Gigabit Ethernet


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Gigabit Ethernet

  1. 1. Gigabit Ethernet Manasa.K CWB0912002, FT-2012 M. Sc. (Engg.) in Electronic System Design Engineering Module leader: Narasimha Murthy K.R M.S.Ramaiah School of Advanced Studies 1
  2. 2. Overview • Introduction • Gigabit Ethernet Layers • Media Access Control (MAC) • Gigabit Media-Independent Interface (GMII) • Auto Negotiation and Physical Media • Advantages • Disadvantages • Conclusion M.S.Ramaiah School of Advanced Studies 2
  3. 3. Introduction • Ethernet is a physical and data link layer technology for LAN. Higher level network protocols like IP/TCP use Ethernet as their transmission medium. • It was developed by Robert Metcalfe in 1980’s. • The first generation Ethernet supported a maximum data rate of 10 Mbps. Later, the second generation Fast Ethernet standards increased this maximum data rate to 100 Mbps. • Now the latest third generation, Gigabit Ethernet provides a data rate of 1000 Mbps and was developed in June 1998 • It is compatible with the existing Ethernets, as it uses the same CSMA/CD and MAC protocols. M.S.Ramaiah School of Advanced Studies 3
  4. 4. Gigabit Ethernet Layers •Gigabit Ethernet (IEEE802.3z) addresses the two lowest layers of the model: •Layer 2, the Data-link layer, which describes how data are organized into frames and sent over the network, and •Layer 1, the Physical layer, which describes the network medium and signalling specifications. M.S.Ramaiah School of Advanced Studies 4
  5. 5. Medium Access Control (MAC) • The MAC layer of Gigabit Ethernet uses same CSMA/CD protocol as Ethernet. • Gigabit Ethernet maintains maximum and minimum frame size of Ethernet, as it is 10 times faster than the Fast Ethernet, to maintain the slot size, the cable length should be reduced to 10meters, which is not useful. • Instead Gigabit Ethernet uses a bigger slot size of 512bytes. *To maintain compatibility with Ethernet, the minimum frame size is not increased instead the carrier event is extended. *If the frame is shorter than 512 bytes, then it is padded with extension symbols. Carrier Extension: M.S.Ramaiah School of Advanced Studies 5
  6. 6. MAC • Carrier extension helps in detecting the collision. It appends a set of special symbols to the end of short MAC frames so that the resulting block is at least 512bytes. • The extension symbols are removed before the FCS is checked by the receiver. So the next layer is not even aware of the carrier extension. Frame bursting: • If the source host has many small frames to send, it can send them in a burst after a MAC arbitration. • Except for the first frame, other frames sent in a burst need not be carrierextended. • If the first frame is larger than 512 bytes, it need not be carrier-extended. • The burst can be as long as 8192 bytes. M.S.Ramaiah School of Advanced Studies 6
  7. 7. Gigabit Media-Independent Interface • The GMII is the interface between the MAC layer and the Physical layer. It allows any physical layer to be used with the MAC layer. • It is an extension of the MII ( Media Independent Interface ) used in Fast Ethernet. It uses the same management interface as MII. It supports 10, 100 and 1000 Mbps data rates. • It provides separate 8-bit wide receive and transmit data paths, so it can support both fullduplex as well as half-duplex operation. • The GMII provides 2 media status signals : one indicates presence of the carrier, and the other indicates absence of collision. The Reconciliation Sublayer (RS) maps these signals to Physical Signalling which is understood by the existing MAC sublayer. • With the GMII, it is possible to connect various media types such as shielded and unshielded twisted pair, and single-mode and multi mode optical fibre, while using the same MAC controller. M.S.Ramaiah School of Advanced Studies 7
  8. 8. GMII The GMII is divided into three sub layers : PCS, PMA and PMD. PCS (Physical Coding Sub layer) • It provides a uniform interface to the Reconciliation layer for all physical media. Carrier Sense and Collision Detect indications are generated by this sub layer. It also manages the auto-negotiation process by which the NIC (Network Interface) communicates with the network to determine the network speed (10,100 or 1000 Mbps) and mode of operation (halfduplex or full-duplex). PMA (Physical Medium Attachment) • This layer serializes code groups for transmission and de-serializes bits received from the medium into code groups. PMD (Physical Medium Dependent) • This sub layer maps the physical medium to the PCS. This layer defines the physical layer signalling used for various media. The MDI ( Medium Dependent Interface), which is a part of PMD is the actual physical layer interface. This layer defines the actual physical attachment, such as connectors, for different media types. M.S.Ramaiah School of Advanced Studies 8
  9. 9. Auto Negotiation and Physical Media • Auto Negotiation was defined in Fast Ethernet to automatically select operational speeds between 10 and 100 Mbps. It was adapted to Gigabit Ethernet primarily to select between duplex mode and the use of link-level flow control. • On a 1000Base-X link, the configuration information exchanged through Auto Negotiation is encoded into a special sequence of 8B/10B codes that transfers 16 bits of configuration information at a time. • On a typical 1000Base-X link, the Auto Negotiation exchange will be completed roughly 40 milliseconds after the cables are plugged in or the equipment is turned on. Physical Media: Unshielded Twisted Pair (UTP-5): 4-pairs Shielded Twisted Pair (STP) Multimode Fiber: 50 mm and 62.5 mm Single-Mode Fiber M.S.Ramaiah School of Advanced Studies 9
  10. 10. Advantages • Increased bandwidth for higher performance. • Full-duplex capacity, allowing data to be transmitted and received at the time so that the effective bandwidth is virtually doubled. • Provides full compatibility with the large installed base of Ethernets and Fast Ethernet nodes. • Low cost of acquisition and ownership. • Transfer large amount of data across the network quickly. M.S.Ramaiah School of Advanced Studies 10
  11. 11. Disadvantages • Not originally designed to support real-time voice and video traffic. works best when working solely with network traffic comprised solely of data. • Cannot prioritize traffic to deliver effective Class of Service (CoS). • Gigabit Ethernet is still not in use. M.S.Ramaiah School of Advanced Studies 11
  12. 12. Summary • Gigabit Ethernet supports data rate of 1000Mbps. • CSMA/CD protocol are same as that of Ethernet and Fast Ethernet. It helps in reducing the collision. • Carrier extension is extended with special symbols so that the block is 512 bytes. Frame bursting is used to achieve higher throughput. • GMII is an interface between MAC and Physical layer, supports half and full duplex modes of operation and also connects various media. • Auto negotiation selects the duplex modes, transfers 16 bit of information data at a time. • Gigabit Ethernet uses higher bandwidth and provides higher performance. • It is still not in use. And it only works with network traffics. M.S.Ramaiah School of Advanced Studies 12
  13. 13. References • Howard Frazier Gigabit Ethernet: From 100 to1,000 Mb Cisco Systems Inc (25th May 2013) • T. C. Tan (August 2000) Gigabit Ethernet and structured cabling Electronics & Communication Engineering Journal (25th May 2013) • Vinay Moorthy Gigabit Ethernet Version 2 CSE IIT Kharagpur ( 26th May 2013) • Gigabit Ethernet available from< archive_article09186a00800c85a6.html >The Internet Protocol Journal - Volume 2, No. 3 (26th May 2013) • Ethernet Introduction to Gigabit Ethernet available from < > ( 26th May 2013) M.S.Ramaiah School of Advanced Studies 13
  14. 14. Thank You M.S.Ramaiah School of Advanced Studies 14