Really Awesome Network Config Differ Tricks we use to forget

Install Rancid

First install rancid via the repositories :

aptitude install rancid

Maybe it will not install the CVS dependency, if it is the case you can still install it later.

Most of files should be located in

/var/lib/rancid/

. Only the config file is located in

/etc/rancid/

The script files which are going to save your configs are located in the

../bin/

directory.

SAVE ALL THE CONFIGS!

Configure Router

Brocade

On Brocade devices, I strugeled at the beginning until I found out the problem was the SSH cryptographic method, and then that I needed the “skip-page-display” option set to get full config saved :

enable read-only-password anypassword
privilege exec level 5 skip-page-display
username rancid privilege 5 password yourpassword

Check that ssh access-list grants you access to the device.

JunOS

set system login class noc permissions view
set system login class noc permissions view-configuration
set system login user rancid authentication plain-text-password/encrypted-password
set system login user rancid class noc

Building a fast CDN with anycast (BGP based)

What is anycast ?

Actually, it’s not a protocol, it is not a variant of multicast or broadcast. Anycast is just the name given to a unicast IPv4 or IPv6 address that’s announced from several routers inside an AS or WAN.

How does it work ?

Anycast lets the internal routing protocols like OSPF, EIGRP or iBGP handle these different announcements and select the fastest path via their respective selection algorithms, i.e. Dijkstra for OSPF.

What does it offer ?

Anycast provides a “geographically” distributed network that enables fast content delivery. Web-services are, as we know, Domain Name System aware and also dependent. Web is global and without frontiers, contents should be accessible and usable from anywhere, but physics are still a reality on planet Earth. Of course, we discovered traffic black holes some years ago but are still facing latency issues when it’s about distributing contents from the one side of the world to the other. Anycast provides, combined with the Domain Name System, a very fast responsiveness of all web-based applications and contents we might want to deliver. Anycast is often used in Content Delivery Networks (CDNs) like Cloudflare or Akamai.