Term
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Definition
Signalling System 7 - Common Channel Signalling.
SS7 applications have greatly expanded, and today includes DB queries, trnasactions, network operations, and ISDN
Out-of-band signalling in the PSTN.
Enhances PSTN by handling call establishment, exchange of info, routing, operations, billing, and support for Intelligent Network services |
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SS7 is important to VoIP and the way it interworks with the PSTN
It's objective was to provide world-wide standard for telephony signalling, but it didn't happen that way. |
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Term
| SS7 networks consist of 3 signalling elements |
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Definition
SSP - Service Switching Point
STP - Signal Transfer Point
SCP - Service Control Point |
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| referred to as signalling points, endpoints, exchanges, switches, or nodes. |
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Term
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| Service Switching Point - End office, or tandem switches that connect circuits, originate, and terminate calls |
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| Signal Transfer Point - Routes all teh signalling messages in the SS7 network |
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| Service Control Point - Provides access to databases for additional routing information used in call processing |
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| SSP > Steps to Complete a call |
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Definition
1. SSP uses called number or database query to begin circuit connection
2. Uses routing table to determine the trunk group and circuit needed to connect the call
3. Signalling setup message is sent to destination SSP
4. Dest SSP responds with an ack granting permission to connect to trunk. |
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Definition
Route or switch all signalling msgs in network based on routing info
Provides logical connectivity between SSPs
Configured in pairs "mated" to provide redundancy |
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Definition
1. Route circuit-based SSP packets to Dest SSPs. packetized, in SS7
2. Non circuit based packets are database queries, and are routed between SSP and SCP. Provides routing number to complete call
3. Measure traffic and usage |
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Term
| STP Global Title Translation |
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Definition
| Centralize the SCP and DB selection. Enables queries to be addressed directly to the STP. Can use this to route msg to other STPs |
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Definition
| Defines network interconnection and separates capabilities into specific areas of functionality. |
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| SCP Database interface protocol conversion |
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All signalling points are connected by links.
Full-duplex, rx tx SS7 messages
56 and 64 kbps |
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Term
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Definition
Associates Signalling
Nonassociated Signalling
Quasi-associated Signalling |
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| SS7 Signalling > Associated |
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Definition
| Simplest form.Signalling and voice paths are directly connected between the two endpoints |
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| SS7 Signalling > Nonassociated |
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Definition
| Most common - Separate logical path for signalling and voice. |
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| SS7 Signalling > Quasi-associated |
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Definition
| separate logical path for signalling, thru minimal number of x-fer points |
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Term
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Definition
A-links -
B-links -
C-links - Cross-links
D-links - Diagonal Links
E-links - Extended Links
F-links - |
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Definition
| Between Signalling ENDPOINTS, and STPs |
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| Bridge Links - between 2 mated pairs of STPs. Peers, operating at the SAME hierarchical level |
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| Cross-links - between an STP and its mate |
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| Diagonal-links - between mated STP pairs of one hierarchical level to a pair from another hierarchical level |
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| Extended Links - between an SSP to alternate STP |
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Definition
| Between two signalling endpoints |
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| Links grouped together when connected to the same endpoint. |
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| Signalling endpoints have statically predefined routes for dest endpoints |
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| Signalling Message Handling - routes SS7 messages. |
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| Statically maintained routing tables. Primary and alt routes. Traffic load shared equally. |
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Definition
SNM function reroutes traffic in SS7 network. Network Link failures.
Linkset rerouting
Alternate link rerouting
Traffic flow rerouting to endpoints. |
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