Fichas
Chapter 3
Fichas del conjunto (17)
- 1When was Ethernet Developed? Who was it developed by? What standards are they measured by?Xerox, 1973
IEE 802.3 - 2Ethernet Frame OrderPreamble (56 bits), SFD (8 bits), Sender Mac (48 bits), Ether Type/length (16 bits), DATA (Layer 3's Payload, 46 to 1500 bytes), Frame Check Sequence (32 Bits)
- 3Preamble / Start Frame Delimiter What does it consist of?Lets receiving NIC know of an incoming frame and where the frame starts
7-byte (56 bit) series of alternating ones and zeros
Followed by 1-byte (8-bit) Start Frame - 4Destination & Source MAC Addresses What does it consist of?Each node on an Ethernet network must have a unique identifying address
Consists of a 48-bit binary address
MAC addresses are included in the frame for both the receiving (destination) and sending (source) node. - 5Type (a/k/a EtherType) What does it consist of?VHelps the receiving computer interpret the frame contents by providing the protocol
Very basic information about the layer 3 data type
e.g. – IPv4 vs. IPv6
Does not distinguish higher-level data, such as email vs. web
Length is implied by the type - 6DataConsists of the layer 3 payload
For example, if the frame is an IP packet, it might include information such as the IP addresses for the sending and receiving nodes, etc. but the Ethernet switch will ignore this as the whole thing is just payload data to the Ethernet protocol. - 7PadMinimum size of an Ethernet frame (including destination, source, type, payload and FCS is 64 bytes (512 bits))
Thus, if a frame’s payload is less than 46 bytes, padding will be added after the payload to ensure that each frame is at least 64 bytes. - 8Frame Check SequenceEnables Ethernet nodes to detect when errors might have occurred in transmission
Mathematical formula is computed at both the sending and receiving node
The sending NIC attaches the remainder of special a formula to the frame
If the remainder of the receiving node’s calculation does not match, we can assume that an error occurred and frame must be resent - 9Collision domains a group of nodes that have the capability of sending frames at the same time (i.e. on the same hub or segment)
Separating a network into smaller collision domains can reduce the number of collisions - 10Carrier Sense Multiple Access/Collision DetectionMultiple Access means all machines have equal access to the wire
Nodes listen to hear if the line is clear and then start sending
If two or more nodes try to send a frame at the same time you have a “collision”
A collision is easy to detect as NICs will receive overlapping signals
When a collision is detected, competing nodes each generate a random number to determine how long to wait before starting again - 11Half-DuplexTransmissions can only travel in one direction at a time
Example: talking on a two-way radio - 12Full-DuplexTransmissions can travel in both directions at the same time
- 13Uplink PortsEnables you to connect two or more hubs using a straight-through cable
A hierarchical configuration will not work with hubs; it can work with switches - 14Crossover CablesAllows two PC’s to talk to each other directly (or connected hubs in the pre-auto-sensing days)
- 15Hubs vs SwitchesHubs only allow for one message to be transmitted at one time, which increases the chances of a collision
Switches allow for separate transmissions to be sent simultaneously without colliding
This allows each point-to-point connection with the switch to achieve the full bandwidth of the network - 16Source Address Tablen order to properly direct frames, switches must know the MAC address of each node
Switches constantly maintain a Source Address Table of MAC addresses to ensure that it knows what is connected to each port
Each port on a switch is its own collision domain
Collisions now only occur in half-duplex - 17Spanning Tree Protocolallows switches to detect loops and block redundant paths
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- CompTia Network + CompTIA Network + Fichas sobre Chapter 3 , creado por Torianna Dixon el 21/09/2024.
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- Torianna Dixon
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