Cabling Cisco MGX RPM Port Adapters
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Table Of Contents
Cabling the MGX RPM Back Cards
MGX-RJ45-4E and MGX-RJ45-4E/B Back Cards
IEEE 802.3 10BaseT Specifications
MGX-RJ45-4E and MGX-RJ45-4E/B Back Card LEDs
MGX-RJ45-4E and MGX-RJ45-4E/B Back Card Receptacles and Cables
Attaching MGX-RJ45-4E and MGX-RJ45-4E/B Back Card Interface Cables
IEEE 802.3u 100BaseT Specifications
Fast Ethernet Back Card Receptacles and Cables
Attaching FE Back Card Interface Cables
Maximum Transmission Distances for FDDI Connections
FDDI Back Card Optical Power Parameters
FDDI SMF Back Card Fiber-Optic Cables
FDDI MMF Back Card Fiber-Optic Cables
Attaching FDDI Back Card Interface Cables
Attaching an Optical Bypass Switch
Cabling the MGX RPM Back Cards
This chapter provides an overview of the RJ45-4E and FE back card functionality, cabling, and connectors as well as procedures for making back card connections. It contains the following sections:
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MGX-RJ45-4E and MGX-RJ45-4E/B Back Cards
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MGX-RJ45-4E and MGX-RJ45-4E/B Back Cards
The MGX-RJ45-4E (PA-4E) and MGX-RJ45-4E/B back cards provide up to four IEEE 802.3 Ethernet 10BaseT interfaces (see Figure 4-1).
Figure 4-1 MGX-RJ45-4E/B Ethernet Back Card
Ethernet 10BaseT Overview
Ethernet is commonly used for all carrier sense multiple access/collision detection (CSMA/CD) local-area networks (LANs), which generally conform to Ethernet specifications, including IEEE 802.3 Ethernet Version 1 and IEEE 802.3 Ethernet Version 2. The slight differences between Ethernet and IEEE 802.3 are implemented in the hardware, and both are supported automatically by the Ethernet 10BaseT back card without any hardware configuration changes. Together, Ethernet and IEEE 802.3 are the most widely used LAN protocols. They are well suited to applications where a local communication medium must carry sporadic and occasionally heavy traffic.
Nodes on a CSMA/CD LAN can access the network at any time. Before sending data, the station listens to the network to determine if it is in use. If it is, the station waits until the network is not in use, then transmits. A collision occurs when two stations listen for network traffic, hear none, and transmit simultaneously. When this happens, both transmissions are damaged, and the stations must retransmit. The stations detect the collision and use backoff algorithms to determine when they should retransmit.
Both Ethernet and IEEE 802.3 are broadcast networks, which means that all stations hear all transmissions. Each station must examine received frames to determine whether it is the intended destination and, if it is, pass the frame to a higher protocol layer for processing.
Each IEEE 802.3 physical layer protocol has a name that summarizes its characteristics in the format speed/signaling method/segment length, where speed is the LAN speed in Mbps, signaling method is either baseband or broadband, and segment length is the maximum length between stations in hundreds of meters.
IEEE 802.3 10BaseT Specifications
Table 4-1 summarizes the characteristics of IEEE 802.3 Ethernet and Ethernet Version 2 for 10BaseT.
Table 4-2 lists the cabling specifications for 10-Mbps transmission over UTP and STP cables.
1 Cisco Systems does not supply Category 3 and Category 5 UTP RJ-45 cables; these cables are available commercially.
2 AWG = American Wire Gauge. This gauge is specified by the EIA/TIA-568 standard.
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MGX-RJ45-4E and MGX-RJ45-4E/B Back Card LEDs
The RJ45-4E and RJ45-4E/B back card contain the enabled LED, standard on all back cards, and one status LED for each port, called the "link" LED. After system initialization, the enabled LED goes on to indicate that the RJ45-4E back card has been enabled for operation. When a 10BaseT port is active, its link LED is on when a port on the RJ45-4E back card is receiving a carrier signal from the network. (See Figure 4-1.) The following conditions must be met before the enabled LED goes on:
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If any of these conditions is not met, or if the initialization fails for other reasons, the enabled LED does not go on.
MGX-RJ45-4E and MGX-RJ45-4E/B Back Card Receptacles and Cables
The interface connectors on the RJ45-4E back card are four individual RJ-45 receptacles. You can use all four simultaneously. Each connection supports IEEE 802.3 and Ethernet 10BaseT interfaces compliant with appropriate standards. The RJ-45 connections require external transceivers. Cisco Systems does not supply Category 5 UTP RJ-45 cables; these cables are available commercially.
Figure 4-2 shows the RJ-45 connectors. See "Cable and Connector Specifications" for pinouts and signals for the RJ-45 connectors.
Figure 4-2 4E RJ-45 Connections, Plug and Receptacle
Warning
Attaching MGX-RJ45-4E and MGX-RJ45-4E/B Back Card Interface Cables
On a single MGX-RJ45-4E or e MGX-RJ45-4E/B back card, you can attach up to four RJ-45 connections.
Note
To connect RJ-45 cables to the MGX-RJ45-4E or MGX-RJ45-4E/B back card, you can
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This completes the RJ45-4E back card cable installation.
Figure 4-3 Ethernet Connection to a 10BaseT Hub
Figure 4-4 Ethernet Connection to a PC Network Interface Card
Fast Ethernet Back Card
Fast Ethernet is commonly used for all carrier sense multiple access/collision detection (CSMA/CD), local-area networks (LANs) that generally conform to Ethernet specifications, including Fast Ethernet under IEEE 802.3u.
IEEE 802.3u is well suited to applications where a local communication medium must carry sporadic, occasionally heavy traffic at high peak data rates. Stations on a CSMA/CD LAN can access the network at any time. Before sending data, the station listens to the network to see if it is already in use. If it is, the station waits until the network is not in use, then transmits; this is a half-duplex operation. A collision occurs when two stations listen for network traffic, hear none, and transmit very close to simultaneously. When this happens, both transmissions are damaged, and the stations must retransmit. The stations detect the collision and use backoff algorithms to determine when they should retransmit.
Both Ethernet and IEEE 802.3u are broadcast networks, which means that all stations see all transmissions. Each station must examine received frames to determine whether it is the intended destination and, if it is, pass the frame to a higher protocol layer for processing.
IEEE 802.3u specifies the following physical layers for 100BaseT:
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Each physical layer protocol has a name that summarizes its characteristics in the format speed/signaling method/segment length, where speed is the LAN speed in megabits per second (Mbps), signaling method is the signaling method used (either baseband or broadband), and segment length is typically the maximum length between stations in hundreds of meters. Therefore, 100BaseT specifies a 100-Mbps, baseband LAN with maximum network segments.
IEEE 802.3u 100BaseT Specifications
Table 4-3 lists the cabling specifications for 100-Mbps Fast Ethernet transmission over UTP, STP, and fiber-optic cables. Table 4-4 summarizes IEEE 802.3u 100BaseT physical characteristics.
Table 4-3 Specifications and Connection Limits for 100-Mbps Transmission
Cable specification
Category 3, 4, or 5, 150-ohm UTP or STP, or multimode optical fiber
Cable specification
Maximum cable length
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1.64 ft (0.5 m) (MII-to-MII cable3 )
Maximum cable length
Maximum segment length
328 ft (100 m) for 100BaseTX
3.28 ft (1 m)4 or 1,312 ft (400 m) for 100BaseFX
Maximum segment length
Maximum network length
656 ft (200 m)4 (with 1 repeater)
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Maximum network length
1 EIA/TIA-568 or EIA-TIA-568 TSB-36 compliant.
2 Cisco Systems does not supply Category 5 UTP RJ-45 or 150-ohm STP MII cables. Both are available commercially.
3 This cable is between the MII port on the FE back card and the appropriate transceiver.
4 This length is specifically between any two stations on a repeated segment.
Table 4-4 IEEE 802.3u Physical Characteristics
Data rate (Mbps)
100
100
Signaling method
Baseband
Baseband
Maximum segment length (meters)
100 m between repeaters
100 m between DTE1 and repeaters
Media
SC-type—dual simplex or single duplex for Rx and Tx
RJ-45MII
Topology
Star/Hub
Star/Hub
1 DTE = data terminal equipment.
FE-TX and FE-FX Back Cards
Figure 4-5 shows the FE back card.
Figure 4-5 Fast Ethernet Back Card
FE-TX Back Card
Each Fast Ethernet port on the FE-TX back card has an RJ-45 connector to attach to Category 5 unshielded twisted-pair (UTP) for 100BaseTX, and a MII connector that permits connection through external transceivers to multimode fiber for 100BaseFX physical media.
FE-FX Back Card
Each Fast Ethernet port on the FE-FX back card has an SC-type fiber-optic connector for 100BaseFX, and an MII connector that permits connection through external transceivers to multimode fiber for 100BaseFX physical media.
Fast Ethernet Back Card LEDs
The FE-TX and FE-FX back cards contain the enabled LED, which is standard on all back cards, and a bank of three status LEDs for the ports. After system initialization, the enabled LED goes on to indicate that the FE back card has been enabled for operation. The LEDs are shown in Figure 4-1.
The following conditions must be met before the enabled LED goes on:
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If any of these conditions is not met, or if the initialization fails for other reasons, the enabled LED does not go on.
The three status LEDs indicate which port is active.
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Fast Ethernet Back Card Receptacles and Cables
The two interface receptacles on the FE back card are:
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You can use either one or the other. Only one receptacle can be used at one time. Each connection supports IEEE 802.3u interfaces compliant with the 100BaseX and 100BaseT standards. The RJ-45 connection does not require an external transceiver. The MII connection requires an external physical sublayer (PHY) and an external transceiver.
Cisco Systems does not supply Category 5 UTP RJ-45 cables; these cables are available commercially. See "Cable and Connector Specifications" for pinouts and signals for the FE-TX RJ-45 connectors.
Figure 4-6 shows the RJ-45 connector used for FE-TX connections.
Figure 4-6 FE-TX RJ-45 Connections (Plug and Receptacle Shown)
Warning
Figure 4-7 shows the duplex SC connector (one required for both transmit and receive). Figure 4-8 shows the simplex SC connector (two required, one for each transmit and receive) used for the FE-FX optical-fiber connections. These multimode optical-fiber cables are commercially available, but are not available from Cisco Systems.
Figure 4-7 FE-FX Duplex SC Connector
Figure 4-8 FE-FX Simplex SC Connector
Depending on the type of media you use between the MII connection on the back card and your switch or hub, the network side of your 100BaseT transceiver should be appropriately equipped with ST-type connectors (for optical fiber), BNC connectors, and so forth. Figure 4-9 shows the pin orientation of the female MII connector on the back card. The back cards are field-replaceable units (FRUs).
The MII receptacle uses 2-56 screw-type locks, called jackscrews (see Figure 4-9), to secure the cable or transceiver to the MII port. MII cables and transceivers have knurled thumbscrews that you fasten to the jackscrews on the FE-TX back card's MII connector. Use the jackscrews to provide strain relief for the MII cable. Figure 4-9 also shows the MII female connector (receptacle).
Caution
Figure 4-9 FE-TX or FE-FX MII Connection (Receptacle Shown)
See "Cable and Connector Specifications" for the MII connector pinout and signals. MII cables are available commercially and are not available from Cisco Systems. The appendix refers to MII cables used between the MII connector on the FE-TX back card and an appropriate transceiver. The connection between this transceiver and your network can be Category 3, 4, or 5, 150-ohm UTP or STP, or multimode optical fiber.
Attaching FE Back Card Interface Cables
On a single FE back card, you can use either the RJ-45 (or SC for FE-FX) connection or the MII connection. (RJ-45, SC, and MII cables are not available from Cisco Systems; they are available from outside commercial cable vendors.) If you have two FE back cards, you can use the RJ-45 (or SC for FE-FX) connection on one back card and the MII connection on the other back card.
Caution
Use the following procedure to connect RJ-45, SC (FE-FX), or MII cables.
Step 1
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Step 2
Caution
Figure 4-10 Attaching the Ferrite Bead around the RJ-45 Cable
Caution
Step 3
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FDDI Back Cards for the RPM/B
FDDI, which specifies a 100-Mbps, wire-speed, token-passing dual-ring network using fiber-optic transmission media, is defined by the ANSI X3.1 standard and by ISO 9314, the international version of the ANSI standard. An FDDI network comprises two token-passing fiber-optic rings: a primary ring and a secondary ring.
A ring consists of two or more point-to-point connections between adjacent stations. On most networks, the primary ring is used for data communication, and the secondary ring is used as a backup. Single attachment stations attach to one ring and are typically attached through a concentrator; Class A, or dual attachment stations (DASs), attach to both rings.
Figure 4-11 shows a typical FDDI configuration with both dual-attached and single-attached connections. Single attachment stations (SASs) typically attach to the primary ring through a concentrator, which provides connections for multiple single-attached devices. The concentrator ensures that a failure or power down of any single attachment station does not interrupt the ring. SASs use one transmit port and one receive port to attach to the single ring. DASs (Class A) have two physical ports, designated PHY A and PHY B, each of which connects the station to both the primary and secondary rings. Each port is a receiver for one ring and a transmitter for the other. For example, PHY A receives traffic from the primary ring and PHY B transmits to it.
Figure 4-11 Typical Configuration with DAS, Concentrator, and Single Attachment
The dual rings in an FDDI network provide fault tolerance. If a station on a dual ring shuts down or fails, such as Station 3 in Figure 4-12, the ring automatically wraps (doubles back on itself) to form a single contiguous ring. This removes the failed station from the ring, but allows the other stations to continue operation. In Figure 4-12, the ring wraps to eliminate Station 3 and forms a smaller ring that includes only Stations 1, 2, and 4. A second failure could cause the ring to wrap in both directions from the point of failure, which would segment the ring into two separate rings that could not communicate with each other.
Figure 4-12 DAS Station Failure and Ring Recovery Example
For example, if Station 1 in Figure 4-12 fails after Station 3 fails, Stations 2 and 4 will each be isolated because no path for communication exists between them. Subsequent failures cause additional segmentation.
Optical Bypass Overview
This section includes information on optical bypass switching with FDDI.
Optical bypass switching avoids segmentation by eliminating failed stations from a ring. An optical bypass switch allows the light signal to pass directly through it, completely bypassing the failed or shut down station.
For example, if an optical bypass switch was installed at Station 3 in the example ring, it would allow the light signal to pass through the switch and maintain its existing path and direction without wrapping back on itself.
The FDDI back cards have an optical bypass switch feature by way of a DIN connection. Optical bypass switches avoid segmentation by eliminating failed stations from the ring. During normal operation, an optical bypass switch allows the light signal to pass uninterrupted directly through itself. When a station with a bypass switch fails, the bypass switch reroutes the signal back onto the ring before it reaches the failed station, so the ring does not have to wrap back on itself.
Figure 4-13 shows an optical bypass switch installed at Station 1. In the normal configuration shown, Station 1 is functioning normally, so the optical bypass switch appears transparent. The switch essentially allows the signals to pass through it without interruption. However, if Station 1 fails, the optical bypass switch enables the bypassed configuration shown on the right.
Figure 4-13 Optical Bypass Operation on a DAS
The optical bypass switch reroutes the light signal by intercepting it before it reaches the failed Station 1 and sends it back out to the ring, allowing the signal to maintain its existing path and direction without wrapping back on itself. However, stations that are operating normally repeat the signal when sending it back out to the ring. Optical bypass switches do not repeat or drive the signal (they just allow the signal to pass through them), so significant signal loss can occur when the downstream neighbor (the next station on the ring) is far away.
Another technique for fault tolerance is dual homing, whereby critical devices are attached to two concentrators. Only the designated primary concentrator is active unless it (or its link) fails. If the primary fails, the backup (passive) concentrator is automatically activated and sustains the ring.
FDDI Specifications
Typically, FDDI uses two types of fiber-optic cable:
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Mode refers to the angle at which light rays (signals) are reflected and propagated through the optical fiber core, which acts as a waveguide for the light signals. Multimode fiber has a relatively thick core (62.5/125-micron) that reflects light rays at many angles. Single-mode fiber has a narrow core (8.7 to 10/125-micron) that allows the light to enter only at a single angle.
Although multimode fiber allows more light signals to enter at a greater variety of angles (modes), the different angles create multiple propagation paths that cause the signals to spread out in time and limits the rate at which data can be accurately received. This distortion does not occur on the single path of the single-mode signal; therefore, single-mode fiber is capable of higher bandwidth and greater cable run distances that multimode fiber. In addition, multimode transmitters usually use LEDs as a light source, and single-mode transmitters use a laser diode, which is capable of sustaining faster data rates. Both types use a photodiode detector at the receiver to translate the light signal into electrical signals.
The FDDI standard sets total fiber lengths of 2 kilometers (1.2 miles) for multimode fiber and 15 kilometers (9.3 miles) for single-mode fiber. (The maximum circumference of the FDDI network is only half the specified distance because of signal wrapping or loopback that occurs during fault correction.) The FDDI standard allows a maximum of 500 stations with a maximum distance between active stations of 2 kilometers.
See "Cable and Connector Specifications," for a description of the mini-DIN optical bypass switch available on the FDDI back cards. The mini-DIN-to-DIN adapter cable (CAB-FMDD=) allows a connection to an optical bypass switch with a DIN connector (which is larger than the mini-DIN connector on the FDDI back cards).
Note
The FDDI back card implementation complies with Version 6.1 of the X3T9.5 FDDI specification, offering a Class A dual attachment interface that supports the fault-recovery methods of DAS. The FDDI back card supports dual homing and optical bypass and complies with ANSI X3.1 and ISO 9314 FDDI standards.
Maximum Transmission Distances for FDDI Connections
The maximum transmission distances for single-mode and multimode FDDI stations are shown in Table 4-5. If the distance between two connected stations is greater than the maximum distance shown, significant signal loss can result.
Table 4-5 FDDI Maximum Transmission Distances
Single-mode
Up to 9.3 miles (15 km)
Multimode
Up to 1.2 miles (2 km)
FDDI Back Card Optical Power Parameters
The multimode and single-mode optical-fiber connections conform to the following optical power parameters:
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FDDI Back Card
The FDDI back cards provide a half-duplex FDDI for both single-mode and multimode fiber-optic cable. The two physical ports (PHY A and PHY B) are available with either single-mode (SC) or multimode MIC receptacles. Each back card's FDDI connection allows a maximum bandwidth of 100 Mbps per the FDDI standard.
The following FDDI back card combinations are available:
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FDDI Back Card LEDs
This section describes the functions of the LEDs on the half-duplex FDDI back cards.
The FDDI back card contains the enabled LED, standard on all back cards, and status LEDs for each port. After system initialization, the enabled LED goes on to indicate that the FDDI back card has been enabled for operation. The LEDs on both half-duplex FDDI back cards are identical.
The following conditions must be met before the enabled LED goes on:
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If any of these conditions is not met, or if the initialization fails for other reasons, the enabled LED does not go on. In addition to the enabled LED, the FDDI back card has the following three LEDs:
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The states of the back card's LEDs and the meanings of each are described in Table 4-6.
Table 4-6 FDDI Back Card LED States
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Not connected
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O
Not possible
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O
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Wrap B
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O
O
Dual homed (B connected to M port)
O
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Wrap A
O
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O
Dual homing back-up (A connected to M port;
B port is not connected)O
O
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Through A
O
O
O
Not possible
1 For the LED patterns "—" means off, "O" means on.
FDDI SMF Back Card Fiber-Optic Cables
This section describes the half-duplex FDDI back card receptacles and cables.
The interface receptacles on the FDDI back card use SC-type connectors for simplex and duplex, single-mode applications. For FDDI single-mode connections, use one duplex SC connector (see Figure 4-14) or two single SC connectors, at both the back card end and the network end (see Figure 4-15). Single-mode optical fiber cable has a narrow core (8.7 to 10/125-micron) that allows light to enter only at a single angle.
Figure 4-14 Duplex SC Connector
Figure 4-15 Simplex SC Connector
Warning
Figure 4-16 shows a view of the FDDI SMF back card.
Figure 4-16 FDDI SMF Back Card
FDDI MMF Back Card
Figure 4-17 shows a view of the FDDI MMF back card.
Figure 4-17 FDDI MMF Back Card
FDDI Back Card LEDs
This section describes the functions of the LEDs on the half-duplex FDDI back cards.
The FDDI back card contains the enabled LED, standard on all back cards, and status LEDs for each port. After system initialization, the enabled LED goes on to indicate that the FDDI back card has been enabled for operation. The LEDs are shown in Figure 4-16 and Figure 4-17. The LEDs on both half-duplex FDDI back cards are identical.
The following conditions must be met before the enabled LED goes on:
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If any of these conditions is not met, or if the initialization fails for other reasons, the enabled LED does not go on. In addition to the enabled LED, the FDDI back card has the following three LEDs:
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The states of the back card's LEDs and the meanings of each are described in Table 4-7.
Table 4-7 FDDI Back Card LED States
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Not connected
—
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O
Not possible
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O
—
Wrap B
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O
O
Dual homed (B connected to M port)
O
—
—
Wrap A
O
—
O
Dual homing back-up (A connected to M port;
B port is not connected)O
O
—
Through A
O
O
O
Not possible
1 For the LED patterns "—" means off, "O" means on.
FDDI MMF Back Card Fiber-Optic Cables
This section describes the half-duplex FDDI back card receptacles and cables.
The interface receptacles on the FDDI back card are MICs for multimode applications. The multimode receptacle is an FDDI-standard physical sublayer (PHY) connector that encodes and decodes the data into a format acceptable for fiber transmission. The multimode receptacle accepts standard 62.5/125-micron, multimode fiber-optic cable using the MIC and, with proper cable terminators, can accept 50/125 micron fiber-optic cable. Fiber-optic cables are commercially available and are not available from Cisco Systems. Multimode uses the integrated MIC shown in Figure 4-18, at both the back card end and the network end.
Figure 4-18 Multimode FDDI Network Interface MIC
Attaching FDDI Back Card Interface Cables
Both single-mode and multimode, dual attachment cable connections are available. Fiber-optic cable connects directly to the FDDI ports. Single-mode uses simplex or duplex SC-type transmit and receive cables. Connect single-mode, dual attachment as shown in Figure 4-19.
Figure 4-19 Single-Mode Dual Attachment with Duplex and Simplex SC-Type Cables and Optical Bypass Control Cable
Multimode uses MIC cables. Connect multimode with Fixed Shrouded Duplex connector as shown in Figure 4-20.
Figure 4-20 Multimode Dual Attachment with MIC Cables and Optical Bypass Control Cable
Attaching an Optical Bypass Switch
An optical bypass switch is a device installed between the ring and the station that provides additional fault tolerance to the network. If an FDDI back card that is connected to a bypass switch fails or shuts down, the bypass switch activates automatically and allows the light signal to pass directly through it, bypassing the back card completely.
Following are general instructions for connecting an optical bypass switch to the FDDI back card; however, your particular bypass switch may require a different connection scheme. Use these illustrations and general guidelines. For specific connection requirements, refer to the instructions provided by the manufacturer of the optical bypass switch.
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A port for connecting an optical bypass switch is provided on the multimode back card (PA-F/FD-MM, shown in Figure 4-21), and the single-mode back card (PA-F/FD-SM, shown in Figure 4-22).
Figure 4-21 Optical Bypass Switch Connection (PA-F/FD-MM)
Figure 4-22 Optical Bypass Switch Connection (PA-F/FD-SM
Note
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