Telnet Page 9 (D Channel Logging)

Telnet Page 9 provides details of the traffic on ISDN’s D channel, messages are output only when they arrive or are transmitted (if may be up to 10 seconds between messages). To maintain the Telnet session in the absence of any other traffic a CR (Carriage Return) character is output to this page every 2 seconds).

Page 9 Sample

           ZyTrax Status page 8 (9910101106)  
 D Channel Log Started... (Hex & Interpretation)

OUT:Time Stamp(00:02:02-03-03400) Len=4
 00 89 01 03                                       ....
LAPD:L2 Sapi=0,Tei=68 C RR N(R)=1 P/F=1
 
 IN:Time Stamp(00:02:02-03-16429) Len=4
 00 89 01 03                                       ....
LAPD:L2 Sapi=0,Tei=68 R RR N(R)=1 P/F=1

 IN:Time Stamp(00:02:20-04-16758) Len=41
 02 ff 03 08 01 14 05 04 02 88 90 18 01 89 34 01   ..............4.
 40 3b 02 81 81 6c 08 a1 38 33 35 38 36 36 32 70   @;...l..8358662p
 08 c1 38 33 35 38 36 36 31                        ..8358661
LAPD:L2 Sapi=0,Tei=127 C UI P/F=0 L3:SETUP Ref=20
IE: BEARER= 64k circuit CHANNEL=B0 SIGNAL ENDPOINT CALLER CALLED

OUT:Time Stamp(00:02:20-04-35546) Len=11
 00 87 02 02 08 01 94 01 18 01 89                  ...........
LAPD:L2 Sapi=0,Tei=67 C INFO N(S)=1, N(R)=1 P/F=0 L3:ALERTing Ref=20
IE:CHANNEL=B0

 IN:Time Stamp(00:02:20-05-50120) Len=38
 02 87 02 04 08 01 14 7b 95 2a 1b 80 94 02 60 3d   .......{.*....`=
 8b 07 38 33 35 38 36 36 32 8d 0b 20 54 65 6c 74   ..8358662.. Telt
 6f 6e 65 20 32 20                                 one 2
LAPD:L2 Sapi=0,Tei=67 C INFO N(S)=1, N(R)=2 P/F=0 L3:INFORMATION Ref=20
IE: DISPLAY

OUT:Time Stamp(00:02:20-06-04665) Len=8
 00 87 04 04 08 01 94 07                           ........
LAPD:L2 Sapi=0,Tei=67 C INFO N(S)=2, N(R)=2 P/F=0 L3:CONNECT Ref=20

Notes:

The D Channel Log Started message will show either the string “(Hex Only)” or “(Hex and Interpretation)”, the latter indicates that the system has been compiled with the D Channel interpretation feature which provides interpretation of ISDN Layer 2, Layer 3 and Management Entity messages. If this feature is not present (Hex only) then hexadecimal strings only are ouput i.e the messages beginning “IN” or “OUT”

Generic Hexadecimal Entry Format

XX:Time Stamp(HH:MM:SS-YY-TTTTT) Len=AA
BB BB BB BB                        CCCC

Where

XX may be IN (incoming D Channel message from the Switch to the Router) or OUT (outgoing D Channel message from the Router to the Switch)

HH is the hours (Note the clock wraps after approximately 1 hour and 58 minutes) the time is therefore relative not absolute)

MM is the number of minutes.

SS is the number of seconds

YY is the number of 100 microsecond (10**-3) intervals.

TTTTTT is the time within the 100 microsecond interval (each number is approximately 2 milliseconds (10**-6)).

AA is the length in bytes of the message (minus all HDLC flags and FCS (Frame check sequence) bytes)

BB is a single Hexadecimal character

CC is a single printable character or “.” if not printable.

Generic Interpreted Entry Format

Layer 2 only

LAPD:L2 Sapi=AA,Tei=BB CC DD N(R)=EE P/F=GG

Layer 2 plus Layer 3

LAPD:L2 Sapi=AA,Tei=BB CC DD N(S)=FF, N(R)=E P/F=GG L3:HHHHHH Ref=II

IE: JJJJ JJJJ

Layer 2 plus Management Entity

LAPD:L2 Sapi=AA,Tei=BB CC DD N(S)=F, N(R)=E P/F=G ME:KKKK=LL

The interpretation uses the CCITT/ITU specifications Q.921 and Q.931 (together with appropriate National documentation)

Layer 2 Fields

AA = Service Access Point Identifier and may take the value 0 = ISDN Call Control messages, 16 = X.25 Call Control and data messages, 63 = Management Entity.

BB = Terminal Endpoint Identifier and if in the range 0 to 63 the TEI is statically allocated, if the in the range 64 to 126 the TEI is dynamically allocated by the network, the value 127 is a Broadcast TEI.

CC may be ither C indicating a Layer 2 Command or R indicating a Layer 2 response. The use of this flag is defined in Q.921 Table 1.

DD indicates the type of message as follows: (see also Q.921 Table 5)

Value	Meaning	Notes
RR	Receiver Ready Normal response or command to a Layer 2 keep alive.	Supervisory format.
RNR	Receiver Not Ready Value set in a response when the terminal is busy and cannot process the command.	Supervisory format.
REJ	Reject	Supervisory format.
SABME	Set Asynchronous Balanced Mode Extended. Sets the link into Multiple Frame Acknowledged mode (MFAM) operation. Response to this command is a UA.	Unnumbered format. No information field allowed.
DISC	Terminates the Multiple Frame Acknowlegded mode operation (but not the link). Response to this command is a UA.	Unnumbered format. No information field allowed.
DM	Disconnected Mode. Used to reply to a SABME if the Router cannot enter MFAM mode.	Unnumbered format. No information field allowed.
UI	Unumbered information. Used to send Layer 3 information when no sequence checking is required.	Unnumbered format.
UA	Unnumbered Acknowledge. Used as a response to either a SABME or DISC command.	Unnumbered format. No information field allowed.
FRMR	Frame Reject. Used when the link is in MFAM to indicate a sequence or other error.	Unnumbered format. Information fields indicate the reason for the failure.
INFO	Information. Used to transfer sequentially numbered frames in MFAM mode follwing a SABME.	Information format

EE is the Transmitters Receive sequence count

FF is the Transmitters Send Sequence count.

GG is the value of the P(oll) / F(inal) flag. The use of this flag is defined in Q.921 (section 5.1).

Layer 3 Fields.

HHHH is the command type and may be one of the following

Value	Meaning	Notes
SETUP	SETUP is issued from either the Router or the Network and initiates a call (incoming or outgoing)
SETUP ACK	Optional esponse from the router or Network to a SETUP message
CONNECT	Indicates that the remote or local user has accepted the call.
CONNECT ACK	Typically only sent from the Network to the Router to indicate that the specified call has been awarded to the user. May be sent from the Router to the newtork by reasons of symetry.
RELEASE	Response to a DISCONNECT message from the network and indicates the Router has disconnected the call.
REL COM	Final step in disconnecting a call and indicates all resources have been released (as well as disconnected) and that the call referece value (II below ) may be used again.
ALERTing	Indicates that user alerting has been initiated i.e. local tones or ringing.
STATUS	Response to a STATUS ENQ message.
INFORMATION	Supplies additional information about a call.
DISCONNECT	Indicates that a call has been terminated either by the local or remote user.
NOTIFY	Contains information about an active call.
STATUS ENQ	Requests the Router or network for information about the call.
PROGRESS	Indicates the progress of a call i.e. ringing on etc.
Type=XX	Unsupported type for the interpretation XX is the hex code.

II is the call reference value allocated by the user or the network and is used to uniquely indentify all messages associated with this call.

JJJJ is the optional Information Element (IE) included with the command. There may be any number of Information Elements and the values supported are (defined in Q.931 Table 4-3 and National Specifications e.g. SR-NWT-001953). Certain information elements are fully interpreted others just contain the keyword of the command. In all cases the keywords are displayed in the order in which they appear.

Value	Hex	Meaning	Notes
BEARER	04	Bearer Capability, may take one of the following values: Speech 3.1k (Audio) Packet (B channel packet services) 64k(DC) (Data Circuit switched)
CHAN	18	Channel Identification. Specifies the channel used, may be D (D channel) B Any (requests and free channel) B1 B2 B None (None specified in the request)
CALLER	6C	Calling Party Number	Q.931 & SR-NWT-001953
CALLED	70	Called Part Number
DISPLAY	2A	Display Text (uses LOCK SHIFT to change to National Character set) provides data which may be displayed on a local LCD display if appropriate.	SR-NWT-001953
KEYPAD	2C	Keypad facility, specifies the characters being entered from the keypad.
SIGNAL	34	Signal specifies the tones or alerting signals being used.
SPID	3A	Service Profile Identifier, a character string used in initializing the ISDN line to identify the profile being used.
REDIR NUM	75	Redirection Number specifies the DN to which calls are being redirected by ISDN Call Forwarding.
REDIRECTING	74	Redirecting Number specifies the number from which calls are being redirected.
USER	7E	User-User Information, specifies a string which may be displayed by the user equipment.
PROGRESS	1E	Progresso Indicator, gives information about events that may occur during the life of a call.
NOTIFICATION	27	Notification Indicator provides information about an active call.
LLC	7C	Lower Layer Compatibility.
HLC	7D	Higher Layer Compatibility.
STATE	14	Call State indicates the status of the current call.
ENDPOINT	3B	Endpoint Identifier. Allocated by the network and uniquely identifies certain information about a call e.g. USID (User Service ID) and TID (Terminal ID).
UNSUP	XX	Specified Information Element is not supported by the analysis function	Full list and codes in Q.931 and National documentation e.g. SR-NWT-001953
CAUSE	08	XXXX is the 4 hex characters (minus the top bits) representing the first two bytes of the cause field (i.e. no diagnostic fields are included)	Defined by SR-NWT-00195

Management Entity

Note: Management Entity is responsible for initializing and maintaining the state of the Router equipment at Layer 2.

KKKKK may take one of the following values

Value	Meaning
Tei Assigned	Indicates that the terminal has been assigned the specified TEI.. Response from the network to a Tei Request
Tei Request	Requests a TEI to be assigned by the network.
Tei Denied	Indicates that the network cannot supply a Tei or the requested TEI.
Tei Check	Request from the network to provide the status of the Tei Router must respond within 1 second or will lose its tei.
Tei Check Response	Response to a Tei Check.
Tei Remove	Removes either a specific Tei or all Tei (tei = 127)

LL specifies the Tei associated with the command, the value 255 indicates the tei is not used, Tei 127 is the management or broadcast Tei and applies to all TEIs supported or assigned to the Router.