsvwg] QoS and IP everywhere Was: Naive question
On Mon, Feb 9, 2015 at 3:47 AM,
<Ruediger(_dot_)Geib(_at_)telekom(_dot_)de<mailto:Ruediger(_dot_)Geib(_at_)telekom(_dot_)de>>
wrote:
As Brian pointed out,
https://datatracker.ietf.org/doc/draft-ietf-tsvwg-diffserv-intercon/ proposes a
method "how to get the labeling/queueing across the AS boundary". Input is
welcome.
Commercial DiffServ interconnection products are available. They may however
not be be widespread.
If you however ask the question how to transit the complete QoS concept and
codepoints of a sending domain to a customer connected to another domain - that
hasn't been standardized yet.
If your expectation is that a consumer (device) sets priorities of packets and
carriers honour these markings, a technical and commercial model accepted by
all parties is required. I'm not aware of one (I'm not interested in discussing
how to get one on this list).
There's also no generally specified set of packet marks within the Best Effort
class, which can transparently cross carrier boundaries on an end to end basis.
That might offer a separation of WAN and LAN or application QoS marks (should
this be useful).
Having had cause to look at Internet architecture in some detail of late for a
paper. I think we have actually lost something important with the push for 'IP
everywhere'.
IP everywhere does not mean that the difference between the network and the
inter-network goes away. Making QoS happen inside a network and across an
Inter-network are two very different problems.
One of the architectural questions that comes up is how do we define the
difference between the Network (packet) layer and the transport layer? I think
the best, cleanest definition is to say that the network layer is stateless. If
you have per packet state then you are doing transport.
Which gives a very clean distinction between IntServ and DiffServ approaches to
QoS. Both require modification of the switches on the path. But IntServ
requires the path to perform some transport layer functions because it requires
per session state.
IntServ:
A A
T <--> t <--> t <--> t <--> t <--> T
N <--> N <--> N <--> N <--> N <--> N
P <--> P <--> P <--> P <--> P <--> P
(where t stands for just the QoS part of transport)
DiffServ:
A A
T T
N <--> N <--> N <--> N <--> N <--> N
P <--> P <--> P <--> P <--> P <--> P
That does not mean IntServ is some abomination denying the basic principles of
the Internet. Modern devices are far more capable than in 1983. There is no
reason to believe that the correct layer at which to cap Inter-network
complexity is some fixed universal constant. But it does show it is likely to
be harder to deploy.
Forgetting the distinction between the network and the inter-network gives us a
choice between only network layer everywhere or only packet layer everywhere.
If we recognize the border, we might end up with a stack something like this:
ZServ:
A A
T Q <-|-> Q T
N <--> N <--> N <-|-> N <--> N <--> N
P <--> P <--> P <-|-> P <--> P <--> P
Any normal interaction is going to involve at least three networks, the
customer network, their ISP's network and the destination network of the
content provider. More usually there will be four networks.