Ethernet: The Definitive Guide by Charles E. Spurgeon Unconfirmed error reports are from readers. They have not yet been approved or disproved by the author or editor and represent solely the opinion of the reader. If you have any error reports or technical questions, you can send them to booktech@oreilly.com. (Please specify the printing date of your copy.) This page was updated April 14, 2008. Here's a key to the markup: [page-number]: serious technical mistake {page-number}: minor technical mistake : important language/formatting problem (page-number): language change or minor formatting problem ?page-number?: reader question or request for clarification UNCONFIRMED errors and comments from readers: [xx] Acknowledgments line 2; "I would like to thank the inventor of Ethernet" is correct. Should _not_ read "inventors" Source: Packet Communication, 1996, Robert M. Metcalfe. 185pp. peer-to-peer.com ISBN 15739-80331 TK5105.3M48 1996 (7) Sidebar, paragraph 1, line 2; change "1998" to "2000" Paragraph 2 should read: "This edition contains 1,515 pages 'incorporating IEEE Std 802.3, 1998 Edition, IEEE Std 802.3ac-1998, IEEE Std 802.3ab-1999, and 802.3ad- 2000.'" [8] Table 1-1; 10BASE2 is listed here as 802.3a-1985 and in 802.3, 2000 Edition, as 802.3a- 1988." Which date is correct? (13) Paragraph 4, lines 3-4; delete "or not" [16] FOIRL, line 4; FOIRL is listed here as being published in 1989 but in 802.3, 2000 Edition, as 802.3d-1987. Which date is correct? (48) item 1, lines 4 and 6; change "each frame" to "successive frames" change "between frame reception" to "between frame receptions" (50) 3rd paragraph, line 1; change "length" to "lengths" (56) 2nd paragraph, lines 1-2; change "the duplex configuration" to "the duplex configurations" (56) 3rd paragraph, lines 2-3; change "detects collision" to "detects a collision" (58) 5th paragraph, line 6; change "value of k (and hence, the range of the number r) exponentially increasing for the..." to "value of k increasing (and hence, the range of the number r exponentially increasing) for the..." {58} last paragraph on page 58; The final paragraph on page 58 states: "If the frame continues to encounter collisions after 16 retries, the interface will give up." In actuality, it is the 16th *attempt* that is the final allowable attempt, which is the 15th *retry*. Stating that 16 retries are allowed is equivalent to stating that 17 total attempts are allowed, which is not the case. (63) Figure 3-3; change "Frame start limit" to "Frame Burst Limit" {83} 2nd full paragraph, line 3; change "which is 46 bytes" to "which contains 46 bytes in the data field" (88) 1st paragraph under "FLP Operation," line 2; change "between each burst" to "between successive bursts" [118] 3rd paragraph; You describe the drawback to Manchester encoding as: "In other words, a 10 Mbps stream of all ones or all zeroes results in a Manchester encoded signaling rate of 20 MHz on the cable." This passage seems to indicate that a stream of all ones or all zeroes results in a 20 MHz signal on the media. If this is the case, I believe this statement is wrong. The stream of all ones or all zeroes would be represented by a 10 MHz square wave signal. A stream of alternating ones and zeroes (good case) would be represented by a 5 MHz square wave signal. This suggest a minimum signal frequency of 5 MHz and a maximum frequency of 10 MHz on the cable using the Manchester encoding scheme. When a Manchester encoding scheme is used, half the bandwidth is wasted because it takes two transitions to represent one bit. This is something you may wish to state in the book. To see this, consider a original clock signal and a data signal representation. If this was your interface, the clock would be a 10 MHz signal and the data signal would never be higher than 5 MHz (alternating ones and zeroes). When this is converted to a Manchester encoding scheme, the Manchester signal line represents the alternating ones and zeroes as a 5 MHz signal, thus no change. However, the stream of all ones or all zeroes results in a 10 MHz signal, a big change. Thus the Manchester encoding scheme caused a data line that never went higher than 5 MHz to be represented by a new signal line that will never go higher than 10 MHz. Thus double frequency representation. If you look at figure 6-8 on page 119, this figure supports my argument. On the 001 pattern, the time between the first zeroes represented by rising edge signals is 100 nsec. This suggest a 100 nsec time period thus 10 MHz. Sorry to be so anile, but I thought this was an important point. (127) 2nd paragraph, line 1; change "The transmit and receive data signals..." to "The transmit or receive data signals..." {138} 1st full paragraph, last line; change "currents" to "potentials" (152) Line 4 of the 3rd paragraph; Under "Fiber Optic Cable" section there is the following sentence: "The wavelength of light used on a 100BASE-TX ...". "100Base-TX should be changed to "100Base-FX" (167) first section heading; Minor formatting: Physical line signaling Is this line supposed to be in the bigger size type? The heading is 12.2.1, but the type size is the one for #.#.#.# (171) Last Paragraph; Text reads "providing a network with a total maximum cable diameter of 200 meters between stations" Diameter should be "Distance" [173] Bottom of page the * foot note; The Cisco catalyst 3500 XL switch appears to make use of a proprietary two port repeater built into a copper GBIC. This allows daisy chaining several switches using 1000-BASE-?? 1/2 duplex mode of operation. The interconnect cable may be proprietary. From the Cisco web site: GigaStack GBIC delivers a low-cost, independent stack bus with a 1 Gbps forwarding bandwidth in a daisy-chain configuration, with up to nine Catalyst 3500 XL or gigabit-enabled Catalyst 2900 series XL switches or a 2 Gbps forwarding rate in a point-to-point configuration (177) 1st line; change "e.g." to "i.e." (182) In Table 13-2, the values should be aligned on the decimal points. {182} In Table 13-2, the Max left end, middle segment, and right end enties for "Excess AUI" should read 4.92, not 4.88. {182} Table 13-2; Excess AUI, according to 802.3 Clause 7.4.3.7, can delay .1028 BT/m. This is 4.93 BT / 48. m; v/c = .6485. (But everything should be rounded to 1 bit time, or at most .1 bit time. AUI is so short, its RT delay/m could be rounded to .1 BT.) [182] Table 13-2; Considering the margin of 0 to 5 bits, round to the nearest bit. Segment Round-Trip Delay Values in Bit Times Left Middle Right RT Max End Segment End Delay/ Segment Length Type (m) Base Max Base Max Base Max meter v/c ____________________________________________________________________ 10BASE-FL 2000 12 212 34 234 157 357 .100 .667 FOIRL 1000 8 108 29 129 152 252 .100 .667 10BASE5 500 12 55 47 90 170 213 .087 .770 10BASE2 185 12 31 47 65 170 188 .103 .650 10BASE-T 100 15 27 42 53 165 176 .114 .585 Excess AUI 48 0 5 0 5 0 5 .103 .650 RT delay/m (100.ns bit times/m) = 2 / [(v/c)*(30.0 m/100.ns)] Include the right-hand column and that last equation to help readers compute their own. Listing longest-to-shortest as above helps keep the numbers in perspective. This table is comprehensible and useful. The original's appearance warns, "Don't go here." [182] Table 13-2; For left and right ends, tabulate only _excess_ delay beyond the minima (7.75 and 152 bit times, respectively). Maximum allowed path excess delay becomes 415 bit times (preferably 410). The comparison of left- to right- direction paths becomes far easier! (Try it.) Round to 0 decimal point; align on decimal. List longest-to-shortest. Say "N/A" for "Excess AUI Base." Segment Excess Delay Values (bit times) RT max. network diameter Segment Left End Mid R. End delay including AUI (m) Type Base Max B. Max B. Max /m v/c (if net all same type) 10BASE-F 5 205 34 234 5 205 .1 .667 4008 FOIRL 0 100 29 129 0 100 .1 .667 3588 10BASE5 4 47 47 90 18 61 .0866 .77 2888 10BASE2 4 23 47 65 18 36 .103 .65 1425 10BASE-T 8 19 42 53 13 24 .114 .585 1200 Excess AUI N/A 5 NA 5 NA 5 .103 .65 N/A This is possible because every multisegment path has at least a left end and a right end, with or without mid segments. It's worth mentioning that _no_ 10Mb/s network shorter than 2700 meters (including AUI) is delay-limited!! So for networks shorter than that, this exercise can be skipped!!! That includes _all_ purely 10BASE-T and 10BASE2 networks. Open the section with that observation. (184) bullet 3; change "0.5 meters" to "0.5 meter" (187) last paragraph, line 4; change "individual segment" to "individual segments" [189] Add the following to the footnote: "IEEE uses _c_ = 3.00 * 10^8 for Ethernet calculations." {196} line 5; change "4.88" to "4.92" {196} paragraph 3; change "9.76" to "9.84" {196} 5th paragraph, last line; Does the fiber base delay value include an assumed 2. meters of AUI cable (hence the 48. rather than 50. meters maximum "excess" AUI)? If so, we have 23. meters excess times 4 cables, for 96 * .1026 = 9.44 bit times. {196} 5th paragraph should read: 100 m * .1026 bit time/m = 10.26 bit times or: 100 m * .1017 bit time/m = 10.17 bit times or: 96 m * .1017 bit time/m = 9.76 bit times {197} table 13-10; 10BASE2 Left End should be 30.73 (using .1026 BT/m) or 30.72 (using 2/.65*30 BT/m). {197} tables 13-10 and 13-11; Excess AUI should be 19.68 bit times, not 19.52. {197} In tables 13-10 and 13-11, the excess AUI length total should reflect the corrections noted above for {182} and {196}. (197) table 13-11; "Quan. Three" should be "Quan. Four" (200) 1st paragraph, lines 5 & 6; change "0.477 bit times" to "0.477 bit time" change "0.954 bit times" to "0.954 bit time" (247) 3rd paragraph; There are a several ways to tell the difference between a normal, straight-through cable, and a crossover cable. "There are several ways" (249) paragraph 1, line 5; change "very" to "ultra" {313} The first two sentences of the last paragraph should be updated to read: "A new 802.3ad link aggregation standard has been developed... This standard was formally adopted in 2000." (339) 4th paragraph, line 2; change "and by 100 for Gigabit Ethernet" to "and by 100 for (full-duplex) Gigabit Ethernet" (380-381) The IEEE standard for Ethernet is quoted as: 802.3, 1998 Edition Information technology--Telecommunications and information exchange between systems--Local and metropolitan area networks--Specific requirements--Part 3: Carrier sense multiple access with collision detection (CSMA/CD) access method and physical layer specifications. This edition includes all contents of the 8802-3:1996 Edition, plus IEEE Std 802.3aa-1998, IEEE Std 802.3r-1996, IEEE Std 802.3u-1995, IEEE Std 802.3x&y-1997, and IEEE802.3z-1998. Price U.S. $387.00 ISBN 0-7381-0330-6 Product Code: SH94652-NYF Should read: 802.3, 2000 Edition IEEE Standard for Carrier Sense Multiple Access with Collision Detection (CSMA/CD) Access Method and Physical Layer Specifications. This edition also includes all contents of IEEE Std 802.3ab-1999, IEEE Std 802.3ac-1998 and IEEE Std 802.3ad-2000. Print: 1562 pages [0-7381-2673-X] [SH94892-NYF] $295.00 * IEEE Mbr: $236.00 PDF: [0-7381-2674-8] [SS94892-NYF] $443.00 * IEEE Mbr: $354.00 (445) Sixth paragraph; BNC stands for Bayonet-Neill-Concelman, the last names of the people who designed the crafty little thing. I have found this explanation in the newsgroup comp.dcomp.cabling under subject "Re: What does SMA and ST stand for?" sent by Philip Kim, pkim@cts.com. (445) Sixth paragraph; Change "names of two designers of coaxial connectors" to "names of two designers of coaxial connectors, Paul Neill and Carl Concelman."