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Network Automation with TCL
My company has a large (and not very well managed) network. Different VLANs have different "ip helper-address" (DHCP) settings. Some of them are pointing to development DHCP, some of them pointing to...
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Excel, AXL, and Cisco CUCM
Introduction  Cisco CUCM (CallManager)'s clumsy web GUI has earned its reputation. :) It might be OK for a small-to-medium business to perform daily operation on the infamous CCMAdmin GUI. But it's...
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Network Virtualization - OVA or QCOW2?
20 years ago, when I was working on my CCIE R/S, I had to borrow a Cisco 2501 router from a friend's company during the weekend and return it before Monday. Routers were too expensive for me (and they...
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Cisco SD-WAN with GNS3
To avoid turning this blog into a book, I assume the following:You are already using GNS3 and know how to build basic routing/switching lab.You understand the concept of GNS3 appliance.You know how to...
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cEdge - Single Image Switch to Controller Mode
cEdge is a Cisco router acting as SD WAN Edge. Cisco's road map is to replace vEdge products with cEdge. cEdge can be on ISR, ASR and CSR, as well as their corresponding virtual variants (such as ISR...
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Revisit "Urgent Priority"
Cisco CUCM (CallManager) has "urgent priority" option for translation patterns and route patterns. At the first glance, it is pretty straight forward. It is usually used with emergency patterns like...
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CUCM Security Tips
CUCM Security TipsWith CUCM in non-secure (default) mode, you may use secure SIP trunk, but you cannot use secure SCCP endpoints (secure media resource, secure SCCP phones). You may try to telnet to...
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Guest Shell on CSR1000v 17.3.2
Software used:GNS3 2.2.17VMware Workstation for Windows 16.1.0Windows 10 x64 Version 20H2 (Build 19042.685)Cisco CSR 1000v (csr1000v-universalk9.17.03.02-serial.qcow2)In VMware Virtual Network Editor,...
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Cisco Expressway (MRA) and AT&T Wireless Interoperability Issue
When deploying a Cisco Expressway MRA(Mobile Remote Access) solution, I ran into a weird interoperability issue with AT&T wireless. The symptom was: MRA calls to AT&T Wireless numbers went...
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Minimalist's SIP Lab
SIP has become dominant in UC(Unified Communications) now. If you're interested in learning/practicing SIP, CUBE, SBC, etc., here are some ideas.Software lab is always better than hardware lab,...
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Minimalist's SIP Lab (Part 2)
With may vendors going virtualization, it is possible to run virtual labs where it requires physical equipment before(such as Cisco ISR routers). CML, VIRL, GNS3, EVE-NG, etc. we all heard about them....
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SFTP Server
Network and UC engineers often need a SFTP server. I've been using FreeFTPd for years due to it's small size and free. However FreeFTPd's encryption algorithm was outdated and not supported by some...
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NFP sponsorship - Microsoft vs. Google
TLDR: Microsoft is much better than Google on NFP(Not for Profit) sponsorship program.I was helping my friend to get sponsorship for his NFP (Not for Profit) organization. Many technology companies...
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Build a $30 Wireless Lab
One of the recent project has quite a lot wireless LAN stuff. So I feel the urge to build a home lab. To build a wireless LAN lab, you need at least two things - a WLC (Wireless LAN Controller) and...
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