Networking Devices: Evaluating Switches and Bridges in Network Design

This assignment delves into the analysis of networking devices, specifically focusing on the functionalities of switches and bridges within a network infrastructure. The first task addresses the issue of Ethernet switches potentially running out of buffers, leading to frame drops. The solution proposed involves increasing Ethernet input ring buffers and utilizing Virtual Output Queues to manage data flow and prevent collisions. The second task evaluates the replacement of hubs and bridges with a single 96-port 10Mbps switch in a network topology. The analysis highlights the inefficiencies of hubs and bridges, particularly their inability to filter data and determine the best path for data packets. The implementation of a switch is recommended to improve network efficiency by reducing traffic, incorporating error checking, and providing dedicated bandwidth to connected hosts. The assignment emphasizes the advantages of switches in terms of collision domain separation and the ability to maintain consistent data transfer speeds, thereby upgrading the original network setup for enhanced performance.

Networking devices 1
NETWORKING BY SWITCHES AND BY BRIDGES

Networking devices 2
NETWORKING BY SWITCHES AND BY BRIDGES
Task (a)
An Ethernet switch may run out of buffers due to several reasons and in turn, drop some
frames before they reach the destination node or switch. Imposing half duplex semantics on
some of the switch ports and halving their data rates may not be a solution. This is because half
duplex Local Area Networks (LANs) may cause devices fail to send or receive data
simultaneously (Held, November 1998). It would mean that we have only escalated our problem
instead of solving it. The working of a half-duplex Local Area Network operates in a way that
when one device sends a data frame, all the other devices connected to the switch listen to the
frame and this is prone to collision. In the attempt to prevent any frame drops, we still want a
condition where all devices connected can send and receive data packets simultaneously without
experiencing collision which is not possible with half-duplex Local Area Network
communication mode.
The best solution we can have to prevent the switch from running out of buffers is
increasing the Ethernet input ring buffers. The use of Virtual Output Queues is also satisfactory
since the sending port will have to wait for the receiving port to have room before sending any
frame (Ciampa, January 9, 2003). This means. If there is no space in the port of receipt for long,
the frames will stay in the sending port buffer. If it is full, then the port will send a signal to the
sending port it is connected to, to pause the transmission and a continue signal when there is a
buffer.

Networking devices 3
Task b. (i)
In the topology above, it is possible to replace the above intermediate devices (the hubs
and bridge) with a single 96-port 10Mbps switch.
The hub as a multiport repeater will send all the packets it receives from the bridge to all the
devices connected to it with no data filtration and therefore, collision domain the collision
domain remains as one. In the data link layer, the bridge will filter all the data packets using the
Media Access Control (MAC) address of their source and destination (Bruce, 2010). Data
packets in the set up will not be efficiently relayed since the hub does not look for the best path
for each data packet but only forwards them (Bird & Harwood, 2002). This will amount to waste
of network resources due to the data packets that may be relayed to all nodes but expected by
only one node.
Including a switch in the setup and doing away with the hub and the bridge will be
possible and we will have a buffer to improve the efficiency of the system. The switch having
more ports compared to the bridge and hub will lead to less traffic in the system and incorporate
error checking function before forwarding the packets.
Task b(ii)
The use of a switch will be an upgrade from the original one. The switch forwards
packets to the correct port only, and thus no data packets are received by the unintended receiver
or wastage of networking resources. This divides the collision domain of the hosts and keeps the
broadcast domain at a constant level (McQuerry, Feb 16, 1998). The switch will be able to
connect all the 80 hosts and give them a constant 10Mbps speed of operation since its buffer will
control the incoming and outgoing data packets. The upgrade is more efficient than the original

Networking devices 4
set up since having the devices connected with the initial topology would not allow any to ever
get to a speed of the 1000Mbps as indicated due to lack of data filtration and forwarding packets
to all the devices (Spurgeon, 2008).

Networking devices 5
References
Bird, D. & Harwood, M., 2002. Networking Components and Devices. [Online]
Available at: http://www.pearsonitcertification.com/articles/article.aspx?p=30191
[Accessed 28 August 2017].
Bruce, H., 2010. Networking: A Beginner's Guide. Fifth Edition ed. s.l.:McGraw Hill.
Ciampa, M., January 9, 2003. Networking BASICS (BASICS Series). Second Edition ed.
s.l.:Course Technology.
Held, G., November 1998. ata Communications Networking Devices: Operation, Utilization and
Lan and Wan Internetworking. Fourth Edition ed. s.l.:Wiley.com.
McQuerry, S., Feb 16, 1998. uthorized Self-Study Guide. Interconnecting Cisco. Network
Devices,. Part 1 (ICND1). Second Edition ed. s.l.:Cisco Press.
Spurgeon, C., 2008. Multi-Segment Configuration Guidelines. [Online]
Available at: http://www.ethermanage.com/ethernet/ch13-ora/ch13.html
[Accessed 28 08 2017].