A data link layer relay, which borders a collision domain. Bridges are usually restricted to interconnecting LANs of the same type. They localize station-to-station traffic by segregating a network into smaller populations. They listen promiscuously on all ports, and record the source identifier of the frame and the source port in a table. The table manages communication between the populations. The bridge uses the contents of the table to forward and filter frames. It will not forward the frame to a destination port if it is on the same port as the source frame.

A bridge forwards broadcast, multicast, and directed unicast traffic to all ports, which minimizes delay but can negatively affect performance. A bridge-based network is prone to broadcast storms in an extreme case. Broadcast frames must also be decoded, and the flooding of broadcasts can significantly reduce network performance. However, bridges are easy to administer, owing to the fact that they learn from the networks themselves.

Types of bridges include transparent bridges, source-route bridges (though that is debatable), source-route/transparent bridges, translating bridges, and encapsulating bridges.

at this point I bow deeply to Radia Perlman

constraints of bridges:

  • They must operate within the 802 addresses.
  • They cannot rerequest packets from the same source.
  • They do not offer firewall protection against broadcast storms.
  • They do not offer fragmentation and reassembly information.
  • Network size is limited to the tens of thousands.

advantages of bridges:

  • Transparent bridges require less configuration than routers
  • They allow an IP node to move within the bridged portion of the topology without changing its IP address
  • They forward unroutable protocols
  • Bridges are faster and cheaper than routers, primarily because the data link header is easier to parse than a network layer header.

In music, a bridge is also a short break in songs, sometimes instrumental. Its purpose is to provide a change of mood and 'let some air' into the song.

The bridge is the command center of a ship, usually elevated above the deck. From here the captain commands his vessel. The bridge contains navigation, steerage and propulsion control.

The part of a submarine recessed into the top of the conning tower. Only used in surface operartions, the bridge is covered when the boat submerges.

Dentally speaking, a bridge is the common word for a fixed partial denture. It is used to replace one or more missing teeth.

Bridges placed in esthetic areas of the mouth are usually made in PFM, or Porcelain Fused to Metal. The metal framework underneath is made of a high-palladium gold alloy in most cases. This makes the gold appear to be white gold in color.

The shortest span bridge is a cantilever bridge. This is created by preparing one tooth for a crown, then creating a two-unit bridge, effectively creating two teeth with one tooth's worth of roots. This can be dangerous, however, in the molar area of the mouth, and is usually restricted to the anterior portion of the mouth in order to avoid preparing more teeth than is necessary. Each prepared tooth is called an abutment.

Most commonly, a bridge will have two abutments, and be three units, or teeth, long. Two of the teeth will receive crowns, and the crowns will suspend a third, artifical tooth between them.

It is important to floss beneath any bridge, to prevent periodontal disease from setting in and causing eventual loss of the teeth.

A bridge might be created under the guideance of a prosthodontist, a dental specialist who has extensive training in this field, and is able to take on more complex cases, such as full mouth restorations.

A bridge is the non-dominant hand position used to hold a pool cue.

The bridge of a bowed string instrument is a meticulously carved piece of wood that sits vertically on the instrument's top (or front, depending on your view). The strings are strung over the bridge, and the vibrations produced by the strings are transmitted into the instrument, thereby making the whole instrument vibrate.

The bridge is not fastened to the instrument, but held in place by the tension of the strings. The placement of the bridge is determined by the f-holes of the instrument. (The f-holes are f-shaped openings in the top of the instrument, allowing air to move out of the instrument, therefore producing sound). The bridge should be placed directly between the f-holes to give the best distribution of the vibrations. Moving the bridge is not something to take lightly.

On the double bass, adjustable bridges is becoming increasingly common. This involves inserting a metal screw into the "legs" of the bridge. The height of the bridge can then be adjusted depending on playing styles, humidity etc. This can be quite handy, but most people believe it could have a slightly detrimental effect to the sound.

When you're playing with the bow, a special technique exists for playing very close to the bridge. This is called sul ponticello. It is also possible to draw the bow directly on the bridge. This produces an extremely soft breath-like sound, barely audible at distances but nevertheless used occasionally by eager composers.

If amplification of a bowed string instrument is wanted, one of the most common techniques is to put special microphones onto the bridge. A number of different types exist. Many double bassists use this kind of amplification instead of placing a microphone in front of the instrument.

Atari 2600 Game
Produced by:Activision
Model Number:AX006
Rarity:4 Scarce
Year of Release: 1980

Activision's sixth game was Bridge. It is of course the Atari version of the card game bridge. (The node above by sazz explains the game better than I ever could). This game gets the job done, and the computer player can be challenging. The one great thing about this game is the unlimited replay value.

Copies of this game with the box are hard to come by. It seems that more adults purchased this game, and didn't bother to keep the boxes like kids liked to. (I still remember the big cardboard box I used to have as a kid, full of the boxes and instruction manual from my Atari games).

From the instruction manual:

You have in your possession the ultimate solitaire bridge game! Bridge by ACTIVISION deals you hundreds of millions of hands at random, provides a computer partner who bids by rules, and even plays as your opponents after you've established a contract. You can play the same hand over and over again until you're satisfied or keep dealing until you find a hand you want to play. Best of all, you'll never again be without a game with Bridge by ACTIVISION. Look inside to see how it's done.

Larry Kaplan is the programmer on this title.


A bridge is a certain type of electrical circuit with resistors placed in a way which allows an observer to figure out the resistance of an unknown resistor, if the resistance of all the others are known. A path from a source diverges into two resistors, which form a square shaped network with two other resistors. The sides of the square are then connected in the middle by a fifth resistor, running down one of the square's diagonals. Here's a diagram of a typical bridge setup:

    |                   |     V 
    |                   |     
    |                   ---/\/\/\--
    |                   |        /|
    |                   \      \  /
    |            R2 --> /    /    \  < -- R3
    |                   \  \      /
   /+\                  |/        |
  /   \                 ---/\/\/--|
 |  V  |                          |
  \   /                      ^    |
   \-/                       |    |  
    |                        R4   |
    |                             |

R5 is that terrible looking thing crossing the middle of the bridge. It's supposed to be a resistor going across the two nodes, one formed by the intersection of R2 and R4, and the other formed by the intersection of R1 and R3. Anyway, bridges have special properties. If (R2)(R3)=(R1)(R4), the current passing through the fifth resistor will be zero. This will help when we want to figure out the resistance of the unknown resistor.

Because the voltage across the middle is zero when (R2)(R3)=(R1)(R4), we can replace R5 with a voltmeter, and know that this condition is true when the voltmeter reads zero. If you wanted to find one resistor's value, you could then replace another resistor with a decade box that has known resistances and adjust until the voltmeter that crosses the bridge returns zero. When it does, the equation (R2)(R3)=(R1)(R4) is satisfied and you can solve for the desired value.

Bridge (&?;), n. [OE. brig, brigge, brug, brugge, AS. brycg, bricg; akin to Fries. bregge, D. brug, OHG. brucca, G. brücke, Icel. bryggja pier, bridge, Sw. brygga, Dan. brygge, and prob. Icel. brU bridge, Sw. & Dan. bro bridge, pavement, and possibly to E. brow.]





3. (Mus.)


4. (Elec.)




Aqueduct bridge. See Aqueduct. --
Asses' bridge, Bascule bridge, Bateau bridge. See under Ass, Bascule, Bateau. --
Bridge of the nose, the upper, bony part of the nose. --
Cantalever bridge. See under Cantalever. --
Draw bridge. See Drawbridge. --
Lattice bridge, a bridge formed by lattice girders. --
Pontoon bridge, Ponton bridge. See under Pontoon. --
Skew bridge, a bridge built obliquely from bank to bank, as sometimes required in railway engineering. --
Suspension bridge. See under Suspension. --
Trestle bridge, a bridge formed of a series of short, simple girders resting on trestles. --


© Webster 1913

Bridge (brij), v. t. [imp. & p. p. Bridged (brijd); p. pr. & vb. n. Bridging.]





To open or make a passage, as by a bridge.

Xerxes . . . over Hellespont
Bridging his way, Europe with Asia joined.




© Webster 1913

Bridge, n.

A card game resembling whist. The trump, if any, is determined by the dealer or his partner, the value of each trick taken over six being: for "no trumps" 12, hearts 8, diamonds 6, clubs 4, spades 2. The opponents of the dealer can, after the trump is declared, double the value of the tricks, in which case the dealer or his partner can redouble, and so on. The dealer plays his partner's hand as a dummy. The side which first reaches or exceeds 30 points scored for tricks wins a game; the side which first wins two games wins a rubber. The total score for any side is the sum of the points scored for tricks, for rubbers (each of which counts 100), for honors (which follow a special schedule of value), and for slam, little slam, and chicane.


© Webster 1913
