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Disable IPv6: Don’t do it!

Most people already have IPv6 capability whether they know it or not.  All Microsoft operating systems such as Windows Vista and all MacOS releases since 10.2 have IPv6 installed enabled by default.  Mobile devices running Android 2.1, Apple iOS 4.0, and Symbian 7.0 are configured likewise as is nearly every *nix variant you can name.  Even the venerable and ubiquitous Windows XP has a latent IPv6 stack which can be activated with a single command.

Typically, IPv6 enabled systems will prefer IPv6 connections over IPv4, so a misconfigured or malfunctioning IPv6 network will cause connectivity problems.  Many popular troubleshooting regimens simply prescribe disabling IPv6 as the “solution,” which really does nothing more than to hide the underlying problem with the IPv6 network.  When you have a network problem that is “solved” by disabling IPv6, you have masked the symptom of a bigger problem that warrants further investigation.

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IPv6 and DNS – Getting your DNS infrastructure ready for IPv6

You can make your named network services available via IPv6 with a few simple steps.  First, your DNS server or DNS service provider should first hand out AAAA DNS records (pronounced quad-A record) which map hostnames to IPv6 addresses.  Second, you should provide PTR records to allow IPv6 Reverse DNS (rDNS) lookups.  Finally, you should take steps to make the DNS server itself reachable via IPv6.

Setup your DNS Server to start serving AAAA records

To allow resolution of hostnames to IPv6 addresses, your DNS Server must respond to requests for AAAA records.  Adding AAAA records to your forward zones will enable clients with IPv6 connectivity to learn the IPv6 addresses of your resources. Be aware there is a small risk that if a requesting client is among the minority with broken IPv6 connectivity, it can appear to the client that your website is down.  Some companies use DNS whitelisting to mitigate such issues, but there are concerns around that approach.

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IOS Performance Monitor – A powerful tool for negotiating SLA with your Service Provider

The only way to be sure of delivering highest quality of experience is by actually measuring QoE of real traffic. In IOS 15.1.3T, we introduced a new embedded monitoring capability to collect packet loss, jitter, delay and response time information for performance evaluation of data, voice and video services. The feature is called IOS Performance Monitor.  (See yesterday’s blog on User Traffic Analysis by Medianet performance Monitor.)   

In December of last year, Cisco IT was running a medianet pilot program for the new IOS performance monitor feature as their ongoing effort to provide high quality and improved services to end users. The pilot was designed to support 50 remote sites equipped with the ISR-891 routers. Two of the pilot sites were small Cisco offices and the remaining was home offices. I was lucky enough to be selected for the pilot.

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User Traffic Analysis by Medianet Performance Monitor

February 28, 2011 at 5:06 pm PST

Network operators are tasked with providing a foundation network that can deliver a variety of applications to their users at any time. For the most part, the network is in the background, humming away while users enjoy the applications. However; once in a while, the application will slow down, or hiccup, and the first suspect is usually the network.

Figure 1 - Poor video quality caused by packet loss.

Sometimes this is not without just cause; the network may be composed of various administrative domains in various states of work, and many things that are outside the domain of control of any network operator (bad fiber, rain clouds, bulldozers, floods etc.). There is the common experience of the ping test passing, but still something wrong within the network. Or the other case, where the ping fails intermittently, but there is no clue about the location of the problem.

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How to get IPv6, now

Unless you have been living under a rock, you should know by now that the IPv4 address pool is exhausted and you need to start using IPv6.  In fact, you may even be convinced.   How can you get your network connected to the growing IPv6 capable Internet, ideally in time for World IPv6 Day

Start with your Internet service provider (ISP).  Although not every ISP currently provides IPv6 service, the list grows in proportion to customer demand.  Free, Comcast, and Softbank are just some examples of prominent ISPs who have large scale public IPv6 trials and rollouts.  Even if your ISP has not announced an IPv6 plan, contact them.  You might be able to become early adopter on an unannounced trial.

In the event that your provider has not yet seized the opportunity to provide IPv6 service, you can seek out a public tunnel broker, a service that allows you to “tunnel” IPv6 packets across an IPv4-only connection to the IPv6 capable Internet.  A number of tunnel broker providers like Hurricane Electric, SixXS and Freenet6 provide tunneling points of presence at many locations worldwide and will gladly issue an IPv6 prefix (or several!) for no charge.  Some tunnel brokers will even provide a BGP feed.  This is an excellent way to start gaining experience with IPv6 connectivity in your network.

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