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VoIP Overview

This section contains the following topics.

About the Avaya IG550 Integrated Gateway

The Avaya IG550 Integrated Gateway consists of the TGM550 Telephony Gateway Module and one or more Telephony Interface Modules (TIMs) that are installed in the slots on the J4350 and J6350 Services Routers to provide VoIP connectivity. The TGM550 is an H.248 media gateway that works with the TIMs to connect IP and legacy analog telephones and trunks over IP networks and enable IP telephones to communicate through analog telephone lines and trunks.

The TGM550 is also connected over a LAN or WAN to a Media Gateway Controller (MGC)—an Avaya media server running Avaya Communication Manager (CM) call processing software. The telephony services on the TGM550 are managed by an MGC located at headquarters or in a branch office. When the primary MGC is located at a remote location, the TGM550 uses standard local survivability (SLS) for partial MGC backup in the event that the connection to the primary MGC is lost. Devices can thereby provide reliable telephony services to branch offices.

Figure 38 shows a typical VoIP topology. The small branch office shown in the expanded illustration on the right is connected over the corporate WAN to the head office through a J6300 Services Router with VoIP modules installed. The Avaya Media Gateway Controller, S8700 Media Server, and integrated Management tools at the head office manage telephony services for headquarters and the branch offices on the WAN, connecting the corporation's legacy analog telephones, VoIP telephones, PCs, and fax machines to the PSTN.

Figure 38: Typical VoIP Topology

Image g016781.gif

VoIP Interfaces

Four types of interfaces on Avaya VoIP modules provide VoIP connectivity on J4350 and J6350 Services Routers:

These interfaces are available on the field-replaceable Avaya VoIP modules listed in Table 69. For more information about interface names, see Network Interface Naming. For more information about the modules, see Avaya VoIP Modules Overview.

Table 69: Interfaces on Avaya VoIP Modules

Module Name

Description

VoIP Interfaces

JUNOS Interface

(type-pim/0/port)

TGM550

Avaya Telephony Gateway Module (TGM)

  • Two analog telephone ports
  • Two analog trunk ports
  • One serial port for console access

vp-pim/0/0

On a VoIP interface, the port is always 0.

TIM510

Avaya E1/T1 Telephony Interface Module (TIM)

One E1/T1 trunk port providing up to 30 E1 or 24 T1 channels

–

TIM514

Avaya Analog TIM

  • Four analog telephone ports
  • Four analog trunk ports

–

TIM521

Avaya BRI TIM

Four ISDN BRI trunk ports providing up to eight channels

–

Only the TGM550 has a JUNOS interface. Because the TIMs do not have corresponding physical interfaces, you cannot configure or administer them with the J-Web interface or the JUNOS CLI. However, you can display TGM550 and TIM status from J-Web Monitor>Chassis pages and with the CLI show chassis command.

Note: TIMs are configured and administered from the TGM550 CLI. For more information, see the Administration Guide and CLI Reference for the Avaya IG550 Integrated Gateway at http://support.avaya.com.

Caution: The TGM550 and TIMs are not hot-swappable. You must power off the router before installing or removing the Avaya VoIP modules. Ensure that the Avaya VoIP modules are installed in the router chassis before booting up the system.

Avaya VoIP Modules Overview

A TGM550 and one or more TIMs installed in a Services Router provide telephony exchange services to a branch office over IP networks. Different TIMs have access ports for different types of VoIP and analog telephones and telephone lines. You connect the telephones and lines to the ports on the TGM550 and the TIMs. VoIP telephones require connection to a Power over Ethernet (PoE) adapter or switch that is plugged into an Ethernet port on the Services Router.

VoIP capabilities on the TGM550 enable the Services Router to provide VoIP services to telephones and trunks that do not directly support VoIP. The TGM550 translates voice and signaling data between VoIP and the system used by the telephones and trunks. TIMs convert the voice path of traditional circuits such as analog trunk and T1 or E1 to a TDM bus inside the router. The TGM550 then converts the voice path from the TDM bus to compressed or uncompressed and packetized VoIP on an Ethernet connection.

Media Gateway Controller

A Media Gateway Controller (MGC) is a media server (call controller) that controls telephone services on the TGM550. An Avaya media server running Avaya Communication Manager (CM) software acts as an MGC for the TGM550.

The following media servers running Avaya Communication Manager can be used as an MGC with the TGM550:

To provide telephony services, the TGM550 must be registered with at least one Media Gateway Controller (MGC). You can configure the IP addresses of up to four MGCs that the TGM550 can connect to in the event of a link failure. The MGC list consists of the IP addresses of the MGCs to connect to and the order in which to reestablish the H.248 link. The first MGC on the list is the primary MGC. The TGM550 searches for the primary MGC first. If it cannot connect to the primary MGC or loses its connection to the primary MGC, it attempts to connect to the next MGC in the list, and so on.

Note: The MGC list is stored in the TGM550. It is not written to the JUNOS configuration file.

You must also administer Avaya Communication Manager on the configured Media Gateway Controllers to support the TGM550. For more information, see the following Avaya IG550 Integrated Gateway manuals at http://support.avaya.com:

Avaya Communication Manager

Avaya Communication Manager (CM) software manages the Media Gateway Controller (MGC). Avaya CM allows you to do the following:

Note: The TGM550 supports Avaya Communication Manager (CM) release 4.0 and later releases. The TGM550 does not support Avaya Communication Manager (CM) releases earlier than release 4.0.

For more information about Avaya CM, see the Administrator Guide for Avaya Communication Manager at http://support.avaya.com.

Dynamic Call Admission Control Overview

Dynamic call admission control (CAC) enables the Media Gateway Controller (MGC) to automatically assign the bandwidth available for voice traffic on WAN interfaces and block new calls when the existing call bandwidth is completely engaged. You configure dynamic CAC on a high-bandwidth primary interface and on one or more backup interfaces with less bandwidth.

Without dynamic CAC, the MGC cannot detect the switchover to the backup link or the resulting changes in network topology and available bandwidth. As a result, the MGC continues to admit calls at the bandwidth of the primary link, causing network congestion and possible jitter, delay, and loss of calls.

Supported Interfaces

Dynamic CAC must be configured on each Services Router interface responsible for providing call bandwidth. You can configure dynamic CAC on the following types of interfaces on Services Routers:

Bearer Bandwidth Limit and Activation Priority

The dynamic CAC bearer bandwidth limit (BBL) configured on an interface specifies the maximum bandwidth available for voice traffic on the interface. The TGM550 reports the BBL to the MGC. When the call bandwidth exceeds the BBL, the MGC blocks new calls and alerts the user with a busy tone.

You configure the dynamic CAC activation priority value on interfaces to specify the order in which the interfaces are used for providing call bandwidth.

Rules for Determining Reported BBL

To assess the WAN interfaces that have an activation priority value and determine a single BBL to report to the MGC, the TGM550 uses the following rules. The reported BBL (RBBL) allows the MGC to automatically control the call bandwidth when interfaces responsible for providing call bandwidth become available or unavailable.

Note: Dynamic CAC works in conjunction with the Avaya Communication Manager (CM) Call Admission Control: Bandwidth Limitation (CAC-BL) feature. If you configure dynamic CAC on WAN interfaces, you must also configure CAC-BL on Avaya CM. For more information about configuring CAC-BL, see the Administrator Guide for Avaya Communication Manager at http://support.avaya.com.

TGM550 Firmware Compatibility with JUNOS Internet Software

The TGM550 firmware version must be compatible with the JUNOS Software version installed on the device. For compatibility information, see the Communication Manager Software & Firmware Compatibility Matrix at http://support.avaya.com.

Caution: If the TGM550 firmware version is not compatible with the JUNOS Internet software version on the router, the router does not detect the VoIP interface (vp-pim/0/0) and the interface is unavailable. For more information, see TGM550 Is Installed But the VoIP Interface Is Unavailable.

If you are upgrading both the TGM550 firmware and the JUNOS Software on the router, first upgrade the TGM550 firmware, and then upgrade the JUNOS Software.

For information about upgrading the TGM550 firmware, see the Administration Guide and CLI Reference for the Avaya IG550 Integrated Gateway at http://support.avaya.com.

TGM550 IP Addressing Guidelines

For operational purposes, the TGM550 is identified as a host on the device. Hence, the TGM550 needs to be assigned an IP address that is reachable both externally and internally from the device. The TGM550 uses this IP address to identify itself when communicating with other devices, particularly the Media Gateway Controller (MGC).

To assign the IP address for the TGM550, you configure the destination address on the vp-pim/0/0 interface. For information about configuring the vp-pim/0/0 interface, see Configuring VoIP Interfaces with Quick Configuration or Configuring the VoIP Interface (Required).

Caution: Applying a new or modified IP address resets the TGM550. Before modifying the IP address, take the following precautions:

  • Log into the TGM550 and enter copy running-config startup-config to save the TGM550 configuration. (For login instructions, see Accessing and Administering the TGM550 CLI.)
  • Ensure that the TGM550 is not currently handling voice traffic.

To enable easier administration of the TGM550, we recommend the following guidelines for assigning the IP address of the TGM550:

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