Network config backups – just the beginning

An emergency switch replacement can ruin your day. However, having network config backups is not enough. Restoring full service may not be as easy as just copying the running configuration from your RANCID CVS repo, or your colleagues hard drive. Restoring the ‘identity’ of your original switch is a multi-step and somewhat complicated process.

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My top five posts – Nov 2015

I’ve written quite a few posts on this blog, but admittedly I’ve slowed down a lot. I have plans to change that soon, but in the mean time I’ve compiled a quick run down of my top-five popular posts by page view. Enjoy!

OSPF – Setting MTU values for Cisco and Juniper This is the top networking post by far.

OSPF – Why have a type-4 LSA  The ‘why-type-4 post’ is a useful one for folks who want a deeper explanation of OSPF operation.

TCAM based forwarding engines You’ve heard about TCAMs for ACLS and QoS before, but this post explains TCAM and and how it functions as a RIB.

Cut-through, corruption and CRC-stomping  On the difficulty of finding corrupt frames when using cut-through.

IPMI Serial-Over-Lan (sol) for server consoles Okay, so I’ll admit it this isn’t a networking post, and it is actually more popular that the in-depth networking stuff I’ve written!

If you want to explore some more popular posts use the Top-10 posts section in the right sidebar


What about software assisted networking? Mad Mad

I don’t want a software defined network, I want a software-assisted network. I want tools that will help prevent common but straightforward mistakes and make it easier to baseline a network.

These tools have to work on real networks. Those messy, brownfield, imperfect networks that everyone maintains, but not everyone admits to owning. I’ve listed five tools below that I wish I had freely available when working on enterprise networks.


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Interface descriptions – your last hope

No, I’m not starting a naming war. Not really. I don’t care if you use ! or # or >> or {} to mark your interface descriptions. I don’t care if you use all-caps or lowercase, or if you feel a fundamentalist zeal about other punctuation.

I want to brave the flames of a naming war to propose that we include ‘hidden’ or ‘undiscoverable’ devices in our interface descriptions. If there is a hidden device, a bump in the wire for example, between you and your neighboring network device then you should mention it in the interface description.

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The many ‘modes’ of multimode

Fiber types are differentiated as multimode or single mode. Single mode was always easy for me to understand but I could never quite understand what ‘multimode’ actually meant. I’m written some notes for myself on this topic that I thought I’d share. I’m sure some physicists will have an allergic reaction to my take, but I’m happy to pay that price to learn a little more.

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Packet pushers podcast – Hardware Resources

It’s been quite a while since I’ve posted here but I wanted to highlight some work I’ve been doing with Greg Ferro and Simon Chatterjee on the Packet Pushers podcast. We recorded a three part series where we dive deep into the guts of networking hardware. All three shows are now published on the packet pushers podcast.

Show 186 – The Silicon Inside Your Network Device – Part 1

Show 187 – The Silicon Inside Your Network Device – Part 2

Show 190 – The Silicon Inside Your Network Device – Part 3

If you’re just arriving here from the Packet Pushers site, I’ve put together a dedicated page to capture all of my hardware-related posts.

The Network Sherpa – Hardware page