10 Gbit / s Ethernet promises to reduce data transmission costs, leading to an explosion of new network services. But do we need so much bandwidth, albeit at a very affordable price?
Over the years, people have cited the user's inexhaustible data transfer as a major motivator for our ever-expanding networks. Each time the Ethernet speed has been increased by a factor of ten (10 times), the user quickly consumes the same amount of bandwidth.
With 1Gbit / s Ethernet (NIC) network interface cards becoming the norm on desktops and workstations, chip vendors will once again be ready to take Ethernet speeds to a new level. , achieving speeds of 10 Gbit / s.
Several new standards are being developed that promise to make Ethernet 10 Gbit / s (10 GE) a major trend. Although Ethernet does not provide first-class functionality that high-speed transactions often require, it is hoped that Ethernet will promote economies of scale that are always consistent with Ethernet because of its widespread use. In many applications, it makes 10 GE more cost effective than other connections such as Fiber Channel. Another cost saving reason is that using Ethernet will reduce the costs of designing, installing, and maintaining the same network management technology.
In February, the Institute of Electrical and Electronics Engineers (IEEE) added the 10 GE 802.3ae fiber optic interface standard to the IEEE 802.3ak or 10Gbase-CX4 standard, for copper cabling. 802.3ae fiber-optic cable tends to be more expensive because it requires single-mode fiber cables, dedicated connectors and manual laser alignment during installation. The organization has just started its 802.3aq study for a multimode version of the 10 GE fiber optic cable designed to operate at distances of more than 200 meters. This standard will be able to utilize fiber cables in data centers, avoiding the need to install single-mode fiber cables.
Copper wires are a cheaper means of transmission and therefore prefer fiber. However, the 10GBase-CX4 standard works at distances of 10 to 20 meters, depending on who you are talking to and this limits the number of applications that can take advantage of it. The 10Gbase-T standard specifies how 10 GE works on copper cables. Two potential versions of 10GBase-T are aimed at 100 meters on a Cat 7 cable and 50 meters on a Cat 6 cable. There are disagreements surrounding whether a Cat 5 cable can operate reliably, Up to 10 Gbit / s across useful distances. For companies that use Cat 5 instead of Cat 6 or 7, 10 GE may not even be an option. Since IEEE plans to complete this standard in 2006, we will have to wait and see.
The technology behind 10 GE is at the heart of core network applications, forming the backbone of networks. In order to achieve high throughput that is expected to reduce the cost of 10 GE, many vendors anticipate deploying 10 GE in enterprise networks when 1 GE is deployed on desktops, in user networks when fiber is out of control and in data centers and storage networks when data usage continues unchecked.
Lessons from history
10 GE promises to change the look of the network so fast that it can be compared to the way CDs change the way you listen to music. However, this time there is another. Previously, there was always a different data format, larger than the commonly used data formats. This data format has caused the amount of available bandwidth to become overloaded. To better understand this, consider the cardinality of the data. "Cardinality" is the number of elements in a given mathematical set (the force of a set). When the modem is running at 300 baud, you will not be able to send large data sets, such as photographs, because voice and text data already occupy all of the available bandwidth. As the connection speed increases, the cardinality of the data that the user can send also increases. PowerPoint presentations and images become the kind of data that you can stream over the network, but streaming-audio becomes the data set that blocks the network. With DSL, audio becomes the kind of data that you can download completely. Downloading video files is possible at 1 Mbit / s, although downloading is more time consuming than viewing or using it directly, and this download is even easier to do at 100 Mbit / s.
With 1 GE, high quality video files become easy to download. Let's take a look at the FTTH case (fiber connected to the home). Passave, a PON chip manufacturer, has announced that it has sold 500,000 FTTH ports based on the IEEE 802.3ah EPON (Ethernet-PON) standard. 1 GE connections are currently being deployed in Japan to each household at less than double the cost of DSL. That bandwidth is more than 1000 times the bandwidth available to most users at less than twice the cost they are spending. The OTL (optical line termination device) separates connections to use passive splitters. Today, each OTL serves 16 households, but Passave says that their separators can handle up to 128 splits if you reinforce them with FEC. PON is the equivalent of a DSLAM in a telephone exchange that can transfer data to up to 5,000 households.
Video is currently representing the highest cardinality data, meaning that there is the greatest demand for bandwidth among the types of data that home users process. The demand for bandwidth for a movie is many times greater than the demand for bandwidth for audio data. Assuming that a DVD movie represents a specific example of a video, each film is equivalent to 4.7 GB or 37.6 Gbit data. If a 1 GE connection works at 10% efficiency, a user can download a 2 hour movie in 376 seconds - a little longer than 6 minutes or about 5% of the time to view the content. Broadcasters also consume the same amount of bandwidth regardless of how many network nodes are involved. Add a 200GB hard drive at home and in about 4 and a half hours, these users can store more than 40 movies with content longer than 80 hours to watch whenever they want.
As the download time decreases, the amount of data that the user uses will increase. In addition, as the latency decreases, real-time services become more feasible. However, you can not ignore the practical limitations of data usage: Whether you continuously transmit uncompressed CD quality audio, at 650 MB / h, or 5.2 Gbit / hour or 124.8 Gbit / day and with a 10% performance, you only have 20 minutes to download a 24 hour content.
The bottom line is that we seem to have reached the limits of data usage. Today, no popular data set uses more bandwidth than video. All other popular forms of data, including text, images, and audio, are at much lower levels. Even high-definition video can be streamed easily. In the media world, high-definition video only requires four times more bandwidth than standard video. As a result, deploying EPON can serve many people with multiple 1 GE connections serving thousands of users. A 10 GE link is not really needed until you get closer to the core.
"Eat all you can" or "eat all you care"?
Many companies are relying on the belief that video will be a major motivator for 10 GE. However, in a world where people are always busy with business, people have to question the value of the video. Most companies do not want their employees to watch movies on company computers and non-commercial videos - such as corporate announcements - will not be a motivator. Companies may only request non-commercial video playback on an infrequent basis, such as once a quarter. In addition, video production is costly or just to serve a small number of viewers and therefore the bandwidth to transmit those video files is just an abnormal demand that is transitory compared to the demand for data traffic. whether daily. For video-intensive applications, such as an online manual for a mechanic, how to install a component, compressed AVI files, and the ability to run efficiently. Results on 100 Mbit / s networks. Broadband, high-quality video will be a case in or of necessity in a business so much as building an infrastructure to transmit it.
Even in commercial networks, video is not broadcast to a large number of viewers with a very limited value. Let us consider the value of video on demand on each bit with a receive node. At a cost of $ 10 for a movie, you can generate about 25 cents of revenue per gigabit of actual data. This number drops dramatically when you consider the performance of the network. In addition, you have to build and maintain a relatively large infrastructure to deliver video to users, either by having a high bandwidth and expensive core network or by setting up a dedicated video server. closer to the user than, such as placing next to a DSLAM.
Compare this case to text messaging-the type that probably has the highest bit-value of any data: 10 cents for a 50-character ASCII message generated $ 250 in revenue. on a gigabit data or 1000 times the revenue generated by the video. The main advantage of video is that it provides a means for users to spend faster; Watching a movie is a lot easier than sending 100 messages. This fact is one reason many companies are interested in networking video commercials.
But how much data can a person use? You can only watch it with the movie one day. Even marketing people who send bulky PowerPoint presentations up to 100 MB in size only account for a fraction of a Gbit / s of GE bandwidth. Only a few users, such as filmmakers and some engineers, work with huge data sets can actually use this bandwidth.
But even these users use less bandwidth than you think. A network administrator, describing the network's impact on engineers working with large systems models, said that these engineers typically download only one component-500 MB to 1 GB-of a large model, instead of downloading the entire model has a capacity of about 4 GB. These models are collections of hundreds or thousands of files. Include the time necessary to query the model database, check the components and download them, to complete the transaction takes 30 to 45 minutes. After that, the engineer can use the rest of the day or even that week to use this data. Even if the engineer is ready to use up from 30 minutes to 1 hour to back up the model's data during the day instead of working with the model, the total amount of data downloaded is 3 GB. With appropriate scripts, users can upload or back up files to the database each night and automatically download them the next day and this will reduce the load. Bandwidth for public networks during peak hours.
Because users have a 1 GE transmission it does not mean they can use the data more quickly, so 10 users with 1 GE connections do not need a 10 GE backlink switch for management. Their circulation data. Some 1 GE lines can serve from hundreds to thousands of users, as demonstrated during FTTH deployment. The main technical challenge now is how to create effective over-subscription mechanisms rather than finding additional bandwidth. And so again, 10 GE showed that it only suited the network core.
So where can 10 GE be used outside the core network? Data centers and SANs (storage area networks) provide two possibilities: the use of passive data and aggregation. An example of using passive data is to make a simple change to the database. The change itself may take only a few bytes, but this change requires modifying the database, which results in the need to back up the entire database. In cases where the path between the SAN and the backup media is private or not depends on the rest of the public data network, the SAN backup task has no effect on the user network segment. /public.
The fact of storage is well known that more and more things need to be archived. It is interesting to note that the bottleneck of SAN data backups is not usually the transmission path, but rather the capacity of the servers to take full advantage of the transmission and data acceptability of the backup media. , such as that of a tape drive. If the transmission line falls into the bottleneck because you have enough servers and tape drives, you can ask yourself why you use most of your bandwidth to back up data you have never before. have been in the past 5 years. Given that selective data backup is a challenging problem but instead of constantly backing up the same data, a smarter solution to handle this problem is to create a backup schedule. orderly.
From a collective point of view, even if one person can not use more than one relative amount of data, thousands of people can. With so many users and many sources of information traffic, congestion has become one of the most difficult issues for the network. When demand for data reaches the bandwidth limit, you must implement more sophisticated "service quality" mechanisms to maintain the real-time characteristics of data and the efficiency of connections. A much easier way than deploying the mechanisms to handle this congestion is simply to increase bandwidth and eliminate congestion. One might argue that the addition of bandwidth can be a very costly solution to resolve disputes.
Another significant obstacle in higher bandwidth solutions for network management is increasing importance, which is the convenience. Companies are calling for their networks to support wireless users in the office and remote access for remote users. This means that users must have access to the same applications they do in their wired office through much narrower connections weighed down by VPNs and Additional security procedures. The convenience requirements will reduce bandwidth requirements to make wireless and remote connections more efficient and viable. On the other hand, convenience is not a pressing issue as concerns over whether 1 GE will be over-booked.
It is all a matter of perception
Whenever a user delays the use of a network, people often blame the network. However, consider a database application in which the user sends a small package to open the database, perform a query, locate the data, download the data, and close the database. In object-oriented languages, levels of abstraction can create a large number of additional procedures and they can block traffic and therefore data can not be moved. This situation indicates that demand is not a faster path but rather a new one.
In the same way, the endless demand for bandwidth no longer expands exponentially. Previously, bandwidth was increased to receive data with a higher cardinality-that is, with a bandwidth requirement at least higher than the previous requirements of a step-to explain the 10-fold jump that followed Traditionally each generation of Ethernet usually provides. However, there is no need for data with a higher cardinality than video, the amount of data we use grows more slowly than the rate at which we need 10 Gbit / s outside the core network. Currently, some 1 GE connections are still less expensive than a 10 GE connection, and these connections can help to alleviate any bottlenecks and this further slows down the need for connections. 10 GE.
Certainly 10 GE will find a suitable location as a connection between switches or inter-campus connectivity, although 1 GE seems to be able to serve this need for all. the objects except the largest companies. However, if 10 GE is deployed primarily at the network core, then there is no high-traffic application leveraging to bring its cost to a competitive level. Someone may still argue that managing a single-protocol network is easier and less costly, but that is a very convincing reason.
