[Detnet] Crosshaul input for consideration in draft-ietf-detnet-use-cases

[Carlos Jesús Bernardos Cano <[e-mail]>]

Hi,

In Seoul we presented draft-bernardos-detnet-crosshaul-requirements-
00.txt as potential input to be considered for "Section 6. Cellular
radio" of draft-ietf-detnet-use-cases. The group agreed that 
contributions from us were welcome to complement/fix the text in the
use cases document.

We have taken -11 version and tried to propose specific changes to the
document. Please find them below for discussion.

----
6.1.1.  Network Architecture

OLD:

Figure 10 illustrates a typical 3GPP-defined cellular network
architecture, which includes "Fronthaul" and "Midhaul" network
segments.  The "Fronthaul" is the network connecting base stations
(baseband processing units) to the remote radio heads (antennas).
The "Midhaul" is the network inter-connecting base stations (or small
cell sites).

NEW:

Figure 10 illustrates a typical 3GPP-defined cellular network
architecture, which includes "Fronthaul", "Midhaul" and "Backhaul"
network segments.  The "Fronthaul" is the network connecting base
stations (baseband processing units) to the remote radio heads
(antennas).  The "Midhaul" is the network inter-connecting base
stations (or small cell sites).  The "Backhaul" is the network or
links connecting the radio base station sites to the network
controller/gateway sites (i.e. the core of the 3GPP cellular
network).
----
6.1.3.  Time Synchronization Constraints

[...]

OLD:

In cellular networks from the LTE radio era onward, phase
synchronization is needed in addition to frequency synchronization
([TS36300], [TS23401]).

NEW:

In cellular networks from the LTE radio era onward, phase
synchronizatio
n is needed in addition to frequency synchronization
([TS36300],
[TS23401]).

Time constraints are also important due to its impact on packet loss.
If a packet is delivered too late, then the packet may be dropped by
the host.
----

----
6.1.4.  Transport Loss Constraints

[...]

OLD:

For packetized Fronthaul and Midhaul connections packet loss may be
caused by BER, congestion, or network failure scenarios.  Current
tools for elminating packet loss for Fronthaul and Midhaul networks
have serious challenges, for example retransmitting lost packets and/
or using forward error correction (FEC) to circumvent bit errors is
practically impossible due to the additional delay incurred.  Using
redundant streams for better guarantees for delivery is also
practically impossible in many cases due to high bandwidth
requirements of Fronthaul and Midhaul networks.  Protection switching
is also a candidate but current technologies for the path switch are
too slow to avoid reset of mobile interfaces.

NEW:

For packetized Fronthaul and Midhaul connections packet loss may be
caused by BER, congestion, or network failure scenarios.  Some
fronthaul functional splits considered by 3GPP require the frame loss
ratio (FLR) to be less than 10E-7 for data traffic and less than
10E-6 for C&M.  Current tools for eliminating packet loss for
Fronthaul and Midhaul networks have serious challenges, for example
retransmitting lost packets and/or using forward error correction
(FEC) to circumvent bit errors is practically impossible due to the
additional delay incurred.  Using redundant streams for better
guarantees for delivery is also practically impossible in many cases
due to high bandwidth requirements of Fronthaul and Midhaul networks.
Protection switching is also a candidate but current technologies for
the path switch are too slow to avoid reset of mobile interfaces.
----

----
6.3.  Cellular Radio Networks Future

[...]

OLD:

o  All form of xHaul networks will need some form of DetNet
   solutions.  For example with the advent of 5G some Backhaul
   traffic will also have DetNet requirements (e.g. traffic belonging
   to time-critical 5G applications).

NEW:

o  All form of xHaul networks will need some form of DetNet
   solutions.  For example with the advent of 5G some Backhaul
   traffic will also have DetNet requirements (e.g. traffic belonging
   to time-critical 5G applications).

o  Different splits of the functionality run on the base stations
   (baseband processing units) and the remote radio heads (antennae)
   could co-exist on the same Fronthaul and Backhaul network.
----

----
6.4.  Cellular Radio Networks Asks

[...]

OLD:

A standard for data plane transport specification which is:

o  Unified among all xHauls (meaning that different flows with
   diverse DetNet requirements can coexist in the same network and
   traverse the same nodes without interfering with each other)

o  Deployed in a highly deterministic network environment

NEW:

A standard for data plane transport specification which is:

o  Unified among all xHauls (meaning that different flows with
   diverse DetNet requirements can coexist in the same network and
   traverse the same nodes without interfering with each other)

o  Deployed in a highly deterministic network environment

o  Capable of supporting multiple functional splits simultaneously,
   including existing Backhaul and CPRI Fronthaul and new modes as
   defined for example in 3GPP.

o  Slicing and Multi-tenancy-capable, supporting: isolating traffic
   (guaranteed QoS) and separating traffic (privacy).

o  Compatible with existing security and synchronization mechanisms,
   such as IEEE1588, IEEE802.1AS.

o  Capable of transporting both in-band and out-band control traffic
   (OAM info, ...).

o  Deployable over multiple data link technologies (e.g., IEEE 802.3,
   mmWave, etc.).
----

Comments are welcome,

Thanks,

Carlos