One of my readers sent me an interesting reliability design question. It all started with a catastrophic WAN failure:
Once a particular volume of encrypted traffic was reached the data center WAN edge router crashed, and then the backup router took over, which also crashed. The traffic then failed over to the second DC, and you can guess what happened then...
Obviously they’re now trying to redesign the network to avoid such failures.
Read more ...
Bit by bit, an NFV ecosystem takes shape.
I recently had to work with a 3rd part to diagnose a link between our devices and came across this handy command. The link in question was a pretty hefty (75m-ish) UTP cable run between a Cisco and HP switch. I have visibility of the Cisco switch, into the structured cabling into the patch panel, and the 3rd parties cable. Unfortunately I didn’t have a DC Operations tech with access to a Fluke, or the ability to interpret the output of a Fluke, but they did have a laptop with a 100Mbps NIC (this becomes important later on).
So I started by running the diagnostic on the production connection. It’s not working, so I don’t have to worry about taking stuff down. This gives me the following:
test cable-diagnostics tdr interface gi7/21
TDR test started on interface Gi7/21
A TDR test can take a few seconds to run on an interface
Use 'show cable-diagnostics tdr' to read the TDR results.
switchA#show cable-diagnostics tdr interface gi7/21
TDR test last run on: July 09 10:30:20
Interface Speed Pair Cable length Distance to fault Channel Pair status
——— —– —- ——————- ——————- ——- ————
Gi7/21 auto 1-2 77 +/- 6 m N/A Invalid Continue reading
The H1N1 Loader appears to be a relatively new downloader family that, to the best of our knowledge, was initially discovered and analyzed by the security community in May 2015. We have seen several samples show up in our malware zoo this Spring and have documented our preliminary findings from a network communications perspective in a short summary report.
These are my notes for IPv6 multicast for the CCDE exam. Overview
IPv6 Multicast Addressing
IPv6 multicast address format includes variable bits to define what type of address it is and what the scope is of the multicast group. The scope can be:
1 – Node
2 – Link
3 – Subnet
4 – Admin
5 – Site
8 – Organization
E – Global
The flags define if embedded RP is used, if the address is based on unicast and if the address is IANA assigned or not (temporary). The unicast based IPv6 multicast address allows an organization to Continue reading
This is a design guide for an enterprise deployment of a dual stack, routed access layer using OSPF as the routing protocol, with a fully routed ECMP core.
The post Dual Stack Routed Access Layer With OSPF Design Guide appeared first on Packet Pushers Podcast and was written by Matt Love.
No Starch Press recently offered me a preview copy of a new book about the GNS3 network simulator, titled The Book of GNS3 written by Jason Neumann. This book covers the new version of GNS3, GNS3 1.x. Here is my review of The Book of GNS3.
The Book of GNS3 effectively serves as a user manual for GNS3. It offers detailed installation and configuration information for GNS3 1.x in one easy-to-access volume. Experienced users will find some new information in this book, especially about the new features available in GNS3 1.x. However, I think the main beneficiaries will be new or inexperienced users of GNS3.
GNS3 is usually used by people who wish to emulate networks of commercial routers from vendors such as Cisco and Juniper. Understandably, Mr. Neumann spends most of the book discussing how to set up GNS3 to run commercial routers and, as much as is possible, switches.
How does this book help those who want to use open-source routers in GNS3? Read the rest of my review to find out.
While I read through this book, I looked for the parts that are relevant to my interests in Continue reading
The HP DemoFriday Q&A on how to enhance optimization & visibility with HP SDN applications is now available.
A second win in China for Nuage.
