A full understanding of the mechanics of uRPF (the different behaviors of the two modes especially), along with knowing the basic configuration and theory of how VACLs work, so when you are faced with tricky word play / config examples of either on a Cisco exam or while on the job troubleshooting a production network! … Continue reading TSHOOT – Unicast Reverse Path Forwarding (uRPF), and VLAN Access-List (VACL) details reviewed for exam day!
There was some lack of depth in my review of ACL's in general, so wanted to jump on my lab to demonstrate some output and concepts for on the job and the exam room. If you read absolutely nothing else in this post, jump down to the bottom where a chaotic looking IPv6 ACL line … Continue reading TSHOOT – IPv6 ACL configs, quirks, and must know IPv6 subnetting for exam day!
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. The basics of GRE and IPSec Tunnel Modes and Packet Formats Basic GRE tunnel configuration has absolutely … Continue reading TSHOOT – GRE DEEP DIVE!!! MTU / Fragmentation / TCP-MSS / PMTUD / Recursive Routing / Interface States / must know information for exam day!
This graphic that I created to help myself understand CEF Hardware Packet Switching is also very similar to the Management Plane vs Control Plane vs Data (Forwarding) plane. Management Protocols run at the Management Plane (hence the name Mgmt Plane) is where Management Protocols such as SSH / Telnet / SNMP / HTTP / HTTPS … Continue reading TSHOOT – Management Plane vs Control Plane vs Data Plane, MPP (Management Plane Protection) review for exam day!
These 3 diagrams have been publicly available for years, I downloaded this TSHOOT Topology off Cisco's official learning forum, post can be viewed here. I doubt this is exactly the Topology used on exam day, it very well could be, however if this is not it the Topology will be something extremely similar to this. … Continue reading TSHOOT – Critical understanding of Cisco Published Topologies, troubleshooting methods, and must knows for exam day!
This will be the BGP Topology you will very likely be working Trouble tickets from on the TSHOOT, it could be iBGP or eBGP, and there is a whole lot of BGP to know even for that! Review of BGP BGP is called a "Path Vector" Protocol that basically is the internet at Layer 3, … Continue reading TSHOOT – Gigantic BGP review, verification commands, and troubleshooting for exam day!
To round off Redistribution series of posts for Dynamic Routing Redistribution, what better way to drive it home, than to Redistribute every Dynamic Routing Domain into every other one and see what we can break? There will be a LOT of output from this lab to demonstrate how to verify and configure / troubleshoot everything … Continue reading TSHOOT – Redistribution Part 5 – The OSPF / EIGRP / BGP / Redistribution lab!
Going back to this above visualization of 2-way Redistribution which is a perfect case use for a Route-Map to perform "Route Tagging" for routes being Redistributed, which assigns tag # values to Routes as they Redistribute and can filter (drop) routes that contain a certain tag value to ensure routes are not re-learned into their … Continue reading TSHOOT – Redistribution Part 4 – Route-Map review, and COMPLETE review of Redistribution issues and Troubleshooting – Must know info for exam day!
I will wrap this up with a look at OSPF and BGP Redistribution, above is a Topology I labbed during ROUTE studies of the BGP MED concept, this is to demonstrate visually the difference of iBGP vs eBGP being the AS that BGP Routers reside in. Troubleshooting Redistribution into OSPF and OSPFv3 OSPF is very … Continue reading TSHOOT – Redistribution Part 3 – OSPF, OSPFv3, and BGP Redistribution review and troubleshooting!
The above graphic is a visual demonstration of how Redistributing routes works, as we are not taking one route from a routing protocol and placing it into another protocol, we are taking routes from the IP table and placing it into "routing protocol data structures" if you remember that phrase. What Route Redistribution is at … Continue reading TSHOOT – Redistribution Part 2 – Detailed review of Redistribution, Seed Metric, RIPv2, RIPng, EIGRP IPv4 and IPv6 behaviors and troubleshooting!
While getting together some command prompt syntax from my lab, I got a jolt of nostalgia from labbing ROUTE, and decided to instead configure the lab Topology shown above as I started configuring my switches for Layer 3 routing and before I knew it I was troubleshooting OSPF and EIGRP Ajdacencies! I will try to … Continue reading TSHOOT – Redistribution Part 1 – Configuring an OSPF / EIGRP / iBGP Lab to completion, ready for Redistribution!
Route-Maps are used for multiple different purposes as shown in the example above, this specific Route-Map itself would never exist in a real world scenario, because the sequences demonstrate several different use cases for Route-Maps in the sequences. Review of sequences from the Route-Map posted above A few concepts of Route-Maps is that the "permit" … Continue reading TSHOOT – Route-Maps, Policy Based Routing (PBR), and Local Policy Routing review and troubleshooting!
Being that it has been quite awhile since my ROUTE, this will contain a lot of core / foundation concepts, and tie them into troubleshooting as I go. That said, here we go! OSPFv2 (IPv4) review and troubleshooting OSPF is configured with a Process # that is locally significant only "router ospf #" and networks … Continue reading TSHOOT – OSPFv2, OPSv3, OSPF Address-Families, huge LSA / LSDB review, and troubleshooting everything OSPF!
The displayed Topology is just an image from a ROUTE lab I ran through years ago, however most of the Review / Troubleshooting will be reviewed in IPv4 as it is exactly the same in IPv6 mode, literally only difference is the IPv6 Multicast Address. Named Mode EIGRP is a whole nother animal, it should … Continue reading TSHOOT – EIGRP for IPv4, IPv6, and the beast of a topic EIGRP “Named Mode” review and troubleshooting!
There are RIPv2 and IPv6 RIPng posts previously regarding this subject, so I will be Rippng (pun intended) right on through this article, if you type "Rip" into the search function a lot of the articles for RIPv2 will be redistribution and one for RIPng which is very straight forward. However those are more focused … Continue reading TSHOOT – Ripv2 and RIPng review and troubleshooting!