Introduction to SS7 – Part 2

Introduction to SS7 – Part 2 Konrad Hammel Sangoma Technologies

Node Addressing • ITU • 14 bits, 3-8-3 format or decimal • ANSI • 24 bits, 8-8-8 format • SPC • Self Point Code • APC • Adjacent Point Code • DPC • Destination Point Code • OPC • Originating Point Code

Sample of using SPC, APC and DPC

Sample using OPC and DPC

Converting Point Codes • Decimal = 1234 • Hex = 0x4d2 • Binary = 0 - 10011010 - 010 • 3-8-3 = 0-154-2

SS7 Stack layers ISUP MAP/INAP Application TCAP Presentation Transport Session SCCP MTP3 Network MTP2 Data Link MTP1 Physical

ISUP • Call Signaling protocol of SS7 • Controls the status of CICs • Resets, blocks, etc • Controls the call setup • Setup, acknowledge, hang-up, etc • CICs • Circuit Identification Code • Integer number that uniquely identifies a time slot on a span • Used by all messages to id the specific channel • ITU Q.762, Q.763. and Q.764 • ANSI (T1.113-YEAR)

Basic Call Messages • IAM • Initial Address Message • Call request • ACM • Address Complete Message • Acknowledges IAM • Starts early media • ANM • Answer Message • Answers the call • REL • Release • Request to hang-up a call • RLC • Release Complete • Acknowledges a REL

Basic Call Flow

Advanced Call Messages • SAM • Subsequent Address Message • Sends additional call setup info (overlap) • CPG • Call Progress Message • Used to signal additional info during call setup • Really only used for Supplementary Services • CON • Connect Message • Can replace ACM+ANM

Advanced Call Flow

Circuit Control Messages • RSC • Reset Circuit Message • Resets a single circuit to idle state • Acknowledged with RLC • BLO • Circuit Blocking Message • Single circuit is put into maintenance block • Receiving side can not make calls on circuit • BLA • Blocking Acknowledge Message • Acknowledges reception of BLO • UBL • Circuit Unblock Message • Removes a previous maintenance block • UBA • Circuit Unblock Acknowledge Message • Acknowledges reception of UBL

Circuit Group Control Messages • GRS • Circuit Group Reset • Resets a range of circuits • Max range is 31 • GRA • Circuit Group Reset Acknowledge • Acks a GRS • CGB • Circuit Group Block • Blocks a range of circuits • Maintenance or Hardware block • CGBA • Circuit Group Block Acknowledge • CGU • Circuit Group Unblock • CGUA • Circuit Group Unblock Ack

COT/CCR • Continuity Message • A test to confirm that a CIC is working properly from end to end • The requested CIC is looped, an audio/test pattern is transmitted on the channel. If the pattern is not successfully received then the test fails. • Used to confirm continuity of the network

Thank you.

Introduction to SS7 – Part 2

Télécharger la présentation

Plus de contenu associé