UNIT-I
1. Define frame relay.
A form of packet switching based on the
use of variable-length link-layer frames.
There is no network layer, and many of the
basic functions have been streamlined or
eliminated to provide for greater
throughput.
2. Define ATM.
Asynchronous Transfer Mode (ATM) is a method for
multiplexing and
Switching that supports a broad range of services. ATM is
a connection-oriented packet switching technique that generalizes the notion of
a virtual connection to one that Provides quality-of-service guarantees. (Or) A
form of packet transmission using fixed size packets, called cells. ATM is the
data transfer interfaces for B-ISDN. Unlike X.25, ATM does not provide error
control and flow control mechanisms.
3. Define ATM adaptation layer (AAL)
The
layer that maps information transfer protocols onto ATM.
4. Name two WAN technologies.
a)
Frame relay.
b)
ATM
5. Write down the advantages of packet switching.
a)
Flexibility
b)
Resource sharing
c)
Robustness
d)
Responsiveness
6. Define jitter
A
phenomenon in real- time traffic caused by gaps between consecutive
packets
at the receiver.
7. How circuit switching networks began to be used increasingly for
data connections?
a).
In a typical terminal-to-host data connection, much of the time the line isidle.
Thus, with data connections, a
circuit-switching approach is inefficient.
b).
In a circuit-switching network, the connection provides for transmission at a
constant data rate. Thus each of the two
devices that are connected must transmit and
receive at the same data rate as the other.
This limits the utility of the network in
interconnecting a variety of host computers
and terminals.
8. Write down the advantages of packet switching network over circuit
switching.
a).
Line efficiency is greater, because a single node-to-node link can be
dynamically shared by many packets over
time.
b).
A packet-switching network can carry out data-rate conversion.
c).
Priorities can be used.
9. What are the
main features of ATM?
1. The service is connection-oriented, with data
transfer over a virtual circuit.
2. The data is transferred in 53 byte packets called
cells.
3. Cells from different VCs that occupy the same
channel or link are statistically
multiplexed.
4. ATM switches may treat the cell streams in
different VC connections
unequally
over the same channel in order to provide different qualities of
services
(QOS).
10. What are the
traffic parameters of connection-oriented services?
1. Peak Cell Rate (PCR)
2. Sustained Cell Rate (SCR)
3. Initial Cell Rate (ICR)
4. Cell Delay Variation Tolerance (CDVT)
5. Burst Tolerance (BT)
6. Minimum Cell Rate (MCR)
11. What are the
quality service (QoS) parameters of connection-oriented services?
1. Cell Loss Ratio (CLR)
2. Cell Delay Variation (CDV)
3. Peak-to-Peak Cell Delay Variation (Peak-to-Peak
CDV)
4. Maximum Cell Transfer Delay (Max CTD)
5. Mean Cell Transfer Delay (Mean CTD)
12. Types of delays
encountered by cells
1. Packetization delay (PD) at the source
2. Transmission and propagation delay (TD)
3. Queuing delay (QD) at each switch
4. Affixed processing delay (FD) at each switch
5. A jitter compression or depacketization delay (DD)
at the destination.
13. What do you
mean by ATM addressing?
An ATM address indicates the location of an ATM
interface in the network
topology.
This means that ATM address is not portable. The prefix of an address is
associated
with a group of interfaces with the same prefix.
14. Types of ATM
network interface.
Two most important interfaces are:
1. User-network interface (UNI)
2. Network-network interface or network-node
interface (NNI).
15. What do you
mean by user-network interface (UNI) and network-network interface or Network-node
interface (NNI)?
UNI is the interface between an ATM end system and an
ATM switch, NNI is
the interface
between two ATM switches.
16. What are the
two sub layers of AAL?
1. Convergence Sub layer (CS)
2. Segmentation and Reassembly Sub layer (SAR).
17. What is the
function of CS?
The Convergence Sublayer (CS) converts the
information stream into four
types of packets streams, called AAL
Type1, Type2, Type3/4, and Type5.The
Npacketformats
match the requirements of the information stream.
18. What are the
subdivisions of CS?
1. Upper, service-specific or SSCS
sub layer
2. Lower, common part or CPCS sub layer.
19. What do you
mean by Type1 traffic?
Type1 traffic is a traffic generated at constant bit
rate, and it is required to be
delivered at
the same rate (with a fixed delay).
20. What is meant
by traffic policing?
In management and control the network must monitor
the data transfer to make
sure that the
source also conforms to the QoS specification and to drop its cells as
appropriate,
is said to be a traffic policing.
21. What are the
functions of management and control?
1. Fault management
2. Traffic and congestion control
3. Network status monitoring and configuration
4. User/network signaling.
22. What are the
layers of BISDN reference model?
User plane, Control plane, Layer management plane,
Plane management plane.
23. What are the
basic tasks required for internetworking over ATM?
Two basic tasks are:
1. Encapsulation of the protocol data unit
2. Routing of bridging of PDU.
24. What are the
functions of user plane?
It compromise the functions required for the
transmission of user information
for instance, for an internet protocol
over ATM, these layers could be
HTTP/TCP/IP/AAL5.
25. What are the
three strategies of IP over ATM?
The three strategies are
1. The classical IP model
2. The short cut models
3. The integrated models.
26. What are the
basic signaling function between the network and user?
The basic signaling function between the network and
user are as follows:
1. The user requests a switched virtual connection
2. The network indicates whether the request is accepted
or not
3. The network indicates error conditions with a
connection.
27. What are the
two basic tasks required for internetworking over ATM?
The first is encapsulation of the protocol data
units, and the second is Routing or
Bridging of
these PDUs.
28. Define fast
Ethernet
Fast
Ethernet refers to a set of specifications developed by the IEEE 802.3
committee to provide a low-cost, Ethernet-compatible LAN operating at 100 Mbps.
29. Tabulate some
characteristics of high speed networks?
|
Fast Ethernet
|
Gigabit Ethernet
|
Fibre channel
|
Wireless LAN
|
Data rate
|
100 Mbps
|
1 Gbps,10 Gbps
|
100 Mbps-3.2 Gbps
|
1 Mbps – 54 Mbps
|
Transmission media
|
UTP,STP, optical fiber
|
UTP, shield cable, optical fiber
|
Optical fiber, coaxial cable, STP
|
2.4 GHz, 5-GHz microwave
|
Access method
|
CSMA/CD
|
CSMA/CD
|
Switched
|
CSMA/polling
|
Supporting standard
|
IEEE 802.3
|
IEEE 802.3
|
Fibre channel association
|
IEEE 802.11
|
30. Define gigabit
Ethernet?
Gigabit
Ethernet, which has a data rate of 1000 Mbps (Or) 1 Gbps. In which collision
domain is reduced. Gigabit Ethernet is mainly designed to use optical fiber,
although the protocol does not eliminate the use of twisted pair cables.
There are
four implementations have been designed for gigabit Ethernet:
a) 1000Base-LX
b) 1000Base-SX
c) 1000Base-CX
d) 1000Base-T
31.List
requirements for WLAN?
a).
Throughput
b).
Number of nodes
c).
Connection to backbone LAN
d).
Service area
e). Battery power consumption
f).
Transmission robustness and security
g).
Collocated network operation
h).
License-free operation
i).
Handoff/roaming
j).
Dynamic configuration
32. List out the
important services of IEEE 802.11?
a)
Association
b)
Reassociation
c)
Disassociation
d)
Authentication
e)
Privacy
33. Mention the
requirements for fibre channels?
a) Full duplex links with two fibers per link.
b) Performance from 100 Mbps TO 800 Mbps on a
single line.
c) Small connectors
d) Support for distances up to 10 km.
e) High capacity utilization with distance
insensitivity.
f) Broad availability.
g) Small
systems
h)
Interface and network protocols.
34. List out the
fibre channel elements?
a) Node: The key elements of a fibre
channel network are the end systems.
b) Fabric:
The collection of switching elements
35.What is the datalink control functions provided by LAPF?
LAPF
core provides a minimal set of datalink control functions consisting of the
following
(i)Frame
delimiting, alignment & transparency.
(ii)Frame
multiplexing/demultiplexing using the address field.
(iii)Inspection
of the frame to ensure that it consist of an integer no. of octets
prior to zero bit insertion or
following zero bit extraction.
(iv)Inspection
of the frame to ensure that it is neither too long nor too short.
(v)Detection
of transmission errors.
(vi)Congestion
control functions.
36. What are the main functions of ATM?
ATM uses
fixed size cells consisting of a 5-octet header & a 48-octet information field. There are several
advantage to the use of small, fixed size cells.
·
First
the use of small cells may reduce queuing delay for a high priority cell because it waits less if it arrives slightly
behind a lower-priority cell that gained access to a resource.
·
Second
it appears that fixed size cells be switched more efficiently which is
important for the very high data rates of ATM.
·
With
fixed size cells it is easier to important the switching mechanism in
hardware.
37. What is virtual path & connection identifier?
The
Virtual Path Identifier (VPI) constitutes a routing field for the network. It
is 8 bits at the user-network interface & 12 bits at the network-network
interface. The latter allows support for an expanded number of VPC’s internal
to the network to include those supporting subscribers & those required for
network management.The VCI is used for routing to & from the end user.
38. What is ATM?
Asynchronous
transfer mode (ATM) also known as cell relay. It is
similar in concept to frame relay. Both frame relay & ATM take advantage of
reliability & fidelity of modern
digital facilities to provide faster packet switching than X.25. ATM is even
more streamlined than frame relay in its functionality & can support data
rates several orders of magnitudes greater than frame relay.
39. list the levels of fiber channel & the function of each level?
FC-0 PHSICAL MODE
Includes optical
fiber for long distance application, co-axial for high speeds over short
distances & shielded twisted pair for lower speeds over short distance.
FC-1 TRANSMISSION POROTOCOL
Defines
the signal encoding scheme.
FC-2 FRAMING PROTOCOL
Deals
with defining topologies, frame format, flow & error control & grouping
of frames into logical entities called sequences & exchanges.
FC-3 COMMON SERVICES
Include
multicasting.
FC-4 MAPPING
Defines
the mapping of various channel & network protocol to fiber channel,
including IEEE 802, ATM, IP & the Small Computer System Interface (SCSI).
40. What is meant by SAR & CS?
The
AAL layer is organized in two logical sub layers:
SAR & CS
SAR: Segmentation And Reassembly sub layer is responsible for
packing
information at the other end.
CS: The
Convergence Sublayer provides the function needed to support specific
application using AAL.
41. Difference b/w AAL ¾ & AAL 3/5
AAL 3/4
|
AAL
3/5
|
(i)In this MID field is used to
multiplex diff streams of data on the same virtual ATM connection.
(ii)A 10 bit CRC is provided for each
SAR PDU.
(iii)In this 8 octets per AAL
SDU, 4 octets per ATM cell.
|
(i)In this MID field is assumed
to that the higher layer software takes care of such multiplexing.
(ii)A 32 bit CRC protects the
entire cpu’s PDU, provides strong protection against bit errors.
(iii)8 octets per AAL SDU, 0
octets per ATM cell.
|
42. Give the data rates for
frame relay & X.25?
The
lower bit rate for X.25 is 64 kbps. The fixed data for frame relay is
1.544mbps. The higher data rate for frame relay is 44.376mbps.
43. Define Ethernet.
As
packet switching has dominated wide area data networking, Ethernet dominates
local area networking. The original experimental Ethernet operated at 3mbps
over coaxial cable. This remarkable over twisted pair & optical fiber as
well as coaxial cable. It was released commercially at 10 mbps & then was
scaled up first to 100bps & none 1 & 10 gbps
UNIT-II
1. When queue will be formed in a network
Queue
will be formed, if the current demand for a particular service exceeds the
Capacity of service provider.
2. What are the characteristics of queuing process/
Characteristics
of queuing process depend on:
a)
Arrival pattern
b)
Service pattern
c)
Number of server
d)
Queue discipline
e)
System capacity
f)
Number of channels
3. What is meant by traffic intensity in queuing analysis? And write
littles formula for single server queue?
Traffic intensity (or) utilization
factor ρ = λ/μ = arrival rate / rate service
Little’s formula ρ = λ TS
r = λ Tr
w = λ Tw
4. Compare Single Server and Multi Server Queue.
S.No
|
Single server model
|
Multiserver model
|
1
|
Congestion statistics for this
model are:M/M/1, M/D/1, M/G/1
|
Congestion statistics for this
model is M/M/N.
|
2
|
Arrival rate = λ
|
Arrival rate for each server =
λ/N
|
5. What is meant by implicit congestion signaling?
When
network congestion occurs, packets get discard and acknowledgement will be
delayed. As a result, sources understand that there is congestion implicitly.
Here, users are notified about
congestion indirectly.
6. What is meant by explicit congestion signaling?
In
this method, congestion is indicated directly by a notification. The
notification may be in backward or forward direction.
7. Define committed burst size (BC)
It
is defined as the maximum number of bits in a predefined period of time that
the network is committed to transfer with out discarding any frames.
8. Define committed information rate (CIR)
CIR
is a rate in bps that a network agrees to support for a particular frame mode
connection. Any data transmitted in excess
of CIR is vulnerable to discard in event of
congestion.
CIR
< Access rate
9. Define excess burst size (Be)
It
is defined as the maximum number of bits in excess of BC that a user
can send during a predefined period
of time. The network is committed to transfer these bits if there is no congestion. Frames with Be have
lower probability to transfer than frames with BC.
10. Define access rate.
For
every connection in frame relay network, an access rate (bps) is defined. The
access rate actually depends on
bandwidth of channel connecting user to network.
12. Write Little’s
formula.
Little’s
formula is defined as the product of item arrive at a rate of λ, and Served
time of items Tr (or) product
of item arrive at a rate of λ and waiting time of an items Tw.
It is given
as, r = λ Tr (or) w
= λ Tw
14. List out the
model characteristics of queuing models.
a) Item population.
b) Queue size
c) Dispatching discipline
15. List out the
fundamental task of a queuing analysis.
Queuing
analysis as the following as a input information.
a)
Arrival rate
b)
Service rate
c)
Number of servers
Provide as output information
concerning:
a)
Items waiting
b)
Waiting time
c)
Items queued
d)
Residence time
16. State Kendall’s
notation.
Kendall’s
notation is X/Y/N, where X refers to the distribution of the
interarrival times, Y refers to the distribution of
service times, and N refers to the number of servers.
The most common
distributions are denoted as follows:
G =
General distribution of interarrival times or service times
GI = General distribution of interarrival times with
the restriction that
Interarrival times are independent.
M =
Negative exponential distribution
D =
Deterministic arrivals or fixed-length service.
Thus,
M/M/1 refers to a single-server queuing model with poisson arrivals(Exponential
interarrival times) and exponential service times.
17. List out the
assumptions for single server queues.
a)
Poisson arrival rate.
b)
Dispatching discipline does not give preference to items based on service
times
c)
Formulas for standard deviation assume first-in, first-out dispatching.
d) No
items are discarded from the queue.
18. List out the
assumptions for Multiserver queues.
a)
Poisson arrival rate.
b)
Exponential service times
c) All
servers equally loaded.
d) All
servers have same mean service time.
e)
First-in, first-out dispatching.
f) No
items are discarded from the queue.
19. State Jackson’s
theorem.
Jackson’s theorem can be
used to analyse a network of queues. The theorem is based on three assumptions:
1.
The queuing network consists of m nodes, each of which
provides an
exponential
service.
2.
Items arriving from outside the system to any one of
the nodes arrive with a
poisson
rate.
3.
Once served at a node, an item goes (immediately) to
one of the other nodes
with a
fixed probability, or out of the system.
20. Define Arrival rate and service rate.
Arrival
Rate: The rate at which data enters into a queuing system i.e., inter
arrival rate. It is indicated as λ.
Service Rate: The rate at which data
leaves the queuing system i.e., service rate.It is indicated as μ.
21. What is meant by congestion avoidance and congestion recovery
technique?
Congestion Avoidance: It is the
procedure used at beginning stage of congestion to
minimize its effort. This procedure
initiated prior to or at point A. This procedure prevent congestion from
progressing to point B.
Congestion Recovery: This
procedure operates around at point B and within region of severe congestion to
prevent network collapse. Here dropped frames are reported to higher layer and
further packet delivery is stopped to recover from congestion.
22. what is the role of de in frame relay?
This bit it indicates frame
priority. The DE can taken value of 0 or 1.
DE=0 means frame network element; it can be discard
the frame during periods of congestion. DE=1, for generally considered as high
priority frames.
23. How does frame relay report congestion?
When the particular portion of the network
is heavily congestion. It is
Desirable to route packets around rather than
through the area of congestion.
23. Define
Qos.
Refers to the properties of a network
that contribute to the degree of
satisfaction that user perceive,
relative to the network performance four service categories are typically under
this term capacity, data rate, latency, delay & traffic losses.
24.
Define committed burst size
The max. amount data that the network agrees
to transfer under normal Condition over a measurement interval T, these data
may or may not be contiguous.
24. Define
excess burst size
The max amount of data in excess of BC that the network will attempt to
transfer under normal condition over a measurement interval T. these data are
uncommitted
UNIT-III
1. Define congestion.
Excessive network or internetwork traffic
causing a general degradation of service.
2. Define congestion control.
A method to limit the total
amount of data entering the network, to amount of data that network can carry.
3. List out the TCP implementation policy option.
a)
Send policy
b)
Deliver policy
c)
Accept policy
d)
Retransmit policy
e)
Acknowledge policy
4. List out the three retransmit strategies in
TCP traffic control?
a.
First-only
b.
Batch
c.
Individual
5. Explain about the congestion control in a
TCP/IP based internet implementation task.
a.
IP is connectionless, stateless protocol that includes
no provision for detecting, much less controlling congestion.
b.
TCP provides only end-to-end flow control and deduce
the presence of congestion.
c.
There is no cooperative, distributed algorithm to bind
together the various TCP entities.
6. list out retransmission timer management
techniques
a.
RTT variance estimation.
b.
Exponential RTO back off
c.
Karn’s algorithm.
7. Write down the window management techniques.
a.
Slow start.
b.
Dynamic window sizing on congestion.
c.
Fast retransmit
d.
Fast recovery
e.
Limited transmit.
8. Define binary exponential back off.
A simple technique for implementing RTO backoff is to multiply the RTO
for a segment by a constant value for each retransmission.
RTO = q * RTO ………. (1)
The equation causes RTO a grow exponentially with each retransmission.
The most commonly used value of q is 2.
9. State the condition that must be met for
a cell to conform.
In
case of ATM, the information flow on each logical connection is organized into fixed-size packets called cells.
Cells should
arrive with in theoretical arrive time but with in CDVT (limitation) cell is
conformed.
10. What are the mechanisms used in ATM
traffic control to avoid congestion condition?
a).
Resource management.
b).
Connection admission control
c).
Usage parameter control
d).
Traffic shaping
11.How is times useful to control
congestion in TCP?
The
value of RTO (Retransmission time out) have a critical effect on TCP’s reaction
to congestion. Hence by calculating RTO effectively congestion can be
controlled.
12. What is the difference between flow
control and congestion control?
Flow control:
The transmitter should not overwhelm the receiver so flow control is performed.
Congestion
control: It aim to limit the total amount of data entering the
network,
to amount of data that network can carry.
13. What is reactive
congestion control and preventive congestion control.
Reactive
congestion control: Whenever a packet discard, occur due to severe
congestion, some control mechanism is needed
to recover from network collapse
these mechanism is reactive congestion control.
Preventive
congestion control: Mechanism to avoid congestion before it occurs.
14. Why congestion control is difficult to implement in TCP?
The
end system is expected to exercise flow control upon the source end system at a
higher layer. Thus it is difficult to implement in TCP.
15. What are the accept policies
used in TCP traffic control?
Accept
policy:
a).
In-order policy
b).
In –window policy.
16. What is meant by silly window syndrome?
If
frequently data’s are send as small segment, the response will be speed in
sender side but it cause degradation in performance. This degradation is called
silly window syndrome.
17. What is meant by cell insertion time?
Cell
insertion time is the time taken to insert a single cell on to the network.
18. What are the mechanisms used in TCP to control congestion?
TCP
congestion control mechanism:
a).
RTO timer management
b).
window management
19. What is meant by open loop and closed loop control in ABR
mechanism?
Open loop
control: If there is no feedback to the source concerning congestion,
this approach is called open loop
control.
Closed loop
control: ABR has feedback to the source concerning congestion; this approach is called closed loop control.
20. What is meant by allowed cell rate (ACR)?
Allowed
cell rate: The current rate at which
source is permitted to send or transmit cell
in ABR mechanism is called allowed cell rate.
21. Define Behavior Class Selector (BCS)
Behaviour
Class Selector (BCS): BCS enables an ATM network to provide different
service levels among UBR connections by associating each connection with one of
a set of behaviour class.
22. What is cell delay variation?
In ATM cell network voice &
video signals can be digitized & transmitted as a system of cells. A key
requirement especially for voice is that the delay across the network be short.
ATM is designed to minimize the processing & transmission overhead to the
networks. So that very fast cell switching & routing is possible.
23. Why retransmission policy essential in TCP?
TCP maintains a queue of segments that have been sent but not yet
acknowledged. The TCP specification states that TCP will retransmit a segment.
If it fails to receive an acknowledge within a given time. A TCP implement may
employ one of three retransmission strategies.
(i) First only
(ii)
Batch
(iii)
Individual
24. Why congestion control in a tcp/ip internet is
complex?
The task is difficult one becoz of
the following factor
(i)IP is a connectionless stateless
protocol that includes no provision for detecting much less controlling
congestion.
(ii)TCP provides only end-to-end
flow control.
(iii)There is no co-operative
distributed algorithm.
25. Write
relationship b/w throughput & TCP window size ‘W’.
S = 1
for W> RD/4
4W /RD
for W< RD/4
Where
W à TCP window size (octets)
R à Data rate at TCP source available to a given TCP
connection.
D à Propagation delay b/w TCP source & destination
over a given TCP
Connection.
26. Define ABR
ABR is the available bit rate. ABR
specifies a Peak Cell Rate (PCR) that it requires. The network allocates
resources so that all ABR applications receive at least their MCR capacity. The
ABR mechanism uses explicit feedback to sources to assure that capacity is
facility allocated.
27. Define CBR (Constant Bit Rate)
The CBR service is perhaps the
simplest to define. It is used by applications that require a fixed data rate
that is continuously available during the connection lifetime & a
relatively tight upper bound on transfer delay. CBR is commonly used for
uncompressed audio & video information.
28. Write the examples for CBR.
Video conferencing
Interactive audio
Audio/video distribution
Audio/video retrieval
PART - B
1 a. Explain TCP flow & congestion control. (10)
b.Explain the Retransmissions Timer management techniques.
(6)
2. Explain the five important window management techniques.
(16)
3. a Explain the congestion control mechanism in ATM
networks carrying TCP traffic. (10)
b.Explain the ATM traffic control (6)
4. a. What are the requirements for ATM traffic and
congestion control? (10)
b. Explain the ATM traffic – related attributes. (6)
5 a.. Explain in detail ABR traffic management. (8)
b. Explain in detail GFR traffic
management. (8)
UNIT-IV
1. Write down the two different, complementary IETF Standards traffic
management
Frameworks?
a).
Integrated services
b).
Differentiated services
2. Write down the current traffic demand viewed by the IS provider?
a).
Limits the demand that is satisfied to that which can be handled by the
current capacity of the
network.
b).
Reserves resources within the domain to provide a particular QoS to
particular portions of the
satisfied demand.
3. Explain about differentiated services?
A
DS framework does not attempt to view the total traffic demand in any overall
or integrated sense, nor does it attempt to reserve network capacity in
advance. In DS framework, traffic is classified into a number of traffic
groups. Each groups is labeled appropriately, and the service provided by
network elements depends on group membership, with packets belonging to
different groups being handled differently.
4. What are the
requirements for inelastic traffic?
a)
Throughput
b) Delay
c) Jitter
d) Packet
loss
5. Give some
applications that come under elastic traffic.
a) E-Mail
(SMTP) – Quite insensitive to changes in delay.
b) File transfer (FTP) – The delay to be
proportional to the file size and sensitive
to changes
in throughput.
c). Network
management (SNMP) – To get through with minimum delay
increases with increased congestion.
d) Remote
Logon and Web Access (TELNET and HTTP) – These are called as
Interactive applications are quite sensitive to delay.
6. State the
drawbacks of FIFO queering discipline?
a) No
special treatment is given to packets from flows that are of higher
priority
(or) are more delay sensitive. If a number
of packets from different flows are
ready to forward, they are handled strictly in FIFO order.
b) If a
number of smaller packets are queued behind a long packet, then FIFO
Queuing results in a larger average delay
per packet than if the shorter
packets were transmitted before the longer packet. In
general, flows of
larger
packets get better service.
c) A
greedy TCP connection can crowd out more altruistic connections.
d) If
congestion occurs and one TCP connection fails to back off, other
Connections
along the same path segment must back off.
7. Distinguish
between inelastic and elastic traffic?
S.No
|
Elastic traffic
|
Inelastic traffic
|
1
|
Elastic traffic is that which can adjust , over wide
ranges, to changes in delay and throughput across an internet and still meet
the needs of its applications
|
Inelastic traffic does not easily adapt, if at all, to
changes in delay and throughput across an internet.
|
2
|
Example is electronic mail(SMTP),file transfer(FTP), Web
access(HTTP),Network management(SNMP)
|
Prime examples is real-time traffic
(Voice chat, Tele conferencing)
|
8. Define the
format of DS field?
Packets are labeled for service
handling by means of the DS field, which is placed in the type of service field
of an IPv4 header or the traffic class field of the IPv6 header.
RFC 2474 defines the DS field
as having the following format: the leftmost 6 bits form a DS code point and
the rightmost 2 bits are currently unused. The DS codepoint is the DS label
used to classify packets for differentiated services.
9. Define DS code point.
A
specified value of 6 bit DS code point portion of the 8 bit DS field in the IP
header which indicate to which class packets belongs and its drop precedence.
10. What is meant by traffic conditioning agreement?
An
agreement that specify rules that are to apply for packets selected by the
classifier. Control functions performed in TCA are metering, marking, shaping
and dropping.
11. Define DS boundary node.
A
DS node that connects one DS domain to the node in another domain.
12. Define DS interior node.
A
node in DS domain, which is not the boundary node is called DS interior node.
13. Define DS node.
A
router that supports DS policies is called as DS node. A host system that uses
DS for application is also called as DS node.
14. Write down the two routing mechanism use in ISA.
a).
Routing algorithm- Decreases local congestion,
reduces delay.
b).
Packet discard- Most recent packet
is discarded, sending TCP entity back
off,Reduces load.
15. List out the ISA components?
a).
Reservation protocol.
b).
Admission control
c).
Management agent.
d).
Routing protocol
16. List out the two principal functionality areas that accomplish
forwarding packets in
the router.
a).
Classifier and route selection.
b).
Packet scheduler.
17. Define TSpec.
ISA
service for a flow of packets is defined on two levels.
a)
A number of general categories of service are provided,
each of which provides a certain general type of service guarantees.
b)
Within each category, the service for a particular flow
is specified by the values of certain parameters.
Together,
these values are referred to as a traffic specification (TSpec)
18. List out the categories of service in ISA.
a).
Guaranteed service
b).
Controlled load service
c).
Best effort service
19. List out the advantages of ISA.
a).
Many traffic sources can easily and accurately be defined by a token bucket
scheme.
b).
The token bucket scheme provides a concise description of the load to be
imposed by a flow, enabling
the service to determine easily the resource
requirement.
c).
The token bucket scheme provides the input parameters to a policing function.
20. Define delay jitter.
The
delay jitter is the maximum variation in delay experienced by packets in a
single session.
21. What is meant by best effort service?
Flows
that are not reserving resources are provided with best effort service. The
network will put best effort to deliver
the packet but if congestion occurs severely it will discard the packet.
22. What is meant by guaranteed service?
Flows
that are reserving resources are provided with guaranteed service. The
service provides assured capacity
levels.
23. Define global synchronization.
Due
to packet discard during congestion, many TCP connections entered slow start
at the same time. As a result, the
network is unnecessarily under utilized for some time. The TCP connections
which entered into slow start, will come out of slow start at about same time
causing congestion again. This phenomenon is called global synchronization.
24. What are the design goals of RED algorithm?
a).
Congestion avoidance
b).
Global synchronization avoidance
c).
Round on average queue length.
25. Define behavior aggregate in per hop behavior.
A
set of packets with the same DS code point crossing a link in a particular
direction is called behavior
aggregate.
26. What is meant by differentiated service?
a).
It does not attempt to view the total traffic demand in integrated sense.
b). It
does not reserve network capacity in advance.
c). It
provides different level of QoS to different traffic flows.
27. What is meant
by integrated service?
The IS
provider
a). Views
the totally of current traffic demand.
b).
Limits the demand with respect to the current capacity handled by the
network.
c).
Reserve resources with in the domain to provide a particular QOS
guaranteed.
UNIT-V
1. What is meant by soft state in RSVP?
RSVP
use connectionless approach, each intermediate router maintain state
information about nature of flow, that will be refreshed by end system at
predetermined amount of time. This is called soft state.
2. Why receiver is responsible to initiate reservation in RSVP?
Each
member (destination) in multicast may require different resources to be
reserved depending on QOS it needs. So it is therefore better for receiver to
make resource reservation.
3. Define session in RSVP?
Once
a reservation is made at a router by a particular destination, the router
considers this as a session and allocates resources for the life of that
session.
Session
is defined by
Session: Destination
IP address
IP protocol identifier
Destination port
4. Define flow specification in RSVP?
The
flow specification of RSVP specifies a desired QOS and is used to set
parameters
in a node’s packet scheduler.
Flow
spec is defined by
Flow spec: Service class
R Spec
T Spec
R
Spec is Reserve Specification
T
Spec is Traffic Specification
5. Define filter specification in RSVP?
Filter
Spec in RSVP defines the set of packets or flow, for which a reservation is
requested.
Filter
Spec is defined by
Filter
spec: Source address
UDP/TCP source port
6. What are the types of reservation style used in RSVP?
a).
Wild card filter reservation style.
b).
Fixed filter reservation style
c).
Shared explicit reservation style
7. What is meant by label merging and frame merging?
Label
merging: The replacement of multiple incoming labels for a particular
forward equivalent class with single outgoing
label is called label merging
Frame
merging: Label merging, when it is applied to operation over frame based
media, then it is called as frame merging.
8. Define label switched swapping in MPLS.
The
basic operation of looking up an incoming label to determine the outgoing label
and forwarding is called Label Swapping.
9. Define label switched hop in MPLS.
The
hop between two MPLS nodes on which forwarding is done using labels is called
Label Switched Hop.
10. What is meant by ingress edge & egress edge in MPLS domain?
Ingress
Edge: label switched router through which packets from internet router
enters into MPLS domain is called ingress edge.
Egress
edge LSR: LSR through which packets leaves the MPLS domain.
11. Define Label switched router in MPLS.
An
MPLS network consists of a set of nodes called label switched router (LSR)
capable of switching and routing packets on the basis of which a label has been
added to each packets.
12. What is purpose of time to live field in label format?
The value of
this field is decremented at each router and the packet is dropped if the count
falls to zero.
13. What is meant by integrated layer processing in RTP?
In
TCP/IP each layer processed sequentially, whereas in integrated layer
processing, adjacent layers are tightly
coupled and they function parallel.
14. What is the function of RTP relays and give its types?
A
relay operating at a given protocol layer is an intermediate system that acts
as both a destination and a source in a data transfer.
15. What is the function of mixer and translator in RTP?
Mixer:
It is source of synchronization. It receives stream of RTP packets from one or
more sources. Combines these streams and forwards a new RTP packet stream to
one or more destinations.
Translator:
It produces one or more outgoing RTP packets for each incoming packets. It
change the format of the data that suite to transfer from one domain to
another.
16. Define MPLS?
Multi Protocol Label Switching is to standardize a
label switching paradigm that integrates layer 2 switching with layer 3
routing. The device that integrates routing and switching functions is called a
Label Switching Router (LSR).
17. Mention the
main features of label switching?
1. Low cost hardware implementation
2. Scalability to very high speeds
3. Flexibility in the management of traffic flows
18. State the
disadvantages of overlay model?
Overlay
model of IP over ATM has the disadvantage that two network
infrastructures need to be managed, each with its own
addressing, routing and
management constraints.
19. What do you
mean by a Label Switched Path (LSP)?
A sequence of Label Switching Routers (LSR) that is
to be followed by a
packet is
called LSP.
20. What are the
resources used by an integrated service model?
Integrated service model
requires resources such as bandwidth and buffers to be explicitly reserved for
a given dataflow to ensure that the application receives its requested QoS
21. What do you
mean by guaranteed service?
The guaranteed service in the
internet can be used for applications that require real time service delivery.
For this application data that is delivered to the application after a certain
time is generally considered worthless. Thus guaranteed service has been designed
to provide a frame bound on the end to end packet delay for a flow.
22. What do you
mean by controlled-load service?
The controlled-load service is
intended for adaptive applications that can
tolerate some delay but that are sensitive to traffic
overload conditions. These
applications typically perform satisfactorily when
the network is lightly loaded but degrade significantly when the network is
heavily loaded.
23. Define RSVP?
Resource Reservation Protocol was designed as an IP
signaling protocol forthe integrated services model. RSVP can be used by a host
to request a specific QoS resource for a particular flow and by a router to
provide the requested QoS along the paths by setting up appropriate states.
24. What are the
features of RSVP?
1. Performs resource reservations for unicast and
multicast applications
2. Requests resource in one direction from a sender
to a receiver
3. Requires the receiver to initiate and maintain the
resource reservation.
4. Maintains soft state at each intermediate router
5. Does not require each router to be RSVP capable
6. Supports both IPv4 and IPv6
.
25. What is the
information’s present in the path message?
1. Phop
2. Sender template
3. Sender Tspec
4. Adspec
26. Define soft
state
When a state is not refreshed
within a certain timeout, the state is deleted. The type of state that is
maintained by a timer is called a soft state.
27. Define SLA?
Service Level Agreement is a
service contract between a customer and a
Service provider that specifies the forwarding
service that the customer will receive. An SLA
includes a Traffic Conditioning Agreement (TCA) that gives detailed service parameters
such as service level, traffic profile, marking and shaping. SLA
can be static or dynamic.
28. What does RTCP provide to the sources?
RTCP
provides:
a)
Quality of service and congestion control
b)
Identification
c)
Session size estimation
d)
Session control
29. What is the advantage of label switching?
It
improves the performance and provides different QOS to different users. It also
speed up IP packet forwarding process and therefore reduce delay and improve
overall throughput of internet.
30. List out the characteristics of MPLS.
MPLS
characteristics that ensure its popularity are:
a)
Connection-oriented QOS support
b)
Traffic engineering
c)
Virtual private network(VPN) support
d)
Multi protocol support
31. What are the reservation & styles in RSVP?
Reservation
(i)Shared
(ii)Distinct
Styles in RSVP
(i)Write card filter reservation style
(ii)Fixed filter reservation style
(iii)Shared explicit reservation style
32. Define forwarding equivalent class (fec)
The
FEC for a packet can be determined by using parameter like
(i)Source/destination IP address
(ii) Source/destination port number
(iii)IP protocol id
(iv)Differentiated services code point
(v)IPV4 flow label
Through
the network known as Label Switched Path (LSP) must be defined.
Forwarding is achieved by doing a simple took u in a prided table that
maps label values to next lop address.
33. Define MPLS Label Format in RSVP MPLS is a mechanism used to speed up
IP packet forwarding process & therefore reduce delay & improve overall
throughput of internet.
Label
value
|
Exp
|
S
|
Time
to live
|
34. Compare Hop-By-Hop Routing & Explicit
Routing
HOP-By-HOP
|
EXPLICIT
|
(i)Each LSR independently
choose the next hop for each FEC.
(ii)It does not support
traffic engineering or policy routing.
|
(i)Ingress LSR specifies all of the LSR’s on an LSP.
(ii)It provides traffic engineering
& policy routing.
|
35. Define The Format Of RTP Leader
V
|
P
|
X
|
CC
|
M
|
PLT
|
SQNO
|
TIME STAMP
|
||||||
SYNCHRONIZATION
SOURCE IDENTIFIERS (SSRC)
|
||||||
CONTRIBUTING
SOURCE IDENTIFIER (CSRC)
|
||||||
.
.
.
.
|
||||||
CSRC IDENTIFIER
|
V à Version (2 bit)
P à padding (1 bit)
X à Extension (1 bit)
CC à CSRC count (4 bit)
M à Marker (1 bit)
PLT à Payload type (7 bit)
SQNOà sequence no. (16 bit)
Time
Stamp à (32 bit)