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This chapter describes the required common equipment hardware that forms the core of the Cisco MGX 8220 shelf. The optional service modules are described in "MGX 8220 Service Modules". This chapter includes the following sections:
The Cisco MGX 8220 is a 19-inch rack-mountable shelf. This shelf provides 16 slots for holding the modules (card sets) that provide the functionality. Each slot is designed to house two cards, a front card and a back card. Cards are installed in a slot as a two card set. A backplane runs across all 16 slots to provide signal connections between front and back cards, and between slots. The backplane also provides power distribution to all slots from dual (redundant) power entry modules installed in the bottom of the shelf.
All external line connections are made on the back cards at the rear of the shelf. These include
Frame Relay lines, the ATM trunk line, and RS-232 lines for the control console.
The Cisco MGX 8220 includes the following common equipment:
Cooling booster assembly (for certain multi-shelf configurations only)
In addition, an optional Cisco-supplied cabinet is available.
The Cisco MGX 8220 shelf is a 19-inch rack-mountable unit conforming to the EIA RS-310-C standard and includes the following measurements:
The shelf contains a card cage with 16 slots. The slots are numbered 1 to 16 from the left looking at the front of the shelf.
A backplane runs across the card cage spanning all 16 slots. The backplane is positioned approximately 14 inches from the front of the cage allowing a function module card to be inserted in the slot from the front and a smaller line module card to be inserted in the slot from the rear.
Slots 1 and 2 are reserved for BNM cards (single or a redundant pair) and slots 3 and 4 are reserved for ASC cards (single or a redundant pair). Slots 15 and 16 are reserved for the SRM (single or redundant pair). Slots 1, 3, and 15 work together as an active or standby set. The same is true for slots 2, 4, and 16. Slots 5 to 14 (10 slots) are available for service modules (or IMATM modules). For 1:N redundancy of T1/E1 service modules, standby cards must use slots 12, 13, and 14.
The shelf can house redundant power entry modules, which are small cards installed horizontally in the bottom rear of the shelf. The Cisco MGX 8220 shelf is powered by -48V DC power sources (single or redundant pair). Each power entry module is equipped with a circuit breaker. The shelf also provides a power receptacle for a cable to the cooling assembly, which is mounted in the rack below the Cisco MGX 8220 shelf (or shelves).
The backplane provides redundant system buses for communication between slots, power distribution to all slots, and communication between front and back cards. Figure 2-1 and Figure 2-2 show the front and rear views of the Cisco MGX 8220 shelf.
The Cisco MGX 8220 backplane contains a main system bus, and the cell bus for communication between card slots. The cell bus consists of two pairs of unidirectional buses (for redundancy), which are used for transferring cells between the cell bus slave modules (FRSM, AUSM, ASC) and the cell bus master (BNM).
The backplane also contains a local bus, which permits the ASC to configure and monitor the BNM and SRM, a BERT bus for bit error rate testing, and a redundancy bus for support of 1:N service module redundancy.
The backplane distributes -48V DC power to all card slots, and all modules are hot insertable.
The typical hardware weights are shown in the following table:
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In DC-powered systems, Cisco MGX 8220 supports one or two power entry modules (PEMs) each of which can be connected to its own independent 48V DC supply. The PEMs are installed horizontally, side by side in the bottom rear of the shelf. (See Figure 2-3.) Each module is powered from a 48V DC power source using three wires.
The 48V DC cable is connected to the power entry module through a 3-position Euro-block connector. The two modules provide power supply redundancy. Each power entry module is capable of supplying enough power for a fully loaded Cisco MGX 8220 shelf.
An illustration of a PEM is shown in Figure 2-3.
Each power entry module contains its own circuit breaker, which also acts as an ON/OFF switch. The circuit breaker is closed by pressing in the large black button until it latches in the closed position. The circuit breaker is opened by pressing the smaller red button. The DC PEM also includes a bracket that is attached to the PEM to provide cable strain relief. See "Installation and Start-Up" for details.
In AC-powered systems, a separate AC power assembly is required. (See Figure 2-4 and Figure 2-5.) This assembly is rack-mounted under the shelf cooling assembly in the rack and is available in both a single and double AC source line version. The power assembly has a modular design and can be configured with up to six power supply modules, each module providing 875W of 48V DC power. The power assembly can provide power for up to four Cisco MGX 8220 shelves, requiring three power supply modules, or four for a (1 for N) redundant power supply configuration. The rear panel has four connectors which supply 48V DC power to the shelves. The first three (1A, 2A, and 3A) connectors also provide power monitoring information to the Cisco MGX 8220 shelf. Another three connectors (1B, 2B, and 3B) on the rear panel provide monitoring information for the second half of the power supply. Special cables are used from the rear of the power assembly to the rear of the shelves to feed power and monitor data to the shelves.
The AC power assembly measures
Each card in an Cisco MGX 8220 shelf draws an average of 21W with a worst-case shelf current of 14.40A.
The circuit breaker in the DC power entry module (PEM) is rated at 15.00A.
The Cisco MGX 8220 circuits are protected as follows:
Each Cisco MGX 8220 board is equipped with a DC/DC converter (Shindengen—HGG05006 or AT&T—JW030A), which has an automatic current limited to 5V output.
A schematic of the DC power system is shown in Figure 2-6.
This section describes the cooling assembly that cools the Cisco MGX 8220 shelf and equipment:
The main cooling unit houses the fans that circulate air through the shelf. This unit is mounted below the shelves. This unit is capable of cooling up to two Cisco MGX 8220 shelves in the same rack. Racks that contain more than two shelves require a booster unit to provide additional cooling. The cooling assembly is powered from the main shelf.
The plenum or a spacer unit is mounted above the shelves to exhaust the warm air.
A single Cisco MGX 8220 shelf is shown in Figure 2-7. For more information on rack assembly and configuration, see "Installation and Start-Up."
The main cooling assembly provides cooling for up to two Cisco MGX 8220 shelves and is mounted in the rack below the shelf (or shelves). The cooling assembly consists of fans that draw air through the front grill and up through the shelf.
An illustration of the cooling assembly is shown in Figure 2-8.
The main cooling assembly measures
The booster cooling assembly is used in racks with more than two Cisco MGX 8220 shelves. It is mounted above the shelves containing the main cooling assembly and below the shelves to which the booster cooling is to be provided. The booster cooling assembly consists of fans that draw air from the shelves below and exhaust air upward through the shelf or shelves above. Each booster supports an additional two Cisco MGX 8220 shelves.
The booster cooling assembly measures
The plenum exhaust chamber is used in installations where the top of the unit must be enclosed. The plenum chamber is mounted in the rack immediately above the shelf or shelves. The chamber exhausts air from the shelf to the rear of the rack. The plenum chamber is the exhaust option recommended by Cisco Systems.
The exhaust plenum chamber measures
The spacer unit is an alternative method for exhausting air from the rack and can take the place of the exhaust plenum. The spacer does not support the attachment of a cable management kit. If used, the spacer unit is mounted in the rack immediately above the shelf or shelves.
Power is supplied to a connector at the rear of the cooling assemblies by a cable running from the bottom middle rear of the Cisco MGX 8220 shelf.
The assemblies provide output signals to the shelf. Using these signals, the cooling assembly performance can be monitored by the BNM cards. The cable delivering DC power to the cooling assembly from the Cisco MGX 8220 shelf also carries these signals to the BNM using the backplane. The signals are such that the model of cooling assembly can be identified and the speed of each fan can be monitored. Each fan generates a fixed number of square-wave pulses per revolution, allowing the speed of the fan to be determined.
A cabinet is available from Cisco to install the Cisco MGX 8220 shelf, the Cisco BPX 8600 series wide-area switch, the ESP, and the Cisco IGX 8400 series wide-area switch. Systems preconfigured in a Cisco-supplied cabinet can be ordered from Cisco.
The cabinet is a 19-inch rack with panels on all sides except the front. The rear panel is a louvered hinged door. The top and bottom are also covered. The cabinet is equipped with casters, brakes, and leveling bolts (see Figure 2-9). Holes at the base allow the cabinet to be secured to the floor for earthquake safety.
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Note Modules are installed in the cabinet in the same manner as installed in a 19-inch rack. |
Modules are installed by inserting them into the front of the cabinet and attaching them to the internal racks. All cables are connected through the rear door.
The vertical height of the cabinet (including casters) is 80.31 inches providing 71.81 inches (41 rack- mounting units) of vertical rack space.
The cabinet is 23 inches wide and 36 inches deep. Since Cisco MGX 8220 modules are typically 22 inches deep, the cabinet provides approximately 12 inches of space behind the mounted Cisco MGX 8220 modules for cables and cable management hardware.
Cisco MGX 8220 modules include a larger front card to provide the functionality of the module, and a smaller back card to provide the connectors and interfaces for external lines. The ASC and the BNM are referred to as the core modules. Both modules must be installed in the shelf. If an optional SRM is also installed, it is considered a core module.
If redundancy is required, a second set of ASC and BNM modules must be configured. Failure of an ASC or BNM causes switchover to the redundant ASC, BNM, and SRM cards. Failure of the active SRM card only causes switchover if the SRM is also included in the redundant set.
This section describes the following core module equipment:
The core modules work with the service modules to provide the following functions:
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Note "MGX 8220 Service Modules", contains information on the functionality of the various service modules. |
A simplified block diagram of the Cisco MGX 8220 hardware is shown in Figure 2-10. As shown by the dashed lines, the ASC, SRM, and cell bus are all 1:1 redundant. This means that one ASC, BNM, and SRM slot set is attached to one cell bus, and the remaining ASC, BNM, and SRM slot set is tied to the other cell bus.
The Cisco MGX 8220 shelf controller (ASC) is a two-card set consisting of an ASC front card and an ASC-BC back card. The shelf can contain a single ASC card set or a dual (redundant) card set.
The ASC provides overall control of the shelf through the cell bus. The ASC back card provides console ports for a user interface to configure and manage the shelf.
The ASC cards are installed in slot 3 and or slot 4. An illustration of the ASC card set is provided in Figure 2-11.
There are three hardware console ports located on the ASC back card.
The maintenance port is an RS-232 port used by a direct connect alphanumeric terminal for inputting command-line interface (CLI) commands. Y-cables cannot be used on this port. This port must be used to make initial IP address assignments on the other ports before the other ports can be used.
The control port and IEEE 802.3 (Ethernet, LAN AUI) ports are used for inputting commands and file transfers (statistics collection and firmware download). The control port communicates using SLIP and the Ethernet port communicates using IP. These ports support TFTP, SNMP, and CLI (through Telnet). The control port can be used with Y-cables for redundancy when a second ASC card set is present.
Some Ethernet transceivers with integrated DB-15 connectors cannot be connected directly to the
LAN AUI Ethernet port on the Cisco MGX 8220 ASC back card because of interference with the ASC back card extractor levers. To overcome this problem, two Ethernet transceiver extenders (one each for a primary and secondary ASC card) are provided.
If you encounter difficulty in connecting an Ethernet transceiver, install an extender on each ASC card.
1. With the retaining clip on the LAN AUI port in the unlocked (up) position, connect the Ethernet transceiver extender to the LAN AUI port on the ASC back card as shown in Figure 2-12.
2. Push the port retaining clip into the locked (down) position to secure the connection.
3. With the retaining clip on the transceiver extender in the unlocked (up) position, connect the Ethernet transceiver to the extender as shown in Figure 2-12.
4. Push the extender retaining clip into the locked (down) position to secure the connection.
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Note Additional access for shelf management is available through in-band communication over the ATM trunk. |
The ASC LED indicators are located on the faceplate of the front card. Table 2-1 describes the LED indicators.
Auto card restore is a feature that allows a service module card to be removed and be hot plug replaced with another service module card, keeping the same configuration. With this feature, the ASC maintains a copy of the configuration for each active service module.
The BNM card set provides the Cisco MGX 8220 trunk interface to a Cisco BPX 8600 series node. There are two major types of BNMs, one supports a T3 or E3 trunk and one supports a 155 Mbps SONET SMF trunk.
Each Cisco MGX 8220 shelf must be equipped with at least one BNM installed in slot 1 or slot 2. A second, redundant BNM can also be installed in slot 1 or slot 2. The primary and the redundant BNMs must be of the same type. Each BNM installed consists of a front and back card set.
The broadband network modules-T3E3 (BNM-T3E3) is a two-card set consisting of a BNM-T3 or E3 front card and a T3E3-D-BC or T3E3-B-BC back card. Either back card can be used with either front card except that the BNC clock connector only works for E1 clock sources. The shelf may contain a single BNM card set or a dual (redundant) card set. The cards are installed in slot 1 and/or slot 2.
An illustration of the BNM-E3/T3 card set is shown in Figure 2-13.
The major function of the BNM is to provide a T3 or E3 ATM interface to a BNI or BXM-T3/E3 card in a Cisco BPX 8600 series node. The BNM also provides the following miscellaneous functions:
Selects which core card to use as the master and which redundant bus to use.
BNM polls the other cards on the bus and grants permission to transmit cells across the bus. Polling is performed on a round-robin basis.
BNM manages the clock selection and synchronization for the entire Cisco MGX 8220 shelf. The BNM selects, regulates, and outputs the selected clock for use by each service module in the shelf. The BNM back card contains a T1/E1 port for inputting an external T1/E1 clock source. Two versions of the line module are available. Version T3E3-B has a BNC external clock connector used with E1 clock timing input. Version T3E3-D has a DB-15 external clock connector used with T1 or E1 clock timing input. The shelf can also obtain clock from the DS3 or E3 trunk itself or use an internal clock source.
BNM provides the activation of four alarm relays, which are wired to a DB-15 connector on the back card faceplate allowing the customer to wire their own cable from the connector to an indicator panel. The four relays are Major Alarm Audible, Major Alarm Visual, Minor Alarm Audible, and Minor Alarm Visual. The pinouts for this connector are provided in "Specifications."
BNM provides a separate path for management of the Cisco MGX 8220 using an ATM VCC from across the ATM network.
The BNM card accepts and transmits ATM cells over a T3 or E3 line interfaces at 44.736 Mbps or 34.368 Mbps respectively, using Cisco StrataCom Trunk Interface (STI) protocol asynchronously.
Framing occurs on the card using C-bit parity. An 8-kHz clock is extracted from the received signal and can be used to synchronize the entire Cisco MGX 8220 system.
The physical T3 or E3 ATM interface to the BNM is achieved using the BNM back card. This physical connection is made with BNC connectors. There are also relays on the back card. These relays provide the continuity or discontinuity between the internal circuitry and the external BNC connectors for the transmit and receive lines.
These relays are also used as a mechanical loopback for the T3 or E3 bit stream.
The Cisco MGX 8220 shelf implements the ATM STI cell format by using slot/channel numbers in the VPI/VCI fields in the cell format used between the BNM and the Cisco BPX 8600 series BNI port. The cell format is shown in Figure 2-14 and Figure 2-15. The format on the left is the general STI format, the format on the right is the Cisco MGX 8220 implementation.
In this format, the virtual circuit is defined by
The CC/FFCI/Supervisory field is used for ForeSight bits and a Supervisory bit.
The BNM-T3/E3 LED indicators are described in Table 2-2. All LEDs are located on the faceplate of the front card.
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The BNM has two push-buttons located on the faceplate of the front card.
The ACO button is a momentary switch and is pressed during a major or minor alarm to deactivate the audible alarm relays and to turn the ACO LED on. Any new alarm causes the relays to be reactivated.
The HIST button is a momentary switch and is pressed to extinguish the history LED if there is no active alarm at the time.
The broadband network module (BNM-155) is a two-card set consisting of a BNM-155 front card and a SMF-155 back card. The shelf can contain a single BNM-155 card set or a dual (redundant) card set. The cards are installed in slot 1 and/or slot 2.
An illustration of the BNM-155 card set is shown in Figure 2-16.
The major function of the BNM-155 is to provide a 155 Mbps SONET ATM interface to a BXM-8-155 port or a BXM-4-155 port in a Cisco BPX 8600 series node. The BNM-155 also provides the following miscellaneous functions:
This function selects which core card to use as the master and which redundant bus to use.
BNM-155 polls the other cards on the bus and grants permission to transmit cells across the bus. Polling is performed on a round-robin basis.
BNM-155 manages the clock selection and synchronization for the entire Cisco MGX 8220 shelf. The BNM-155 selects, regulates, and outputs the selected clock for use by each service module in the shelf. The BNM-155 back card contains a T1/E1 port for inputting an external T1/E1 clock source (both D-15 and BNC are available). The shelf can also obtain its clock source from the SONET trunk itself or use an internal clock source.
BNM-155 provides the activation of four alarm relays that are wired to a DB-15 connector on the back card faceplate, allowing the customer to wire their own cable from the connector to an indicator panel. The four relays are Major Alarm Audible, Major Alarm Visual, Minor Alarm Audible, and Minor Alarm Visual. The pinouts for this connector are provided in "Specifications."
The BNM-155 provides a separate path for management of the Cisco MGX 8220 shelf using an ATM VCC from across the ATM network.
The BNM-155 card accepts and transmits ATM 53-byte cells over a SONET line interface at 155.52 Mbps using ATM UNI or ATM B-ICI protocols.
In UNI mode, 20 virtual circuit connections per slot are supported.
In NNI mode, 340 virtual circuit connections per slot are supported.
The SMF-155 back card provides a physical single-mode fiber optic SONET OC-3 interface conforming to ANSI T1.105 and GR-253-CORE standards. This interface uses SC connectors. When used in a redundant configuration, redundant cabling is provided through Y-cables.
The BNM-155 LED indicators are described in Table 2-3. All LEDs are located on the faceplate of the front card.
Table 2-3 BNM-155 LED Indicators
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The BNM-155 has two push-buttons located on the faceplate of the front card.
The ACO button is a momentary switch and is pressed during a major or minor alarm to deactivate the audible alarm relays and to turn the ACO LED on. Any new alarm causes the relays to be reactivated.
The HIST button is a momentary switch and is pressed to extinguish the history LED if there is no active alarm at the time.
The inverse multiplexing for ATM trunk module (IMATM) is housed in the Cisco MGX 8220 shelf in a service module slot. IMATM is an extension to the Cisco BPX 8600 series BNI card that supports Cisco BPX 8600 series ATM trunks over multiple (up to 8) T1 and E1 lines instead of single T3 or E3 line. The IMATM does not use the Cisco MGX 8220 cell bus as other service modules do, but provides its own trunk to the Cisco BPX 8600 series.
A service redundancy module (AX-SRM-T1/E1) provides three major functions for service modules: bit error rate testing (BERT) of T1 and E1 lines and ports, loop back of individual nx64 channels toward the CPE, and 1:N redundancy. The AX-SRM-3T3 also provides bulk distribution of T1 lines. This section described the following:
Figure 2-17 shows an illustration of the AX-SRM-T1/E1 card.
The SRM cards provide the following functions:
When a service module line or port has been put into loopback mode, the SRM can generate a test pattern over the looped line or port, read the received looped data, and report on the error rate. This operation can be performed on a complete T1 or E1 line, on a fractional T1 or E1 line, on a DS0 bundle (NxDS0), or on a single DS0 channel. The SRM can support BERT only one line or channel at a time.
BERT is capable of generating a variety of test patterns including all ones, all zeros, alternate one zero, double alternate one zero, 223-1, 220-1, 215-1, 211-1, 29-1, 1 in 8, 1 in 24, DDS1, DDS2, DDS3, DDS4, and DDS5.
Service module redundancy provides 1:N redundancy for multiple groups of service modules where a group can consist of N active and one standby service modules. The redundant service module in a group must be a superset (with respect to functionality) of the cards. For example, one group could contain all the FRSMs and another all the AUSMs.
1:N redundancy must be configured by the user. When the failure of an active card in a group is detected by the ASC, the SRM is ordered to invoke 1:N redundancy for that group. The back card of the failed service module now directs data to and from the standby service module. With the SRM-T1/E1, when 1:N redundancy is invoked for a group, it is not available to the other groups or to other service modules in the group using 1:N redundancy. Another failure in any group results in a shelf alarm. This restriction does not apply to the SRM-3T3, for example, the SRM-3T3 can support multiple group failures.
The installation of an SRM is optional. If SRMs are installed in a shelf with redundant ASCs and BNMs, the shelf must also have redundant SRMs. If a shelf has a single ASC and BNM pair (no redundancy), the SRM must be installed in the appropriate slot.
All LEDs are located on the faceplate of the front card. The SRM-T1/E1 LED indicators are described in Table 2-4.
Table 2-4 SRM-T1/E1 LED Indicators
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The SRM-3T3 service redundancy module provides bulk distribution of T1 circuits to the 4-port or 8-port T1 service modules. Rather than individually cable each of the 40 or 80 incoming T1/E1 lines to an MGX 8220 edge concentrator, the MGX 8220 backplane is designed with a distribution bus that allows an AX-SRM-3T3 to distribute T1s received "in bulk" to T1-based service modules. This eliminates the need for T1 back cards for each service module and the associated cabling and potential overloading of the digital cross-connect system port. The AX-SRM-3T3 provides a method to bring in from one to three T3 interfaces that can be demultiplexed to their constituent T1s, providing up to 28, 56, or 80 T1s to be distributed to T1 service modules over the distribution bus. Both 4-port and 8-port service modules are supported in any combination. The AX-SRM-3T3 supports the following features:
Out of the maximum possible 84 T1 channels (3 times 28), up to 80 channels can be active at any time. Any T1 channel in a T3 line can be distributed to any four/eight port on a service module in any slots 5 to 14 without restriction.
The AX-SRM-3T3 can also be operated in "nonbulk mode" on a port-by-port basis. For a port configured in nonbulk mode, bulk distribution is disabled and the SRM acts as a AX-SRM-T1/E1 providing BERT and 1:N redundancy functions only.
Figure 2-18 shows an illustration of the AX-SRM-3T3 cards.
Posted: Thu Nov 20 21:42:48 PST 2003
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