Module 12: Wireless Protocols Flashcards
Mobile Ad Hoc Networks (MANET)
formed by wireless hosts which may be mobile without necessarily using a pre-existing infrastructure
may need to traverse multiple links to reach a destination
why care about MANET?
challenges in MANET
limited wireless transmission range
broadcast nature of the wireless medium (hidden terminal problem)
packet losses due to transmission changes
mobility-induced route changes
mobility-induced packet losses
battery constraints
potentially frequent network partitions
why is routing in MANET different?
Taxonomy of MANET Routing Protocols
trade-offs (proactive vs. reactive)
Which one of the following would you select for low latency?
(proactive or reactive)
proactive (routes are pre-calculated so you don’t have to add this additional latency)
dynamic source routing (DSR)
What is true about DSR?
DSR stands for Dynamic Source Routing
DSR has route caching
DSR is a reactive protocol
(NOT a protocol for wired networks)
Route Error
DSR - hidden terminal problem
could cause messages to be lost
but we could introduced randomness to avoid collision
hurts route latency but better choice than collisions
DSR optimization: route caching
use of route caching
Use of route caching: can reduce propagation of route requests
this also reduces the collision problem
route caching: BEWARE
DSR advantages
DSR disadvantages
Which of the following is not a disadvantage of the DSR?
This protocol needs to periodically flood the network in order to build a local view of the network in each node
real problems:
This protocol has stale routes problem
The connection setup delay is higher
There could be hidden terminal type of problems
recap: link state
OLSR = optimized link state routing
Which of the following is the difference between Link State Routing and OLSR when a node X sends a broadcast message?
In OLSR the broadcast message is only forwarded by its multipoint relays, whereas in Link State Routing the broadcast message is forwarded by all its neighbors
DTN
delay tolerant network
epidemic routing protocol: dealing with network partitions
epidemic routing protocol
In epidemic routing protocol, when two nodes are adjacent to each other, the two nodes send all of their own messages to each other.
False
If a source, S, wishes to transmit a message to a destination but no connected path is available, then S will send the data to any nodes that are close by and leverage carriers to transitively deliver the message to its destination at some later point in time.
False
ZRP - zone routing protocol
hybrid!
ZRP
intr-zone routing
inter-zone routing
If given a node X, and another node Y which is more than d hops away from X, then
Routes from X to Y are maintained reactively
