Network Hardware

Network hardware mostly works on layer 1, layer2 and layer3 on the OSI reference model. Cisco router operates at layer3 of the OSI model. While bridge; Switch works on layer 2 on the OSI model. Knowing the network hardware is essential in designing the computer network as in the previous networking scenario the Guinea mining.

1. Ethernet Hubs

Ethernet Hubs are considered as legacy network hardware that cannot utilize the LAN bandwidth efficiently. Therefore we are not using this network hardware in the scenario, but we need to know why it is not popular anymore.

Ethernet Hubs operate at layer 1 of the OSI model that functions as multiport repeaters or amplifiers. They share the limited bandwidth (10Mbps) amongst all network hardware, defining a single collision and broadcast domain. Due to CSMA/CD (collision control mechanism) and the limitation of shared Ethernet, hubs effectively only allow at best 30-40% network throughput. This bandwidth is then shared between all network hardware devices in the LAN. At very high network transmission rates, the use of a single collision domain (Hub topology) results in a statistically large number of data collisions, station timeouts and data retransmissions.

Network Hardware - Hub

Using hubs in high speed LANs will result in poor network performance, excessive data collisions and the potential for devices to time out and disconnect from the network.

Hubs also allow network data to be sniffed and sensitive information to be intercepted.

2. Switches

All the network configurations in this scenario will use Switches as network hardware for computer connections to the network. Network hardware switches greatly improve the throughput of Ethernet networks. Network hardware switches allow the migration to mixed 10/100 Mbps and higher speeds, and greatly reduce the impact of data collisions on the LAN. Intelligent switches offer numerous performance and management advantages, including the definition of virtual LANs (VLANs) and the ability to perform multicast control (necessary for video conferencing applications). Many switches also support the ability to perform special link aggregation which can provide additional bandwidth to the LAN when required.

Switches network hardware have characteristics as follows:

1. Learn MAC addresses of the network hardware connected to it.
2. MAC address table is built and maintained
3. Broadcast/multicast frames are flooded to all ports
4. Spanning Tree Protocol (STP) is used to eliminate bridging loops

Which network hardware switches are recommended to deploy in the networking scenario?

1. Provides 100 Mbps switched connection to the desktop
2. Provides 1 Gigabit to servers and inter-switch links (uplinks)
3. Support command line, SNMP v2 and Telnet based management
4. Support Spanning Tree Protocol (STP)
5. Support VLAN
6. Support Virtual Trunking Protocol for interlink VLAN across multiple switches
7. Support STP protocol per VLAN basis
8. Provide IP multicast support

Network Hardware - Switches

3. Routers

Network hardware that operates at layer 3 – network layer in the OSI model is Router. Routers are network hardware that provide internetwork connectivity between different networks and make intelligent packet forwarding possible. Routers are used to connect to WAN services technologies and can optionally provide basic network security through packet filtering (extended access-lists).

Network Hardware - router

Network hardware router is like a computer, it has internal components that you need to be familiar with in regards to the router storage:

1. ROM: preprogrammed, non-writable memory containing bootstrap program – the operating system IOS software and the Power-on Self-test (POST) program

2. Flash: non-volatile but programmable memory containing the proprietary Cisco operating system (IOS) program.

3. RAM: volatile memory containing the running operating system and configuration information.

4. NVRAM: non-volatile but persistent memory that contains the backup copy of the startup configuration (startup-config) file and virtual configuration register.

Note that the content of non-volatile memory (such as ROM, flash, and NVRAM) remain when the router is powered-off. The contents of volatile memory (RAM) will lost when the router is powered down.

The following are the characteristics of the network hardware router:

• Layer 3 address is always used for all determination where all the information will travel to destination addresses
• Path selection is always optimal
• Packet forwarding is based on entries in a route table. Optimal path can be selected by many possible choices.
• Router use routing protocols to communicate route information with other routers. For large networks the use of dynamic routing protocols such as RIP; EIGRP; OSPF are required.
• By default all routers will block broadcast packets
• Must use both layer 2 (MAC address) and layer 3 addresses
• Security and control can be implemented at layer 3 by using extended access control list

Selecting network hardware router for your Wide Area Network infrastructure should has the following standard:

1. Support IP routing
2. Should be modular and rack-mounted (optional)
3. Support to OSPF routing protocol for connecting to the core WAN of your global corporate.
4. Support to the necessary WAN connection types when required such as Frame relay; ISDN; analogue PSTN and ATM.
5. Support extended access lists (packet filter)
6. Cisco IOS 12.1 or above
7. Support command l ine interface, Telnet and SNMP v2 management.
8. Support IP multicasting (CGMP, IGP and PIM)

Internetwork functionality is greatly influenced by the performance and configuration options provided by the provisioned router and interconnecting WAN service. Such options as Quality of Service (QoS), IP multicast and extended access-lists may not be available on low-end non-approved routing platforms, thus making the deployment of services such as VoIP and interactive message collaboration impossible.

See also:

• Computer networking hardware
• Router connection – the basic guideline
• The best wireless routers – the tips
• The urgency of tape backup solutions