ACP-WG S- /WP-01
International Civil Aviation Organization
24/03/16
WORKING PAPER
AERONAUTICAL COMMUNICATIONS PANEL (ACP)
MEETING OF THE WORKING GROUP S (Surface)
Web Meeting 19 - 24 March 2016
Agenda Item xx: Xxx
DSCP Values for AEROMACS)
(Presented by Bruce Eckstein, Harris)
SUMMARY
During the WG-I 2 March 2015 meeting, an action was assigned to review the
AeroMACS DSCP proposed values to assure consistency with existing DOC9896 DSCP values.
1.
INTRODUCTION
1.1
The AeroMACS manual has been updated with values for the Differentiated Services
Code Point (DSCP) in the 18th meeting of the Working Group Surface (WG-S). During the joint meeting
with the Working Group Internet (WG-I) it was identified that the DOC-9896 has established DSCP
values for the ATN and that the chosen values for AeroMACS did not appear to be consistent with the
ATN assigned DSCP values. WG-I requested that WG-S review the AeroMACS DSCP proposed values
and align them as appropriate.
2.
DISCUSSION
2.1
The following table identifies the values associated with the IP uses of DSCP values. The
generic columns identify the standardized DSCP values, labelling and use of the values. ATN mapping
column identifies the DOC 9896 selected values and is the DSCP values that AeroMACS should be
consistent with. The current values for AeroMACS DSCP are provide for reference and the recommended
values to align the AeroMACS DSCP values with DOC 9896 DSCP values are provided.
Generic Layer 3
Generic Layer 2
Decimal
value
DSCP
value
PHB
Meaning
Drop
probability
Equivalent IP
precedence value
Precedence
Value
0
000000
CS0
Default
N/A
000 - Routine
Routine
8
10
12
14
16
18
20
001000
001010
001100
001110
010000
010010
010100
CS1
AF11
AF12
AF13
CS2
AF21
AF22
Low
Medium
High
001 - Priority
001 - Priority
001 - Priority
22
010110
AF23
24
011000
CS3
26
011010
AF31
Low
011 - Flash
28
30
011100
011110
AF32
AF33
Medium
High
011 - Flash
011 - Flash
32
100000
CS4
34
100010
AF41
Low
100 - Flash override
36
38
40
100100
100110
101000
AF42
AF43
CS5
Medium
High
100 - Flash override
100 - Flash override
46
101110
EF
N/A
48
110000
CS6
56
111000
CS7
ATN
Mapping
BE
Current AeroMACS
Recommended AeroMACS
CoS
DEFAULT,
APT1,
APT2
Scheduling
Traffic
Priority
BE
N/A
ATS3
nrtPS
N/A
AOC1
nrtPS
N/A
Emergency
Video
rtPS
NET
rtPS
N/A
ATS1
ATS2
rtPS
rtPS
1
2
CoS
DEFAULT,
APT1,
APT2
Scheduling
Traffic
Priority
BE
N/A
AOC1
ATS3
nrtPS
nrtPS
N/A
N/A
Emergency
Video
rtPS
ATS2
rtPS
N/A
Priority
AIDC
Immediate
Low
Medium
010 - Immediate
010 - Immediate
High
010 - Immediate
CM
ATSMHS
Flash
Voice
Recording
Flash override
CPDLC
ADS-C
Voice
Signaling
NET
rtPS
N/A
ATS1
rtPS
N/A
VoIP1,
VoIP2,
VoIP3
ertPS
N/A
Critical
101 Critical
Voice
Internetworking
Control
Network
Control
VoIP1,
VoIP2,
VoIP3
ertPS
N/A
2.2
It should be noted that RFC 2474 indicates that where a code point is not mapped to a
standardized or local use per-hop behaviour (PHB), it SHOULD be mapped to the Default PHB. This
note restricts the use of AeroMACS DSCP to the standardized DSCP values.
2.3
AOC1 was upgraded to a low probability of drop because if AOC is using priority it is
assumed that they do want it to get thru and not be dropped as indicated by the previous assignment.
2.4
ATS2 was upgraded to a medium probability of drop as it is assumed that ATS
messaging has performance values associated and that current assignment of the high probability of a
drop is assumed as being inconsistent with the ATS performance needs.
2.5
ATS 1 was upgraded to a Flash-Override value to be consistent with the DOC 9896
assignment for CPDLC and ADS-C. It is proposed to maintain the medium probability of a drop as it is
very unlikely to be dropped due to the Flash-Override rating.
3.
ACTION BY THE MEETING
3.1
The ACP WG-S is invited to consider updating the AeroMACS DSCP values to align
with the DOC-9896 DSCP values.