networking n stuff

Monday, July 23, 2018

IPv6 Lab: ISP & Client Side using Linux and Cisco

So I got really tired of reading about some basic IPv6  stuff and then forgetting it in a couple of months due to lack of practice and decided to set up a lab, which will contain both ISP and client sides.
This is what my topology will look like:

Components used:
  • Client_PC: Linux box with Ubuntu Server 18.04 installed with rdnssd (which is required to receive list of DNS servers via RA);
  • Home_Router: Linux box with Ubuntu Server 18.04 installed with wide-dhcpv6-client and radvd. (I had to install wide-dhcpv6-client, cause isc-dhcp-client, which comes by default, barely has any decent documentation and I wasn't even able to find out if it supports some of the features we're going to use in this lab);
  • ISP_R1: Cisco C7200 15.2(4)S6. It's used as DHCPv6 server as well.
How I'm going to assign IPv6 addresses to devices (I'll cover the details of different ways to achieve this further)
  • Client_PC: no DHCPv6 at all, only Stateless Address Autoconfiguration
  • Home_Router: DHCPv6.

Thursday, January 11, 2018

PPP LCP Keepalives & Troubleshooting it on Junos

Until the last week I had quite vague understanding of how LCP keepalives work - it was just one of those underlying protocols you have general knowledge about but never really go in details with. However, last week I encountered a problem that required slightly deeper understanding of how it works, and since some of the important details are not emphasized in the sources I read, I decided to write a short note on this topic.

So, how does it work? Let's take a look on a capture taken between a PPPoE server and a Linux client: