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Networking Chapter 4
Terms in this set (52)
What are the 4 components of Network Security?
Confidentiality, Authentication, Message Integrity, Access and Availablility
What is Confidentiality?
Only Sender and Receiver should be able to read their message contents (sender encrypts, receiver decrypts)
What is Authentication?
Sender and Receiver want to confirm eachothers identity
What is Message Integrity?
Ensure message is not altered
What is Access and Availablility?
services must be accessible and availalbe
what are the two kety network layer funcitons?
forwarding and routing
move packets from routers input to appropriate router output
determine route taken by packets from source to destination
- routing algorithms
what is forwarding and routing analogous to?
forwarding: process of getting trhrough single interchange
routing: process of planning trip from source to destination
what are the two planes of the network layer?
data and control
describe some elements of the data plane
-local per router function
-determines how datagram arriving on router input port is forwarded to router output port
describe the control plane
network wide logic
determines how datagram is routed among routers along end to end path from source host to dest host
what are two control plane approaches
traditional routing algorithms: implemented in routers
software defined networking: implemented in remote servers
how does a per router control plane work
individual routing algorithm components are in each and every router and interact with each and every router in the control plane .
how does a logically centralized control plane function?
a distinct typically remote controller interacts with local control agents
what is the most commonly used network service model?
internet network architecture
the routing management control plane is ____ware
it operates in the ____Second time frame
the forwarding data plane is _____ware
it operates in the ___Second time frame
what is destination based forwarding?
only based on ip address itself
what is generalized forwarding?
based on any set of the header field values
what is longest prefix matching?
when looking for forwarding table entry for a given destination address, use longest address prefic that matches destination address
see slide about destination based forwarding in chapter 4 for more information
what does longest prefix matching typically use ?
ternary content addressable memories or tcams
why is switching fabric needed?
to transfer packets from input buffer to appropriate output buffer
what is the switching rate?
rate that packets can be transfered from inputs to outputs
how is switching rate measured?
as multiple of input./output line rate
what are the three types of switching fabric
memory, bus, crossbar
switching rate must accomodate the number of _____.
what is head of the line blocking ?
when queued data gram at the head of the queue prevents others from moving forward
how is input port queueing buffer calculated
round trip time multiplied by link capacity divided by
incoming and outcoming ports aka N flows squared
How does first in first out work?
packets are sent out in order of arrival
at which ports do packet queues occur
input and output ports
can many packets be transfered in parallel if their ouput ports are different?
explain head of the line blocking
if two packets at the front of two input queues are destined for the same output queue then one packet will be blocked and must wait at the input queue.When this occurs the packet behind the waiting packet that was destined for the same port must wait too. Even if the packet is going to a port that no other packet is going to.
what is drop tail?
when there is not enough memory to buffer an incoming packet, a decision must be made to drop the arriving packet, which is known as drop tail. ** it can also be removed, or one or more can be removed that are already queued to make room for the newly arrived packet.
where is a packet scheduler located and how many packets are selected from the queue by it?
output and one
HW question explain difference between routing and forwarding
Forwarding decides which road to choose next. Occurs locally.
Routing is network wide and determines end-end paths.
Hw question what is the role of a forwarding table
a table that stores values that help routers determine where to send packets.
Hw question: discuss why each input port in a high speed router stores a shadow copy of the forwarding table.
allows forwarding decisions to be made locally at each input port without invoking a centralized routing processor on a per packet basis and avoids a centralized processing bottleneck.
what is priority queueing
arriving packets at output link are classified into priority classes upon arrival at the queue.When choosing a packet to transmit, the priority queueing discipline will transmit packets from highest priority class that has a nonempty queue ( has packets waiting for transmission).
in priority queuing which would receive priority ?
voip, smtp or imap
what is non preemptive priority queuing?
transmission of a product is not interupted once transmission has begun
what is round robin weighted fair queuing?
packets are sorted into classes like priority queuing but it alternates service amongst classes
what is Work conserving queuing discipline
Never allows the link to remain idle when packets of any class are queued.
Weighted fair queuing
serve packets in circular manner class 1,2,then 3.
what is Type of service field in a data gram?
helps distinguish real time(internet telephony) datagrams from non real time such as ftp
how is datagram length calculated?
its data plus header
field is 16 bits long max size is 65,535 bytes
does ipv6 allow for fragmentation?
what is the purpose of time to live in regards to datagrams
ensures datagrams dont circulate forever in the network
when is the protocol field in datagrams used when they reach the final destination or before they are sent?
what happens when an error is detected in a datagram
the router discards it
Hw Q does tcp and ip perform error checkking at both transport and network layers?
First only the ip header is checksummed at the ip layer, while the tcp and udp checksum is computed over the entire tcp/ udp segment.Second, tcp/udp and IP do not necessarily both have to belong to the same protocol stack.
**IP can carry data that will not be passed to TCP/UDP.
what is MTU
max amount of data link layer frame can carry
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