ISP Design Guide: Separation of network functions – introduction and overview

PDF link is here

A reference guide for new & existing ISPs that need to understand network functions and separation.

“How do I add redundancy?”
“How do I scale?”
“How do I reduce downtime and operational costs?”

These are questions that I get asked practically every day as a consulting network architect that designs and builds ISPs.

In most cases the answer is the same whether the ISP uses fixed wireless broadband, copper or fiber to deliver the last mile – separation of network functions.

This illustrated guide is intended to define the topic and create visual context for each function using a network drawing. It’s the first in a new series on this subject.

A new series of content

This topic is deep and there is a lot to unpack so this will be the first segment in a series of blog posts and videos covering function separation.

Large ISPs typically already embrace the philosophy of separating network functions, so the focus of this series will be to help new or growing regional ISPs understand the design intent and the challenges/costs of running networks that don’t separate network functions.

WISP cheat sheet for MPLS/VPLS MTU

A guide for working with MTU and MPLS in a Wireless ISP

MPLS/VPLS MTU math can be complicated and is always a struggle to unravel.

To make it a little easier and put it into a WISP context, I designed this cheat sheet on 8.5 x 11 (to print for those that actually trust printers) and used common WISP equipment like MikroTik routers, Ubnt and Cambium radios with real world MTU values.

The MTU values are displayed in layers to make it easier to see where each value fits.

PDF is here

A starting point

These values are meant to be a starting point by representing the minimum values required for MPLS/VPLS with a single 802.1q VLAN tag.

In general, after going through hundreds of WISP migrations, I’ve found it to be easier to implement the minimum values required when working on a production WISP to identify the effective lowest MTU in the network.

Once the network equipment has been modified and has been running in a stable way on the minimum values, then higher values can be considered and implemented (now that the effective lowest MTU on the network is documented)