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Lessons Learned - Check List

Before dive into the lessons learned, have to set the stage where I've gathered this information.  Past 10+ years I've consulting multiple large scale SP networks and executed complex DC migrations.  These lessons captured when I failed to notice something and to enforce in the future activities. As the title of this blog have to share what I've learned to a wider audience. Some are well-known fact but keeping a note will help to do a quick check before each meeting. I'll divide it into three parts will follow up with 1.        Don't expect customer knows his/her network: This is especially true in large SP networks; There may be multiple reasons I've seen few widely; components added to patch temporary, stay lifelong and people tend to forget it.  Added functionality no more used and people around that already left the company.  Therefore don't take everything customer says 100% true there is always surprise waits for you. ...
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Fixing high DPI issues with Java Application

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Cisco optical tools (CTP / CTC ) typically come with Java based application. These applications don't work properly on new laptops with high DPI.  I found the fix for the issue in following site : http://superuser.com/questions/988379/how-do-i-run-java-apps-upscaled-on-a-high-dpi-display "You can modify a Java 8 install to work correctly, using a program to modify the EXE manifests. I changed the setting from true to false in the manifests inside of java.exe and javaw.exe, and now my Swing programs scale correctly in Windows 10 high dpi. I used Resource Tuner to this.]"  it fixed the issue but i think we need to keep modifying when java updates automatically. You might not be able to edit directly on default directory.  Take the java.exe and javaw.exe outside the programfiles ( eg : desktop) modify and copy back the files.
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Being a lazy networking guy - Accessing Excel data from Python

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Most of the time during the initial network design stage I keep lots of data in Excel. While implementation usually do manual work to extract the data from excel and convert it as CLI configuration. following example I've simulated to create the interface description from the data i've populated in excel. Following tools required in windows : (if you are a Linux guy most probably not reading this :) ) you can find the python windows executable in following URL : Python download link I'm using notepad++   with PyNPP , you can install this from plugin manager. you need to edit the python location in PyNPP option. Installing openpyxl is quite easy on Windows, you can find pip at C:\Python34\Scripts\pip.exe just run following command to install openpyxl "C:\Python34\Scripts> pip install openpyxl " You can do lot of stuff your imagination is the limit . have a look on the openpyxl import openpyxl wb = openpyxl.load_workbook('test.xlsx') sheets ...
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Device upgradtion consideration

It's important to consider certain things when upgrading to a newer device. Rack Space power [ AC/ DC / socket type ( C14/C15 - C19/C20 etc) Rack type and mounting brackets and screws IOS Feature comparison does all the features supported in the newer image - double check [ sometime we downgrade the device eg: move the powerful device where most needed] Access to the technicians Interface Type and fibre patch cords [ lc / sc / fc ] , length. If we are moving the device from a different location, ensure that it is properly transported and wrapped in appropriate cartons before proceeding with the migration plan.
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CCIE SP TCL IOS XR reachability Script with source address

Following Script will work to check the reach-ability in IOS XR with source address Execute run tclsh Then you can place the TCLSH commands : set i "9.9.0.3" foreach X { 9.9.0.1 9.9.0.2 } { ping -s $i $X } Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 9.9.0.1, timeout is 2 seconds: !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 9/11/19 ms Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 9.9.0.2, timeout is 2 seconds: !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/9 ms
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wireshark continous capture on windows - dumpcap

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I've noticed Wireshark memory utilization increases when we use the GUI and it crashes eventually when we use it for continuous capture. Therefore better to use the dumpcap utility which comes with wireshark. First find out the interface , using dumpcap -D C:\Program Files (x86)\Wireshark>dumpcap.exe -D 1. \Device\NPF_{0A4C8668-EAC9-457F-9337-3C4EFCD43AAF} (Ethernet) 2. \Device\NPF_{1F2A8923-0CAD-4160-BBD7-EB11D6B45883} (VirtualBox Host-Only Network) 3. \Device\NPF_{1BB23144-4E34-42D9-92AB-C939B21119A3} (WiFi 2) 4. \Device\NPF_{3C5A536B-5BF8-42AA-A139-32FB360DA95C} (WiFi) 5. \Device\NPF_{A8EF2C83-9A49-4A9E-96E4-2128784ABD6B} (VMware Network Adapter VMnet1) 6. \Device\NPF_{EDB4678A-A120-47A1-A5BF-950A6F1DFA0E} (Local Area Connection 2) 7. \Device\NPF_{F33132F7-A8F9-4E2D-8D35-32A9F662C1C8} (VMware Network Adapter VMnet8) then start the capture, we can define the parameter which rotate the file ( eg: duration , bytes ) Output (files): -w name of file to sav...
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IPv6 link-local duplicate bring the ipv6 traffic on POS interface

Issue : ipv6 route not installed , interface up  , ipv6 protocol down. Image : IOS XR 4.2.4 - GSR12810 show ipv6 interface brief #show ipv6 interface brief POS0/2/0/1 [Up/Down] fe80::387c:dfff:fee6:b908 2001:x:x:x::1e But interface is up /up show int POS0/2/0/1 POS0/2/0/1 is up, line protocol is up (APS not Configured ) if you check the ipv6 interface its reveals hence the interface deteced duplicate link local its brings down the ipv6 protocol. #show ipv6 interface pos 0/2/0/1 [KPOS0/2/0/1 is Up, ipv6 protocol is Down, Vrfid is default (0x60000000) IPv6 is down (link local duplicate), link-local address is fe80::387c:dfff:fee6:b908 [DUPLICATE] Global unicast address(es): 2001:x:x:xx::1e, subnet is 2001:x:x:x::1c/126 [TENTATIVE] Joined group address(es): ff02::1:ffe6:b908 ff02::2 ff02::1 Quite strange issue , can related to multiple bug ids : CSCtq57619, CSCeh47611 and CSCtq55280 i've resolved issue after...
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