LAN Switches: A Trend Worth Following…

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Aswitch is a special type of hub that forwards packets to the appropriate port
based on the packet’s address, automatically learns network addresses, and

gives each sender-receiver pair the full bandwidth of the network. A switch

segments networks into different subnets, thus keeping the network from being

overloaded with traffic.

Typically, a switch can either be unmanaged or managed. A managed switch can

either be a stackable switch or a chassis switch.

n Unmanaged

Switches: The unmanaged standalone switches are gradually replacing hubs in

most networks. These switches allow simultaneous transmission of multiple

packets via an internal high-speed data channel. The learning function in the

switch stores the address and corresponding port number of each incoming and

outgoing packet in a routing table. This information is subsequently used to

filter packets whose destination address is on the same segment as the source

address.

A typical unmanaged switch comes with the following features:

• Automatic detection of MDI-X and MDI crossover

• Conformation to IEEE 802.3 10BASE-T and IEEE 802.3u 100
  
  BASE-TX specifications

• Store-and-forward scheme to forward packets

• Frame filtering and forwarding for each port

• Automatic MAC address learning and aging

• Automatic local traffic filtering

• Auto-negotiation on duplex mode

n Stackable

Switches: The stackable switches are those where different standalone

switches are combined to perform the function of a single large switch.

A typical stackable switch comes with the following features:

• Fault tolerance so that if one switch fails, the other
  
  switches in the stack can continue to operate

• Port redundancy so that if one port fails, a backup port
  
  can be automatically substituted

• Hardware/software to let the user manage the switches
  
  using the Simple Network Management Protocol

n Chassis

Switches: These are much larger with several chassis/line cards, each having

several ports.

In addition, switches are also classified by the

functionalities of the layers of the OSI model of networking.

n Layer

2 switches: These are manageable switches that enable an administrator to

monitor the traffic passing through each port and to configure each port in the

switch. Besides, a typical layer 2 switch comes with the following features:

• IEEE 802.1D Spanning Tree support

• GVRP (GARP VLAN Registration Protocol) support for VLAN
  
  membership management

• IGMP snooping, to prevent broadcast traffic from flooding
  
  to all the ports within the switch.

• Link aggregation to improve the uplink traffic
  
  performance and provide link redundancy.

• IEEE 802.1Q/p support for VLAN and priority

n Multiple

Layer Switches: Switches support multiple layers (2, 3, and 4) protocols to

protect against obsolescence and to add new services such as traffic

classification, protocol filtering, and multicast to handle and prioritize

different types of traffic.

A typical multilayer switch has the following features:

• Supports RIP v1, v2 and OSPF routing functions.

• Supports multi-netting assigning multiple IP protocol
  
  interfaces to the same physical port

• Supports classless inter-domain routing (CIDR) to enable
  
  the efficient allocation of the IP address space

• Serves as DHCP server or client or relay

• Serves as DNS server or proxy

• Access control list for enhancing security purpose

• Bandwidth management for better usage

BUYING TIPS

n Proper Assessment:

It is imperative to have a proper assessment of the LAN requirements of an

organization. One important aspect to be kept in mind is the sort of

applications that are normally used, as the LAN capacity/speed would be

dependent on that.

n LAN

Layer/level: One should keep in mind the layer/level of the LAN where the

switch is going to be deployed. A chassis switch would be better deployed in the

head office, while a stackable switch would be better in the branch offices.

n Upgradation

Option: Multilayer switches are upgradable, but not beyond layer 3. In case

of organizations using multimedia applications, it is advisable to go for layer

4-7 switches.

n Enhancing

Performance: A switch will improve performance for any file servers or

workstations connected directly to it. Small network can use a switch instead of

a hub to give workstations maximum speed. If a network is large, it should have

at least one switch in every high-traffic workgroup. As a general rule, try to

get every file server, critical workstations, and print server connected

directly to a switch.

n Running

High-speed Applications: When a network will be using high-speed

applications like multimedia or video generally speaking, every workstation and

file server that will be using multimedia or video should be connected to a

switch to avoid transmission delays. Anywhere a 10/100 Fast Ethernet hub is

required small workgroups and large network alike will benefit more from using a

10/100 switch to maximize performance over a mere 10/100 hub alone.

n Full Duplex:

16 or 24-ports switches should run at 10/100 full duplex and have an auto

sensing capability

n Seamless

Connection: Should be perfect for running 10BaseT, 100BaseTX and 100BaseFX

hardware seamlessly

n Data Flow

Control: Data flow control should be able to filter out faulty data packets

n Data Packet

Switching: Must be capable of advanced store-and-forward data packet

switching

Market Information

The movements in the telecom space were also responsible for the switches

market being the most vibrant in the last fiscal. The total switches market in

the country has grown from Rs 798.7 crore in the last year to Rs 960.4 crore

this year, growing by 20 percent. Cisco has a 65 percent share of the switches

market too, with the main competition coming from Intel, Cisco and D-Link. In

the high-end chassis-based Layer 3 switch category, the main competition was

between Cisco and Enterasys, while Nortel dominated the Layer 4-7 segment.

The market witnessed compartmentalization of switches into various

categories. In terms of numbers, unmanaged fast Ethernet switches were sold in

large quantities. Among managed switches, 24 port switches were the most

popular.

The layer 3 switches sales did not really pick up. Even now there are more

layer 2 switches being sold than layer 3 switches.

This is because it is not very easy to configure the layer 3 switches. The

layer 3 market in India itself is not very well defined.

What a network needs is a high backbone coupled with a non-blocking

architecture, and only then will the features of the switch be best exploited,

be it layer 3, 4 or 5.

EXPERTS PANEL Anand Mehta, marketing manager, D-Link Manoj Chugh, president, Cisco Systems Ravi Chauhan, vice president, Nortel Networks