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4.25.2013

IPv6 Index

Here is an index page for the IPv6e post. Hope you enjoy

IPv6 Part 1 - The Basics

IPv6 Part 2 - Address Assignment and Neighbor Discovery

IPv6 Part 3 - Routing

 Some might have seen the IPv6 routing post pop up a few days back and then disappear. The post almost got scrapped all together. Basically what happened was after finalizing and proofing I tried to publish the post and Blogger freaked out on me. I finally got the post published just to find out over 8 hours of work was lost and my initial post outline was published instead of the final draft. I then pulled the post.

90% of my work was lost and I tried multiple things to recover to no avail. I originally wasn't going to recreate the post because my time is very limited. The idea of loosing all the work ate at me for a few days until I finally decided to suck it up and bang through it.I can now sleep good at night...

Lesson learned. Always create and edit post in something other than the compose window. When finished copy, paste and make small changes.

Thanks again everyone for checking out my blog!! Also feedback is always welcome and encouraged.

4.22.2013

IPv6 Part 3 - Routing

Routing for IPv6 is pretty similar to routing for IPv4. If your comfortable with routing, you should pick up IPv6 routing quickly. Since IPv6 has underlying differences in how it operates you just need to adjust your thinking a little to grasp IPv6 routing.

As for routing protocols, not much has changed and the basics for all of them still operate the same. But there are some differences and we will go over those today. Im not going into detail about each protocol and  I am assuming you already have a solid understanding of how the IPv4 version of each operates.

4.19.2013

IPv6 Part 2 - Address Assignment and Neighbor Discovery

Alright so we have established what an IPv6 address is, what it looks like and what the different address types are and how they are used. I also went over basic configurations of each on a Cisco device. So how are link-local addresses assigned? Or what is this auto-configuration and why not just use DHCPv6?

Calm down, calm down!! This post will get into those specifics and also cover IPv6 neighbor discovery. So let's keep this ball rolling!!

4.18.2013

IPv6 Part 1 - The Basics

I was first introduced to IPv6 during my CCNP studies about 3+ years back but have not been exposed to IPv6 in production outside of disabling it on anything supporting the feature. For that reason I always seem to struggle with keeping the details of IPv6 fresh in my head.

Im going to start with the basics, then move on to IPv6  address assignment and neighbor discovery and then finish up with supported routing protocols. So lets get started...

4.05.2013

OSPF Network Types Part 7 - Multipoint Non Broadcast

Last post of the OSPF Network Type series!! I hope it was as good for you as it was for me.

The last option for your OSPF network type is Multipoint Non Broadcast. As mentioned in the Multipoint post Multipoint Non Broadcast has the ability to apply accurate cost to routes when calculating the metric on Multipoint link who have different bandwidth coming in from the spoke.

4.04.2013

OSPF Network Types Part 6 - Multipoint

Alright, so you decided to go with a partial-mesh Frame-Relay WAN and read my last post on NBMA and choose the route of Multipoint. Great!

Now its time to look into the features of Multipoint or what is sometimes called Point-to-Multipoint (P2MP). The reason its called P2MP is because it acts just like a group of individual P2P links connected to the same hub. Awesome we love P2P links!

Here is a breakdown of Multipoint features for your enjoyment!
  • Treats network as a collection of P2P links
  • Sends hellos as Multicast to 224.0.0.5
  • Neighbor Discovery
  • No DR/BDR election (hence no 224.0.0.6)
  • Hello/Dead timers 30/120
Unlike Broadcast and NBMA Multipoint updates the next-hop value when forwarding an LSU sent from a DRother. This makes Multipoint the better of the three options to choose for your partial-mesh. But just like the other OSPF network types Multipoint has its pit-falls you need to watch out for.

OSPF Network Types Part 5 - NonBroadcast (NBMA)

If you haven't check out Part 4 on OSPF Broadcast network types it wouldnt hurt to run through it now. NBMA is pretty much the exact same as Broadcast with the same pitfalls mentioned before. The key difference between the two is NMBA is geared for,

wait for it...

wait for it...

non Broadcast networks :)

So, Broadcast is geared towards Ethernet segments and NBMA is geared towards Frame-Relay and ATM circuits. Got it!!

This also means multicast HELLOs and discovery will not happen (via 224.0.0.5 and 224.0.0.6) on NBMA networks so you must configure your neighbors manually. Here is a quick breakdown of features in NBMA and then we will dig into the pitfalls.
  • Default on multipoint NBMA media (Frame Relay main interface or multipoint FR interface)
  • HELLOs sent as unicast
  • Manually defined neighbors (only on DR and BDR)
  • Performs DR/BDR election
  • Hello/Dead timers 30/120
  • No DR preemption

4.03.2013

OSPF Network Types Part 4 - Broadcast

Point-to-Point and Loopback network types are the only two I have had any real world experience with. By following best practice and proper design techniques, these are the only two you should need. P2P sub-interfaces on a mesh and partial-mesh Frame-Relay WAN are the recommended solution and keep things simple (as you will find out soon...)

But for the CCIE and a full grasp of OSPF, you need to understand the other 4 and their uses. So lets dig in.

OSPF Network Types Part 3 - Loopback

Well since I rambled on and on about P2P network types I had to give loopback network types their own post. I hope you feel special LOOPBACK!

OSPF loopback network types are pretty straight forward. Any hardware or software loopback interface defaults to LOOPBACK for the OSPF network type. 

Routes learned off a loopback interface are considered to be stub networks and propagated throughout the OSPF network as /32 subnets. This makes sense as loopback interfaces are most commonly used to identify the router for management purposes most commonly for RIDs. The loopback does not share a segment with other devices.

OSPF Network Types Part 2 - Point-to-Point


The name pretty much explains it all. P2P network types are used when connecting two OSPF routers who share a directly connected segment. Here are the characteristics of the P2P network type:
  • Default for serial interfaces (HDLC or PPP)
  • Neighbor discovery
  • Multicast AllSPFRouters (224.0.0.5) used for all neighbor communications
  • No DR/BDR election (thus no Type 2 LSAs)
  • Adjacencies are formed as long as HELLO parameters match
  • Hello/Dead Timers 10/40 seconds
  • Cisco proprietary

4.02.2013

OSPF Part 1 - The Basics

OSPF is the topic for discussion up now, and this one is going to be a multi-parter! I've always thought I had a good understanding of OSPF network types, but running through my CCIE studies I quickly found out I only have a basic understanding of each. So with these post I hope to dig deep into each area and expose the inter-workings.

First up is a quick overview of the basics. If you have worked with OSPF or made it through your CCNP or even CCNA this information will not be new (I hope...). I'm not going deep with these subjects but just giving a refresher.

Now let's quit the yapping and get started!