Organizing Large Network Design
From Wikipractice
Work in progress: This article is being reviewed
Contents |
Introduction
When installing, deploying or migrating large infrastructure, organization of the work is the key criteria. This is what makes the difference between success and failure of a project. This also lead in satisfaction or dissactisfaction of customer and people involved in the project. The present document gives some idea and best practice to organize a large infrastructures deployment, based on experience acquired in large very infrastructure deployment.
This document is entirely focused in defining a strategy that allow industrial deployment.
Why a new infrastructure has to be deployed ?
There are many reasons why a new infrastructure has to be deployed: equipment presently in use are end of life, technology is obsolete. However, the major need for a new infrastructure is to put in place new services for supporting the business and strategy of the company.
How to organize the project
There are plenty of documentation related to best practice in project management. Therefore this document will not focus the project management itself, but more on the way to organize the design and implementation of a large infrastructure: this is, to my sense, the key part of the project which will condition the rest of its organization. The main steps of the organizational part are described below:
- Define the service the infrastructure will have to support.
- Classify these services according to their business importance as well as their technical requirement. This classification will be used for the definition of quality of service later.
- Enumerate the sites and location which will be impacted by the project.
- For each site, enumerate the services which will be used there.
- Define users categories for the different type of services.
The following paragraphs will detail the point enumerated above.
Note: The complete strategy described below is focused on creating standard design and services, to allow an industrial deployment and management of the infrastructure.
Define the services
What is my infrastructure for ?
In order to answer that question, you have to enumerate all services and applications running on your infrastructure. This includes business needs as well as technical requirment. It is crucial to know what you will have to carry on your network before starting to design and migrate it.
As an example, IP Telephony is not tolerant to jitter, delay and packet loss: however, it requires few bandwidth per user depending on the codec used.
Classification of the services
What is the business importance of each of my services ?
All the services running on your infrastructure don't have the same business importance. Even more tnat this: depending on the time, some services might be more important that other.
For example:
- ERP might be much more important, in some business, at the end of the fiscal year, when account are closed.
- IP telephony is always the highest priority in a call center.
- E-mail could be of the highest priority just a few days of the year, when the answer of a very important has to be sent.
The best way to classify the different services is to try to much to the different class of service. Most of the time this amount will be limited to 4:
- Real Time
- High priority
- Medium priority
- Best effort
Depending on the manufacturer of equipments or habits, the terms can vary.
When your classification is finished, make sure your top management will validate it and sign: this will solve issue of everyone thinking that his service is much more important than the other. This will also help you to justify additional costs if the management decides to change one or more priority in the service.
Enumeration the locations involved by the project
What should I migrate or upgrade ?
After having answered that question, you should have a list of all sites or locations you will have to upgrade or migrate. This is usually done through an audit. This must contain:
- The amount of users (the list is even better)
- The amount of port used which includes
- The amount of user ports
- The amount of server ports
- The amount of printer ports
- All additional devices connected to the location's network
- The amount of port per type and per cabinet or communication room
Try to also evaluate the way the site or location evolved the one or two last years. The result of this analysis will allow you to forecast the amount of port you might ned in the near future.
Enumeration services used on each location
What is used where ?
The goal of this step is to define a common denominator for all locations or sites, which will help us to create standard design for industrial deployment and management. The idea is to minimize as much as possible exceptions.
While doing this exercise, you might be surprised to notice that services installed on some locations are not used while consuming resources.
Definition of users categories per service
What do my users need and how could I classify them ?
You have different users with different needs and different power using your infrastructure. As withs services, the idea is to create category of users sharing the same characteristics:
- Type of phone used.
- type of applications used.
- Amount of bandwidth consumed.
- Hierarchy level of the user (member of the board might need special attention).
Having sorted out the different characteristics, you will now be able to create classes of users. Avoid to create too many categories. You might have to create categories per services. You could for example create categories for IP telephony, and another one for data service. This depends strongly on the organization of your company.
Define your traffic management strategy
Traffic management is the way you will be handlinf your communication flow across the network. It starts at the end user workstation or phone, and end at your server, voice gateway, Internet acess router, video server, etc.
Before starting any deployment, you need to know how your traffic will be handled, which class of services you will configure, how much bandwidth you will allocate to them.
You also need to know if you plan to split different types of traffic between different VLANs. At this point, it is important to note that most IP Telephony manufactures strongly suggest to separate data from voice traffic in different VLANs.
Organizing your design
As said at the beginning of this document, the strategy is to standardize as much as possible to allow industrial deployment, which is the only one that is cost effective. In order to proceed in that way, you will now create site categories, like A,B,C,... and for each category, you will create one or more design type.
A good practice is to use letters for site categories and number for design type.
Categories
The site category classification depends more on the business needs and could be linked to SLA and the design type depends more on the technologies. It is up to you to define the categories that best fit your business, keeping in mind that there are some technology boundaries.
Example of site categories
As an example, site categories could go from A, for the smallest sites, to F for the largest. Again, this is only an example and might be different for your business needs.
Category A could be defined as follow:
- Amount of users: up to 4
- Amount of servers: 0
- IP Telephony: no
- Data services (coming from your service list): file sharing, ERP, Internet access.
- SLA: A
Category B could be defined as follow:
- Amount of users: 16
- Amount of servers: 1
- IP Telephony= yes
- Data services (coming from your service list): file sharing, ERP, Internet access.
- SLA: B
Design type
The goal of design type is to create as much as possible templates which just have to be slightly adapted to fit the site needs. As an example, a design type would contain:
- The standard list of equipment
- The list of VLSNs
- The default configuration
- etc.
A good practice is to create a document with has variable to be filled while designing like IP subnets and addresses, etc. IP addressing should be defines in the IP Address Plan.
When linking your design type to category, try to keep some capacity margin to allow some evolution on the site. This could be, for example, having 10% user margin on each location.
Example of design type
Design type 1, which would match category A above, could be defined as follow:
- LAN ports: 8
- Access router: DSL
Design type 2, which would match category B above, could be defined as follow:
- LAN ports: 24
- Access router: medium, leased line 512Kbps
- Voice gateway: small
