I initially stuck my TSHOOT GRE Deep Dive into the CCIE DMVPN bucket, but there is no such thing as too much practice or repetition, so get ready for some more here 🙂 Back to the basics of GRE and why this ancient protocol has any relevance It routes almost ANY kind of traffic which … Continue reading DMVPN – Review of GRE Tunnel setup, do’s and dont’s for configuration, case uses for a GRE Tunnel, and more!
The graphic above shows a VPN Tunnels two modes (Transport and Tunnel), along with how their payloads differ when configured with AH (Authentication only) and ESP (Encryption) on the tunnel, and what protocols correlate with all of it. (After watching the content of the CCIE R/S VPN Technology course, this article more than sums up … Continue reading TSHOOT – GRE DEEP DIVE!!! MTU / Fragmentation / TCP-MSS / PMTUD / Recursive Routing / Interface States / must know information for exam day!
Since we are now efficient at all things GRE and IPSec VPN at this point, that makes for a smooth transition into DMVPN , though I want to be crystal clear that the ROUTE Blueprint mentions only "Describe DMVPN (Single Hub)" so I will not be configuring it all over again, I do have a … Continue reading VPN: DMVPN, NHRP, and mGRE – Brief initial configuration review, verification review, and a link to all the gritty details!
So this is very odd to me after going through the last two posts of GRE and IPSec configuration, however once I found good information, configuration was a breeze. **PLEASE READ EXAM DAY NOTE AT END OF POST FOR SCENARIOS WHERE THE ROUTES HAVE TO BE IN THE DYNAMIC ROUTING PROTOCOL FOR OTHER ROUTERS** You … Continue reading VPN: DEEP Dive into GRE over IPSec configuration, explanation, and very easy actually once you are familiar with GRE and IPSec!
Now I've spent hours and hours trying to figure GRE out, this was not included in my CCNP ROUTE material except for some DMVPN using mGRE, however I did want to know for practical purposes how to encapsulate broadcast / multicast traffic over an IPSec tunnel which in turn needs a GRE tunnel as there … Continue reading VPN: DEEP Dive into GRE Tunnel configuration over OSPF, explanation of behaviors and how to overcome them!
This first image is a break down of the different types of VPN Packet Type by the headers / trailers (or lack thereof), and the following of your typical IPSec VPN Packet Type: The VPN generic representation of the IPSec VPN Packet above works for a general review, but there are details in the headers … Continue reading VPN: DEEP Dive into different VPN Packet Types, Packet Headers, and the differences between VPN Packets and their Modes!