Re: [5gangip] I-D Action: draft-johansson-cc-for-4g-5g-00.txt

[Rex Buddenberg <[e-mail]>]

Dirk,

I just read the i-d and found it to be like viewing 4G through a WiFi
prism.  This gets some points, but it misses a lot.

Try this (I've no idea how to fit this stuff into the datatracker....;):

- topology.  WiFi is a LAN technology -- reach from last router to end
system.  So it's always at the fringe of the internet.  It's not used
for router-router interconect.  
     But the 4G protocols provide a contention-free MAC that is stable
under overload (it's also spectrum-efficient and manageable, qualities
that WiFi signally lacks).  The contention-free MAC makes the protocols
suitable for extending the internet to _routers_ on mobile platforms
(e.g. ships, aircraft, ambulances, fire trucks, to state a few rather
important ones).  This upsets a few norms that we've had in the (mostly
wired) internet over the past couple decades.

- capacity.  The terrestrial internet is composed of mostly fiber optic
links provisioned in the 10s of G territory. Further we can routinely
react to congestion by picking up a dark fiber pair and provisioning it.
We've solved the congestion control in the terrestrial WAN by
overprovisioning (actually since 1968).  
     But the radio-WAN is spectrum-limited, not technology limited.
Most 4G stuff yields 1-2 M of capacity (four orders of magnitude, or
10000x, less than the terrestrial-WAN).  And that capacity is shared
across all the subscriber stations in the segment.  So we do know
_where_ the congestion will occur -- at the routers bordering the
radio-WAN.  (Hint: there's a role for diff-serv, imho).

- shared medium.  The terrestrial WAN is overwhelmingly made up of fiber
optic cabling.  (So there's no MAC at all in those layer 2 protocols).
But the radio-WAN is, er, radio.  Shared medium.  This presents a
requirement and an opportunity:
  o the requirement is for some means of sharing the medium -- a MAC.
And you have two choices -- contention and contention-free.  By embrace
of 4G/5G in the discussion group, you've opted for the latter (only
correct choice for radio-WAN).  
  o the opportunity is the there is all-sudden an enormous payoff to
multicast.  Because it provides bandwidth efficiency at exactly the
place you need it most -- the inelastic capacity radio-WAN.       


I'd hope that this discussion would lead to maturing things like
multicast IP, multicast transport protocols and multicast applications
that actually use multicast.  
    The corollary is that we need end-to-end (layer 6/7) security in
these applications, along with management agents.  

I can (vaguely) see a host of problems, looming out there.  A taste:
  - multicast groups would be highly dynamic.  
  - PKI management for true end-end security is much more involved than
we've gotten so far.
  - management (to meet the third principle of high availability
engineering) has to be much better than it is now (involved discussion
of what 'better' means herein).  
  - congestion control.  There are beaucoup knobs in the 4G protocols
but not much idea how to control them or link them to higher layer
protocols.  For example, what should the linkage between diff-serv and
tyhe 802.16 MAC be?  And how should an emergency phone call be able to
differentiate itself fron a non-urgent phone chat?  Set the DSCP?  How
many apps do that these days?


Hoping this starts a productive discussion ....


b



 



On Thu, 2015-10-15 at 15:44 +0200, [e-mail] wrote:
> Dear Fuyou, all,
> Thank you for posting the announcement to the list. I think this draft is useful describing some performance issues due to wireless characteristics occurring and impacting upcoming systems (e.g. jitter due to as well as without congestion) and which have to be mitigated by correspondingly improved access and transport control mechanisms in future (5G) networks.
> BTW other aspects which could be discussed here may also be related to SFC/SDN/NFV/... issues such as described in draft 
> "Service Function Chaining Dataplane Elements in Mobile Networks" http://www.ietf.org/internet-drafts/draft-aranda-sf-dp-mobile-00
>  ... but also in various others listed rather exhaustively in http://tools.ietf.org/googleresults?cx=011177064926444307064%3Arsqif7nmmi0&q=5G&cof=FORID%3A9 
> ;-)
> 
> Thanks for joining the discussion!
> Best Regards
> Dirk 
> -----Original Message-----
> From: 5gangip [mailto:[e-mail]] On Behalf Of Miaofuyou (Miao Fuyou)
> Sent: Donnerstag, 15. Oktober 2015 03:57
> To: [e-mail]
> Subject: [5gangip] FW: I-D Action: draft-johansson-cc-for-4g-5g-00.txt
> 
> 
> > -----Original Message-----
> > From: I-D-Announce [mailto:[e-mail]] On Behalf Of 
> > [e-mail]
> > Sent: Thursday, October 15, 2015 2:17 AM
> > To: [e-mail]
> > Subject: I-D Action: draft-johansson-cc-for-4g-5g-00.txt
> > 
> > 
> > A New Internet-Draft is available from the on-line Internet-Drafts 
> > directories.
> > 
> > 
> >         Title           : Congestion control for 4G and 5G access
> >         Author          : Ingemar Johansson
> > 	Filename        : draft-johansson-cc-for-4g-5g-00.txt
> > 	Pages           : 14
> > 	Date            : 2015-10-14
> > 
> > Abstract:
> >    This memo outlines the challenge that 4G and 5G access brings for
> >    transport protocol congestion control and also outlines a few simple
> >    examples that can improve transport protocol congestion control
> >    performance in 4G and 5G access.
> > 
> > 
> > 
> > The IETF datatracker status page for this draft is:
> > https://datatracker.ietf.org/doc/draft-johansson-cc-for-4g-5g/
> > 
> > There's also a htmlized version available at:
> > https://tools.ietf.org/html/draft-johansson-cc-for-4g-5g-00
> > 
> > 
> > Please note that it may take a couple of minutes from the time of 
> > submission until the htmlized version and diff are available at tools.ietf.org.
> > 
> > Internet-Drafts are also available by anonymous FTP at:
> > ftp://ftp.ietf.org/internet-drafts/
> > 
> > _______________________________________________
> > I-D-Announce mailing list
> > [e-mail]
> > https://www.ietf.org/mailman/listinfo/i-d-announce
> > Internet-Draft directories: http://www.ietf.org/shadow.html or 
> > ftp://ftp.ietf.org/ietf/1shadow-sites.txt
> 
> _______________________________________________
> 5gangip mailing list
> [e-mail]
> https://www.ietf.org/mailman/listinfo/5gangip
> 
> _______________________________________________
> 5gangip mailing list
> [e-mail]
> https://www.ietf.org/mailman/listinfo/5gangip