I want to first say the top half of this will be the heavy duty CCNP ROUTE details needed for the exam, I'll try to fill in the differences as much as I can in the middle, and at the bottom is a real world way for actual network admins to configure and view Netflow … Continue reading Netflow : Heavier ROUTE config on top half, light weight config for real world at the bottom, some comparison of v5 to v9!
If needed I'll just use the IP SLA Topology I configured for an demonstration purposes, but wanted to touch on maybe some CCNA topics of encapsulation of Ethernet interfaces, as well as PPPoE as the exam will ask some questions about it. One interesting thing that I found when looking at my interfaces, the default … Continue reading PPPoE: PPP Layer 2 Encapsulation Over Ethernet, Phases of connection setup explained, along with Terminology!
IP SLA explanation and examples of when to use it An IP SLA (Service Level Agreement) is an agreement between the Service Provider and (you) the customer, that you will get an agreed upon level of uptime / bandwidth for your money, and IP SLA configuration on a router is a mechanism to measure and … Continue reading IP SLA configuration, verification, “object tracking” configured and explained, quite an extensive subject and read so brace yourself!
As I only have two routers in my lab running IOS 15.x, and 12.x is not NTPv4 capable, I've decided to review it between just these two routers to demonstrate new features brought by 15.x code that I couldn't in my previous lab involving the whole WAN Topology. To start there are a quite a … Continue reading NTP: Demonstrated between 2 routers running IOS 15.x to demonstrate NTPv4 Authentication and other concepts! (Edited with more content 5/20/17)
I will be using this Topology not as an OSPF course, but to perform Policy Based Routing (PBR) to influence how traffic travels from R5 to destination network 172.12.23.0, but first we need to review the basics of PBR: PBR effects packets on the Ingress interface it is configured on, not traffic generated by the … Continue reading Policy Based Routing / Local Policy Routing, and Route-Map configuration and explanation, review for exam day!
Apologies for how terrible the Topology is, I took an existing picture and put some purple arrows leading off the ABR's, indicating that this is actually where Type 4 LSA's are created. Now ASBR's create Type 5 LSA's which of course are External / Redistributed routes which are shared throughout the entire routing domain across … Continue reading OSPF: Type 4 LSA’s, who creates them, why they create them, a relatively shorter post for once!
OSPF Summarization is done only on ABR and ASBR routers in your OSPF domain, and use two completely different commands, but what if a router is an ABR and an ASBR? For example, did you know that using the command "default-information originate ..." you are telling the router to create a Type 5 LSA to … Continue reading OSPF: Important details regarding Summarization and Default Routes for exam day, it’s a long but worthwhile read!
For those who have forgotten how LSA's work between Area's, let us refresh your memory: Type 1 and 2 LSA's live within their own Areas to create the SPF Tree ABR's extract the Network / Subnet Mask information to create a Type 3 LSA which it then floods into the other Area (Summary LSA in … Continue reading OSPF: Route filtering between Areas (Inter-Area) configured and explained!
To calculate the best path to a route, first the router builds an LSDB that is then run against the SPF Algorithm, which then comes up with its best paths to subnets. Ultimately what makes it into the IP Route Table is decided by CEF, which views all protocols different tables to decide the best … Continue reading OSPF: Metric (Cost) Calculation for both Intra-Area and Inter-Area explained, and Metric fine tuning for path selection!
Sticking with this Topology in case I need to lab something for demonstration, it is clear what routers are where. To begin, every router within any given Area should have an identical copy of the LSDB, and that only Type 1 and Type 2 LSA's are flooded only within the Area they originated. The Database … Continue reading OSPF: Database Exchange Process including messages, neighbor states, and all things neighbor forming related!
When you first configure a router in an Area via an OSPF instance, you are creating a Link State Database, that already contains entries for different LSA Types. Each router considers itself to be the Root of what is called the "Shortest Path First Tree", which is a mapping via LSA's from neighbor routers, which … Continue reading OSPF: LSA Type 1 (why it’s unique), explanation of SPF Tree, and a handy show command for exam day!
I pulled this topology from my older posts when I took a deep dive into the world of LSA's, how to read the Topology table like a laundry list and under stand it, and what type of routers did what. First I want to list links that are absolutely vital to read and understand for … Continue reading A collection of IMPORTANT links to review and know for exam day, then a quick overview of LSA Types / OSPF Router Types!
The OSPF RID has a much more significant role in a neighbor formation than with EIGRP, obviously because that it what it uses to identify its neighbor rather than the IP address of the physical interface the neighbor was learned on. So what if two routers were to have the same Router ID? That question … Continue reading OSPF: Duplicate RID’s in the same Area and between Areas, and MTU Mismatches on OSPF links, explained!
This conversation really begins with the interface on which OSPF is operating on, and the Layer 2 encapsulation that it is being used on the interface, like above over my NBMA I am running Frame-Relay as the Layer 2 encapsulation. From this information alone OSPF knows whether it can Broadcast across the network, if it … Continue reading OSPF: Every OSPF Network Type, configuring them, and them explained to painful detail with a lot of output / config examples!
This will be our topology for most of Review, though I am currently leaving Area 34 and Area 15 out of the equation since we aren't really worried about those for review. You can create a process and an Area by configuring OSPF directly on an interface, rather than making the process and adding the … Continue reading OSPF: Creating OSPF from the interface, playing with Hello / Dead timers, intro to Hello-Multiplier and other good review!
The DEVNET GRIND! 