Gigabit Ethernet

In computer networking, Gigabit Ethernet is the term applied to transmitting Ethernet frames at a rate of a gigabit per second. The most popular variant 1000BASE-T is defined by the IEEE 802.3ab standard. It came into use in 1999, has replaced Fast Ethernet in wired local networks due to its considerable speed improvement over Fast Ethernet, as well as its use of cables and equipment that are available and similar to previous standards. Ethernet was the result of research conducted at Xerox PARC in the early 1970s, evolved into a implemented physical and link layer protocol. Fast Ethernet increased the speed from 10 to 100 megabits per second. Gigabit Ethernet was the next iteration; the initial standard for Gigabit Ethernet was produced by the IEEE in June 1998 as IEEE 802.3z, required optical fiber. 802.3z is referred to as 1000BASE-X, where -X refers to either -CX, -SX, -LX, or -ZX. IEEE 802.3ab, ratified in 1999, defines Gigabit Ethernet transmission over unshielded twisted pair category 5, 5e or 6 cabling, became known as 1000BASE-T.

With the ratification of 802.3ab, Gigabit Ethernet became a desktop technology as organizations could use their existing copper cabling infrastructure. IEEE 802.3ah, ratified in 2004, added two more gigabit fiber standards: 1000BASE-LX10 and 1000BASE-BX10. This was part of a larger group of protocols known as Ethernet in the First Mile. Gigabit Ethernet was deployed in high-capacity backbone network links. In 2000, Apple's Power Mac G4 and PowerBook G4 were the first mass-produced personal computers to feature the 1000BASE-T connection, it became a built-in feature in many other computers. Half-duplex gigabit links connected through repeater hubs were part of the IEEE specification, but the specification is not updated anymore and full-duplex operation with switches is used exclusively. There are five physical layer standards for Gigabit Ethernet using optical fiber, twisted pair cable, or shielded balanced copper cable; the IEEE 802.3z standard includes 1000BASE-SX for transmission over multi-mode fiber, 1000BASE-LX for transmission over single-mode fiber, the nearly obsolete 1000BASE-CX for transmission over shielded balanced copper cabling.

These standards use 8b/10b encoding, which inflates the line rate by 25%, from 1000 Mbit/s to 1250 Mbit/s, to ensure a DC balanced signal. The symbols are sent using NRZ. Optical fiber transceivers are most implemented as user-swappable modules in SFP form or GBIC on older devices. IEEE 802.3ab, which defines the used 1000BASE-T interface type, uses a different encoding scheme in order to keep the symbol rate as low as possible, allowing transmission over twisted pair. IEEE 802.3ap defines Ethernet Operation over Electrical Backplanes at different speeds. Ethernet in the First Mile added 1000BASE-LX10 and -BX10. 1000BASE-X is used in industry to refer to Gigabit Ethernet transmission over fiber, where options include 1000BASE-SX, 1000BASE-LX, 1000BASE-LX10, 1000BASE-BX10 or the non-standard -EX and -ZX implementations. Included are copper variants using the same 8b/10b line code. 1000BASE-CX is an initial standard for Gigabit Ethernet connections with maximum distances of 25 meters using balanced shielded twisted pair and either DE-9 or 8P8C connector.

The short segment length is due to high signal transmission rate. Although it is still used for specific applications where cabling is done by IT professionals, for instance the IBM BladeCenter uses 1000BASE-CX for the Ethernet connections between the blade servers and the switch modules, 1000BASE-T has succeeded it for general copper wiring use. 1000BASE-KX is part of the IEEE 802.3ap standard for Ethernet Operation over Electrical Backplanes. This standard defines one to four lanes of backplane links, one RX and one TX differential pair per lane, at link bandwidth ranging from 100Mbit to 10Gbit per second; the 1000BASE-KX variant uses 1.25 GBd electrical signalling speed. 1000BASE-SX is an optical fiber Gigabit Ethernet standard for operation over multi-mode fiber using a 770 to 860 nanometer, near infrared light wavelength. The standard specifies a maximum length of 220 meters for 62.5 μm/160 MHz×km multi-mode fiber, 275 m for 62.5 μm/200 MHz×km, 500 m for 50 μm/400 MHz×km, 550 m for 50 μm/500 MHz×km multi-mode fiber.

In practice, with good quality fiber and terminations, 1000BASE-SX will work over longer distances. This standard is popular for intra-building links in large office buildings, co-location facilities and carrier-neutral Internet exchanges. Optical power specifications of SX interface: Minimum output power = −9.5 dBm. Minimum receive sensitivity = −17 dBm. 1000BASE-LX is an optical fiber Gigabit Ethernet standard specified in IEEE 802.3 Clause 38 which uses a long wavelength laser, a maximum RMS spectral width of 4 nm. 1000BASE-LX is specified to work over a distance of up to 5 km over 10 μm single-mode fiber. 1000BASE-LX can run over all common types of multi-mode fiber with a maximum segment length of 550 m. For link distances greater than 300 m, the use of a special launch conditioning patch cord may be required; this launches the laser at a precise offset from the center of the fiber which causes it to spread across the diameter of the fiber core, reducing the effect known as differential mode delay which occurs when the laser couples onto only a sma

Sellwood Riverfront Park

Sellwood Riverfront Park is a city park of about 7.6 acres in southeast Portland, in the U. S. state of Oregon. Located at Southeast Spokane Street and Oaks Parkway, the park has paths, picnic tables, a stage, a boat dock on the Willamette River, a dog off-leash area. A mill site overgrown with Himalayan blackberries, the south half of the park includes a parking lot, the boat launches, a large grassy area suitable for picnics and lawn games; the north end of the park is a native-plant wetland and riparian zone featuring marsh plants and willows. A formal path winds through the wetland, home to frogs and dragonflies, an informal path follows the river bank toward Oaks Amusement Park to the north. Running parallel to Oaks Parkway along the east side of the park is the Springwater Corridor, a hiking and biking trail linking the park to Oaks Bottom Wildlife Refuge and downtown Portland, as well as the amusement park. Directly east of the park on the far side of the Springwater Corridor is Sellwood Park.

The Macadam Bay Club is across the river from the park, north of the club lies Butterfly Park. Portland Parks & Recreation arranges free, public concerts in the park during the summer. Performances in 2010, all held on Monday evenings, consisted of four separate concerts, one apiece devoted to soul music and rhythm and blues, alternative pop, rock. Off-leash area map

Piano Trios, Op. 1 (Beethoven)

Ludwig van Beethoven's Opus 1 is a set of three piano trios, first performed in 1795 in the house of Prince Lichnowsky, to whom they are dedicated. The trios were published in 1795. Despite the Op. 1 designation, these trios were not Beethoven's first published compositions. He recognized the Op. 1 compositions as the earliest ones he had produced that were substantial enough to fill out a first major publication to introduce his style of writing to the musical public. Allegro, 44 Adagio cantabile, 34 Scherzo. Allegro assai, 34 Finale. Presto, 24The first movement opens with a similar figure to that of the third movement of Mozart's 20th Piano Concerto. Adagio, 34 - Allegro vivace, 24 Largo con espressione, 68 Scherzo. Allegro, 34 Finale. Presto, 24 Allegro con brio, 34 Andante cantabile con Variazioni, 24 Minuetto. Quasi allegro, 34 Finale. Prestissimo, 22Unlike the other piano trios in this opus, the third trio does not have a scherzo as its third movement but a minuet instead; this third piano trio was reworked by Beethoven into the C minor string quintet, Op. 104.

Piano Trio No. 1, Piano Trio No. 2, Piano Trio No. 3: Scores at the International Music Score Library Project Performance of Piano Trio No. 1 by the Claremont Trio from the Isabella Stewart Gardner Museum in MP3 format Performance of Piano Trio No. 3, I Allegro con brio