Cisco Voice Guru

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Question the Guru

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This week, I received an email from a reader of the blog.  Let’s call him Sergio Flores.

Sergio asked me a lot of great questions. Most of these questions were ones that I asked myself during the long and arduous nine months prior to passing the CCIE lab.

You know, so much time and energy is invested into this endeavor that you hope against hope that once you pass it will be worth it.

Aside from trekking in the Himalayan mountains (which I’ve done), getting married and growing a family (which I’m doing), the CCIE has been the most mentally/physically/emotionally trying experience I’ve ever gone through.

Was it worth it?  Hmm…  Is the Pope Catholic? ;)

Since his letter was so relevant to CCIE preparation, I’m going to share snippets of it in this blog post and answer his questions.  Perhaps more people than just Sergio can benefit from my answers.
Read the rest of this entry »

Written by Matthew Berry

August 24th, 2011 at 7:04 pm

One Year Anniversary: CCIE #26721

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One year ago today, I was sitting in the Cisco CCIE lab in San Jose, CA, typing away at a terminal.  It was my first attempt at the lab and, thank God, my last.  I walked out of the building in the afternoon absolutely fried and utterly nervous about the results.

The next afternoon, after having flown back to Minneapolis, I sat in my living room hitting “Refresh” on my web browser every 10 seconds.  Everything hung in the balance.  Would I pass and be done with this season of life?  Would I fail and have to go back to the lab, develop a new plan, and try again in thirty days?

Suddenly, the refresh took a bit longer…  Could it be? Read the rest of this entry »

Written by Matthew Berry

August 16th, 2011 at 8:27 am

Posted in Blog,Featured

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IOS Shell in IOS 15.1(4)M

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JOY!  Cisco IOS now supports a shell environment!

IOS 15.1(4)M and later releases contains a feature called IOS.Sh that, when enabled, provides a user with a shell environment.  Here’s what Cisco says:

The is designed to be familiar to users. This is done by implementing a control language that is similar in many ways to various open source CLI interfaces. A system administrator with a UNIX background can easily understand and use the new features, and an experienced Cisco IOS CLI user can easily learn and use these features as enhancements. is also mostly backward compatible with the existing Cisco IOS CLI, with a few obvious exceptions. This means that CLI commands that are entered on the router will probably continue to work as before. However, users should be aware that some commands may need to be invoked differently if users want to take advantage of the

Once IOS.Sh is enabled, you have some powerful abilities:

  • Defining and using environment variables
  • Using control constructs to automate repetitive tasks
  • Creating and using functions
  • Using a new set of ‘built-in’ function, that provide various text processing facilities.
  • Using extended pipelines to use the output of one command as input for another one.
  • Evaluating logical and arithmetic expressions for tests and variable setting.
  • Using online ‘manual’ pages describing these changes.

Here’s my question: How do you see this changing the way we work as engineers?  Thoughts?


Written by Matthew Berry

March 29th, 2011 at 7:44 am

Posted in Blog

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Deploying IPv6 in a Cisco UC Environment – Part 5

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In this post, we continue our look into IPv6 and its implementation in a Cisco UC environment.

Will customers begin using IPv6 in their internal networks?  Time will tell.  However, it does us all a lot of good to understand the implications and caveats of using this new IP version.

IPv6 Best Practices: Single-Site Model

IPv6-enabled Phones:

  • Configuration: IPv4 and IPv6 (dual stack)
  • Use IPv6 for signaling to CUCM
  • Prefer IPv6 over IPv4 for media

PSTN Gateways:

  • Standard: CUCM SIP trunk to IOS SIP gateway
  • Configuration: IPv4 and IPv6 (dual stack)
  • ANAT enabled
  • Use IPv6 for signaling to CUCM
  • Prefer IPv6 over IPv4 for media

Note 1: Regarding the usage of MTPs in a dual stack environment, CUCM SIP trunks and SIP gateways can be configured to use either of the following:

  • SIP Early Offer (MTP required checked and used for every call.)
  • SIP Delayed Offer (MTP Required unchecked, although MTPs may be inserted dynamically for some calls for conversions between IPv4 and IPv6 addresses.)

Note 2: Regarding workarounds to decrease MTP usage:

If a single dual-stack gateway is used and the cluster-wide preference for media is set to IPv6, an MTP will be used for all calls to IPv4-only devices to convert from IPv4 to IPv6.

If the widespread use of MTPs is not acceptable in the single-site deployment, configure two PSTN gateways instead of just one. Configure one as a dual-stack SIP gateway using SIP Delayed Offer as described above, and the other as a standard IPv4-only gateway.

Calling search spaces and partitions can then be used to direct PSTN calls from IPv4-only and dual-stack devices to their respective gateways.

Campus LAN:

If the campus LAN is Layer 2 only, enable Multicast Listener Discovery (MLD) to reduce unwanted multicast traffic in the LAN.

If the campus LAN is Layer 3 enabled, configure switches to support dual-stack (IPv4 and IPv6) routing.

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Written by Matthew Berry

March 28th, 2011 at 1:14 pm

Posted in Blog

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Contact Center for Dummies

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I never imagined I’d do this, but today I am posting a document that was produced by Avaya.  It’s a “For Dummies” guide on contact center that provides some helpful information from a business standpoint.

Not every engineer deal with contact center.  Depending on your company, there may even be specialized employees who interact with the business for you.  Either way, this is a great document to review and have available.

Contact Center for Dummies (right click, “Save As”)

CC for Dummies

Written by Matthew Berry

March 14th, 2011 at 8:19 am

Posted in Blog

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