FYI, I discussed this topic with Marco as P2P, and copied my
comments/questions and his answers below.
Best regards,
Shunsuke
--
General Comments and questions:
[SH] I assume that 3GPP 5G architecture is designed to provide basic
control of user plane traffic with UPFs (and corresponded SMFs), and
policy enforcements, such as QoS control, steering, or charging, would
be done at UPF(s) in bi-direction. In other words, a UPF is deployed at
place where some traffic handling is needed. Then, do you have any
requirements to handle user plane traffic on N6 interface?
[ml] that depends a lot on the deployment. Today all policies are in the
UPFs and these are associated with data networks, hence N6 is
potentially short. If we think about scenarios where we decouple the
binding of a UPF to a data network, e.g. by sharing a UPF for traffic
from multiple data networks, these data networks should have policies to
route downlink traffic to the right UPF, in particular if there a more
than one. Also, relocation of a UPF while maintaining the UE's IP
address changes the IP address from a routable to a non-routable
address. Hence, ID-LOC protocols, for example, can be used to steer
traffic to the new UPF by using default routes in the transport network.
We see this not necessarily required for all traffic, but for some
deployments, in particular for future industry verticals. Moving the UPF
while maintaining the session may in some cases more efficient
(signaling costs, etc) than adding more and more UPFs which serve as
PSAs, or adding more ULCL UPFs to route to a local data network.
[SH] The current user plane protocol study proceeded in 3GPP CT4 mainly
focuses on N9 interface, and N3 and N6 are out of scope. Do you have any
plan to propose to expand the scope to 3GPP CT4?
[ml] well, it would be nice, hence we want to extend the data plane
discussion to N6 in the IETF first. We tried to being some of these
cases to 3GPP SA2 some years ago, but the reaction was obvious that
SGi/N6 is out of scope. Let me say this way: I am not sure how CT4 will
treat the new protocols for N9/N3, hence nothing may change. Bringing in
N6 allows us to apply IETF protocols and enable new use cases.
Small comments:
[SH] Regarding some figures representing 5G architecture, UPFs should be
connected with N9 interface and every UPF must have N4 interface.
[ml] Absolutely, but we did not want to sketch the complete architecture
as it's already in many other IETF drafts we refer to. If you think it's
confusing, we can add N4, no problem.
[SH] As you may know, there is some difference between definition of
data/user plane on 3GPP and IETF, and thus it's better to describe the
definition in this document.
[ml] good point. We can describe it, but let's see if in any of the
existing drafts there is a definition, so we can align it.
On 2018/09/21 4:37, Marco Liebsch wrote:
Folks,
we submitted a new ID which extends the current data plane discussion
from N9/N3 to N6 interfaces
of the mobile system’s architecture.
We could discuss the use cases, problem statement and principles with
some before submission, but
post this initial draft to get the larger community’s feedback before we
update with more details and the
received feedback.
Your comments are appreciated.
Best regards,
marco
Name: draft-fattore-dmm-n6-cpdp-trafficsteering
Revision: 00
Title: Control-/Data Plane Aspects for N6 Traffic
Steering
Document date: 2018-09-20
Group: Individual Submission
Pages: 12
URL:
https://www.ietf.org/internet-drafts/draft-fattore-dmm-n6-cpdp-trafficsteering-00.txt
Status:
https://datatracker.ietf.org/doc/draft-fattore-dmm-n6-cpdp-trafficsteering/
Htmlized:
https://tools.ietf.org/html/draft-fattore-dmm-n6-cpdp-trafficsteering-00
Htmlized:
https://datatracker.ietf.org/doc/html/draft-fattore-dmm-n6-cpdp-trafficsteering
Abstract:
Current standardization effort on the evolution of the mobile
communication system reconsiders the mobile data plane protocol. The
IETF DMM Working Group has work that proposes and analyzes various
protocols as alternative to the GPRS Tunneling Protocol for User
Plane (GTP-U) for an overlay deployment in between the mobile
device's assigned data plane anchor and its current radio base
station, which are denoted as N9 and N3 interfaces. In the view of
some future deployment and the original intent per the very early DMM
WG charter, a mobile device's data plane anchor may be highly
distributed and re-selected for optimization throughout a mobile
device's communication with one or more correspondent services. Such
re-configuration has impact on the packet routing in between the
mobile device's data plane anchor and the one or multiple data
networks hosting the services, which is denoted as N6 interface.
This draft proposes and discusses a solution to control, setup and
maintain traffic treatment policy on the cellular communication
system's N6 interface while taking the UE's PDU session settings per
the cellular system's control plane, such as QoS and locator
information, into account.
_______________________________________________
dmm mailing list
[email protected]
https://www.ietf.org/mailman/listinfo/dmm
--
----------------------------------
Shunsuke Homma
<[email protected]>
TEL: +81 422 59 3486
FAX: +81 422 60 7460
NTT Network Service Systems Labs.
Musashino city, Tokyo, Japan
----------------------------------
_______________________________________________
dmm mailing list
[email protected]
https://www.ietf.org/mailman/listinfo/dmm
