Network Layer Flashcards
transport segment from sending to receiving host
Network layer
Two key network-layer
functions
forwarding
routing
three types of switching fabrics
memory
bus
crossbar
cyclically scan class queues, sending one
complete packet from each class
Round Robin (RR) scheduling:
priority scheduling:
send highest priority
queued packet
discard policy:if packet arrives to full queue: who to discard?
tail drop: drop arriving packet
priority: drop/remove on priority basis
random: drop/remove randomly
connection between
host/router and physical link
interface:
The address in a block must be
The first address must be evenly divisible by the
number of addresses.
power of 2
contiguous
*The first address in the block can be found by setting the rightmost
32 − n bits to
zero
*The last address in the block can be found by setting the rightmost
32 − n bits to
1s
*The last address in the block can be found by setting the rightmost
32 − n bits to
2^32−n.
Three-Levels Hierarchy: Subnetting
The organization has its own mask : network mask
Each subnet must also have its own mask: subnet mask
all routers have complete
topology, link cost info
centralized (global)
how does an ISP get block of addresses?
ICANN: Internet Corporation for Assigned
Names and Numbers
router knows physicallyconnected neighbors, link
costs to neighbors
decentralized
