• Incoming Path
• Outgoing Path

This section describes the incoming and outgoing paths of the signaling transferred from the PSTN to the IP network.

It refers to the path of boards through which signaling messages from the PSTN are processed by the SG7000 and routed to the IP network, as shown in Figure 1.

http://localhost:7890/pages/31185837/04/31185837/04/resources/public_sys-resources/icon-note.gif NOTE:

• When the front board of the SEPU is the SBPU, the SEPU can be configured with only the SHPU or SLPU.

• When the front board of the SEPU is the SBPE, the SEPU can be configured with the SHPE.

This section takes the SBPU, the front board of the SEPU, for an example to describe the PSTN-IP signaling path.

Figure 1 PSTN -> IP signaling path
http://localhost:7890/pages/31185837/04/31185837/04/resources/images/ch_system_principle_020_0070_fig010.png

Incoming Path

• The E1 interface of the SEPU provides a TDM PCM interface to access standard 64 kbit/s or 2 Mbit/s signaling links.

• Based on the data configuration, the SEPU checks if the signaling link should be processed by the SBPU in the same slot. If yes, the SEPU processes MTP1 messages, extracts signaling time slots, and transmits upper layer messages to the SLPU/SHPU in the same slot through the internal highway, as path (1) shown in Figure 1. Otherwise, the SEPU transfers the signaling messages to the SEPU in the same slot with the destination SBPU through the H.110 bus. The destination SEPU processes MTP1 messages, extracts signaling time slots, and transmits upper layer messages to the SLPU/SHPU in the same slot through the internal highway, as path (2) shown in Figure 1.

• The SLPU/SHPU processes MTP2, MTP3, and SCCP messages.

Outgoing Path

• The SLPU/SHPU analyzes the DPC to query the route information. If the outgoing link is configured on the current board, the SLPU/SHPU sends the message to the current SBPU and then the SBPU sends the message to the SBPI, as shown by (1) in Figure 1. If the outgoing link is not configured on the current board, the SLPU/SHPU sends the message to the current SBPU and then the SBPU sends the message to the target SBPU. After that, the target SBPU sends the message to the SBPI through the internal network cable, as shown by (3) in Figure 1.

• The SBPI performs MAC layer message processing on the signaling messages and sends the IP packet to the VIEB through the physical connection, as path (4) shown in Figure 1.

• The IP signaling packet is sent to the IP network through the FE interface on the VIEB, as path (4) shown in Figure 1.

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