1. What are the network support layers and the user
support layers? Network support layers:
The
network support layers are Physical layer, Data link layer and Network layer.
These deals with electrical specifications, physical connection, transport
timing and reliability.
User support layers:
The user
support layers are: Session layer, Presentation layer, Application layer. These
allow interoperability among unrelated software system.
2. With a neat diagram explain the relationship of
IEEE Project to the OSI model?
Other
layers Other
layers
Network Network
Logical
Link Control Data
link
Media
Access Control
Physical Physical
The IEEE
has subdivided the data link layer into two sub layers:
· Logical
link control (LLC)
· Medium
access control (MAC)
LLC is
non-architecture specific. The MAC sub layer contains a number of distinct
modules, each carries proprietary information specific to the LAN product being
used.
3. Why IPv6 is preferred than IPv4?
Through
IPv6 we can identify more networks or systems than IPv4.
4. Define ICMP.
ICMP uses
the source IP address to send the error message to the source of the datagram.
ICMP always reports error messages to the original source.
5. Why we migrate from IPv4 to IPv6?
·
Despite all short-term solutions, such as
subnetting, classless addressing, and NAT, address depletion is still a
long-term problem in the Internet.
·
The Internet must accommodate real-time audio and
video transmission. This type of transmission requires minimum delay strategies
and reservation of resources not provided in the IPv4 design.
·
The Internet must accommodate encryption and
authentication of data for some applications. No encryption or authentication
is provided by IPv4.
To
overcome these deficiencies, IPv6 (Internetworking Protocol, version 6), also
known as IPng (Internetworking Protocol, next generation), was proposed and is
now a standard.
6. What is the use of NAT?
NAT
(Network Address Translation) is the process where a network device, usually a
firewall, assigns a public address to a computer inside a private network.
7. What are the responsibilities of network layer?
The
network layer is responsible for the source-to-destination delivery of packet
across multiple network links. The specific responsibilities of network layer
include the following:
Logical
addressing.
Routing.
8. What is a virtual circuit?
A logical
circuit made between the sending and receiving computers. The connection is
made after both computers do handshaking. After the connection, all packets
follow the same route and arrive in sequence.
9. What are data grams?
In
datagram approach, each packet is treated independently from all others. Even
when one packet represents just a place of a multipacket transmission, the
network treats it although it existed alone. Packets in this technology are
referred to as datagram.
10. What are the two types of implementation
formats in virtual circuits?
Virtual
circuit transmission is implemented in 2 formats.
·Switched
virtual circuit
·Permanent
virtual circuit.
11. What is meant by switched virtual circuit?
Switched
virtual circuit format is comparable conceptually to dial-up line in circuit
switching. In this method, a virtual circuit is created whenever it is needed
and exits only for the du ration of specific exchange.
12. What is meant by Permanent virtual circuit?
Permanent
virtual circuits are comparable to leased lines in circuit switching. In this
method, the same virtual circuit is provided between two uses on a continuous
basis. The circuit is dedicated to the specific uses.
13. Define Routers.
Routers
relay packets among multiple interconnected networks. They Route packets from
one network to any of a number of potential destination networks on internet
routers operate in the physical, data link and network layer of OSI model.
14. What is meant by hop count?
The
pathway requiring the smallest number of relays, it is called hop-count routing,
in which every link is considered to be of equal length and given the value
one.
15. How can the routing be classified?
The
routing can be classified as,
•
Adaptive routing
•
Non-adaptive routing.
16. What is time-to-live or packet lifetime?
As the
time-to-live field is generated, each packet is marked with a life time,
usually the number of h ops that are allowed before a packet is considered lost
and accordingly, destroyed. The time-to-live determines the lifetime of a
packet.
17. What is meant by brouter?
A brouter
is a single protocol or multiprotocol router that sometimes act as a router and
sometimes act as a bridge.
18. Write the keys for understanding the distance
vector routing.
The three
keys for understanding the algorithm are
Knowledge
about the whole networks
Routing
only to neighbors
•
Information sharing at regular intervals
19. Write the keys for understanding the link state
routing.
The three
keys for understanding the algorithm are
•
Knowledge about the neighborhood.
• Routing
to all neighbors.
•
Information sharing when there is a range.
20. How the packet cost referred in distance vector
and link state routing?
In
distance vector routing, cost refer to hop count while in case o f link state
routing, cost is a weighted value based on a variety of factors such as
security levels, traffic or the state of the link.
21. How the routers get the information about
neighbor?
A router
gets its information about its neighbors by periodically sending them a short
greeting packet. If the neighborhood responds to the greeting as expected, it
is assumed to be alive and functioning. If it does not, a change is assumed to
have occurred and the sending router then alerts the rest of the network in its
next LSP.
22. What are the four internetworking devices?
The four
internetworking devices are,
·Repeaters
·Bridges
·Routers
·Gateway
23. Define IP address.
IP
address is the 3-bit number for representing a host or system in the network.
One portion of the IP address indicates a networking and the other represents
the host in a network.
24. What is Token Bus?
Token Bus
is a physical bus that operates as a logical ring using tokens. Here stations
are logically organized into a ring. A token is passed among stations. If a
station wants to send data, it must wait and capture the token. Like Ethernet,
station communicates via a common bus.
25. What is token passing?
Stations
may attempt to send data multiple times before a transmission makes it onto a
link. This redundancy may create delays of indeterminable length if the traffic
is heavy. Token ring resolves this uncertainty by requiring that stations take
turns sending data. Each station may transmit only during its turn and may send
only one frame during each turn. The mechanism that coordinates this rotation
is called token passing.
26. Define Masking?
Masking
is the process that extracts the address of the physical network from an IP
address.
27. What are the rules of boundary-level masking?
The rules
of boundary-level masking
• The
bytes in the IP address that corresponds to 255 in the mask will be repeated in
the subnetwork address
• The
bytes in the IP address that corresponds to 0 in the mask will change to 0 in
the subnetwork address
28. What are the rules of nonboundary-level
masking?
· The bytes
in the IP address that corresponds to 255 in the mask will be repeated in the
subnetwork address
·The bytes
in the IP address that corresponds to 0 in the mask will change to 0 in the
subnetwork address
·
For other bytes, use the bit-wise AND operator
29. Define Gateway.
A device
used to connect two separate networks that we different communication
protocols.
30. What is LSP?
In link
state routing, a small packet containing routing information sent by a router
to all other router by a packet called link state packet
Glossary:
Address Resolution Protocol (ARP): In TCP/IP, a protocol for obtaining the physical addressof a node
when the Internet address is known.
Anycast Address: An address that defines a group of computers with addresses that
have thesame beginning.
Base Header: In IPv6, the main header of the datagram.
Broadcast Address: An address that allows transmission of a message to all nodes of a
network.
Broadcasting: Transmission of a message to all nodes in a network.
Checksum:A value used for error detection. It is formed by adding
data units using one'scomplement arithmetic and then complementing the result.
Classful Addressing: An IPv4 addressing mechanism in which the IP address space is
dividedinto 5 classes: A, B, C, D, and E. Each class occupies some part of the
whole address space.
Classless Addressing: An addressing mechanism in which the IP address space is not
dividedinto classes.
Client Process: A running application program on a local site that requests
service from arunning application program on a remote site.
Compatible Address: An IPv6 address consisting of 96 bits of zero followed by 32 bits
of IPv4.
Core-Based Tree (CBT): In multicasting, a group-shared protocol that uses a center router
asthe root of the tree.
Datagram Network:A packet-switched network in which packets are independent
from eachother.
Differentiated Services (DS or Diffserv):
A class-based QoS model designed for IF.
Dijkstra's algorithm: In link state routing, an algorithm that finds the shortest path
to otherrouters.
Direct Delivery: A delivery in which the final destination of the packet is a host
connected tothe same physical network as the sender.
Distance Vector Multicast Routing
Protocol (DVMRP): A protocol based on distance
vectorrouting that handles multicast routing in conjunction with IGMP.
Distance Vector Routing: A routing method in which each router sends its neighbors a list
ofnetworks it can reach and the distance to that network.
Dynamic Host Configuration Protocol
(DHCP): An extension to BOOTP that dynamicallyassigns configuration
information.
Firewall: A device (usually a router) installed between the internal network
of an organizationand the rest of the Internet to provide security.
Forwarding: Placing the packet in its route to its destination.
Fragmentation: The division of a packet into smaller units to accommodate a
protocol's MTU.
Frame: A group of bits
representing a block of data.
Integrated Services (IntServ): A flow-based QoS model designed for IP.
Internet address: A 32-bit or l28-bit network-layer address used to uniquely define
a host on aninternet using the TCP/IP protocol.
Internet Control Message Protocol (ICMP):
A protocol in the TCP/IP protocol suite thathandles error and
control messages.
Internet Control Message Protocol,
version 6 (ICMPv6): A protocol in IPv6 that handleserror
and control messages.
Internet Group Management Protocol
(IGMP): A protocol in the TCP/IP protocol suite thathandles
multicasting.
Internet Protocol (lP): The network-layer protocol in the TCP/IP protocol suite
governingconnectionless transmission across packet switching networks.
Internet Protocol version 4 (IPv4): The current version of Internet Protocol.
Internet Protocol, version 6 (IPv6): The sixth version of the Internet Protocol.
Link State Routing: A routing method in which each router shares its knowledge of
changes inits neighborhood with all other routers.
Mapped Address: An IPv6 address used when a computer that has migrated to IPv6
wants tosend a packet to a computer still using IPv4.
Multicast Routing: Moving a multicast packet to its destinations.
Multiple Unicasting:Sending multiple
copies of a message, each with a different unicastaddress.
Network Address Translation (NAT): A technology that allows a private network to use a setof private
addresses for internal communication and a set of global Internet addresses for
external communication.
Open Shortest Path First (OSPF): An interior routing protocol based on link state routing.
Path Vector Routing: A routing method on which BGP is based; in this method, the
ASSthrough which a packet must pass is explicitly listed.
Protocol Independent Multicast (PIM): A multicasting protocol family with two members,PIM-DM and PIM-SM;
both protocols are unicast-protocol dependent.
Protocol Independent Multicast, Dense
Mode (PIM-DM): A source-based routing protocolthat
uses RPF and pruning/grafting strategies to handle multicasting.
Protocol Independent Multicast, Sparse
Mode (PIM-SM): A group-shared routing protocolthat is
similar to CBT and uses a rendezvous point as the source of the tree.
Reverse Address Resolution Protocol
(RARP): A TCPIIP protocol that allows a host to find itsInternet
address given its physical address.
Unicast Address: An address belonging to one destination.
Unicast Routing: The sending of a packet to just one destination.
Unicasting: The sending of a packet to just one destination.
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