University:
York University
Course:
AP/ITEC 1610 | Introduction to Computer Programming
Academic year:

2023
Views:

336

Pages:

2
Author:

Nick T.

Multiple Access Links and Protocols 2 types of links Point-to-point: single sender/receiver Broadcast: multiple senders/receivers attached to link Shared radio: 4G/5G, WiFi, satellite Multiple access protocol Collision if node receives 2+ signals at same time A distributed algorithm that determines how nodes share the channel Communication about how to share has to use the channel itself Taxonomy (organization) Taking turns: nodes take turns, but nodes with more to send can take longer turns Random access: allow collisions, then recover from them Channel partitioning: divide channel into smaller pieces Could be by time, frequency, or code Allocate piece to node for exclusive use MAC Addresses Written out in hexadecimal notation Cannot do longest prefix matching - must be exact match MAC goes with device Address Resolution Protocol How to determine interface's MAC address, knowing its IP address ARP Table: Each IP node (host/router) on LAN has a table 1. Broadcast ARP query Destination = MAC address 2. Relevant host replies with ARP response Giving MAC address Routing to another Subnet Focus on addressing at IP (datagram) and MAC layer (frame) levels A knows B's IP address A knows IP address of first hop router → R A knows R's MAC address 1. After A creates IP datagram with IP source A, dest B A creates link-layer frame containing datagram A sets R's MAC address as frame's destination 2. After R receives frame, it removes datagram and passes it up to IP 3. IP layer creates new frame with destination B's MAC address Gets this by issuing request in B's subnet 4. B receives frame and passes it up the stack