Gigabit Ethernet Interconnect Technology

Transcription

1 Gigabit Ethernet Interconnect Technology By Lisa A. Huff Segment Marketing Manager, Communications Gigabit Ethernet Description Ethernet is the world's most pervasive networking technology. More than 85% of all installed network connections were Ethernet at the end of This represents over 200 million interconnected PCs, workstations and servers. In 1999, 91% of all shipped network equipment were Ethernet based. Ethernet operates at a 10 Mbps (Megabits per second) data rate and uses a BNC coax interface connector. In 1995, the Fast Ethernet standard was approved by the IEEE. Fast Ethernet provided 10X higher bandwidth (100 Mbps) and utilizes a RJ45 interface connector. This established Ethernet as a scaleable technology. With the emerging Gigabit Ethernet (1000 Mbps or 1 Gbps) standard, it is expected to scale even further. Gigabit Ethernet will provide a straightforward migration path from Fast Ethernet. The Gigabit Ethernet standard is being pushed by an industry consortium called the Gigabit Ethernet Alliance. 11 companies formed the alliance in May of 1996 after IEEE announced the formation of the 802.3z Gigabit Ethernet Standards project. At last count, there were over 95 companies in the alliance from the networking, computer and integrated circuit industries. Where is it used? Initially, Gigabit Ethernet is being deployed as a backbone in existing networks. It can be used to aggregate traffic between clients and "server farms," and for connecting Fast Ethernet switches. It can also be used for connecting workstations and servers for high bandwidth applications such as scientific modeling, medical data transfer, Internet/Intranet, data warehousing and desktop video conferencing. See Figure 1 for where Gigabit Ethernet fits. In reality, corporate networks will be hybrids of Gigabit Ethernet, ATM (Asynchronous Transfer Mode), Fibre Channel and other legacy technologies such as FDDI, Ethernet, Fast Ethernet and Token Ring. Essentially, five types of hardware are needed to upgrade an existing Ethernet/Fast Ethernet network to Gigabit Ethernet: Gigabit Ethernet Network Interface Cards (NICs) Aggregating switches that connect Fast Ethernet to Gigabit Ethernet

2 Gigabit Ethernet switches Router interfaces Gigabit Ethernet repeaters (or Buffered Distributors) The five most likely network upgrade scenarios are as follows: 1. Upgrading switch to switch connections 2. Upgrading switch to server connections 3. Upgrading a fast Ethernet backbone 4. Upgrading a Shared FDDI backbone 5. Upgrading High performance workstations Figure 1: Where Gigabit Ethernet fits (Byte magazine) General Interconnect/Cabling Requirements The Gigabit Ethernet standard specifies single-mode, multi-mode fiber, short- 2

3 haul twinax and long-haul UTP copper cable. The cabling distances to be supported are given in the following table: CABLE TYPE DISTANCE (meters) Single-mode fiber (9 micron) Multi-mode Fiber (62.5 micron) Multi-mode Fiber (50 micron) Short-haul copper (twinax; shielded quad) Long haul copper (Cat 5 UTP) 3000 m m 550 m 25 m m Figure 2: Extreme Networks' Summit 48 workgroup switch (left) and Packet Engines' PE-4884 backbone switching router (right) Short Haul Copper (HSSDC - MetaGig ) Application MetaGig is a hot pluggable, impedance controlled serial I/O connector system supporting data rates up to 2500 Mbps that make it suitable for Gigabit Ethernet (Style 2) copper cabling technology. The Style 1 connector is a DB9 9-pin D-sub connector that is specified but not preferred for this application. Figure 3 shows FCI's MetaGig product. Figure 3: MetaGig Connector and Cable Assemblies Receptacle (Equipment Side) The receptacle is an eight position blade-on-beam shielded connector 3

4 designed for high speed serial data applications. There are currently two versions of the receptacle; bulkhead mount and PCI card mount. The hot pluggable receptacle includes first make-last break ground and power contacts. FCI product offerings are listed below: Part Number Description Bulkhead mount PCI mount x PCI assy - x ports (x = 1 to 4 ports) x PCI mounting bracket - x ports (x = 1 to 4 ports) Plug Kits & Copper Cable Assemblies The cable plug will accept AWG cable. The cable assemblies include equalized and unequalized versions. The equalization circuit depends upon the cable length and data rate of the application. Lengths range from 1 to 30 meters. Equalizers are used to extend the length of the copper cabling. They are embedded in the plug connector on the cable assemblies at lengths greater than 25 meters. The following plug kits and cable assemblies are standard product available: Part Number Description Plug kit xxx xxx xxx MetaGig to MetaGig Cable assy (unequalized) MetaGig to MetaGig Cable assy (equalized) MetaGig to DB9 Cable assy (unequalized) Long Haul Copper (ModJack - Cat5e or Cat6) Application The copper long haul applications use the same RJ45 connector that has been used for Fast Ethernet applications with added filtering to improve the EMI. FCI has a number of variations of this connector. 4

5 Transition from Copper to Optics Figure 4: NetJack connector Figure 5 shows the cost comparison between an optical link and a copper link. When a user is attempting to determine which media type to choose, the decision is usually made predominantly on cost. At this time, the crossover point between copper and optics is beyond the usable length for copper. This is due mostly to the cost of the optical transceivers. As transceivers continue to drop in price, the crossover point may reach lengths where copper is traditionally used. Figure 5: Optical versus Copper cost Figure 6: Optical GBIC Module and Rail Figure 7: Copper GBIC Module and Rail Short and Long Haul Optical Application For lengths greater than 30 meters, or in instances where EMI is a problem, optical interconnects are used. The connector approved for optical Fibre Channel is the duplex SC. This connector can be used with multimode and single mode optical fiber. When implemented with a short wave transceiver, 50µm or 62.5µm multimode cable is used. These cables can be used in an OFC (Open Fiber Control) or Non-OFC environment. Maximum lengths on short wave lasers with multimode fiber are 500m for 50µm, and 300m for 5

6 62.5µm assemblies. Use of long wave transceivers and single mode cable can increase the maximum length up to 10,000 m. Figure 8: SC Fiber Optic Cable Assembly --> Backplane High Speed Interconnect solutions The Metral connector family is well suited for high density, high speed applications. Metral is a connector system based on a 2mm centerline. The standard product was developed and is being used primarily in Telecommunications equipment but has been approved and is being designed in Datacom equipment today. This connector is modular and stackable and can stack signal, power, coax and fiber optic modules. Metral HS is suited for data rates up to 1.5 Gbps. Metral HS+ and HB (Figure 9) can be utilized for speeds up to and including 5 Gbps. Figure 9: Metral HB Backplane connector Next Generation Gigabit Ethernet The IEEE committee has just started work on the 10 Gigabit Ethernet specification which is expected to be drastically different as far as protocol 6

7 and management layers go but similar in physical layer. No project has been approved for work on a copper I/O interface specification but there are several companies interested in copper connections at 10 Gbps. It is projected that in order to achieve 10 Gbps on copper, 4 ports at 2.5 Gbps would be easiest to implement. The MetaGig connector is able to do this today. One channel at 10 Gbps may be achievable but much more research must be conducted in order to prove this. The optical interconnects have no issue with 10 Gbps. Small form factor optical connectors will be used with Gigabit Ethernet and 10 Gigabit Ethernet. These include the LC, MT-RJ, and SG. These connectors are being deployed for higher density applications such as the small form factor GBIC and small form factor transceivers. These connectors allow a single port to take up less than half the space of a SC port. Products are being introduced using all of these connectors at 2.5 Gbps data rates today and research on 10 Gbps transceivers has started. Figure 9: LC Fiber Optic Cable Assembly Figure 10: MT-RJ Fiber Optic Cable Assembly Summary Gigabit Ethernet is an emerging technology. By 2002, Gigabit Ethernet is expected to out-sell ATM by $600M. Gigabit Ethernet paves the way for highspeed end-to-end connections from the backbone to the server to the desktop for the huge installed base of Ethernet/Fast Ethernet customers. The connectors outlined above will be paramount in implementing Gigabit Ethernet topology. 7