CS1000 Architecture
Components:
| Call Server | Holds Customer Database Processes Calls |
||
|---|---|---|---|
| ▲ ELAN ▼ | |||
| Signaling Server |
Terminal Proxy Server (TPS) | Links IP Sets to Call Server
Uses UNISTIM protocol (proprietary Nortel) | |
| H323 & SIP Signaling Gateway | Standards based signalling for Virtual Trunks | ||
| Network Routing Service (NRS) |
Resolves DN to IP addresses for H323/SIP & UNISTIM
SIP Redirect Server / H.323 Gatekeeper UNISTIM Network Connect Server (NCS) | ||
| Personal Directory | Up to 100 names and numbers per IP Set user | ||
| Element Manager | GUI for Call Server and NRS Management | ||
| ▲ ELAN ▼ ▲ TLAN ▼ | |||
| Media Gateway(s) | Houses 'Intelligent Peripheral Equipment' (IPE)
Provides IP to TDM conversion via Media Cards | ||
IP Network:
- There are two networks, plus a High Speed Pipe (HA only):
| ELAN | Equipment LAN (ELAN): a private management network for CS1K components. The Call Server connects only to the ELAN network. |
| TLAN | Telephony LAN (TLAN): the 'public side' where IP trunks and sets are connected. It may also be referred to as the Customer LAN (CLAN). |
| HSP | High Availability (HA) systems use a High-Speed Pipe to link both Call Server cores. |
Notes:
Call Server:
- The Call Server stores the telephony and customer databases and options.
- Pseudo TTY Ports (PTY's) are used for administration on the ELAN network (via SSH).
- Zones provide Call Admission Control (CAC). The zone strategy determines CODEC selection based on the type of call and available bandwidth. CAC is necessary to prevent too many calls affecting call quality (a non-issue in TDM networks).
Note: IP sets reside on the TLAN, or a network attached to it. They need to communicate with the Call Server (on the ELAN) in order to make and receive calls. This is accomplished by registering with the Signalling Server.
Signalling Server:
- The Signalling Server runs several applications, but sets use the Terminal Proxy Server (TPS) to register and and communicate with the Call Server.
- When a set registers, TPS records its Virtual TN and IP address so it can identify it. In the Call Server the set is defined using the Virtual TN.
Media Gateway(s):
- A Media Gateway, such as the MG1010, provides slots for digital and analog / station and trunk cards.
- A Media Gateway Card (MGC) performs IP to TDM conversion, and provides a path to legacy TDM sets and trunks.
Call Flow:
- When an IP set makes a call it messages the Call Server via the TPS on the Signalling Server. The Call Server locates the TN of the endpoint and manages the connection (via the ELAN).
- If the endpoint is another IP set, the Call Server signals the destination via the TPS. When the call is established, the voice travels directly from IP Set to IP Set (via the TLAN).
- If the endpoint is a TDM set, the call server messages the Media Gateway to allocate a TDM/IP resource and signals the destination TN. The voice path conducts via a DSP on the Media Card.