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20 Cards in this Set
- Front
- Back
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Two key chapter ideas |
1. Long distance LAN technologies 2. Switching |
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Name 3 key concerns with LAN design |
1. Capacity 2. Maximum Delay 3. Distance |
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What technology can be used to connect a machine to a distant LAN? |
Fiber modems can be used to extend a LAN, but they do not increase signal strength. A fiber modem is connected to both the computer and the remote LAN |
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Name the primary characteristics of a Repeater |
1. it is an analog device 2. It does not know anything about packets or signal coding. 3. It simply amplifies the input signal ( regenerates or reconditions the signal) |
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T/F - A bridge forwards all packets from one lan segment to another |
True, it receives all packets sent on a segment and forwards them to the other segment, i.e. promiscuous mode |
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Can a computer tell wether it is connected to a bridged LAN? |
No, a broadcast frame is received by all computers on a bridged network, without any knowlege of a bridge. |
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What are the major characteristics of an adaptive or learning bridge? |
1. Learning bridges use MAC addresses to "filter" the frame, it does not forward a frame into another segment unless necessary ( for example in a multicast or broadcast environment). 2. These bridges learn the source addresses of the computers on the network. |
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How can a bridged network outperform a non bridged one? |
By allowing simultaneous messages on each segment, where the source and destination of the message is contained within a segment. The bridge will not forward frames to the other segment unless it is needed. |
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How does a distributed spanning tree support bridged networks |
1. A DST is implemented by bridge components. and defines the network as nodes in a graph. 2. The DST prevents cycles in the network that would otherwise allow packets to circulate indefinitely. |
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Describe the STP, spanning tree protocol. |
The STP consists of three steps: 1. Elect a Root note - bridges multicast a packet with their ID, the bridge with the smallest ID becomes the root. 2. Each bridge computes the shortest path to the root. 3. Operation: Forward packets. An interface on the shortest path will forward a packet, those not on the shortest path are blocked. |
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Explain the differences between a hub and a switch |
A hub is an analog device that forwards signals, where a switch is a digital device that forwards packets. |
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An ethernet switch is a __________ switch |
Layer 2 |
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T/F A switch contains bridges |
False. A switch consists of an intelligent interface attached to each port and a central fabric providing simultaneous transfers |
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What are the 3 parts of a switch interface? |
1)a processor, memory and related hardware to process a packet. It consults a forwarding table, and sends the packet across the "fabric" to the proper output port. The interface will buffer incoming packets for sending to busy output ports. |
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What is an advantage of a switched lan over a hub? |
Parallelism. A hub does one transmission at a time, but a switch supports multiple INDEPENDENT transmissions at the same time. |
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Define a VLAN switch |
A "manager" can configure a switch to emulate multiple independent switches. I.E. Define a few ports to operate as "LAN1" and a few other ports to define "LAN2" etc. It operates just as multiple LANS would, only forwarding packets to the other VLANS as necessary |
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VLAN switches can divide computers into _______ |
Separate broadcast domains that define multiple virtual LANS within one physical LAN structure |
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How does a VLAN decrease broadcast latency? |
With VLANS, broadcasts only go to a Server's VLAN clients, not to all machines.Name |
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Name and describe the types of VLAN's |
Port based Mac based Protocol based |
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A port based VLAN provides what primary features? |
1. Traffic Isolation - frames to/from a group of ports may only be sent to those ports. 2. Dynamic membership - ports can be dynamically assigned among VLAN's 3. Forwarding between VLAN's - done via routing as a regular switch |
