Talk:Synchronous optical networking
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The first paragraph refers to the ITU, but the link leads only to a disambiguation page. It should probably be spelled out (I assume the correct meaning is International Telecommunication Union).
The statement "For example, four OC-3 or STM-1 circuits can be agregated to form a 622 Mbit/s circuit designated as OC-12 or STM-4." is a bit misleading. Actually an OC-12 is not an encapsulation of 4 OC-3s as is implied. An OC-12 contains 12 STS-1s (OC-1 at optical level) and as such can carry 4 OC-3s, however each STS-1 is carried without any type of "wrapper" within the OC-12. I'm probably being overly picky but hey, you might as well make it as clear as possible.
P.S. aGGregated has 2 "g"s ;-)
"The current state of the art is the OC-192 or STM-64 circuit, which operates at rate of just under 10 Gbit/s." The current state of the art is actually OC-768.
"It is defined by GR-253-CORE from Telcordia." Isn´t it defined by ITU-T´s G707?
- The "agregated" is still there... why didn't you fix it? Fixed. Mga 03:05, 29 May 2005 (UTC)
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[edit] 10 Gigabit Ethernet and OC-192/STM-64
This article used to say they were compatible, but now it doesn't. Could somebody knowledgeable elaborate? - mako 06:29, 26 Apr 2005 (UTC)
The signals are not directly compatible, however many manufacturers produce cards that allow 10GigE signals to be carried over SDH/SONET or STM-64 DWDM signals (also variants that carry 1 or 2x 1GigE signals over STM-16). For example, Marconi MSH2K Optical Core Switch (link to commercial site) - gjk 10:55, 13 July 2005 (UTC)
- Actually, 10GbE has two different types of PHYs. One is the LAN-PHY which looks a lot like the lower speed Ethernet PHYs. The other is the WAN-PHY which was specifically intended for interworking with the SDH/SONET network: it has the same frame format as an STM-64 with VC-4-64c (OC-192 with STS-192c SPE) - bit rate is a bit lower than the LAN-PHY. A WAN-PHY which additionally observes the SDH/SONET clock specifications fits seamlessly into the SDH/SONET network. BertK 22:21, 15 July 2005 (UTC)
- Also note that a single NE's compatibility with 10GbE doesn't mean that intermediate NEs will be able to support it. 10GbE is very close in flavor to STS-192c, which most NEs don't support. Also, 10GbE doesn't really make use of a lot of the SONET overhead and features: These are basically turned off which could drive an actual SONET Network crazy.
Aside from that, many new SONET NEs support it, though frankly when you're concatenating at that level you'll probably have optical networking equipment (as opposed to SONET) do things like protection.
[edit] NE?
Suddenly in the text is the abbreviation "NE". What's that?
- Network Element BertK 18:04, 23 January 2006 (UTC)
[edit] Equipment vendor listing?
An anonymous user that has a decent editing history originally added three links to different Nortel systems that do SONET. I removed those. A different link has now been added back, again by the anonymous user, to a top level for all SONET systems at Nortel. Do we want a list of vendors on the article at all? If so, it will slowly go out-of-date as vendors merge, change names, go out of business, or new ones are created. Having the list also invites more churn on the article. Not only that, but it isn't a short list (Here is an incomplete list):
Alcatel,
Anda Networks,
Appian Communications,
Cisco Systems,
Coriolis Networks,
ECI Telecom Communications,
Fujitsu Network Communications,
Internet Photonics,
Lucent Technologies,
Mahi Networks,
Marconi,
Nortel Networks,
Photonic Bridges,
RAD Data Communications,
Sycamore Networks,
Siemens ICN,
Tejas Networks,
Tellabs,
Turin Networks,
White Rock Networks
Or we could add several links to the ODP (dmoz.org), who actually attempts to be a directory. Mrand 00:40, 24 February 2006 (UTC)
gea-141020: Agreed, the list of SONET equipment vendors doesn't belong in this article. Eventually, however, it might be useful to have an article that shows North American SONET equipment deployment by network and Vendor, although there's a lot of other SONET-related articles that should be written first. In that context, of course, Nortel will seem pretty important, along with Lucent, Alcatel, Fujistu and, possibly, Cisco. Maybe DSC, too. Those vendors probably outweigh the little guys by 1000s to one, so there is merit in mentioning names within the right context.
[edit] SDH != SONET
If someone wants to specifically know about SDH, I think this is the wrong article. There are differences (not only in labels), and there is certainly more (channels, how they are multiplexed, headers, units, pointers etc.).
Therefore I propose that a new article, solely about SDH, is forked from this one.
- I disagree that a forked article is needed. Here's my opinion: SDH is so close to SONET that a forked article would result in massive amounts of duplicated information. Units (are you referring to Mbps?), and pointers are all the same. Headers (you referring to overhead?) are almost identical. Multiplex schemes are somewhat different, but have massive overlap. I'm not sure what you are referring to by channels, but if it's the naming difference (which I actually assume is what you meant by "labels"), then yes, they are named different. But a (single) well written article would be able to handle the multiple names. At most, I think a second article would only need to explain SDH naming and multiplexing, while referring back to the main SONET/SDH article for everything else. Regards, Mrand 05:50, 29 March 2006 (UTC)
MW: I just came to this page for the first time. It was immediately apparent that the article contains information on two different things. SDH and SONET are two different standards. Because they are two completely different standards, there should be two completely different articles. If one wishes to summarize Synchronous networks in one page, that would be fine, and that article could link to SONET and SDH. But similarity is not enough reason for one article. There are two seperate articles for IPv4 and IPv6. And those are just varients of one standard. There are probably 1000s of examples of why there should be 2 articles on these 2 different standards. MatthewWilder 20:13, 25 May 2006 (UTC)
agree with u on that one MW: I thought of another example. This article is akin to having an article on Sonny and Cher but naming it "Sonny". And an article on Sonny and Cher is reasonable, since they were compatible (at least at times). Anyway, the names are so close that I couldn't resist this comparison. MatthewWilder 20:21, 25 May 2006 (UTC)
CT: I agree that an explanation of SONET and SDH can co-exist on the same page, but the differences should be clear. The payload data rate gets tricky when you start dealing with virtual concatenation (VCAT) and virtual containers and tributaries, e.g. STS-3c/VC-4 SPE is 149.76Mbit/s whereas STS-3 SPE is 150.336Mbit/s. For more information, see http://www.zytrax.com/tech/data_rates.htm or RFC 3255 at http://www.ietf.org/rfc/rfc3255.txt. ChrisTracy 01:30, 16 June 2006 (UTC)
GB: Sonet and SDH are two seperate, distinct entities. They have different overheads, support different line rates as basic units (VC4 vs. STS.) Frankly, the VC3 had to be invented to create a comparison for the two standards. SDH has LO and HO overheads, where as Sonet has a single overhead. Yes, they both use the same methods for OAMP and mostly the same bytes, but SDH has two levels, and they support different timing sources (same idea coming origianlly from a Sonet clock, but different formats.) Having these in the same article should change the title to Optical Network Protocols or something along those lines. GregBouchillon 09:51, 20 September 2006 (UTC)
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- Actually, SONET and SDH are intimately related standards: they were developped jointly and published within months of each other. In fact SONET is a so-called 'regional subset' of the international SDH standard, so everything in SONET is also in ITU-T SDH (be it with a different name) - so the above claims must be the result of some confusion. (Also note that currently maintenance of SONET standards is done by changing the SDH standards and then refering to those.) Other regions like Europe or Japan also specify their own subset, but keep calling this subset SDH (like all PDH is called PDH, no matter if its DS1, E1 or J1 based). This seems to be causing confusion, most often between the European (ETSI) SDH and the international (ITU-T) SDH.BertK 20:46, 4 October 2006 (UTC)
- I proposed a split. My guess is that someone smarter than me can make the differences clearer. User:Luis F. Gonzalez
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- There are no differences per se: there is an international superset specified by ITU-T (formerly CCITT) called SDH and a number of regional subset specified by regional standards bodies like ATIS OPTXS (formerly ANSI T1X1), ETSI, TTC,... For historical reasons, the North American regional subset happens to be called SONET and uses different terminology, but it's still the same [1].
- That doesn't mean a split article is not a good idea: I'd like to see a main article on international SDH, including the joint history, and multiple articles on the regional subsets (ETSI SDH, SONET, others?). The SONET article would be special in that it would have pre-standardization history [2] and a terminology cross-reference.BertK 20:46, 4 October 2006 (UTC)
SDH and Sonet Difference
SDH is used in European Contries Sonet is used in American Conuntries
To be more precise: SDH is deployed all over the world, except for North America where SONET is deployed. Huub v H 20:08, 12 March 2007 (UTC)
And both of them have a significant amount of diffrence in Data rates.
Also the processing of the overhead information is different between SDH and SONET (see http://www.van-helvoort.eu/ and selct standards work) Huub v H 20:08, 12 March 2007 (UTC)
You definitely have two (or three) separate animals here, although they basically started with the same parent. SONET as a North American standard follows ANSI T1.105-2001. SDH is the European standard and falls under the ITU-T G.707 & G.708 standards. Additionally we can further extend the article if we discuss Optical Transport Networks (OTN) and the ITU-T G.709/Y.1993 (and replace the 10 Gbps discussion). A comparison is required between the three to show their similarities and highlight their differences. As a start, why don't we concentrate on making three separate sections (one each on SONET, SDH, and OTN)? JEdwards47 19:48, 3 October 2006 (UTC)
- SONET and SDH are basically the same or at least closely related animals. OTN is a completely separate standard: SDH/SONET signals are clients to OTN signals, like PDH signals were clients to SDH/SONET networks.BertK 20:46, 4 October 2006 (UTC)
gea-141020: I wrote most of this article and worked at Bellcore/Telcordia in the group responsible for GR-253 (I also co-wrote a book on SONET with the inventor of SONET). In my opinion, one could modify this article to better include the differences between SDH and SONET, which are minimal at the OC-N and STS-N levels. Where you DO need an additional article(s), however, is in handling the subrate packaging of PDH signals. In other words, everything that happens below the OC-3 level, including how you build up from the E1 level to an OC-3. For that matter, another article is probably needed describing the same process for North America. But once you getup to the true SDH/SONET transport containers at the line and section llayer (which have different names in SDH, sorry) then t's all basically the same and can be handled by one article.
A separate article for SDH wouldn't be the end of the world, however.
[edit] Putting "optical" on SDH is a misnomer
For crying out loud, the SDH hierarchy was defined for use over *copper* wire, not optical!
When SDH was defined, real use of optical fiber for communication was still the lab rats' wet dream, and Real Men used coax and microwave relays. Article needs splitting, badly. --Alvestrand 19:19, 4 February 2007 (UTC)
When SDH was developped E4 (140 Mbit/s) was already deployed over (optical) fiber, and SDH was based on this experience. SDH has only one line signal defined for electrical transport: The STM-1 signal ES1, its companion optical is STM-1 OS1 and up STM-4, STM-16, STM-64 STM-256. The Electrical interface is used intraoffice and the optiacl interfaces are deployed interoffice. Huub v H 20:17, 12 March 2007 (UTC)
