Lecture 8 Network Installation, Performance and Management

1. Lecture 8 Network Installation, Performance and Management

Network Installation

Network Performance

Network Management

When putting together costs for installation of a network, there are many hidden costs to be allowed for.

The reasons for this relate primarily to the need to minimize disruption both now and in the future.

Networks should be cabled with sufficient capacity for the future both in terms of traffic as well as connected ports, accessible pull boxes, etc. and should have all networking devices accessible to allow for quick replacement should any device fail.

Depending on the nature of the business and the network, disruption to the network could cost the company millions of pounds.

Three styles of wiring

Natural

Standardized

Structured

Natural this is the natural structure which has evolved over a period of time. Likely to include legacy cabling from previous networking layouts. Generally arises as the network expands in an ad hoc manner to meet the companies changing needs.

Standardized This arose through attempts to standardize the cabling on a particular technology. In order to solve the problems associated with natural wiring, they would run one high capacity system everywhere (often coax cable based) in an attempt to give suitable performance to all locations.

Unfortunately as demand continued to rise, yet more cabling was required often requiring a completely different wiring topology and perhaps of a different cable type from that already installed.

Structured The next solution basically breaks the problem into parts and cables accordingly.

Sockets (typically RJ45) are sited close to the users/printers/telephones and wired back using individual 8 core cables to patch panels in a wiring closet where there are Ethernet hubs, switches, token ring MAUs or telephone voice panels.

These patch panels then link together the various systems within the area to form an overall integrated computer networking and telecom system. These are then linked back to a central area.

Currently, the structured approach is the preferred choice and is used extensively through the University.

Using the structured cabling approach, it is relatively easy to change network topologies. Relocation of users, peripherals and telephones are also much easier.

It is common practice nowadays to floodwire buildings to minimise the need for additional cabling at a later stage. Often six ports will be wired for each likely user of the system to provide some level of expansion within the system. Typically a user will utilize three ports (computer, printer and telephone).

The first step in all but the smallest of networks is to plan the installation. This generally will start with Capacity Planning to determine cabling types and necessary equipment.

You must check for sources of noise which may interfere with the system.

In larger installations, you should be aware of the expected growth/decline of the company, new business areas and practices and likely staff movements.

Consider flood wiring with a high wiring ratio (perhaps 8:1 or 10:1) without necessarily fitting all sockets and equipment, etc.

Unless you are in the business of cabling, it is likely to be more economical and beneficial to contract this to a specialist. Cabling often involves holes to be cut in the building infra-structure requiring a suitable knowledge of structural issues.

The installation must meet all the requirements of the Health and Safety regulations

It is not recommended that you undertake an installation requiring structural alteration to a building without the help of suitably qualified specialists neither will your insurance company.

Care must be taken when connecting buildings in close proximity. Cables may need to be raised to high levels to allow high vehicles to pass underneath. However cables elevated to this height face other dangers, such as interference with power lines and lightning strikes.

Also if supply to the neighbouring building is from a different source, ground currents between the two systems are potentially lethal.

Use of fibre optic cable is now essentially standardised.

Structured Cabling normally uses either Unsheilded Twisted Pair (UTP) or Shielded Twisted Pair (STP)

UTP normally comes in three grades

CAT-3 (three twists/metre)

CAT-4 (four twists/metre)

CAT-5 (five twists/meter)

The higher the twists/meter, the better the screening factor and higher the price.

After completion of the network cabling and before it goes live, several procedures should be adopted.

Measure cable drops to equipment and document results.

Fully document the network and draw plans noting any IP numbers on the plans.

Baseline the network performance with specialist testing software (such as Sniffer)

This process will help identify faults as they arise in the future.

In order to ensure the network remains in good condition it is important that this be effectively managed.

Network Management falls into two main categories, namely

User Issues

Technical Issues

It is effective management of these two key factors that keep a network in good shape performing close to its theoretical performance.

Maintenance of User accounts creating users, passwords managing network disk space, freeing up of locked-up accounts.

Security issues associated with a large number of users, creation of group accounts to permit groups to work freely with each other etc.

The object of User maintenance is to try to keep the network at all times available and accessible without compromise on security issues.

Preparation and activation of contingency plans should the network be unavailable.

Technical issues divide into three distinct areas

Backup Maintenance

Software Maintenance

Performance Maintenance

Back-up maintenanceis in many ways the most critical. In case of disaster or accidental deletion, data can be retrieved.

Backups must be taken at regular intervals based on a corporate decision of what data interval you are prepared to loose. If the interval is too long, then either more frequent backups must be taken or consider investment be made in RAID technology.

Software Maintenancerequires the networking of various software applications, including upgrades and patches to be applied, audit trails protecting and printing.

Also includes the maintenance of of network devices, resetting print queues, maintenance of print servers, etc.

Management of interconnection devices (bridges, repeaters, gateways, etc.) using management tools utilizing, for example, Simple Network Management Protocol (SNMP).

Performance Maintenance Probably the most contentious of all issues. Once a network is installed or upgraded, the demand for its services is likely to increase. Also as users become more competent, information will be accessed more frequently putting even more traffic through the system.

Knowledge of which protocol to use and the appreciation of the effects at high data rates are essential when designing a system to ensure that system performance is maintained. It is not just capacity that is important but also the system throughput.

Reliability and Availability . One Hundred percent reliability is not possible but companies must be prepared to accept costs of installing extra cabling and equipment as a contingency.

Equipment purchased should have high MTBF (mean time between failures) rating as well as low MTTR (mean time to repair).

Designers should also choose products from reliable manufacturers who can be obtained quickly in the event of a failure. Also the availability of technical support from the vendor can also be important.

Check out JANET BackBone document on download page

NorMAN North East Metropolitan Area Network

Sunderland University Network Design

Lecture 8 Network Installation, Performance and Management

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Transcript of Lecture 8 Network Installation, Performance and Management