Chapters 5-6 Flashcards
(40 cards)
Where the overarching control of network routing happens when considering the routing between near or distant nodes.
The Network Control Plane
Each router determines its own forwarding table by communicating with other router in the local network
Per-Router control
Routers talk to a centralized routing controller which determines the routing and tells the routers how to route traffic by providing tables
Logically centralized control
Looks at other nodes and chooses the path with the least immediate cost that has not been visited yet
Dijkstra’s algorithm (Link-State)
Link-State protocol that uses Dijkstra’s algorithm, and also addresses the problem of scale in the internet, while guaranteeing security and autonomy
OSPF (Open Shortest Path First)
Each domain has a router that links to other domains, which deals with traffic coming into and out of the domain it manages
Border Gateway Protocol (BGP)
Select route with the least cost to the next hop router
Hot Potato Routing
Length of a MAC address
48 bits
Length of a TCP header
16 bits
Length of a UDP header
8 bits
Length of an IPv4 address
32 bits
Length of an IPv6 address
128 bits
hosts, routers, switches, and Wi-Fi access points
Nodes
encapsulating the network-layer datagram with a link-layer frame before transmitting. A frame has a data field which is the network-layer datagram, a header, and a tail which contains a checksum for error correction
Framing
When there is a single sender and single receiver on the link this is a simple matter, but when there are multiple nodes on the link then protocols (such as the MAC protocol) help sort out the messages
Link access
Acknowledgement and retransmission over high-error-rate links (e.g. Wi-Fi), but may not offer reliable delivery service over more reliable links
Reliable delivery
Detect single bit errors
Single bit parity
Two-dimensional bit parity
Detect and correct single bit errors
The value of k-bit integers added together to form a sum used to check for flipped bits during transmission
Checksum
Length of TCP and UDP checksums
16 bits
Each node assigned a code that it uses to encode data
Code Division Multiple Access(CDMA)
All nodes transmit frames of the same length all at the beginning of a slot, if there is a collision it detects it and transmits again before the end of the slot
Slotted ALOHA
Listen before speaking, if someone else is speaking at the same time stop for a random amount of time. More propagation delay more likely collisions will occur
Carrier Sense Multiple Access (CSMA)
Node stops transmitting when it senses that another node is transmitting at the same time
CSMA/CD (Collision Detection)
