Introduction

Concept

NDAT stands for Network Design Automation tool. The Idea is to use MS Visio, as a specialized network CAD system and create low level design documents in visual way.

NDAT allows to use some drawing automations during design process and automatically exports data to table views.

Solution applicability

Biggest effort can be achieved on large network projects with low level design (LLD) phase.

However, features that help automate some device placement and linking tasks, can be used in any IT infrastructure projects with LLD phase.

If project includes only high level design (HLD) phase, NDAT can increase time expenses.

Design process change

Some LLD phase table documents are known to be extremely hard to create. The hardest one is links (cabling) table. And it is extremely hard to modify it during project in case of device placement changes.

Design process "as is":

Usually, infrastructure desing documenting process includes following steps or phases:

Step 1. Draw device placement plans (racks), draw linking diagram, draw L3 diagram, and, if needed, L4 traffic flows diagram.
Step 2. Manually create some work tables, to hand them over to field engineers:
- device naming and placement table;
- linking table;
- device and interface config table;
- detailed addressing plan;
- BGP session table;
- etc.

Design process "to be":

NDAT is intended to simplify infrastructure design documenting process in the following way:

Step 1. Draw device placement plans (racks), draw linking diagram (L2 diagram), draw L3 diagram, and, if needed, L4 traffic flows diagram. Use some drawing automations.
Step 2. Automatically create table reports to include them to LLD document set, or to provide them to field engineers
- device placement tables;
- link tables;
- patch-cord counts;
- automatically generate L2 and L3 interface description;
- detailed per-interface IP addressing plan;
- device, VRF and interfaces config tables (not fully supported in current release);
- BGP session table;
- static routes table;
- allowed traffic flows (in future releases).

Expected effects

NDAT usage expected affects are:

Automatic diagram to table consistency, decreased mistakes frequency;
Decreased total time expenses to produce LLD, while relatively increased time spent to develop network diagrams;
Decreased work table production time from days-weeks to hours. Increased LLD updateability.

Proof of concept

NDAT PoC was developed as VBA script set and was tested on large network project (complex enterprise Internet border, two DCs, 100+ network devices).

Achieved results:

In a critical moment during network designing/building process, we succeeded in providing customer additional project documents:
- device cabling info, including devices we were not responsible for;
- IP addressing info, including devices we were not responsible for.
Some documents were not developed manually at all, but were actively used during project implementation phase and were included in final LLD:
- linking (cabling) table and port L2 config parameters;
- detailed IP addressing plan;
- detailed list of BGP sessions;
- static routes table.
During project these tables were repeatedly [re]generated according to design changes (changes concerned IP addressing, device placement, traffic routing scheme).