Control / Facilitate CDN traffic with
~ Mikrotik Router ~
First some DRY theory !
CDNs replicate content in multiple places. There’s a better chance of content being closer to the user, with fewer hops, and content will run over a more friendly network. The general idea of a CDN is to deliver content as fast as possible to the user without compromising the user’s experience. Usually, a CDN have global location servers, called Point of Presence. These PoPs store data as cache. When a user requests for a website, the nearest PoP will handle the request using stored cache.
The BIG players such as Google in order to enhance user experience have tried to get as close to the user as possible by direct peering with the regional service providers and provide contents using CDN (Content delivery network) providers. Google is having its own CDN network branded as a service called Google Global Cache (GGC)
Nowadays all the major ISPs have CDN facility , which tremendously helps them to reduce burden on there internet feed. Without CDN, cost of real internet bandwidth will be a heavy burden for any OP. With CDN user will get better video streaming experience.
I know few ISP’s here in Karachi (& one particularly originated from Gulshan Area) which totally relies on CDN (more than 50-60% of there internet data is routing via CDN) , I have used one of them, there real internet speed is pathetic but if you browse YT/FB they works excellent.
Scenario:
Our upstream ISP have CDN server installed in there data center & traffic going to CDN have no limit. But we want to control the traffic as following
1 Mb package Users break up for bandwidth controlling …
- 1mb internet bandwidth
- 1mb CDN bandwidth
So if a user is surfing the internet he will get full 1mb internet speed, & if he uses the traffic going to YOUTUBE CDN , He will get another 1 mb (additional).
Virtually he will get 2mb in total.
Using Mikrotik, we can achieve this task by using Firewall Mangle & Queues Tree. Same can be done with Mangle & PCQ base simple queues too. It’s a debatable topic on what to use, & depends on the selection, mangle marking method would also be changed.
Every network is different so one configuration cannot fit all. Number of users & traffic volume plays vital role in selection of marking / queue type to use.
Choose the marking/queue type wisely to save your Mikrotik CPU from becoming Mr. SPIKY 
YKWIM 
Disclaimer: This is just an example for sharing purposes ONLY & yes there are many other methods and tuning techniques you can adopt to make this process much more efficient.
Script !
#=================================================== # CDN PACKET MARKING SCRIPT using Mangle/Queue.Tree # By Syed.Jahanzaib # Email: aacableAThotmailDOTcom # https://aacableDOTwordpressDOTcom # March 2019 #=================================================== # Address list name which is created dynamically by radius or you can go with manual method too # This is important ... it can be done by varieties of ways, select one that matches your network design #1Mb #2Mb #Create Address List which will contain CDN server's IP addresses /ip firewall address-list add address=1.2.3.4/24 list=cdn_list add address=5.6.7.8/32 list=cdn_list # Copy paste following rules & make sure to move these MANGLE rules to TOP position, # so that they can be applied before any other rule, (for cdn) /ip firewall mangle add action=mark-packet chain=postrouting dst-address-list=cdn_list new-packet-mark=cdn_1mb_up passthrough=no src-address-list=1Mb add action=mark-packet chain=postrouting dst-address-list=1Mb new-packet-mark=cdn_1mb_down passthrough=no src-address-list=cdn_list add action=mark-packet chain=postrouting dst-address-list=cdn_list new-packet-mark=cdn_2mb_up passthrough=no src-address-list=2Mb add action=mark-packet chain=postrouting dst-address-list=2Mb new-packet-mark=cdn_2mb_down passthrough=no src-address-list=cdn_list # Define Queue Type & limitation that we want to provide to each package /queue type add kind=pcq name=1mb-cdn-download pcq-classifier=dst-address pcq-dst-address6-mask=64 pcq-rate=1024k pcq-src-address6-mask=64 pcq-total-limit=1024KiB add kind=pcq name=1mb-cdn-upload pcq-classifier=src-address pcq-dst-address6-mask=64 pcq-rate=1024k pcq-src-address6-mask=64 pcq-total-limit=1024KiB add kind=pcq name=2mb-cdn-download pcq-classifier=dst-address pcq-dst-address6-mask=64 pcq-rate=2048k pcq-src-address6-mask=64 pcq-total-limit=2048KiB add kind=pcq name=2mb-cdn-upload pcq-classifier=src-address pcq-dst-address6-mask=64 pcq-rate=2048k pcq-src-address6-mask=64 pcq-total-limit=2048KiB # Add Queue/Speed Limitation using above Queue Types to firewall mangled/marked packets /queue tree add name="CDN - 1mb - upload" packet-mark=cdn_1mb_up parent=global priority=1 queue=1mb-cdn-upload add name="CDN - 1mb - download" packet-mark=cdn_1mb_down parent=global priority=1 queue=1mb-cdn-download add name="CDN - 2mb - upload" packet-mark=cdn_2mb_up parent=global priority=1 queue=2mb-cdn-upload add name="CDN - 2mb - download" packet-mark=cdn_2mb_down parent=global priority=1 queue=2mb-cdn-download # Script Ends Here.
1mb users CDN usage Graph.
As shown in above example image, 1mb users are using 227 mb of CDN (YT) bandwidth, (it was off time with lesser number of users, in peak traffic reaches in Gb’s) & real internet bandwidth is free OR available for other tasks/users, thus providing relief to the real internet bandwidth pipe.
Regard’s
Syed Jahanzaib
