Unit-2
(Physical and Data Link Layer)
IEEE 802 standards for LAN
The IEEE 802 is a set of protocols that is employed in the management of network
protocols. In IEEE standard IEEE 802.3, IEEE 802.4, and IEEE 802.5 are known as
Ethernet, token bus, and token ring networks. Each standard has its own topology,
access control, and frame format .
What is IEEE 802.3?
IEEE 802. 3 is the standard of Ethernet that is used in the bus topology, whereby the
devices are connected directly to the communication line and are served in turns to
enable them to access the line. The CSMA/CD protocol is used by the network in
order to manage the access acknowledging collision while it is trying to put through
data packets. For data sending, a device has to listen in order not to interrupt some
other device that may be transmitting. In case two devices are transmitting at the
same time, this is handled by collision detection that will ensure both devices are
made to stop transmitting, after which transmission is resumed after a certain interval
of time has been created.
Advantages of IEEE 802. 3
Simple Protocol: CSMA/CD makes the ease of implementation of Ethernets.
Cost-effective: IEEE 802. 3 uses basic technology without modems and other
modem fancy equipment; thus, it avoids the need to make extra expense in
installation or for timely maintenance.
Widespread Adoption: Currently, Ethernet is one of the most popular established
network standards across the globe, which simply means that compatibility of
Ethernet hardware and software equipment will comprise switches, routers, and
NICs.
Disadvantages of IEEE 802.3
Decreased Efficiency at High Loads: If the number of devices in the network
rises, then the collision incidences are more frequent, hence pulling down the
efficiency and the throughput of large networks.
Not Suitable for Real-Time Applications: Due to the fact that it is a collision-
based system, IEEE 802. 3 is not good for real-time operation requirements such
as video conferencing and live streaming, playing games, and so on.
Limited Priority Support: Many networks do not have a mechanism of identifying
which of the data packets is more important than others. This is particularly the
case where several packages of data have to get to a specific destination before
other nonurgent packages like videos or voice do.
,What is IEEE 802. 4?
IEEE 802. 4 explains what token bus standards are. Token passing is a protocol in
which there is a token—a specific data packet that passes through the stations that
may be formed in a bus or tree topology. Every station that possesses the token is
allowed to transmit data, and therefore, there can never be a collision of data. Thus,
this token-passing method is more controllable with access than to the CSMA/CD due
to the structured store and forward nature of the protocol.
Advantages of IEEE 802. 4
High Efficiency Under Heavy Load: Token Bus networks are specifically ideal for
high-traffic networks, as collisions are completely eliminated notwithstanding the
size of the network.
Prioritization of Stations: Standard: IEEE 802. 4 It makes some stations have
charge over others so as to ensure that the important jobs are processed first. This
is important, especially in industrial applications or the overall network, when some
or certainly certain data has to be updated in real time, for instance.
Real-Time Traffic Support: This is because it allows real-time data transfer since
the token allows only those who have authorized access to the network; it is
therefore ideal in the industrial area that needs frequent data transfer.
Disadvantages of IEEE 802. 4
Complex Protocol: Token passing protocol, which is much more complex to be
implemented in comparison to CSMA/CD. It employs other interface equipment, for
instance, the modems, and therefore, the general start-up and operational costs of
such a system are usually high.
Less Flexibility: Logical ring also suggests that for opposing Ethernet networks,
adding or removing the stations in the network is complicated.
Obsolete in Modern Networks: Today the token bus networks are not widely
used due to Ethernet and are very easily substitutive by others faster, cheaper, and
simpler networks.
What is IEEE 802. 5?
The token ring standard is one in which the stations aggregate IS in what can
physically be referred to as a ring where the token is passed from one station to
another. Like in Token Bus, the token grants permission to send, but the physical
layout of the network is not the same. URLs in the ring create positions for a token in
the organization of the token ring.
Advantages of IEEE 802. 5
No Collision: Like in Token Bus, Token Ring does not have collision data in the
network because only one station sends data in the network at a particular period
of time.
Support for Large Data Transfers: Other vile standards which he pointed that
regulated the size of fields in the data frames differed from the IEEE 802. 5 is for
, variable size data frames which makes its use useful in instances that involve large
data frames such as file transfer or a video stream.
Real-Time and Interactive Applications: Because there is no limit in data field
size and very efficient network topology, Token Ring most suits for real-time
applications like video conferencing, online games, and client-server activities.
Disadvantages of IEEE 802. 5
Moderate Complexity: Relative to the other network, the token ring can be
considered as moderate complex because, in order for the communication
between the stations to occur properly, modems are needed. This is time-
consuming and expensive, hence contributing to the total cost of developing the
network.
Dependency on Token: Of course, the entire network is associated with the
functionality of the token. The problem with this setup is that if the token has been
lost or becomes corrupted, the network halts and would take time before sorting,
which in the process creates downtimes.
Less Popular in Modern Networks: Token Ring networks are comparatively
costly and elaborate than the Ethernet networks and hence are not so widely used
as the latter. Ethernet dominates current-day networks because of the simplicity of
the technology and the fact that it is cheaper than the token ring.
Difference between IEEE 802.3, 802.4 and 802.5
IEEE 802.3 IEEE 802.4 IEEE 802.5
Topology used in
Topology used in IEEE Topology used in IEEE 802.5
IEEE 802.4 is Bus or
802.3 is Bus Topology. is Ring Topology.
Tree Topology.
Size of the frame
Size of the frame format in Frame format in IEEE 802.5
format in IEEE 802.4
IEEE 802.3 standard is standard is of the variable
standard is 8202
1572 bytes. size.
bytes.
There is no priority given in It supports priorities In IEEE 802.5 priorities are
this standard. to stations. possible
Size of the data field is 0 to Size of the data field No limit is on the size of the
1500 bytes. is 0 to 8182 bytes. data field.
Minimum frame required is It can handle short It supports both short and
, IEEE 802.3 IEEE 802.4 IEEE 802.5
64 bytes. minimum frames. large frames.
Efficiency decreases when Throughput &
Throughput & efficiency at
speed increases and efficiency at very
very high loads are
throughput is affected by high loads are
outstanding.
the collision. outstanding.
Modems are
Like IEEE 802.4, modems are
Modems are not required. required in this
also required in it.
standard.
Protocol is Protocol is moderately
Protocol is very simple.
extremely complex. complex.
It is not applicable on Real It can be applied for Real time
time applications, applications and interactive
It is applicable to
interactive Applications applications because there is
Real time traffic.
and Client-Server no limitation on the size of
applications. data.
IEEE 802.3, IEEE 802.4, and IEEE 802.5 to suit different needs of the network
topology and functionality. While IEEE 802. 3 (ethernet) is the most used
because of its simplicity and also because the cost is relatively cheap as
compared to the rest, IEEE 802. 4 (token bus) and IEEE 802. 5 (token ring)
ensure that there is structured access control as well as high throughput in
cases that demand real-time processing of data. But token bus and token ring
are much more complicated as compared to Ethernet, and they are not used
widely in modern networks as well.
(Physical and Data Link Layer)
IEEE 802 standards for LAN
The IEEE 802 is a set of protocols that is employed in the management of network
protocols. In IEEE standard IEEE 802.3, IEEE 802.4, and IEEE 802.5 are known as
Ethernet, token bus, and token ring networks. Each standard has its own topology,
access control, and frame format .
What is IEEE 802.3?
IEEE 802. 3 is the standard of Ethernet that is used in the bus topology, whereby the
devices are connected directly to the communication line and are served in turns to
enable them to access the line. The CSMA/CD protocol is used by the network in
order to manage the access acknowledging collision while it is trying to put through
data packets. For data sending, a device has to listen in order not to interrupt some
other device that may be transmitting. In case two devices are transmitting at the
same time, this is handled by collision detection that will ensure both devices are
made to stop transmitting, after which transmission is resumed after a certain interval
of time has been created.
Advantages of IEEE 802. 3
Simple Protocol: CSMA/CD makes the ease of implementation of Ethernets.
Cost-effective: IEEE 802. 3 uses basic technology without modems and other
modem fancy equipment; thus, it avoids the need to make extra expense in
installation or for timely maintenance.
Widespread Adoption: Currently, Ethernet is one of the most popular established
network standards across the globe, which simply means that compatibility of
Ethernet hardware and software equipment will comprise switches, routers, and
NICs.
Disadvantages of IEEE 802.3
Decreased Efficiency at High Loads: If the number of devices in the network
rises, then the collision incidences are more frequent, hence pulling down the
efficiency and the throughput of large networks.
Not Suitable for Real-Time Applications: Due to the fact that it is a collision-
based system, IEEE 802. 3 is not good for real-time operation requirements such
as video conferencing and live streaming, playing games, and so on.
Limited Priority Support: Many networks do not have a mechanism of identifying
which of the data packets is more important than others. This is particularly the
case where several packages of data have to get to a specific destination before
other nonurgent packages like videos or voice do.
,What is IEEE 802. 4?
IEEE 802. 4 explains what token bus standards are. Token passing is a protocol in
which there is a token—a specific data packet that passes through the stations that
may be formed in a bus or tree topology. Every station that possesses the token is
allowed to transmit data, and therefore, there can never be a collision of data. Thus,
this token-passing method is more controllable with access than to the CSMA/CD due
to the structured store and forward nature of the protocol.
Advantages of IEEE 802. 4
High Efficiency Under Heavy Load: Token Bus networks are specifically ideal for
high-traffic networks, as collisions are completely eliminated notwithstanding the
size of the network.
Prioritization of Stations: Standard: IEEE 802. 4 It makes some stations have
charge over others so as to ensure that the important jobs are processed first. This
is important, especially in industrial applications or the overall network, when some
or certainly certain data has to be updated in real time, for instance.
Real-Time Traffic Support: This is because it allows real-time data transfer since
the token allows only those who have authorized access to the network; it is
therefore ideal in the industrial area that needs frequent data transfer.
Disadvantages of IEEE 802. 4
Complex Protocol: Token passing protocol, which is much more complex to be
implemented in comparison to CSMA/CD. It employs other interface equipment, for
instance, the modems, and therefore, the general start-up and operational costs of
such a system are usually high.
Less Flexibility: Logical ring also suggests that for opposing Ethernet networks,
adding or removing the stations in the network is complicated.
Obsolete in Modern Networks: Today the token bus networks are not widely
used due to Ethernet and are very easily substitutive by others faster, cheaper, and
simpler networks.
What is IEEE 802. 5?
The token ring standard is one in which the stations aggregate IS in what can
physically be referred to as a ring where the token is passed from one station to
another. Like in Token Bus, the token grants permission to send, but the physical
layout of the network is not the same. URLs in the ring create positions for a token in
the organization of the token ring.
Advantages of IEEE 802. 5
No Collision: Like in Token Bus, Token Ring does not have collision data in the
network because only one station sends data in the network at a particular period
of time.
Support for Large Data Transfers: Other vile standards which he pointed that
regulated the size of fields in the data frames differed from the IEEE 802. 5 is for
, variable size data frames which makes its use useful in instances that involve large
data frames such as file transfer or a video stream.
Real-Time and Interactive Applications: Because there is no limit in data field
size and very efficient network topology, Token Ring most suits for real-time
applications like video conferencing, online games, and client-server activities.
Disadvantages of IEEE 802. 5
Moderate Complexity: Relative to the other network, the token ring can be
considered as moderate complex because, in order for the communication
between the stations to occur properly, modems are needed. This is time-
consuming and expensive, hence contributing to the total cost of developing the
network.
Dependency on Token: Of course, the entire network is associated with the
functionality of the token. The problem with this setup is that if the token has been
lost or becomes corrupted, the network halts and would take time before sorting,
which in the process creates downtimes.
Less Popular in Modern Networks: Token Ring networks are comparatively
costly and elaborate than the Ethernet networks and hence are not so widely used
as the latter. Ethernet dominates current-day networks because of the simplicity of
the technology and the fact that it is cheaper than the token ring.
Difference between IEEE 802.3, 802.4 and 802.5
IEEE 802.3 IEEE 802.4 IEEE 802.5
Topology used in
Topology used in IEEE Topology used in IEEE 802.5
IEEE 802.4 is Bus or
802.3 is Bus Topology. is Ring Topology.
Tree Topology.
Size of the frame
Size of the frame format in Frame format in IEEE 802.5
format in IEEE 802.4
IEEE 802.3 standard is standard is of the variable
standard is 8202
1572 bytes. size.
bytes.
There is no priority given in It supports priorities In IEEE 802.5 priorities are
this standard. to stations. possible
Size of the data field is 0 to Size of the data field No limit is on the size of the
1500 bytes. is 0 to 8182 bytes. data field.
Minimum frame required is It can handle short It supports both short and
, IEEE 802.3 IEEE 802.4 IEEE 802.5
64 bytes. minimum frames. large frames.
Efficiency decreases when Throughput &
Throughput & efficiency at
speed increases and efficiency at very
very high loads are
throughput is affected by high loads are
outstanding.
the collision. outstanding.
Modems are
Like IEEE 802.4, modems are
Modems are not required. required in this
also required in it.
standard.
Protocol is Protocol is moderately
Protocol is very simple.
extremely complex. complex.
It is not applicable on Real It can be applied for Real time
time applications, applications and interactive
It is applicable to
interactive Applications applications because there is
Real time traffic.
and Client-Server no limitation on the size of
applications. data.
IEEE 802.3, IEEE 802.4, and IEEE 802.5 to suit different needs of the network
topology and functionality. While IEEE 802. 3 (ethernet) is the most used
because of its simplicity and also because the cost is relatively cheap as
compared to the rest, IEEE 802. 4 (token bus) and IEEE 802. 5 (token ring)
ensure that there is structured access control as well as high throughput in
cases that demand real-time processing of data. But token bus and token ring
are much more complicated as compared to Ethernet, and they are not used
widely in modern networks as well.
