In a bus topology you have a terminator which absorbs unused packet(noise).What happens in the case of a ring topology?
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You have asked three questions in the last few hours that are all very homeworky. This is not a site where we answer your homework questions for you. This is a site for professionals. At the very least, you could explain your understanding of it and ask for clarification rather than just asking us to answer your homework for you.– MDMarraAug 21, 2010 at 22:14
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Who are you to judge if its homework or not?I am a programmer and now coming to the field of networking.Its really dissapointing that you degrade someones questions like that.– user51911Aug 23, 2010 at 13:11
2 Answers
This assumes that you are speaking of token passing rings.
Most (all?) physical layer devices only accept packets addressed to them. In the early Ethernet days using COAX (10Base2, 10Base5) the terminator was used to prevent reflection of the data.
Most (all?) token passing ring technologies would re-generate the unchanged packet if the packet was not addressed to the PHY layer. A packet that traversed the entire network would be consumed by the sender.
In ring technologies the token controlled the ability to transmit new data.
In the case of other ring technologies, such as SONET, data is written into specific time-slots, so there is no token. Generally the time-slots have some fixed bandwidth associated with them, in the case of SONET it is an STS-1 or STM1.
This ring is not a real uninterrupted line like 10Base2-Ethernet, but every node is a terminator. It receives the packet on one side and sends it out again on the other side if it wasn't meant for this node. Otherwise, it justs send out the token again, without any data.
Additionally, there is a controller station that destroys packets after a certain time when no other node feels responsible for it.
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Where is that "Controller station"in real practise?– user51911Aug 21, 2010 at 20:19
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Every station connected to the network is called a monitor. Among them, a so called active monitor is elected with a specific process, which then does this controlling. But in real practise, Token Ring is pretty much dead, I guess.– SvenAug 21, 2010 at 20:36