Fast Down Detection

Fast down detection or sub-second link failure detection is needed in a modern networks. Network operators of modern networks require that they can detect failure in sub-second and react to either soft or hard failures as quickly as possible.

The following are the two categories of fast down detection.

1. Polling

One of the method […]

UNetLab Common Issues

These are the common issues I encountered in setting up UNetLab and how I fixed these issues. I’m sharing this so UNetLab users will benefit from it. I will constantly update this list as I progress.

Issue 1: UNetLab is complaining about – Neither intel VT-X or AMD-V found. Solution: Find the .vmx file for […]

Access VMware ESXi Console from Ubuntu 14.04

VMware has no native VSphere client for Linux hosts and VMware pushes its users to use the VMware web client. There is a workaround for this but it doesn’t give you the full benefits of using a full pledge VSphere client in Windows, however it gets the job done.

To access VMware ESXi console from […]

Cisco TelePresence Touch Panel Stuck in Downloading Software

Issue: Cisco TelePresence touch panel stuck in downloading software after system boots up.

Platform: Any Cisco TelePresence endpoints that support touch Panel.

Findings: I didn’t really find out what causes the Cisco TelePresence Touch Panel stuck in downloading software after systems boots up. I have tried three ways in resolving this issue and they […]

H323 NAT address not configured

Issue: Cisco TelePresence endpoint cannot make H323 point-to-point call to another Cisco TelePresence endpoint. Both endpoints are standalone H323 and no Gatekeeper. Symptom is when calling from either endpoint the call automatically get disconnected after few seconds.

Platform: EX, SX, MX and Integrator C series TelePresence endpoints Software version: Any version as long it supports […]

Anonymous SIP Calls

This document walks you through on how to implement anonymous SIP calls in a Cisco Voice Gateway (e.g 28xx/38xx, 29xx/39xx).

1. Enable privacy at the header level in the SIP message. This setting affects all calls (applied globally).

voice service voip sip privacy header

2. This dial-peer configuration prevents the calling-party number from being shown. […]

OpenVPN DNS Issue

Issue: OpenVPN connects successfully but cannot resolved hostnames when browsing. It looks like an OpenVPN DNS issue.

Platform: Ubuntu 14.04 LTS (Trusty Tahr) Software version: OpenVPN 2.3.4

OpenVPN logs indicated the DNS configuration was successfully pushed from OpenVPN server to client.

Tue Oct 14 05:08:39 2014 SENT CONTROL [changeme]: 'PUSH_REQUEST' (status=1) Tue Oct 14 05:08:40 […]

Extension Mobility Login is Unavailable (23)

Issue: Cisco 7821 SIP IP Phone intermittently login to Extension Mobility service. Error displayed on the phone was Login is Unavailable (23).

Platform: Cisco 7821 SIP IP Phone running on firmware version 10.1(1)SR1 Cisco Unified Communications Manager version 10.5.1.10000-7

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Time Source […]