Route Redistribution - Part 1

ccie r/s ccnp r/s Sep 25, 2018

Introduction to Route Redistribution 

Until there is one routing protocol to rule them all, there is a need to have multiple routing protocols peacefully coexist on the same network. Perhaps Company A runs OSPF, and Company B runs EIGRP, and the two companies merge. Until the newly combined IT staff agrees on a standard routing protocol to use (if they ever do), routes known to OSPF need to be advertised into the portion of the network running EIGRP, and vice versa.

Such a scenario is possible thanks to route redistribution, and that’s the focus of this blog post. Other reasons you might need to perform route redistribution include: different parts of your own company’s network are under different administrative control; you want to advertise routes to your service provider via BGP; or perhaps you want to connect with the network of a business partner. Consider the following basic topology.

  

In the simple topology show above, we’re wanting OSPF and...

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5 SDN Concepts You've Gotta Know

ccie r/s ccna r/s ccnp r/s Nov 28, 2017
 

I recently did a Facebook Live session covering 5 major Software Defined Networking (SDN) concepts. If you missed the live session, or just want to watch a replay, check out this video.

We cover:

  1. Intro to SDN
  2. Python Installation
  3. Basic Python Programming
  4. Configuring a Router with Python
  5. APIC-EM Applications

BONUS: I'm offering viewers of this video $50 off my Fundamentals of Network Programmability video training series. That means, you only pay $147, as compared to the regular price of $197. To get your $50 discount, click HERE.

Enjoy!

Kevin Wallace, CCIEx2 (R/S and Collaboration) #7945

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OSPF Route Filtering

ccie r/s ccnp r/s Nov 14, 2017
 

Let's say you have one or more IP routes that you don't want appearing in a router's IP routing table. The reason might be for security or for router performance, as a couple of examples. With OSPF, there are three primary ways to accomplish this route filtering:

  • Filter a route coming in from another autonomous system, as part of a redistribution configuration.
  • Filter a route between areas, using a filter list.
  • Filter a route from being installed in an single router's IP routing table, using a distribute list.

This video discusses these three approaches, and it demonstrates the configuration of two of these approaches (because redistribution is a topic unto itself).

Enjoy the video!

Kevin Wallace, CCIEx2 (R/S and Collaboration) #7945

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Configuring Quality of Service Using MQC

The Need to Know MQC in a World of Automation

These days, Quality of Service (QoS) can be configured relatively easy. If we’re using the APIC-EM as a network controller to manage our routers and switches, we can simply point and click our way through the EasyQoS utility and have a very robust QoS configuration applied to our devices. Even at the command line interface (CLI) of a router a switch, we could invoke the power of AutoQoS VoIP (to optimize QoS settings for voice traffic, or (just on routers) AutoQoS for the Enterprise (to discover network traffic patterns and create a customized QoS configuration to reflect our network’s specific characteristics).

However, what if you need to make an adjustment to such dynamically generated QoS settings? If you examine the underpinnings of any of these QoS automation tools, you’ll see they all use the same approach to configure most (of not all) of their QoS settings. This approach is called Modular QoS CLI, or MQC for...

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Fundamentals of Auto Smartports

ccie r/s ccna r/s ccnp r/s Sep 26, 2017
 

The Auto Smartports feature available on Cisco Catalyst switches allows a port to automatically detect that you’ve attached a device it can recognize (e.g. a Cisco IP Phone, wireless access point, video surveillance camera, etc.)

Then, it runs a macro on that port to apply a "best practice configuration," including QoS, STP, and security settings.

This video introduces you to this exciting feature and gives you a configuration demonstration.

For scaling automatic configurations beyond a single switch, check out Cisco’s Software Defined Networking (SDN) solutions. In fact, you can sign up for my Free SDN Mini-Course by clicking HERE.

Kevin Wallace, CCIEx2 (R/S and Collaboration) #7945

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BGP Route Reflectors

ccie r/s ccnp r/s Aug 15, 2017

A BGP-speaking router, by default, will not advertise an Internal BGP (iBGP) route to an iBGP neighbor. One solution for this issue is to create a full mesh of neighborships within an Autonomous System (AS). However, that approach doesn’t scale well.

A more scalable solution is to use a BGP Route Reflector. That’s the focus of this new video I created for you. You’ll see the issue BGP has with iBGP-learned routes and how to overcome that issue with a BGP Route Reflector configuration.

Enjoy the video!

Kevin

Kevin Wallace, CCIEx2 (R/S and Collaboration) #7945

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Understanding EIGRP Part 6 (Router ID and Neighborship Requirements)

ccie r/s ccna r/s ccnp r/s Feb 23, 2017

This blog post wraps up our series on Understanding EIGRP by discussing two final topics:

  • The EIGRP Router ID
  • EIGRP's Neighborship Requirements

Let's begin our discussion by considering the EIGRP router ID.

EIGRP Router ID

Each EIGRP-speaking router has an associated EIGRP router ID (RID). The RID is a 32-bit value written in dotted decimal format, like an IPv4 address. A router’s EIGRP RID is determined when the EIGRP process starts. Interestingly, EIGRP uses the same steps to RID calculation as does OSPF. The following list identifies these step, in sequential order:

Step 1. Use the configured RID value (using the eigrp router-id rid EIGRP router configuration mode command).

Step 2. If no RID is configured, use the highest IPv4 address on a loopback interface in the up/up state.

Step 3. If no loopback interface is configured with an IPv4 address, use the highest IPv4 address on a non-loopback interface.

Interestingly, while EIGRP requires a router to have a RID, the...

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Understanding EIGRP – Part 5 (Static Neighbors)

ccie r/s ccna r/s ccnp r/s Feb 05, 2017

Typically, an EIGRP-speaking router dynamically discovers its neighbors, by sending multicast Hello messages. However, there is an option to statically configure those neighbors, and communicate with them via unicast messages. This is rarely done, but could on rare occasion be useful.

Consider for example a Frame Relay WAN. Imagine that router A has an interface configured with ten Frame Relay permanent virtual circuits (PVCs). At the other end of two of those PVCs resides EIGRP-speaking routers. However, the other eight PVCs do not have an EIGRP-speaking router at the far end. In such a topology, if router A’s WAN interface was participating in EIGRP, then router A would have to replicate its EIGRP Hello message and send a copy out all ten PVCs, resulting in an increased processor burden on router A and increased the bandwidth usage (unnecessarily) on the eight PVCs not connecting to an EIGRP router. This is the type of situation that would benefit from our statically...

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Fundamentals of the Internet of Things (IoT)

It's another one of those buzzwords we're hearing a ton these days, the Internet of Things, or IoT for short.

But what exactly is it, and how's it going to impact us as networking professionals? That's what you'll learn in this new video: 

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Understanding EIGRP – Part 4 (Passive Interfaces)

ccie r/s ccna r/s ccnp r/s Jan 31, 2017

Sometimes, we might want a router interface to participate in an EIGRP routing process (in order to advertise that interface's network) without that interface sending out EIGRP Hello messages. That's what we'll cover in this blog post.

By the way, this is the fourth posting in a series on Understanding EIGRP. If you missed any of the earlier postings, you can check them out here:

Previously, we talked about the network net-id wildcard-mask command issued in EIGRP router configuration mode. This command causes two primary actions:

  1. Sends EIGRP Hello multicast messages out any interface whose IP address falls within the network address space specified by the network command.
  2. Advertises the subnet of any interface whose IP address falls within the network address space specified by the network command....
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