Medium Access Sublayer
• Topology of the Network
– Bus, Ring, Tree
• Protocols
– IEEE 802.3 for bus topology
– IEEE 802.4 for token bus
– IEEE 802.5 for token ring
– FDDI – for fibre ring
– IEEE 802.11 for wireless networks
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Network Topologies and Transmission Techniques in Broadcast Networks, Slides of Computer Networks
An overview of various network topologies, including bus, tree, and ring, and the protocols used in each, such as ieee 802.3, ieee 802.5, and fddi. It also discusses transmission techniques in broadcast networks, including key assumptions like carrier sense, continuous time, and slotted time.
Typology: Slides
2012/2013
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Medium Access Sublayer
- Topology of the Network
- Bus, Ring, Tree
- Protocols
- IEEE 802.3 for bus topology – IEEE 802.4 for token bus – IEEE 802.5 for token ring – FDDI – for fibre ring – IEEE 802.11 for wireless networks
- Protocols
- Bus, Ring, Tree
Network Topology
Hubs/switches
intermediatehubs
Bus topology
Tree topology:
Network Topology
Multipoint media
terminators
Tree and Bus Topologies
-^ multipoint medium - all stations attach through appropriate hardwareinterface called tap directly to the medium – full duplex operations on the bus – data propagates the length of medium in both directions – at each end bus terminated - absorbs any signal
Î^ removes it from the bus
- tree has a head end – since data propagated to all stations – addressingrequired!
Ring Topology
-^ Repeaters joined by point to point links in a closedloop. •^
no buffering
-^
unidirectional links
-^
destination recognises its frames & copies it
-^
frame removed by source
-^ In all topologies ONLY one station transmits at atime
Transmission in Networks
-^ Networks - Point-to-Point – Broadcast Networks -^ Broadcast networks - Only one station transmits at a time
Æcompetition
- who gets access to the channel
- conference calls:
- between six people – only one channel –
- Who gets access? -^ multiaccess or random access channels
- between six people – only one channel –
- conference calls:
Key Assumption in Broadcast
Networks
- Station model
- N independent stations– Each user generates a frame for transmission– Pr[frame generated in time
] =
–^
arrival rate for new frame
- Once frame generated – station blocks
- does nothing until frame transmitted.
t Δ
t λΔ
λ
Key Assumption in Broadcast
Networks
- Single channel assumptions:
- Single channel for all communication – All stations can transmit and receive on it – All stations get a fair share of the channel
Key Assumption in Broadcast
Networks
- Continuous time:
- Frames can begin at any instant of time – No master clock dividing time into discreteintervals.
- Slotted time:
- time divided into slots – frames start at the beginning of a slot – multiple frame / slot
- Slotted time:
- Frames can begin at any instant of time – No master clock dividing time into discreteintervals.
Key Assumption in Broadcast
Networks
- Carrier Sense:
- Station can tell whether channel is in use – If carrier sensed – do not transmit
- What is carrier sense – an electrical signal -^
- Station can tell whether channel is in use – If carrier sensed – do not transmit