Author Archives: RedNectar Chris Welsh

About RedNectar Chris Welsh

Professional IT Instructor. All things TCP/IP, Cisco or VoIP

Why Easter doesn’t it fall at different times in different time zones

This year for example, tonight’s full moon occurs after midnight in places between the International date line and the UTC+11 time zone. So according to the formula, Kiwi kids should have to wait another week before breaking open those chocolate eggs. Continue reading

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Posted in blog, opinion | Leave a comment

CSMA/CD and full duplex for wireless? It could be coming

The problem with existing wireless communications is that once a device starts transmitting, it doesn’t know if another device has transmitted at the same time until it has finished transmitting. This may be the solution to evercome that Continue reading

Posted in blog, opinion, wifi, wireless network | Tagged , | Leave a comment

Why have WordPress made it soooo hard to follow someone?

 I won’t start a tirade of things you STILL can’t do on WP, but I am going to have a whinge about one feature you have obscured. Continue reading

Posted in opinion, rant, wordpress | Tagged | 2 Comments

RedNectar’s HX Pre-Install Checklist

  Completing Cisco’s Pre-installation Checklist for Cisco HX Data Platform will capture all the information you need, but not necessarily in the order you need it, and for a single site only.  So, I decided to write a version that gets the … Continue reading

Posted in Cisco, Data Center, Data Centre, Hyperflex, UCS | Tagged , , , | Leave a comment

ISIS, COOP, BGP and MP-BGP in Cisco ACI

Let me start with a picture.  Imagine a simple 2leaf/2spine topology with HostA attached to to Leaf1 and with HostB attached to to Leaf2. Enter IS-IS. The leaves and spines will exchange IS-IS routing updates with each other so that Leaf1 sees that it has two equally good paths to reach Leaf2, and Leaf2 sees that it has two equally good paths to reach Leaf1. Now think about the hosts. This is where COOP comes in. BGP is not needed until an external router is connected. Continue reading

Posted in ACI, ACI configuration, APIC, Cisco, Data Center, Data Centre, EPG, L3 Out, L3out | Tagged , , | Leave a comment

Guest Post! WTF Are all those Checkboxes? (ACI L3 Outs) – Part 2 of ???

Originally posted on Come Route With Me!:
My friend and colleague Mr. Jason Banker recently ran into some good times with the mysteries of the ACI L3 Out Checkbox Madness! He Slack’d me and told me he’d found some clowns…

Posted in GNS3 WorkBench

Non overlapping VTEP IP addresses in Cisco ACI

Cisco recommends that “The TEP IP address pool should not overlap with existing IP address pools that may be in use by the servers (in particular, by virtualized servers).”
Let me tell you a reason much closer to reality why you might want to avoid overlapping your Cisco ACI TEP addresses with your locally configured addressing scheme. Continue reading

Posted in ACI, ACI configuration, APIC, Cisco, Data Center, Data Centre | Tagged , , , ,