Transcript ACP-WGC11-WP27-ETDMA Study results network

AGCFG meeting Brussels
18/09/2006
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Technique et de
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Présented by
Luc Deneufchatel]
ETDMA Study results:
Sous-titre
facultatif de la of
diapositive
Integration
ETDMA
subnetwork within an ATN/IP
network
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Agenda
direction de la Technique
et de l’Innovation
• 1. End-to-end connectivity
i.
VDL/ETDMA architecture
ii.
Protocols stack model
iii. Mobility management
iv. Addressing requirements
v.
QoS management
• 2. Guaranteed QoS
i.
At ATM services level
ii.
At ETDMA network level
iii. End-to-end
iv. In the Internet
• 3. Conclusion
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End-to-end connectivity
Objectives
– Definition of protocols stack model for end-to-end connectivity
(without using ISO 8208, identification of ETDMA users)
– Clarify the role of each protocols stack layer
– Describe service primitives
– Define addressing requirements
– Describe QoS management (“soft” guaranteed QoS)
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End-to-end connectivity
ETDMA architecture
ETDMA
Sub-Network
ETDMA
Network Users
ATN G/G Router
ATN
Applications
ATN A/G Router
Cluster 1
GNI
IPv6 Router
WAN
ATN A/G Router
Cluster 2
GNI
TCP/IP
Applications
IPv6 Router
IP Router
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End-to-end connectivity
Protocols stack model
TCP/IP
Stack
ATN
Stack
IP SNDCF
ATN SNDCF
1
ATN
Stack
TCP/IP
Stack
ATN SNDCF
IP SNDCF
2
ETDMA Network Layer
ETDMA Network Layer
3
GNI
Bridge
4
A/G CS
WAN
WAN
5
ETDMA
Ground
Router / End System
A/G CS
Ground
ETDMA Station
ETDMA
Airborne
Router / End System
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End-to-end connectivity
First contact
TCP/IP
Stack
ATN
Stack
ISH PDU
IP SNDCF
Join Event
- List of fixed
ETDMA users
- Ground station ID
Join Event
- Aircraft ID
- GNI ID
ATN SNDCF
ETDMA Network Layer
ATN
Stack
TCP/IP
Stack
ISH PDU
ATN SNDCF
SN-Service.Available
(Aircraft ID + Ground Station ID)
GNI
IP SNDCF
ETDMA Network Layer
Bridge
Channel 0
WAN
Ground
Router / End System
A/G CS
A/G CS
ETDMA
ETDMA
WAN
Ground
ETDMA Station
Airborne
Router / End System
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End-to-end connectivity
Data transfer
– LREF compression: specific to CLNP and thus provided in Frame Mode
SNDCF proper (refer to ATN specifications)
– Deflate compression: part of ETDMA network layer and it requires a low
probability of re-ordering! Problem: ETDMA Data Link layer provides a
high probability of re-ordering (use of ETDMA Classes of Service).
Adaptations are thus necessary:
• Frame Mode SNDCF proper should handle ETDMA QoS to request appropriate
ETDMA QoS before compression
• One Deflate compressor should be used for each ETDMA QoS (one channel
should be established for each ETDMA QoS)
• Deflate function has to be implemented at the link layer level
• ETDMA network should transit data using the requested ETDMA QoS
– Priorities: priorities should not be used after Deflate compression =>
priorities should not be used at ETDMA Data Link level
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End-to-end connectivity
Data transfer
– Delivery reliability: at Data Link level, ETDMA should implement
acknowledgements and a CRC
– Service primitives: description of parameters and behaviour (uplink)
Air/Ground
Router
Ground
ATN
Stack
ETDMA
Sub-network
ATN
ETDMA
SNDCF
1
ETDMA
NL
2
ETDMA ETDMA ETDMA
GNI
A/G CS
GS
3
4
Airborne
Router
ETDMA
Radio
ATN Airborne
ETDMA
ATN
SNDCF Stack
ETDMA ETDMA
A/G CS
NL
5
6
CLNP
PDU
10
7
8
9
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End-to-end connectivity
Handoff
– Handoff between Ground Stations in same cluster has only a minor impact
on air and ground:
• On ground side, it will be handled by the GNI
• On airborne side, the ETDMA radio should recognize that it is still connected to
the same ETDMA sub-network, using first part of the address of ground
ETDMA users (A/G Routers) advertised using the GSC.
– Handoff between Ground Stations in different clusters has more impact on
air and ground:
• On ground side, it will be handled by the previous GNI (leading to Leave Event)
and the next GNI (leading to Join Event)
• On airborne side, the ETDMA radio should recognize that it is no longer
connected to the same ETDMA sub-network, using first part of the address of
ground ETDMA users (A/G Routers) advertised using the GSC. This will lead to
Join and Leave Events.
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End-to-end connectivity
Addressing requirements
Physical ETDMA User ID
Upper Stack ID
1 byte
ETDMA Network ID
User ID
1 byte
1 byte
Ground-based ETDMA User address
Aircraft ID
Upper Stack ID
3 bytes
1 byte
Mobile ETDMA User address
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End-to-end connectivity
QoS management
– ETDMA Classes of Service
• Frame Mode SNDCF proper should have capability to handle ETDMA Classes of Service to
request appropriate ETDMA Class of Service
• ETDMA link layer should use one Deflate compressor for each ETDMA Class of Service (one
logical channel for each ETDMA CoS).
• ETDMA Ground Stations and radio should transmit data using the requested ETDMA Class of
Service.
– Priorities
• Priorities should be used before and not after compression i.e. at the level of the Frame Mode
SNDCF and not at the level of ETDMA.
• Some mechanisms should be implemented to allow the ETDMA network layer to know status
of sending queues within lower layers.
– Integrity
• ETDMA should implement an acknowledged service between an ETDMA Ground Station and
an ETDMA radio. A CRC should be used.
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Guaranteed QoS
Objectives
– Investigate the implementation of guaranteed QoS (“hard” guaranteed
QoS) at ATM services level using ETDMA capabilities
– Methodology:
• Analyse the gap between “guaranteed QoS at ATM services level” and
“guaranteed QoS at ETDMA network service level”
• Review solutions implemented in the Internet to provide a “guaranteed QoS”
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Guaranteed QoS
At ATM Services level
– Operational requirement for a “hard” guaranteed QoS
– Several possible solutions for guaranteed QoS implementation:
• Time stamps could be added in messages sent by the ATM service. Main drawback:
sending of additional information (time stamps)
• Timers could be implemented at ATM services level (current solution with ATN). Main
drawback: lack of responsiveness and requires a reply at ATM service level
• Network service could support the provision of compulsory and guaranteed QoS.
Main drawback: additional mechanisms must be implemented
– ATN Classes of Communications should be re-defined as they are not adapted
to the implementation of guaranteed QoS to meet operational requirements
– Guaranteed QoS applicability:
• A flag is required to indicate whether the ATM service requests “best-effort”,
“compulsory” or “guaranteed” service
• Operational context may need to be considered to set this flag!
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Guaranteed QoS
At ETDMA network level
– QoS provided in an ETDMA cell from a user viewpoint:
• Guarantee of a minimum QoS (maximum transit delay and minimum throughput), which
essentially depends on the size of slots, the size of families and ETDMA frame duration.
• Actual QoS, which depends on the current traffic load conditions (number of aircraft
inserted into the ETDMA cell).
– QoS provided in a multi-cells environment:
• Minimum QoS (maximum transit delay and minimum throughput) that ETDMA can
guarantee to an aircraft is expected to change when moving from one cell to another one.
– QoS provided at ETDMA network level:
• Integrity using CRC
• Priorities before compression (at ETDMA network layer)
• QoS parameters in SN-UnitData.Request service primitive: QoS category, ETDMA QoS,
Max Transit Delay
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Guaranteed QoS
End-to-end
– Main issue is to implement the guarantee of a maximum transit
delay:
• Need to estimate the maximum one-way ATN mobile sub-network
transit delay
• Need to estimate the maximum one-way ATN end-to-end transit delay
• Need to provide this information to end users
• Need to report anomalies
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Guaranteed QoS
In the Internet
– Initial development to provide a “best-effort” service: not adapted to
carry real time traffic that requires a guaranteed transit delay and
minimum throughput
– Integrated Services (IntServ) model
– Differentiated Services (DiffServ) model
– None of those models really provide a « guaranteed » QoS
– No real benefit to be taken from the IP world and there is a strong
need to further investigate the issue and to address the necessary
evolutions required at transport layer level