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Extending Zeroconf Services: Cache Tuning

Introduction

With the introduction of Cisco mDNS Service Discovery Gateway in IOS, customers that have implemented the solution are observing client behavior they haven’t seen prior to extending services across subnet boundaries. One of the effects is the duplicate name issue seen when devices with enabled services are moved from one L3 subnet to another L3 subnet and these two subnets happen to be connected to the same router/switch running the Service Discovery Gateway (SDG).

Background

When devices (like a Mac OS X computer) offer a service such as Remote Login (SSH) or Screen Sharing (VNC), they will announce these services using mDNS/Bonjour/Zeroconf using their hostname as configured in ‘System Preferences -> Sharing -> Computer Name’ (see Fig. 1).
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Success with Cisco Bonjour Services Directory

July 24, 2013 at 5:00 am PST

Have you seen this video?

For those of you who are not familiar with the technology, Bonjour is a multicast DNS(mDNS) based protocol used to advertise and connect to network services such as printers, file servers, TV’s. With the BYOD explosion and increased use of mobile devices for work in the office and classroom, Bonjour is applicable not only at home, but also in enterprise. Last Christmas with the 7.4 release, Cisco introduced the Bonjour Services Directory optimized for enabling enterprise campus environments to share Bonjour services across Layer 3 networks.  In this blog, I will share some details about how a K-12 school successfully deployed Cisco wireless solution to provide Bonjour Services. As a special treat, I will also discuss some details on Bonjour enhancements included with the upcoming 7.5 release.

St. Margaret’s Episcopal School (SMES) is a K-12 school based in Orange County California serving about 1200 students. The wireless deployment consisted of 30 Cisco 1140 Series Access Points , a Cisco 1260 Series Access Points and some Cisco 1130 Series Access Points managed by a Cisco 5508 Series Wireless LAN Controller. The wired access deployment included various Catalyst 3750, 2960 and 2950 Series Access Switches. Cisco Networking Assistant(CNA) allows them to keep a bird’s eye view on all the equipment.

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Cisco Service Discovery Gateway – Enabling Zeroconf in Enterprise Networks

Cisco Service Discovery Gateway – Enabling Zeroconf in Enterprise Networks

I’ll admit it: I’m what others call an Apple fan boy. One of the many reasons for being one is the polished user experience and the ease-of-use of their products. One of the underlying technologies that enables the user to discover devices and services on the network is Zeroconf or, as Apple calls it, Bonjour.

Zeroconf consists of three major components:

  • Address auto configuration,
  • Naming –and–
  • Service discovery.

If your network doesn’t have a DHCP server or you haven’t statically assigned an IP address to your host, most operating systems will use an automatic private IP address. I’m not going into much detail on address auto configuration except that this is typically done using a technique called APIPA (Automatic Private IP Addressing) for IPv4 the host will use the famous 169.254.0.0/16 addresses or, in case of IPv6, by using link-local addresses only (FE80::/10) which has been designed into IPv6 as a basic functionality from day one. Also, naming is not of much of a concern in the context of this discussion. However, it is worth mentioning that Zeroconf names can contain Unicode characters and whitespace, which can make those names a lot more user friendly and meaningful contrary to pure DNS names.

The more interesting part, as it pertains to Zeroconf, is the service discovery. Read More »

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Santa’s Gift for Wireless Admins This Holiday Season

Last week, a friend of mine jokingly asked me, “So, what is Santa bringing to Cisco’s wireless customers this holiday season?”

I couldn’t help but grin because I already knew what many of you are now aware of: Santa’s wireless holiday delivery came early this year, with Release 7.4 now posted on Cisco.com.

We at Cisco’s Wireless Networking Group are really excited to show off this shiny new release. 7.4 is jam-packed with 40+ features to improve the everyday lives of Cisco wireless customers.

You must be thinking: But you just released feature-heavy 7.3 in October AND new products, such as Virtual Wireless Controller and the highly scalable Wireless Controller 8510!

So what makes 7.4 so special? We specifically chose each feature with the goal of creating an uncompromised user-experience while keeping wireless network administrators happy by making it easy manage their WLAN more efficiently. The 7.4 release specifically focuses on four main pillars:

  • Quality of Experience for Wireless Users
  • Improved Security & Spectrum intelligence
  • Improved performance for small deployments
  • Ability to deploy innovative IT services using mobile apps

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Network wide Bonjour® – How would you support Bonjour across multiple VLANs?

As the saying goes, “every stick has two ends”. While laptops, smartphones and tablets have enabled us to be more mobile without compromising on being “connected,” with it comes challenges such as WIFI accessibility, power consumption and your ability to find network based services, like a printer wherever you happen to be.

To facilitate the ability for an end user to discover Services on a network, various Service Discovery protocols have been introduced. One of the most popular is DNS-SD (DNS-Service Discovery), which in conjunction with mDNS (multicast DNS) make up Apple’s offering called Bonjour. Bonjour enables end users to discover Services on their local network. While Bonjour is focused on smaller networks (e.g. Home Networks) with the advent of mobile customers wanting to discover services in close proximity, Bonjour becomes an ideal option to facilitate that. However, as Bonjour utilizes mDNS which is constrained to a single VLAN, customers are not able to discover services across multiple VLANs.

There are a few approaches being proposed to support Bonjour across multiple VLANs:

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