1、 AMERICAN NATIONAL STANDARD FOR TELECOMMUNICATIONS ATIS-0900002.2009(R2014) Synchronization Standard Physical Interconnection for Ethernet-Based Timing Distribution As a leading technology and solutions development organization, ATIS brings together the top global ICT companies to advance the indust
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11、Disclaimer Cyclic Redundancy Checksum DSI Digital Signal Level 1 (1544 kbit/s) EFM Ethernet in First Mile ELFEXT Equal-Level FEXT FEXT Far-End Crosstalk FOCIS Fiber Optic Connector Intermateability Standards GMII Gigabit Media Independent Interface IEC International Electrotechnical Commission IEEE
12、Institute of Electrical and Electronics Engineers IETF Internet Engineering Task Force ISO International Organization of Standards ITU-T International Telecommunication Union Telecommunications Standardization Sector MAC Media Access Controller MAU Medium Attachment Unit MDI Medium-Dependent Interfa
13、ce MDI-X Medium-Dependent Interface Crossover MII Media Independent Interface MMF Multi-Mode Fiber NE Network Element MEXT Near-End Crosstalk NTP Network Time Protocol PCS Physical Coding Sublayer PDU Protocol Data Unit 6This document is available from the Alliance for Telecommunications Industry So
14、lutions (ATIS), 1200 G Street N.W., Suite 500, Washington, DC 20005. 7This document is available from the Internet Engineering Task Force (IETF). ATIS-0900002.2009 4 PHY Physical Layer PLS Physical Layer Signaling PMA Physical Medium Attachment PMD Physical Layer Medium Dependent PSELFEXT Power-Sum
15、ELFEXT PTP Precision Time Protocol RFC Request For Comments (IETF standards document) RX Receive SFF Small Form Factor SFP Small Form-Factor Pluggable SMF Single-Mode Fiber STP Shielded Twisted Pair TIA Telecommunications Industry Association TSG Timing Signal Generator TX Transmit UTP Unshielded Tw
16、isted Pair WDM Wavelength Division Multiplexing 3.2 Definitions 3.2.1 Fast Ethernet: Fast Ethernet is a generic term for Ethernet standards that carry traffic at a nominal rate of 100 Mbit/s. The transmission uses a synchronous line coding format (“continuous carrier”) and there can be an auto-negot
17、iation process at start-up to determine the “master” and “slave”. In the current application involving timing distribution, the TSG end is always the “master”. 3.2.2 100Base-TX: 100BASE-TX (T=“Twisted“ Pair Copper) is the predominant form of Fast Ethernet, and runs over two pairs of Category 5 (“Cat
18、5”) or higher cable. A typical Category 5 cable contains 4 pairs and can therefore support up to two 100BASE-TX links. Each cable link can have a maximum distance of 100 m (330 ft). Typically, 100BASE-TX uses one pair of twisted wires in each direction, providing 100 Mbit/s of throughput in each dir
19、ection (full-duplex). The information provided at the MII is 4-bits wide clocked at 25 MHz. 4B5B coding is used to provide dc equalization and spectral shaping, and in the process generate a 125Mbit/s line bit- rate. The principal standard is IEEE 802.3 6 (see Clause 24 and Clause 25). 3.2.3 100Base
20、-T4: 100Base-T4 was an early implementation of Fast Ethernet requiring four twisted copper pairs of Category 3 (“Cat3”) or higher cable. Of these, one pair is designated for transmit, one for receive, and the other 2 could be either transmit or receive as negotiated by the end units. The line coding
21、 follows an 8B6T format and the signal on the cable is tri-level. The principal standard is IEEE 802.3 (see Clause 23). 3.2.4 100Base-T2: 100Base-T2 utilizes two copper pairs. The data is encoded in 4-bit blocks resulting in two 3-bit blocks (4B6B), and each 3-bit block is modulated onto the line us
22、ing a 5-level scheme (3 of the 8 possible levels are disallowed). It is addressed in IEEE Standard 802.3 (see Clause 32). 3.2.5 100Base-FX: (F = ”Fiber” optical cable) is a version of Fast Ethernet over optical fiber using the same 4B5B encoding as 100Base-TX. It uses a 1300 nm wavelength and uses t
23、wo strands of optical fiber, one for receive (RX) and the other for transmit (TX). For half-duplex connections, the maximum cable length is 400 m (1,310 ft); for full-duplex connections, the maximum length is 2 km (6,600 ft) over ATIS-0900002.2009 5 multimode fiber. Longer distances are possible whe
24、n using single-mode fiber. It uses a different wavelength than 10Base-FL (10 Mbit/s Ethernet) and is not backwards-compatible. The principal standard is IEEE 802.3 (see Clause 24 and Clause 26). 3.2.6 100Base-SX: 100BASE-SX is a version of Fast Ethernet that uses two strands of multi-mode optical fi
25、ber (one receive and one transmit). The wavelength used is 850nm, allowing it to be backward-compatible with 10Base-FL (10 Mbit/s Ethernet). 100BASE-SX can operate at distances up to 300 m (980 ft). The shorter wavelength (850 nm) and the shorter distance permit the use of less expensive electro-opt
26、ical components. 3.2.7 100Base-LX: 1000BASE-LX (L = ”Long wavelength”) refers to a standard for gigabit Ethernet using a long wavelength - between 1270 and 1355 nm (typically 1300 or 1310 nm) - laser and can operate over a distance of up to 5 km over single-mode fiber. It can also operate over multi
27、-mode fiber with a maximum segment length of 550m. This is covered in IEEE 802.3, Clause 38. 3.2.8 100Base-BX10: 1000-BASE-BX10 (B = “Bidirectional”) achieves full-duplex transmission over a single strand of single-mode fiber using wave division multiplexing (WDM), using 1490 nm for one direction an
28、d 1310 nm for the other. This is covered in IEEE 802.3, Clause 59 and Clause 66. The BX versions were developed for Ethernet in the First Mile (EFM). 3.2.9 100Base-T: 1000BASE-T (also known as IEEE 802.3ab) refers to gigabit Ethernet over copper cable of Category 5 (the same as 100BASE-TX) but Categ
29、ory 5e (“Category 5 enhanced“) and Category 6 (Cat6) cable may also be used and are often recommended. 1000BASE-T requires all four pairs to be present. This is covered in IEEE 802.3, Clause 40. 3.2.10 100Base-TX: 1000Base-TX is a standard released by the Telecommunications Industry Association (TIA
30、) (TIA/EIA-854) that uses only two pairs in each direction but requires Category 6 cable. Note that 1000BASE-T and 1000BASE-TX are actually different standards. 4 FAST ETHERNET SIGNALS 4.1 Electrical Signal 100Base-TX 100BASE-TX (T=“Twisted“ Pair Copper) runs over two pairs of Category 5 (“Cat5”) or
31、 higher cable. Each cable link can have a maximum distance of 100 m (330 ft). 100BASE-TX uses one pair of twisted wires in each direction, providing 100 Mbit/s of throughput in each direction (full-duplex). The information provided at the MII is 4-bits wide clocked at 25 MHz. 4B5B coding is used to
32、provide dc equalization and spectral shaping, resulting in a line bit-rate of 125Mbit/s. The principal standard is IEEE 802.3 (see Clause 24 and Clause 25) (see 6 or 10). 4.2 Optical Signal 100Base-FX 100BASE-FX (F = “Fiber” optical cable) delivers a 100 Mbit/s information rate over two strands of o
33、ptical fiber, one for receive (RX) and the other for transmit (TX), using a wavelength of1300 nm. 4B5B coding is used to provide dc equalization and spectral shaping resulting in a line bit-rate of 125Mbit/s. For full-duplex connections, the maximum length is 2 km (6,600 ft) over multimode fiber. Lo
34、nger distances are possible when using single-mode fiber. The principal standard is IEEE 802.3 (see Clause 24 and Clause 26) (see 6 or 10). ATIS-0900002.2009 6 4.3 Optical Signal 100Base-SX 100BASE-SX is a version of Fast Ethernet that uses two strands of multi-mode optical fiber (one receive and on
35、e transmit) for distances of up to 300m (980 ft) using a wavelength of 850nm. 4.4 Optical Signal 100Base-BX 100BASE-BX (B = “Bi-directional”) is a version of Fast Ethernet over a single strand of optical fiber utilizing wavelength division multiplexing (WDM) to separate the transmit and receive dire
36、ctions. There are two versions: 100Base-BX10-D and 100Base-BX10-U that are described in IEEE 802.3, Clause 58 and Clause 66 (see 6 or 10). 5 GIGABIT ETHERNET SIGNALS 5.1 Electrical Signal 1000Base-T 1000BASE-T (T = “Twisted” pair copper) provides an information rate of 1000 Mbit/s over 4 pairs of un
37、shielded twisted pair (UTP) Category 5 or higher cabling; Category 5e (“Category 5 enhanced“) or Category 6 (Cat6) cable are recommended. Each pair is used for both directions and echo-cancellation employed to achieve 4-wire behavior. The transmission uses a synchronous line coding format (“continuo
38、us carrier”) and there can be an auto-negotiation process at start-up to determine the “master” and “slave”. In the current application involving timing distribution between a TSG and a network element, the TSG end shall be provisioned as the “master”. The principal defining standard is IEEE 802.3,
39、Clause 40 (see 6 or 10). 5.2 Optical Signal 1000Base-SX 1000BASE-SX (S = “Short wavelength”; X = “fiber”) provides an information rate of 1000 Mbit/s over two strands (one for TX, one for RX) of multi-mode optical fiber of length up to 220m using a wavelength of 850 nm. This is covered in IEEE 802.3
40、, Clause 38 (see 6 or 10). 5.3 Optical Signal 1000Base-LX 1000BASE-LX (L = “Long wavelength”, X = “fiber”) provides an information rate of 1000 Mbit/s over two strands of fiber (one for TX, one for RX) using a long wavelength - between 1270 and 1355 nm (typically 1300 or 1310 nm) - laser over a dist
41、ance of up to 5 km of single-mode fiber or 550m of multi-mode fiber. This is covered in IEEE 802.3, Clause 38 (see 6 or 10). 5.4 Optical Signal 1000Base-BX10 1000-BASE-BX10 (B = “Bidirectional”; X = “fiber”) provides an information rate of 1000 Mbit/s over a single strand of single-mode fiber using
42、wavelength division multiplexing (WDM), using 1490 nm for one direction and 1310 nm for the other. This is covered in IEEE 802.3, Clause 59 and Clause 66 (see 6 or 10). ATIS-0900002.2009 7 6 CABLING 6.1 Electrical (Copper) Cabling 6.1.1 Fast Ethernet (100Base-TX) There are two principal choices for
43、cable types to support 100Base-TX: 1) unshielded twisted pair (UTP); and 2) shielded twisted pair (STP). The cable requirements to support 100Base-TX are provided in IEEE 802.3, Clause 24 (see IEEE Std. 810-2001) and reference ISO/IEC 11801 (see 8) and TIA/EIA-568-B:1995 (see 1). The cable must be c
44、omprised of: a. Two pairs of Category 5 or higher (e.g., 5E or 6) unshielded twisted pair (UTP) balanced 100-ohm cable meeting the requirements of ISO/IEC 11801 Class D (defined up to 100 MHz); or b. Two pairs of 150-ohm balanced shielded twisted pair (STP) cable. The shield is connected at the TSG
45、and left unconnected at the NE. Alternative cabling systems may be employed provided they meet the performance of Category 5 UTP; the requirements thereof are provided in IEEE 802.3 Clause 25 (see 6) (see also IEEE Std. 802-2001, 5) and summarized in Annex C. The cable between the TSG and NE/hub/swi
46、tch must connect pins 1 and 2 (transmit) on the TSG jack (see 7.1.1.1) to pins representing receive on the NE/hub/switch, and pins 3 and 6 (receive) on the TSG jack must connect to pins representing transmit on the NE/hub/switch. The maximum length of the cable between TSG and NE shall be less than
47、100m. UTP cables have no shield conductor. If functionally equivalent shielded cable is used, then the shield can be left floating or it can be grounded at one end. Grounding at the TSG end is recommended. NOTE: Connectorized cables that connect pins 1 and 2 at one end to pins 1 and 2 at the other (
48、and pins 3 and 6 to pins 3 and 6) are called straight-through. Cables that connect pins 1 and 2 at one end to pins 3 and 6 at the other (and pins 3 and 6 to pins 1 and 2) are called crossover. In most cases, if the link between the TSG and the NE is through a hub or switch, then the connecting cable
49、s/jumpers (between the TSG and hub/switch and NE and hub/switch) need to be straight-through; if the link between the TSG and the NE is direct or through a router, then the cables/jumpers need to be of the crossover type. 6.1.2 Gigabit Ethernet (1000Base-T) The most common choice of cable type to support 1000Base-T is Category 5 (“Cat5”) UTP cable. The cable must be comprised of four-pair Category 5 or higher (e.g., 5E or 6) unshielded twisted pair (UTP) balanced 100-ohm cable as per ANSI/EIA/TIA-568-B:1995 and meet
