CCITT defined DTE facilities
In order to support the OSI Network Service over a packet switching network
CCITT has specified a number of end-to-end DTE facilities. These facility fields
are validated by the network for correct facility code, facility code not duplicated
etc. but the contents of the facility are not acted on by the network but are
passed through the network unchanged.
In order to support these facilities the following have been added -
a) facility field maximum length increased to 109 bytes
b) CCITT specified DTE facility marker added
Beginning of marker | OSI DTE facility Marker |
00 | 0F |
| | |
| 00 | 00000000 | Marker 000F = DTE facility marker........#
X.2 LEVEL 3 PER CALL FACILITY | X.2 (1984) | UK(a) | UK(b) | interworking | |||
OPTIONS | REF CLASS | now | now | R5a | R5b | R6 | |
DTE facilities | . | ||||||
DTE facility marker | . | ||||||
calling address extension | . | ||||||
called address extension | . | ||||||
minimum throughput class | . | ||||||
end to end transit delay | . | ||||||
expedited data negotiation | . |
&UKa& = yUKa support
CCITT defined DTE facilities are supported at release 4
It is not a subscription option, it will be allowed in calls provided both
ends of the call are DX2s
*** check --- what if call is transiting through DX1s ***
The network will clear the call if:
* The CCITT facility marker must come after the normal facilities not before. If there are any normal facilities after the CCITT marker the call will be cleared 034D.
* called and calling address extension limited to 16 bytes (32 BCD digits)
9.1 CCITT defined DTE facilities - Calling Address
extension facility
Description of Facility
+-----------------------------------------------------------------------+
| CB calling address | length | use | BCD address |
| extension | in bytes| | |
+-----------------------------------------------------------------------+
^
|
bits 8 7
--------
0 0 = to carry a calling address
assigned according to
recommendation X.213
ISO 8348
0 1 = reserved
1 0 = other (to carry a calling
address not assigned
according to X.213
1 1 = reserved
bits 1-6
--------
length (in BCD digits) upto 40
of address
3
| | |
| CB | 11001011 | Calling Address extension facility.......#&UKa& =
yUKa support
Yes, supported in release 4.
Only the facility code and length are validated by Public Network. This facility is passed through the network transparently
This facility will facilitate interworking with private networks.
9.2 CCITT defined DTE facilities - Called Address
extension facility
Description of Facility
+-----------------------------------------------------------------------+
| C9 called address | length | use | BCD address |
| extension | in bytes| | |
+-----------------------------------------------------------------------+
_
+--------+
|bits 8 7|
+--------|
|0|0|= to carry a called address
| | | assigned according to
| | | recommendation X.213
| | | ISO 8348
|0|1|= reserved
|1|0|= other (to carry a called
| | | address not assigned
| | | according to X.213
|1|1|= reserved
+---+
bits 1-6
--------
length (in BCD digits) upto 40
of address
3
| C9 | 11001001 | Called Address extension facility........#&UKa&
= yUKa support
Yes, supported in release 4.
Only the facility code and length are validated by Public Network. This facility is passed through the network transparently
FR22 - Called address extension .................. M = Mandatory
Therefore release 4 is compatible with ONA for this option.
Implementation issues
This facility will facilitate interworking with private networks.
9.3 CCITT defined DTE facilities - Minimum Throughput Class
Description of Facility
Minimum Throughput Class Negotiation
0A | Minimum Throughput Class| |
^ | |
| | |
bits 1-4 = from called DTE | |
bits 5-8 = from calling DTE | |
3=75 bps 4=150 bps 5=300 bps | |
6=600 bps 7=1200 bps 8=2400 bps | |
9=4800 bps 10=9600 bps 11=19200 bps | |
12=48000 bps |
| 0A | 00001010 | Minimum Throughput Class.................#&UKa&
= yUKa support
Yes, supported in release 4.
Only the facility code are validated by Public Network. This facility is passed through the network transparently
RD 0004 part 8:1.C (PICS proforma Public Network1984)
FS23 - Minimum Throughput class negotiation........ M = Mandatory
FR23 - Minimum Throughput class negotiation........ M = Mandatory
Therefore release 4 is compatible with ONA for this option.
Implementation issues
Public Network cannot guarantee a given throughput class. This value is end-to-end so it does not affect us directly.
9.4 CCITT defined DTE facilities - end-to-end transit delay
Description of Facility
end-to-end transit delay
CA | length | cumulative | requested end- | maximum acceptable |
2,4 or 6 | transit delay | to-end transit | end-to-end transit | |
2 bytes | delay 2 bytes | delay 2 bytes |
| CA | 11001010 | End-to-end transit delay.................#Transit delay
is expressed in milliseconds. The value of all ones indicates that the cumulative
transit delay is unknown or exceeds 65534 milliseconds.
&UKa& = yUKa support
Yes, supported in release 4.
Only the facility code and length are validated by Public Network. This facility is passed through the network transparently
FS24 - end-to-end transit delay ................... M = Mandatory
FR24 - end-to-end transit delay ................... M = Mandatory
Therefore release 4 is compatible with ONA for this option.
Implementation issues
Public Network cannot guarantee a given transit delay. This value is end-to-end so it does not affect us directly.
9.5 CCITT defined DTE facilities - priority facility
Description of Facility
D2 | length | target values for | lowest acceptable values |
1 to 6 | priority of data | for priority of data on | |
on connection 3 bytes | connection 3 bytes |
| D2 | 11010010 | Priority facility........................#
9.6 CCITT defined DTE facilities - Protection facility
Description of Facility
protection facility
D3 | length | length of protection value | protection value
00xxxxxx reserved 01xxxxxx source address specific 10xxxxxx destination address specific 11xxxxxx globally unique |
_
|
| D3 | 11010011 | Protection facility......................#
9.7 CCITT defined DTE facilities - Expedited data negotiation
facility
Description of Facility
Expedited data negotiation facility
0B | Value |
xxxxxxx0 = no use of expedited data | |
xxxxxxx1 = use of expedited data |
| 0B | 00001011 | Expidited data negotiation facility......#
&UKa& = yUKa support
Yes, supported in release 4.
Only the facility code is validated by Public Network. This facility is passed through the network transparently