This chapter provides an overview of the Cisco Catalyst 4000 Access Gateway Module (AGM) and describes its applications, features, and supported modules.

This chapter contains these major sections:

AGM Features

The AGM provides integrated telephony and routing capabilities for the Catalyst 4000 family switches with the following system features:

Voice gateway to the Public Switched Telephone Network (PSTN) with a choice of digital (T1, E1, ISDN Primary Rate Interface (PRI), Basic Rate Interface (BRI) or analog foreign exchange office (FXO)) interfaces. These interfaces can be used to connect to a variety of PBX/PABXs.
Analog voice gateway with foreign exchange station (FXS) interfaces for fax machines, speakerphones, modems, and analog phones.
Advanced telephony services, including voice conferencing and transcoding for analog phones, IP phones, and Cisco Survivable Remote Site Telephony (SRS Telephony) for robust and resilient call control.
Cisco IOS routing, including support for IP, IPv6, IPX, and System Network Architecture (SNA), WCCPv2, and NAT.
Secure IP WAN connectivity with firewall, intrusion detection, and hardware-based encryption.
Centralized IP Telephony features through Cisco CallManager, with features to Enterprise branch offices via Cisco Survivable Remote Site Telephony (SRS Telephony) and IOS Telephony Services (ITS).

AGM Applications

The AGM is typically used in IP telephony campus and large branch office applications. These applications are described in this section.

IP Telephony Campus

The Catalyst 4000 family switches support inline power for IP telephones that are usually deployed in wiring or distribution closets at a campus. These switches can be equipped with the AGM to support the IP telephony campus application.

Figure 1-1 Shows the AGM deployed in an IP telephony campus application.

Figure 1-1: IP Telephony Campus Application of Catalyst 4000 Family Switches with AGMs

Large Branch Office

The AGM can be deployed at large branches with up to 192 users as an integrated voice gateway and WAN router. In this deployment, the Catalyst 4000 family switches can be equipped with the AGM to support the large branch office application. This application uses all the features listed in the AGM Features section.

Figure 1-2 Shows the AGM deployed in a large branch office application with up to 192 users.

Figure 1-2: Large Branch Office Application of a Catalyst 4000 Family Switch with an AGM

Catalyst 4000 Switch Integration

The AGM is a physically integrated but functionally independent Cisco IOS router inside the switch. It is connected to the switch by a Gigabit Ethernet 802.1Q trunk on the backplane that supports multiple VLANs. It can be used with the Catalyst operating system on the Supervisor II or with Cisco IOS on Supervisor III and IV, but it must be configured separately from the Supervisor Engine.

The AGM can be configured and monitored from the following locations:

the console port on the AGM
the management port (10/100 ethernet) on the AGM
the console or management port on the Supervisor Engine (with the session or attach module command)

Figure 1-3 shows the front-panel of the AGM. You can see the console port on the lower left and the Fast Ethernet port immediately to the right of the console port.

Figure 1-3: Access Gateway Module Fast Ethernet and Console Ports

The AGM ports are named according to their positions in their respective slots. From the left, the slots are numbered 1, 2, 3, and 4. Slots 1 and 2 are for VWICs, slot 3 is for VICs, and slot 4 is for multiflex modules.

A VWIC, VIC, or WIC can have one or more ports, so ports on the interface modules are sequentially numbered starting with 0 for the right-most port and increasing by one in the right to left direction.

Note The inverse port-numbering order is inherited from existing VWIC, VIC, and WIC port-numbering conventions.

Hardware Features

The AGM supports the following hardware features:

A DSP bank with 24 DSPs (4 SIMMs with 6 DSPs each) supporting a maximum of 96 voice channels.
Two voice or WAN interface module (VWIC) slots—Support VWICs, voice interface modules (VICs), and WAN interface modules (WICs).
One VIC slot—Supports the same VWICs and VICs as slots 1 and 2, but does not support WICs.
One multiflex slot—Reserved for the 8-Port and 16-Port RJ21 FXS modules.
One Fast Ethernet port—Reserved for management purposes only. It does not support data switching or routing.
One console port—For configuration purposes, you can connect via terminal or modem.
One Gigabit Ethernet backbone interface—Standard IOS Gigabit Ethernet interface with the following exceptions:

Supports 802.1q instead of ISL
Cannot be shut down without losing communication with the Supervisor Engine

Encryption Service Adapter (ESA)—High-performance data encryption module to offload some of the encryption processing from the AGM main processor and to improve performance.

Cisco Catalyst 4000 DSP Set

The Cisco Catalyst 4000 DSP set for the AGM includes 4 SIMMs with 6 DSPs each for telephony services. The DSPs are required for analog or digital voice gateway support as well as for advanced voice services such as conferencing or transcoding.

For information on the voice services enabled by the DSPs, see Voice Gateway Features and Advanced Voice Services in the Software Features section.

Cisco Catalyst 4000 8-Port and 16-Port RJ-21 FXS Modules

The Cisco Catalyst 4000 8-port and 16-port RJ-21 FXS modules can be installed in the high density analog flexslot on the AGM. By providing services to fax machines, speakerphones, modems, and analog phones, the FXS ports emulate a PSTN central-office (CO) or PBX.

Calls from analog phones and fax machines connected to the FXS ports can be connected to the PSTN or another analog phone via TDM switching on the AGM module itself, or converted to VoIP for connection to an IP phone or for transmission across the IP WAN.

Note The FXS interfaces are separated into power domains to provide power protection between domains and to ensure that ports not directly affected continue to operate.

Cisco Catalyst 4000 Encryption Service Adapter

The Encryption Service Adapter (ESA) for the AGM supports an integrated package of routing, firewall, intrusion detection, and virtual private network (VPN) functions. The ESA provides up to ten times the performance of software-only encryption by offloading the encryption processing from the router central processing unit (CPU). The ESA can be used to connect branch offices to the enterprise IP WAN, mobile users, partner extranets, or service provider managed customer premises equipment (CPE). Other ESA hardware features include:

3 DES encryption/decryption on two duplex E1 links with 64-byte packets. This translates to a data rate of 8 mbps and 15 kbps, respectively
Simultaneously support 10 tunnels and 60 security associations
4 Internet Key Exchange (IKE) SA setups per second

Data Interface Modules

Data interfaces can be installed in the two VIC/WIC slots on the AGM. Table 1-1 describes the data interface modules supported by the AGM.

Table 1-1: Data Interface Modules

Module

Description

WIC-2A/S

Dual asynchronous or synchronous serial ports

WIC-2T

Two-port serial WAN interface module

Note WIC-1T is not supported

WIC-1DSU-T1

One-port T1/ fractional T1 with CSU/DSU

WIC-1DSU-56K4

One-port four-wire 56 or 64 kbps CSU/DSU

VWIC-1MFT-T1

One-port T1/ fractional T1 multiflex trunk with CSU/DSU

VWIC-2MFT-T1

Two-port T1/ fractional T1 multiflex trunk with CSU/DSU

VWIC-2MFT-T1- DI

Dual-port T1/fractional T1 multiflex trunk with CSU/DSU (Drop and insert is not supported)

VWIC-1MFT-E1

One-port E1/fractional T1 multiflex trunk with DSU

VWIC-2MFT-E1- DI

Dual-port E1/fractional T1 multiflex trunk with DSU

VIC-2BRI-S/T- TE

User side S/T only, no 144 kbps and 80 kbps leased line

Note The VIC-2BRI is used for BRI data connectivity and can be installed in any of the VIC slots.

Note DSPs are required for voice support on the VWICs.

Note VWICs can be used in any WIC or VIC slot.

Note Primary Rate Interface (PRI) dial-up data connections are not supported at this time.

Voice Interface Modules

There are two types of voice interface modules supported by the AGM:

VIC modules can be installed in the VIC slot or the two VIC/WIC slots on the AGM
VWIC modules can be installed in any of the VIC slots on the AGM

Table 1-2 describes the voice interface modules supported by the AGM.

Table 1-2: Voice Interface Modules

Module	Description
VIC-2FXS	Two-port FXS voice/fax interface module
VIC-2FXO	Two-port FXO voice/fax interface module (North American version)
VIC-2FXO-EU	Two-port FXO voice/fax interface module (European version)
VIC-2BRI-S/T-TE	Two-port BRI S/T terminal equipment voice/fax interface module (also supports data)
VWIC-1MFT-T1	One-port T1/fractional T1 multiflex trunk with CSU/DSU
VWIC-2MFT-T1	Dual-port T1/fractional T1 multiflex trunk with CSU/DSU
VWIC-2MFT-T1-DI	Dual-port T1/fractional T1multiflex trunk with CSU/DSU, no DI
VWIC-1MFT-E1	One-port E1/fractional T1 multiflex trunk with DSU
VWIC-2MFT-E1	Dual-port E1/fractional T1multiflex trunk with DSU
VWIC-2MFT-E1-DI	Dual-port E1/fractional T1 multiflex trunk with DSU and no DI

Signaling Support on AGM

Table 1-3 describes the signaling supported by the AGM.

Table 1-3: Signaling Supported by the AGM

Signaling	T1-CAS/PRI	E1-CAS/PRI	E1-R2	BRI
H 323	Yes	Yes	Yes	Yes
MGCP	Yes	E1PRI Only	No	No

Switch-Type Support on AGM

Table 1-4 describes the switch-types supported by the AGM.

Table 1-4: Switch-types supported by the AGM.

Signaling	T1-CAS/PRI	E1-CAS/PRI	E1-R2	BRI
QSIG	H 323/MGCP	Yes	Yes	H 323/MGCP
NI	H 323/MGCP	H 323/MGCP	H 323/MGCP	H 323/MGCP
5ESS	H 323/MGCP	H 323/MGCP	H 323/MGCP	H 323/MGCP
4ESS	H 323/MGCP	H 323/MGCP	H 323/MGCP	H 323/MGCP
DMS100/250	H 323/MGCP	H 323/MGCP	H 323/MGCP	H 323/MGCP
EURO	H 323/MGCP	NA	H 323/MGCP	H 323/MGCP

Software Features

This section describes the AGM software features.

Telephony Call Control

The AGM supports several options for telephony call control:

Cisco Call Manager (CCM) can be used for centralized call control for numerous VoIP gateways, including the AGM, at campus and branch sites. The AGM supports both MGCP and H.323v2 interfaces to the CCM.
SRST is an IOS-based backup for the CCM that resides on the AGM itself. SRST automatically takes over call control if connectivity to the CCM is lost.
ITS software can be used for distributed call control.

Voice Gateway Features

The AGM can provide voice gateway support for up to 96 voice channels, or up to 48 channels if conferencing or transcoding are enabled. The AGM supports the following voice gateway services:

VoIP encapsulation—10, 20, 30, 40, 50, and 60 msec packet sizes
Voice Compression—G.711 and G.729a encoding
Fax Support—Cisco Fax Relay and G.711 Fax Passthrough support
Modem Support—G.711 Modem Passthrough support
IP Header Compression—CRTP
Echo Cancellation—8 to 64 msec echo cancellation support, depending on interface type
Signaling Types—T1 channel-associated signaling (CAS), ISDN Primary Rate Interface (PRI), Basic Rate Interface (BRI)

Advanced Voice Services

The AGM supports advanced voice services such as conferencing and transcoding:

Conferencing—when conferencing is enabled, 4 DSPs are allocated to conferencing. Each DSP supports 1 conference x 6 parties or 2 conferences x 3 parties. The AGM supports both meet-me and ad-hoc conference modes.
Transcoding—when transcoding is enabled, 8 DSPs are allocated to conferencing. Each DSP transcodes 2 full duplex voice channels between G.711 and G.729a.

Routing Services

The AGM supports the following Cisco IOS routing services:

Routing Protocols—IP (v4), IPv6, IPX, SNA
Routing algorithms—OSPF, BGP, and more
NAT
WCCP v2
10 kpps 802.1q inter-VLAN routing

The link to Feature Navigator is:

http://www.cisco.com/cgi-bin/Support/FeatureNav/FN.pl

Security

The AGM provides the same security to voice and video networks that is available for data networks. The AGM supports the optional Cisco IOS Software Firewall Feature Set, Cisco IOS Intrusion Detection Service (IDS), IP Security (IPsec) with data encryption standard (DES), and Triple DES (3DES). Hardware encryption using the onboard encryption accelerator provides significantly higher performance than software-based encryption, and frees processor capacity for other services.

The following encryption features are supported:

56-bit DES encryption using Cipher Block Chaining (CBC) mode
168-bit 3DES encryption using CBC mode
MD5 and SHA-1 hashing, including support for the HMAC transform with IPSec AH and ESP
Support for Diffie-Hellman key exchange
RSA and DSA public key signature and verification (when implemented by IOS IPSec Crypto Engine)

QoS

The AGM can identify user applications, such as voice or multicast video, and classify traffic with the appropriate priority levels. QoS policies are enforced using Layer 2 and 3 information such as 802.1p and IP precedence. The AGM queues employ weighted random early detection (WRED) and weighted round-robin (WRR) to ensure that QoS is maintained as packets traverse the network.

To ease the deployment of QoS, the AGM supports Cisco QoS Policy Manager (QPM). QPM is a complete policy management tool that enables provisioning of end-to-end differentiated services across network infrastructures with converged voice, video, and data applications. The combination of QPM and CiscoWorks Service Management Solution enables network administrators to adjust service levels in accordance with defined QoS policies. The end result is network-wide intelligent, and consistent QoS that enables performance protection for voice applications while reducing costs for growing networks.

Resiliency

The AGM provides the following tools to enhance the resiliency of networks:

SRS Telephony provides resiliency for IP phones when they lose connectivity with the Cisco Call Manager (For complete information on the feature, go to the following url: http://wwwin.cisco.com/access/mce/solutions/ent/voice/srst/
HSRP provides resiliency for IP packets
BRI backup provides resiliency for WAN connections

Network Management Support

The AGM supports the following tools for network management:

Simple Network Management Protocol (SNMP)
CiscoWorks
Cisco Voice Manager (CVM)
Cisco CallManager

Table of Contents

Overview