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Table of Contents

Introducing the MGX 8250

Introducing the MGX 8250

This chapter contains a brief outline of the features of the Cisco MGX 8250. An illustration of the AC-powered version of the 8250 appears in Figure 2-1.


Figure 2-1: MGX 8250


MGX 8250 System Overview

The Cisco MGX 8250 is a high density edge concentrator designed for Service Providers needing flexibility for aggregation of IP, voice, Frame Relay, circuit emulation and ATM services.

The MGX 8250 is a highly flexible IP+ATM narrowband edge concentrator for high-density aggregation of services. The MGX 8250 can act as a stand-alone edge concentrator or as a feeder node for the Cisco BPX 8600 series & MGX 8850 switches. The MGX 8250 Edge Concentrator offers up to 1.2 Gbps of IP + ATM switching capacity.

The Cisco MGX 8250 edge concentrator supports:

The Applications of the MGX 8250

The MGX 8250 operates in two operational applications:

For a description of how to configure the switches for a particular application, see "Configuring the MGX 8250."

Universal Edge Architecture

The MGX 8250 can support a wide range of services over narrowband and mid-band user interfaces. It maps all the service traffic to and from ATM by using standardized interworking methods.

The supported interfaces for user-traffic are:

The optional Service Resource Module-3T3 (MGX-SRM-3T3/B) can support up to 80 T1 interfaces over its three T3 lines and provide 1:N redundancy for the T1 and E1 cards.

The modular, software-based system architecture enables the 8250 to support new features through downloadable software upgrades or new hardware modules.

The MGX 8250 backplane supports a minimum of 1.2 Gbps of non-blocking switching up to
45 Gbps. Individual line rates range from DS0 through OC-12.

Standards-Based Conversion to ATM

The MGX 8250 converts all user information into 53-byte ATM cells by using the appropriate ATM Adaptation Layer (AAL) for transport over the ATM backbone network. The individual service modules segment and reassemble (SAR) cells to eliminate system bottlenecks. The following list shows the applicable AAL for each service:

MGX 8250 Enclosure and Power

The MGX 8250 enclosure contains up to 24 service modules (I/O cards) and 4 optional Service Redundancy Modules (SRMs) provide redundancy. It resides in either in a 19-inch or a 23-inch rack. The closed, 19-inch Cisco-built rack also has an optional seismic anchor. The system can accept power from either a DC or an AC source. See Table 2-1.


Table 2-1: Power Supply Options
Model Description

MGX-DC

MGX 8250 DC PEM and MBX-CAB-AC/DC

MGX-AC1-1

NR AC system for MGX 8250: AC shelf, 1 feed, 1 PS, MGX-CAB-AC/DC

MGX-AC2-2

Red AC pwr, red AC feed, AC shel, 2 PS, 2 MGX-CAB-AC/DC

PS-1200-AC

1200 Watt power supply for AC systems

MGX 8250 Management

To give you access for control purposes, the MGX 8250 supports high- and low-level user interfaces. You can use the Cisco WAN Manager application (formerly StrataView Plus) for connection management, the CiscoView application for hardware configuration, and a command line interface for low-level control of hardware functionality and connection control. An assortment of ports and protocols supports these user-interfaces. For communicating with the MGX 8250, the control port (SLIP protocol only), the LAN (Ethernet) port, and the in-band ATM connection (feeder application only) all support access by the command line interface (CLI) via Telnet, TFTP, and SNMP protocols.

The downloadable firmware on each card determines the functionality, and you can upgrade functionality by downloading new firmware through a TFTP application on a workstation or a PC.

The current status and configuration parameters of the MGX 8250 modules reside in a Management Information Base (MIB). The firmware on each card updates the MIB as changes in status and configuration occur.

Converting Single-Height Slots to Double-Height Slots

The wiring on the Cisco MGX 8250 backplane requires you to consider the conversion sequence and other details when you convert single-height slots to double-height slots. One slot conversion means that you convert four single-height slots to two double-height slots. Be aware of the following before you convert the slots:

With a factory-installed Cisco MGX 8250 node, the single- and double-height cards reside in the preassigned locations. Refer to Figure 2-2 for an illustration of an enclosure that shows installed cards and center guide modules. Certain slots have a small, L-shaped bracket holding in the card. All instances of this bracket are the card slots immediately to the right of an enclosure wall (or bulkhead). The system has three such brackets.


Figure 2-2: Front View of an AC-Powered Cisco MGX 8250


Each center guide module is secured by either a vertical support bracket or a simpler support bracket. Most center guide modules rely on the vertical support bracket. Three locations use the small support bracket: at the left wall of the card cage and at the bulkhead to the right of slot 8 or slot 14. For an illustration of a center guide module with support bracket, see Figure 2-4. For an illustration of a center guide module with vertical support bracket, see Figure 2-3.

Warning Use extreme caution when executing the following steps with system power turned on.

To convert four single-height slots to two double-height slots in an operational system:

Step 1   Remove the cabling from the back card unless the back card applies to the double-height configuration after the conversion.

Step 2   Remove the back card.

Step 3   Remove the front card.

Step 4   Repeat steps 2 and 3 for every other single-height module you remove.

Step 5   Rotate the screw that holds in the vertical center guide module.

Where either the left wall of the card cage or a bulkhead exists on the left of the single-height card slots, a simple, L-shaped bracket holds in the center guide module.

Step 6   If the center guide module has either type of wall to the left, unscrew the track attached to the wall. If necessary, remove cards to unscrew it.

Step 7   Remove the vertical support bracket by moving it up and down until you can take it out. A hole becomes visible in the center guide module for inserting a screwdriver.

Step 8   Insert a screwdriver and loosen the long screw that holds in the center guide module.

Step 9   Remove the center guide module.

Step 10   Install the double-height front card and back cards as needed.

A simpler situation exists when you install a new MGX 8250 in a non-Cisco rack or an existing Cisco cabinet: just unscrew the center guide module and remove it. If the enclosure has the optional front door, blank faceplates are not necessary. With no door, you must install a blank faceplate if you create two double-height slots but install only one card.


Figure 2-3: Center Guide Module with Support Bracket



Figure 2-4: Center Guide Module with Vertical Support Bracket


Module Descriptions

This section includes a summary of the modules used in the MGX 8250, followed by detailed descriptions of the modules:

Summary of MGX 8250 Cards

The MGX 8250 supports core cards and service modules. The Processor Switching Module (PXM) and optional Service Resource Module (SRM) are core cards. In addition to the PXM being a core card, it is also part of a a card set. A card set consists of a front card, a back card, and a daughter card. Service modules are not combined in this manner and are never part of a card set. Instead, service modules provide the interface to the transport technologies of the CPE—Frame Relay, ATM, and so on. The MGX 8250 enclosure contains up to 24 service modules (I/O cards) and 4 optional Service Redundancy Modules (SRMs) provide redundancy. A card set consists of a front card with its attached daughter card and a back card (or line module). The front card contains the processing intelligence and, on the daughter card, the firmware that distinguishes the interface (OC-3, T3, E3, and so on). The back card is a simple card that provides the electrical interface for one or more lines of a particular type. The MGX 8250 front and back cards are the:

Note   For configuration information on the Voice Interworking Service Module (VISM), see the Voice Interworking Service Module Installation and Configuration Guide
Note   For configuration information on the Route Processor Module (RPM), see the Cisco Route Processor Module Installation and Configuration Guide.

Redundancy for Service Modules

Service modules can have either 1:1 redundancy or 1:N redundancy. For information on installation requirements, refer to the section titled "Service Resource Module" in this chapter. For configuration steps, see the section for the SRM in "Card and Service Configuration."

Refer to the CiscoView user documentation for instructions on using the CiscoView application to configure redundancy.

1:1 Redundancy

For 1:1 redundancy, place the card sets in adjacent slots and connect the appropriate Y-cable to the paired ports on the active and standby cards. Applicable service modules are:

Hot Standby

For hot standby, place the card sets in the same shelf and connect the appropriate Y-cable to the paired ports on the active and hot standby cards. The hot standby card will automatically configure itself to match the configuration of the primary card. This process may take up to eight minutes. After the configuration transfer process is completed, the transfer from the primary to the hot standby card takes less that one second regardless of the number of connections. Any subsequent changes to the primary card are automatically transferred to the hot standby card configuration so the two cards maintain the same configuration. Refer to the "Redundancy for Frame Service Modules" section for instructions for setting up a redundant pair. Applicable service modules are:

To determine the hot standby status of the system, use the command dsphotstandby.

1:N Redundancy

For 1:N redundancy, an MGX Service Resource Module-3T3 (MGX-SRM-3T3/B) card set is necessary. It supports 1:N redundancy for the following:

With 1:N redundancy, a group of service modules has one standby module. Redundancy by way of the redundancy bus on the MGX-SRM-3T3/B requires the redundant card group to have one of the following special back cards for redundancy support:

Processor Switching Module

This section describes the unique requirements for installing the Processor Switching Module (PXM) card set and briefly describes the features of each associated back card. The PXM card set consists of the PXM front card, the PXM User Interface back card (PXM-UI or PXM-UI-S3), and various uplink back cards that can serve as either a trunk or a UNI. Each description includes a faceplate description and a list of applicable cables. For instructions on how to configure the PXM functionality for 8250 and network control, see "Configuring the MGX 8250." For lists of the physical details of PXM cards, standards compliances, and so on, see "System Specifications."

Caution Handle the PXM front card very carefully to preserve the alignment of the attached disk drive. Do not drop or bump the PXM.
Caution Before using the 8250, verify that the daughter card on the PXM corresponds to the uplink card type. Serious damage may result if the power is on and these cards are mismatched.
Note   If you accidentally insert a back card for a service module into slot 7, 8, 23, or 24 then observe incorrect 8250 operation, check for bent or damaged pins on the backplane and the back card.

PXM Front Card

Primarily, the PXM1, shown in Figure 2-5, controls the 8250 and provides 1.2 Gbps of non blocking, shared memory switching. In addition, the PXM features are:

For descriptions of 8250 configuration tasks, see "Configuring the MGX 8250." For descriptions of how to modify partitioning, specify APS, and add UNI-port connections, see "Card and Service Configuration."


Figure 2-5: PXM Front Card


PXM User Interface Back Cards

This card contains ports for communication and control. This card is also used to connect the system to an external clocking source. Install this card in the upper half of the back of the PXM.

See the "Access Ports" section for more information on the PXM back card ports.

There are two options for the PXM User Interface back card:

PXM-UI (standard)

The PXM-UI back card shown in Figure 2-6 provides:

PXM-UI-S3 (optional)

The PXM-UI-S3 back card shown in Figure 2-7 provides Stratum 3 clocking:

Note   The LAN2 and CLK2 ports on the PXM-UI-S3 are NOT supported in this release. All external connections are made with the LAN1 and CLK1 ports.

Making External Clock Connections

If external equipment or a local digital central office is to provide synchronization, the external clock source is connected to the PXM-UI or PXM-UI-S3 back card.

Stratum 4 Backcard

External clocking sources are connected to the PXM-UI back card (Figure 2-6).

Stratum 3 Backcard

External clocking sources are connected to the PXM-UI-S3 back card (Figure 2-7).

Note   The LAN2 and CLK2 ports on the PXM-UI-S3 are NOT supported in this release. All external connections are made with the LAN1 and CLK1 ports.

See "Configuring the MGX 8250," for further information on configuring an external clocking source.


Figure 2-6: PXM-UI back card



Figure 2-7: PXM-UI-S3 back card


Alarm Output Connection

Dry contact relay closures are available for forwarding MGX 8250 alarms to an alarm system. Separate visual and audible alarm outputs are available for major and minor alarm outputs. The MGX 8250 alarm outputs are available on a DB-15 connector on the PXM-UI-S3 back card faceplate. Refer to "Cabling Summary," for the pinouts on this connector. Use switchboard cable for running these connections.

SMFLR-1-622 Back Card

An illustration of the long-reach OC-12 card appears in Figure 2-8. For specifications on this card, refer to "System Specifications." Note that Automatic Protection Switching (APS) requires the "B" model—an SMFLR-1-622/B.


Figure 2-8: OC-12 Long-Reach Back Card


SMFIR-1-622 Back Card

The intermediate-reach OC-12 back card appears in Figure 2-9. For specifications on this card, refer to "System Specifications." Note that Automatic Protection Switching (APS) requires the "B" model—an SMFIR-1-622/B.


Figure 2-9: Intermediate-Reach OC-12 Back Card


SMF-155 Back Card

The SMF-155 back card provides a physical single-mode fiber optic SONET OC-3 interface that conforms to ANSI T1.105 and GR-253-CORE standards. This interface uses SC connectors, and redundant configurations are supported through Y-cables. See Figure 2-10 for an illustration of the OC-3 back card. For specifications on this card, refer to "System Specifications." Note that Automatic Protection Switching (APS) requires the "B" model—an SMF-155/B.


Figure 2-10: Four-Port OC-3 Back Card


BNC-2T3 Back Card

An illustration of the two-port T3 back card appears in Figure 2-11. For card specifications, refer to "System Specifications."


Figure 2-11: BNC-2T3


BNC-2E3 Back Card

Two versions of the BNC-2E3 card are available. The BNC-2E3A applies to Australia only, and the BNC-2E3 applies to all other sites that require E3 lines on the PXM uplink card. An illustration of the two-port E3 back card appears in Figure 2-12. For specifications on this card, refer to "System Specifications."


Figure 2-12: BNC-2E3


ATM UNI Service Module

The MGX-AUSM-8T1/B and MGX-AUSM-8E1/B (or simply "AUSM/B" as a generic reference to both card sets) are multipurpose front cards that use an eight-port T1 or E1 back card. The AUSM/B supports the following applications:

    1. ATM Inverse Multiplexing N x T1 and N x E1 trunking

  This application supports inverse multiplexed trunks between BPX 8600 series network nodes through MGX 8250 switches and remote MGX 8250 switches.

    2. ATM UNI card with eight ports to provide a high port density service module

  With all 24 available slots installed with the AUSM/B cards, a single MGX 8250 can support up to 192 individual T1 or E1 lines.
  In UNI/NNI mode, each card can support 1000 data connections and 16 management connections.

    3. UNI/NNI access to CPE and other networks

  This application allows access over an UNI to IMA-based CPE and over an NNI to another ATM network.

    4. NNI/NNI access to CPEs

  This application supports ATM ports over single T1 or E1 line and IMA ports over multiple lines (connected to IMA-based CPE).

The following back cards are compatible with the AUSM/B:

The AUSM/B has the following features:

AUSM Front Card

The AUSM/B front card oversees all major functions of the ATM interface. It contains firmware for both the T1 and the E1 line interfaces and downloads from the PXM the appropriate code when it recognizes the back card type. An illustration of an eight-port AUSM/B front card appears in Figure 2-13. For specifications on this card, refer to "System Specifications."


Figure 2-13: AUSM/B-8T1 or AUSM/B-8E1 Front Card


Table 2-2 contains a list of eight-port LED indicators:


Table 2-2: Eight-Port AUSM/B LED Indicators
Type of LED Color Description

PORT LED

Green

Green indicates the port is active.

Red

Red indicates a local alarm on the port.

Yellow

Yellow indicates a remote alarm on the port.

Off indicates the port has not been activated (upped).

ACTIVE LED

Green

On indicates the card set is in active mode.

STANDBY LED

Yellow

Slow blink with Active LED off means the card is in the boot state.

Fast blink with Standby LED on means card is receiving firmware.

Fast blink indicates the service module is passing BRAM channel information to the PXM.

Steady yellow indicates the card is in Standby mode and the firmware is executing ADMIN code.

FAIL LED

Red

Steady Red with Active and Standby LEDs off indicates either the card is in the Reset condition, the card has failed, or the card set is not complete (no line module).

Steady Red with Active LED on indicates the card was active prior to failing.

Steady Red with Standby LED on indicates the card was standby prior to failing.

Back Cards for the AUSM/B

The MGX-AUSM-8T1/B and MGX-AUSM-8E1/B use the generic eight-port T1 or E1 line modules that operate with the eight-port service modules. The standard T1 version of the back card has eight RJ-48 connectors. The standard versions of the E1 back card have either eight RJ-48 connectors or eight pairs of SMB connectors. To support 1:N redundancy through an MGX-SRM-3T3/B card set, special versions of the RJ-45 back card must exist in the system

Redundancy Support for the AUSM

Redundancy support for the AUSM requires an MGX-SRM-3T3/B card set and the special versions of the RJ-45 back cards that support redundancy. See Figure 2-14 and Figure 2-15 for illustrations of the back cards. Differences exist in certain aspects of redundancy support for the MGX-AUSM-8T1/B and MGX-AUSM-8E1/B. For details on the requirements for redundancy through an MGX-SRM-3T3/B, refer to the section in this chapter titled "Service Resource Module."


Figure 2-14: Standard RJ-48 Back Card for the MGX-AUSM-8T1/B



Figure 2-15: Standard RJ-48 and SMB Back Cards for the MGX-AUSM-8E1/B


Frame Service Modules

This section describes installation requirements that are particular to the various types of Frame Service Modules (FRSMs). For hardware and other specifications on the FRSMs, refer to "System Specifications." For descriptions of how to configure the card, lines, and ports and add Frame Relay connections, refer to "Card and Service Configuration." The supported FRSM front cards and related back cards are:

An FRSM can reside in any slot except 7, 8, 15, 16, 31, and 32. In addition, any card for which you specify 1:N redundancy through the redundancy bus and the MGX-SRM-3T3/B cannot go in slot 9, 10, 25, or 26. Whenever possible, the VHS cards should go in the upper bay of the card cage because the upper half of the backplane provides higher bandwidth at each slot.

Very High Speed Frame Service Modules

FRSM-VHS supports Frame Relay services on a T3, E3, or HSSI interface. (The collective name for the MGX-FRSM-2CT3, MGX-FRSM-2T3E3, and MGX-FRSM-HS2 is Very High Speed Frame Service Modules—FRSM-VHS for short). The distinction between the front cards is the firmware operation. The FRSM-VHS group consists of:

Example illustrations of the FRSM-VHS front and back cards appear in the figures that follow.
Figure 2-16: MGX-FRSM-2CT3



Figure 2-17: MGX-FRSM-2T3E3



Figure 2-18: MGX-FRSM-HS2



Figure 2-19: BNC-2T3



Figure 2-20: BNC-2E3



Figure 2-21: SCSI2-2HSSI


Four-Port FRSM for V.35 or X.21

The MGX-FRSM-HS1/B supports four V.35 or four X.21 ports. Each port can operate in DTE or DCE mode. The mode depends on the type of attached cable. The information in this section lets you determine the correct cabling for the intended mode of each port. For a description of card, line, and port configuration, see "Card and Service Configuration." An illustration of the MGX-FRSM-HS1/B front card appears in Figure 2-22. The multifunction 12IN1-S4 back card appears in Figure 2-23. Cabling descriptions follow Figure 2-22.

Note   The MGX-FRSM-HS1/B does not support redundancy, so redundancy is not a consideration for deciding on a slot for the card. Nevertheless, it should be in the lower bay due to cell bus speed.

Figure 2-22: MGX-FRSM-HS1/B Front Card Faceplate


The cable models come from the Cisco 12IN1 series of cables. (See Table 2-3.) Each cable can have a male or female connector at the far end. Also, the available clock sources depend on the mode. In DTE mode, the clock source is either line or ST (ST is a wire in the cable). For DCE, the clock source is the front card. See Table 2-4 for the relationship between cabling and modes and Table 2-5 for part numbers.


Table 2-3: 12IN1-S4 Back Card Cable Types
Cable Type X.21 V.35

DCE

X.21 DCE

V.35 DCE

DTE

X.21 DTE

V.35 DTE


Table 2-4: Cabling and Clock Sources for the MGX-FRSM-HS1/B
Mode Type of Cable Clock Source Mode of Far End

DTE

DTE

line

DCE (male or female connector at far end)

DCE

DCE

internal

DTE (male or female connector at far end)

DTE_ST

DTE

ST line

DCE (male or female connector at far end)


Table 2-5: Cabling Types and Part Numbers X.21 and V.35
Type of Cable Far End Connector Part Number

X.21 DTE

male (standard)

72-1440-01

X.21 DCE

female (standard)

72-1427-01

V.35 DTE

male (standard)

72-1428-01

V.35 DTE

female (atypical)

72-1436-01

V.35 DCE

female (standard)

72-1429-01

V.35 DCE

male (atypical)

72-1437-01

V.35 DTE-DCE

72-1441-01

Straight-through

72-1478-01

Loopback plug

72-1479-01
Note   The cable type and part number are printed on a plastic band located near the smaller connector.

Figure 2-23: 12IN1 S4 Back Card Faceplate


Eight-Port FRSM With T1 or E1

The eight-port FRSMs support channelized or unchannelized service on either T1 or E1 lines.

Figure 2-24 (applies to both MGX-FRSM-8T1 and MGX-FRSM-8E1), and Figure 2-25 and Figure 2-26 (primary and redundant back cards for T1 and E1) show these cards.


Figure 2-24: MGX-FRSM-8T1



Figure 2-25: Standard RJ-48 Back Card for the MGX-FRSM-8T1



Figure 2-26: Standard RJ-48 and SMB Back Cards for the MGX-FRSM-8E1


Redundancy for Frame Service Modules

FRSMs can have either hot standby, 1:1 redundancy, or 1:N redundancy. For 1:1 redundancy, a Y-cable is necessary. The very high speed MGX-FRSM-2CT3, MGX-FRSM-2T3E3, and MGX-FRSM-HS2 use Y-cable redundancy. For 1:N redundancy, an MGX-SRM-3T3/B (but no Y-cabling) is required. Differences may exist in the way the MGX-SRM-3T3/B supports redundancy for a particular T1 or E1 configuration. Refer to the section titled "Service Resource Module" in this chapter and the Service Resource Module description in "Card and Service Configuration."

Note   The MGX-FRSM-HS1/B does not support redundancy.

Hot Standby

For hot standby, place the card sets in slots on the same card shelf and connect using an appropriate Y-cable to connect each hot standby pair. To view the hot standby status of the system, use the dsphotstandby command.

1:1 Redundancy

For 1:1 redundancy, place the card sets in adjacent slots and connect a Y-cable for each pair of active and standby ports. On the CLI, configure the card for redundancy by executing the addred command. For instructions on how to use the CiscoView application to configure redundancy, refer to the CiscoView user-documentation.

1:N Redundancy

1:N redundancy for the eight-port FRSMs requires an MGX-SRM-3T3/B. With 1:N redundancy, a group of service modules includes one standby module. For installation requirements, see the "Service Resource Module" section in this chapter. For configuration requirements, see the section on the MGX-SRM-3T3/B in "Card and Service Configuration."

Circuit Emulation Service Module

The main function of the Circuit Emulation Service Module (CESM) is to provide a constant bit rate (CBR) circuit emulation service by converting data streams into CBR AAL1 cells for transport across an ATM network. The CESM supports the CES-IS specifications of the ATM Forum.

The eight-port models AX-CESM-8T1 and AX-CESM-8E1 let you configure an individual physical ports for structured or unstructured data transfer. A card set has an AX-CESM-8T1 or AX-CESM-8E1 front card and one of the following back cards:

Redundancy for the Eight-Port CESM

Redundancy for the AX-CESM-8T1 and AX-CESM-8E1 is available through the MGX-SRM-3T3/B. The support is 1:N and so requires that the group contain one redundancy back card. The redundancy back card must be the special R-RJ45 version. For information on installation requirements, refer to the "Service Resource ModuleG" section. For configuration requirements, see the section on the SRM in "Card and Service Configuration." For instructions on how to use the CiscoView application to configure redundancy, refer to the CiscoView user-documentation.


Figure 2-27: Front Cards for the Eight-Port CESM


LED Indicators for the Eight-Port CESM

The description of the LEDs on the eight-port CESM front card appear in Table 2-6.


Table 2-6: LED Indicators for Eight-Port CESM
Type of LED Color Meaning

PORT LED

Green

Green indicates the port is active.

Red

Red indicates a local alarm on the port.

Off indicates the port has not been activated (upped).

ACTIVE LED

Green

On indicates the card set is in active mode.

STANDBY LED

Yellow

Slow blink without the Active LED indicates the card is in the boot state.

Fast blink with the Standby LED indicates the card is being downloaded.

Fast blink indicates the service module is passing BRAM channel information to the PXM1

Steady yellow indicates the card is in Standby mode and the firmware is executing ADMIN code.

FAIL LED

Red

Steady Red with Active and Standby LEDs off indicates either the card is in the Reset condition, the card has failed, or the card set is not complete (no line module).

Steady Red with Active LED on indicates the card was active prior to failing.

Steady Red with Standby LED on indicates the card was standby prior to failing.

Both standby and red LED lit indicates self-test failure.


Figure 2-28: Standard RJ48-8T1 Back Card



Figure 2-29: Standard RJ48-8E1 and SMB-8E1 Back Cards


Service Resource Module

The MGX-SRM-3T3/B (or "SRM" for short) can provide 1:N redundancy for the T1 and E1 cards as well as bulk distribution for T1 cards. It has no communication with higher speed service modules, such as the MGX-FRSM-2CT3 and MGX-FRSM-HS2. See Figure 2-30 for an illustration of the MGX-SRM-3T3/B front card and the MGX-BNC-3T3-M back card.

The multifunction SRM has the following capabilities:

General Installation Requirements for the MGX-SRM-3T3/B

The following are card-level characteristics that apply to any SRM installation:

Bulk Distribution and Redundancy Support

The use of bulk distribution affects the requirements for SRM and service module back cards:

For bulk distribution, the T3 lines connect to an external multiplexer. The T1 lines on the other side of the multiplexer connect to the CPE. The SRM converts the received traffic from its T3 lines to T1 channels and sends the data to linked service modules. For instructions on linking T1 channels and card slots to the MGX-SRM-3T3/B, see "Card and Service Configuration."

For bulk distribution of T1 lines, note the following about the MGX-SRM-3T3/B:

Note   Upon replacing the failed card, you must switch back to normal operation because the node does not automatically do so.

Figure 2-30: MGX-SRM-3T3/B Card Set


Voice Service: The VISM

The Voice Interworking Service Module (VISM) is a high-performance voice module for the Cisco MGX 8230, MGX 8250 and MGX 8250 series wide-area IP+ATM switches. This module is suitable for all service provider voice applications and offers highly reliable standards-based support for voice over ATM and voice over IP.

The VISM provides toll-quality voice, fax and modem transmission and efficient utilization of wide-area bandwidth through industry standard implementations of echo cancellation, voice-compression and silence-suppression techniques.

Service Provider Applications

The MGX 8250 with VISM is the industry's most flexible and highest density packet voice solution giving the customers the capability to provide VoIP, VoMPLS, VoAAL1 and VoAAL2 thus enabling service providers to deliver new revenue generating voice services using their existing network infrastructure.

Point-to-Point Trunking

Service providers worldwide are rushing to grow and transition their voice traffic onto packet based infrastructure and stop further expenditure on TDM equipment. With its standards based AAL2 implementation, the MGX/VISM can be used to provide a cost effective solution for an integrated voice and data network. By moving all point-to-point TDM voice traffic onto the packet network, cost savings of up to five times can be achieved through efficient use compression, voice activity detection and AAL2 sub-cell multiplexing while guaranteeing transparency of all existing voice services. In addition to the immediate bandwidth savings, the trunking application realizes all the benefits of a single voice+data network. Migration to switched voice services can easily be done through the introduction of a softswitch without any changes on the MGX/VISM platform.

Integrated Voice/Data Access

With the MGX/VISM and Cisco's access products such as the MC3810, service providers can now offer integrated voice and data services on a single line(T1/E1) to their enterprise customers. By eliminating the high cost of disparate voice and data networks, service providers can build a single network that will enable them to deliver current and future voice and data services.

At the customer premises, the MC3810 acts as a voice and data aggregator. All the customers voice (from the PBX) and data (from the routers) traffic is fed into the MC3810. AAL2 PVCs are established between the CPE device and the VISM. By enabling VAD and using compression, tremendous bandwidth savings are realized. CAC (Connection Admission Control) can be used to control bandwidth utilization for voice traffic. All the voice signaling traffic is passed transparently to the PSTN from the VISM. CAS is transported over AAL 2 type 3 cells and CCS is transported over AAL5.

Switched Voice Applications

The VISM supports industry standard media gateway control protocol (MGCP) for interworking with a variety of Softswitches (Refer to eco-system partners) to provide TDM voice offload onto packet networks. The VISM together with a SoftSwitch (Call Agent) can be used to provide switched voice capability for local tandem, long distance tandem and local services. In conjunction with a Softswitch, the VISM can act as high density PSTN gateway for H.323 and SIP based networks.

Core Functions

The VISM card provides the following services to support voice over ATM networks:

Voice Compression

The VISM supports the following standards-based voice coding schemes:

Support for a range of compression allows customers to select the compression quality and bandwidth savings appropriate for their applications; 32-kbps ADPCM, and 8-kbps CS-ACELP compression provide very high-quality and low-bit-rate voice, while reducing total bandwidth requirements.

Voice Activity Detection

Voice activity detection (VAD) uses the latest digital-signal processing techniques to distinguish between silence and speech on a voice connection. VAD reduces the bandwidth requirements of a voice

connection by not generating traffic during periods of silence in an active voice connection. Comfort noise generation is supported. VAD reduces bandwidth consumption without degrading voice quality. When combined with compression, VAD achieves significant bandwidth savings.

Onboard Echo Cancellation

The VISM uses digital signal processor (DSP)-based echo cancellation to provide near-end echo cancellation on a per-connection basis. Up to 128 ms of user-configurable near-end delay can be canceled. Onboard echo cancellation reduces equipment cost and potential points of failure, and facilitates high-quality voice connections. The echo cancellor complies with ITU standards G.164, G.165, and G.168.

Fax and Modem Detection

The VISM continually monitors and detects fax and modem carrier tones. When a carrier tone is detected from a modem or a fax, the channel is upgraded to PCM to ensure transparent connectivity. Fax and modem tone detection ensures compatibility with all voice-grade data connections.

QOS

The VISM takes full advantage of all the various QOS mechanisms available for IP+ATM networks. IP TOS and Precedence values are configurable on the VISM. For VoIP, either the RPM (integrated routing module on the MGX) or an external router can be used for advanced QOS mechanisms like traffic classification, congestion avoidance and congestion management. Also, in conjunction with RPM, VISM can take advantage of the QOS characteristics of MPLS networks (VoMPLS). The MGX's advanced traffic management capabilities combined with it's intelligent QoS management suite gives VISM the ability to support voice services which need predictable delays and reliable transport.

Integrated Network Management

Cisco WAN Manager (CWM) is a Telecommunications Management Network standards based network and element management system that enables operations, administration, and maintenance (OA&M) of the VISM along with MGX 8XXX. CWM provides an open API for seamless integration with OSS and 3rd party management systems.

Key Features

The VISM uses high performance digital signal processors and dual control processors with advanced software to provide a fully non-blocking architecture that supports the following functions:

VISM Physical Interfaces

Two front cards, VISM-8T1 and VISM-8E1, are available for the MGX 8250 platform. Each has eight T1 or E1 line interfaces.

The following 8-port back cards are used:

Redundancy

The VISM redundancy strategy is the same as for any of the 8-port cards in the MGX 8250. For VISM-8T1, 1:N redundancy is supported via the Line Modules (LMs) using the SRM-3T3 or the SRM-T1E1 and it is supported with the distribution bus using the SRM-3T3. For VISM-8E1, 1:N redundancy is supported only via LMs using the SRM-3T3 or the SRM-T1E1.

Physical Layer Interface T1

The physical layer interface T1 provides the following features:

Line Rate:

1.544Mbps +/- 50 bps

Line Interface Connector:

Balanced 100-ohm RJ48C

Synchronization:

The Transmit clock can be selected from one of the following sources: Loop time clock, or to the 8220 Shelf clock derived on the BNM

Line Code:

Bipolar 8 Zero Substitution (B8ZS) as specified in ANSI T1.408

Line Framing:

Extended Superframe Format (ESF 24 frame Multiframe) as ANSI T1.408

Input Jitter Tolerance:

Per ATT TR 62411

Output Jitter Generation:

Per ATT TR 62411 using normal mode synchronization

Physical Layer Alarms:

LOS, LOF, AIS, RDI

Physical Layer Interface E1

The physical layer interface E1 provides the following features:

Line Rate:

2.048 Mbps +/- 50 bps

Line Interface Connector:

Balanced 120-ohm RJ48C, unbalanced 75-ohm SMB

Synchronization:

The Transmit clock can be selected from one of the following sources: Loop time clock, or to the 8220 Shelf clock derived on the BNM

Line Code:

HDB3 (E1)

Line Framing:

16 frame Multiframe as in G.704

Input Jitter Tolerance:

As specified in ITU G.823 for the 2.048 Mbps

Output Jitter Generation:

As specified in ITU G.823 for the 2.048 Mbps

Physical Layer Alarms:

LOS, LOF, AIS, RDI

VISM Card General

The VISM card provides the following general features:

VISM front card:

AX-VISM-8T1/8E1

7.25" X 16.25"

VISM line modules:

AX-RJ48-8T1-LM

7.0" X 4.5"

AX-R-RJ48-8T1-LM

7.0" X 4.5"

AX-RJ48-8E1-LM

7.0" X 4.5"

Electrical and Safety Standards 

Description

Parameters

 Interfaces


 Eight T1 or E1


 T3 with optional SRM module


 Up to 5760/4608 (E1/T1) G.711 channels per MGX chassis


 Voice Coding/Compression 


 PCM (G.711)


 ADPCM (G.726)


 CS-ACELP (G.729a/b)


 When mixing compression types, the overall capacity varies between 145 and 240 channels per VISM.


 Voice Activity Detection


 Configurable threshold on a per-channel basis


 Echo Cancellation


 Per G.164, G.165, and G.168, programmable up to 128 msec


 Fax and Modem Transmission


 Using PCM connection, 240 channels per module


 PCM Encoding Types


 µ-Law or A-Law encoding


 End-to-end conversion available


 Channel Gain Control


 -8 dB to +6 dB


 Quantizing Distortion Added


 2.5 quantizing distortion units (QDUs) with 32-kbps ADPCM over one hop plus 0.7 QDUs with digital loss packet assembler/disassembler (PAD) (µ-Law or A-Law)


 Nominal Transmission Loss


 0 dB at 1 kHz


 Power Consumption


 60 watts (estimated)


 Weight (including Back Card)


 Approximately 1.74 lbs


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Posted: Mon Oct 2 16:43:42 PDT 2000
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