It’s time for another video. This time I’m covering some useful tools for handling fiber cleaning and testing in the datacenter.
Video – Fiber cleaning and testing
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Test – Throughput alchemy using a snake topology
Sometimes it’s best not to trust network vendor datasheets. Nothing quite beats a controlled test of a network device in your lab with your config and your required features. But if you want to load test multiple ports on your 10G device-under-test (or DUT), then things can get very expensive, very fast. In this post I’ll show a test topology that will help you turn 10Gbps of test traffic into 640Gbps or more.
Career – Zen and the art of network maintenance
Getting Zen
‘Zen and the art of motorcycle maintenance‘ by Robert Pirsig is a modern classic. When I first read this book I didn’t quite get the zen I was looking for. But then again maybe I was trying too hard which isn’t very zen-like. It is a wonderful book and although I missed many of the metaphors I gleaned some solid advice on how to enjoy my work. I think Pirsig’s motorcycle maintenance tips can help us in our day-to-day life. I’ve even dared to add a few tips of my own.
OSPF – Setting MTU values for Cisco and Juniper
MTU mismatches are the primary reason an OSPF adjacency becomes stuck in the EXSTART state. After hellos are exchanged and the routers become neighbors, each OSPF speaker advertises the IP MTU of it’s local interface in a Data Base Description (DBD) LSA. If there is a mismatch you’ll probably just adjust the configuration to be identical on both ends of the link and be done. However, when you try to peer two OSPF routers with different network operating systems, things start to fall apart fairly quickly.
OSPF – Sequence numbers are sooo negative
OSPF Sequence Numbers
Image: Numbers by eye/see – some rights reserved
When an OSPF router originates an LSA for the first time, it will choose the sequence number 0×80000001. The 0x prefix means it’s a hexadecimal number, where each hex character represents a four bit binary word. This post discusses why the OSPF sequence number begins with 0×8, and some quirks when counting with signed numbers.
Design – Security involvement in design and audit stage
Designed to fail
Security audits are a fantastic way to improve the security of your network. A good auditor can highlight critical flaws in your design and configuration before they are launched into the big bad world. However I think there is a massive issue with security audits; they are designed to fail.