Eric Stewart: Running Off At The Mouth

Networking

When Packet Captures Lie: vPC Settings To Watch Out For

by on Apr.05, 2018, under Networking, Technology

One of my worst weaknesses as a network admin is that (mostly due to a weird conflux of laziness and time restrictions) I tend to not read up on a topic as much as I should before I implement; or at the very least, I don’t retain what I do read and put certain settings in without considering that there might be serious ramifications. Such is the case with vPC; I don’t know it as well as I should, and I trust it even less, but it’s being used in our data center (DC) networks heavily. So it was that during the load balancer migration I’m in the middle of, I came across a case where vPC made a packet capture lie.

Leave a Comment :, , , more...

When Ethernet Doing What Ethernet Does Is Inconvenient: Layer 2 Load Balancing

by on Apr.05, 2018, under Networking, Technology

It’s been a while since I’ve posted. If I’m not busy at work, I’m avoiding anything related to work. One issue I’ve been working on for a long time has involved a load balancer migration from one vendor to another. I ran into an issue which was brought about by the new vendor claiming our configuration was supported … only to find later on that it was not. This is not wholly their fault – we’ve been doing load balancing in possibly an unusual way for quite some time. Read on for the hows and they whys, and why you occasionally have to watch out for Ethernet doing exactly what Ethernet does.

Leave a Comment :, , more...

Cisco Live 2018: The Where And The Who

by on Mar.05, 2018, under Networking, Technology

Yes, it’s been a year, and I haven’t really touched the site all that much. But as Cisco Live is right around the corner, I did the Internet version of meeting in a dark parking garage with a source, and got some information about Cisco Live 2018. Check out the scoop!

Leave a Comment :, more...

CiscoLive 2017: Still Learning, Still Having Fun

by on Jul.07, 2017, under Networking, Technology

Cisco Live was in Las Vegas again this year, and it was hotter (in more ways than the weather) than last year! I learned quite a bit and had a lot of fun. But fair is fair: There are things I would like to see changed. Still – if you’re a networking professional that touches Cisco equipment, going to Cisco Live is a benefit you can’t ignore.

Leave a Comment :, , more...

“Breaking” Cisco Live 2017 News: Closing Guest Speaker!

by on May.09, 2017, under Networking, Technology

So – I’m going this year. Flight, hotel, classes all booked (just need to squeeze in possibly a CCNP TSHOOT exam and I’m all set). But I have some news hot off the presses: I know who’s going to be giving the closing keynote! And of course, some additional social gaming has been added to this year’s event.

Leave a Comment :, more...

Cisco Live 2017 – A Preview

by on Apr.19, 2017, under Networking, Technology

While not for certain yet, it’s at least in the plans that I go this year. Cisco Live is once again in Las Vegas this year, so read on for my preview, advice, and some official information courtesy of the Cisco Live team!

Leave a Comment :, more...

What Do You Call 28,000 Geeks In Las Vegas?

by on Jul.20, 2016, under Networking, Technology

A) A Week With Friends
B) Summer Camp

C) A Learning Experience

D) Cisco Live 2016

E) All Of The Above

1 Comment :, more...

deny ip any any: What You Need On An “in” ACL For DHCP And HSRP To Work

by on Apr.28, 2016, under Networking, Technology

It’s been my experience that “ip access-group <acl> in” is rarely used. Most of the time, people look at the “out” form of the command. In this post, I will explain how to view the different directionality of the “in” vs “out” and then review the issues that you can encounter with respect to DHCP and HSRP when it comes to ending an “in” ACL with a “deny all” at the end.

Leave a Comment :, , , more...

The Network As A Symptom: Subnets

by on Apr.21, 2016, under Networking, Technology

Related to my previous post about “The Network As A System”, during my time on call, I got another request that stated: “I need a port opened between 10.0.0.24 and 10.0.0.56. I know they’re on the same subnet, but I’m getting timeouts when trying to connect between them.”

The thing is, they weren’t on the same subnet.

Leave a Comment :, more...

The Network As A Symptom: DNS

by on Apr.21, 2016, under Computers, Networking, Technology

We have an on call rotation at $JOB where, for a week, a given engineer is responsible for responding to after hours phone calls as well as tickets and ACL requests. During a recent turn of mine with the football, I got an ACL request that didn’t make sense, and after working it through with the DB Admin that made the request, I figured I’d write this. It’s sad that it’s probably mostly networking people that read the blog, because they already understand everything this will explain. It’s the DBAs, Developers, and other IT support personnel that could benefit from what I go over here.

Leave a Comment :, more...