Cisco Spans the Gap Between Private Data Centers and Public Clouds
Cisco worked with the cloud titans, but it had to do most of the heavy lifting.
Strategic IT Transformation at Symantec
Moving from an outsourcing to an insourcing model helped boost agility and reduce operational costs.
Network Interconnection videos have been added into Self Paced SP Training
Recently, I published Self Paced Service Provider Training Course. I didn’t make an Internet wide announcement yet as I still upload the content to the course. Though I haven’t announced it yet, some people have already purchased it and the previous Instructor Led Service Provider course attendees got the access to the self paced […]
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The Cost of Networking Hardware (and Disaggregation)
Eyvonne Sharp wrote an interesting blog post describing the challenges Cisco might have integrating Viptela acquisition, particularly the fact that Viptela has a software solution running on low-cost hardware.
Guess what… Cisco IOS also runs on low-cost hardware, it’s just that Cisco routers are sold as a software+hardware bundle masquerading as expensive hardware.
Read more ...Performance progression of IPv6 route lookup on Linux
In a previous article, I explained how Linux implements an IPv6 routing table. The following graph shows the performance progression of route lookups through Linux history:
All kernels are compiled with GCC 4.9 (from Debian Jessie). This version is
able to compile older kernels as well as current ones. The kernel configuration
is the default one with CONFIG_SMP, CONFIG_IPV6,
CONFIG_IPV6_MULTIPLE_TABLES and CONFIG_IPV6_SUBTREES options enabled. Some
other unrelated options are enabled to be able to boot them in a virtual machine
and run the benchmark.
There are three notable performance changes:
- In Linux 3.1, Eric Dumazet delays a bit the copy of route metrics to fix the undesirable sharing of route-specific metrics by all cache entries (commit 21efcfa0ff27). Each cache entry now gets its own metrics, which explains the performance hit for the non-/128 scenarios.
- In Linux 3.9, Yoshifuji Hideaki removes the reference to the neighbor
entry in
struct rt6_info(commit 887c95cc1da5). This should have lead to a performance increase. The small regression may be due to cache-related issues. - In Linux 4.2, Martin KaFai Lau prevents the creation of cache entries for most route lookups. The Continue reading
IPv6 route lookup on Linux
TL;DR: With its implementation of IPv6 routing tables using radix trees, Linux offers subpar performance (450 ns for a full view — 40,000 routes) compared to IPv4 (50 ns for a full view — 500,000 routes) but fair memory usage (20 MiB for a full view).
In a previous article, we had a look at IPv4 route lookup on Linux. Let’s see how different IPv6 is.
Lookup trie implementation
Looking up a prefix in a routing table comes down to find the most specific entry matching the requested destination. A common structure for this task is the trie, a tree structure where each node has its parent as prefix.
With IPv4, Linux uses a level-compressed trie (or LPC-trie), providing good performances with low memory usage. For IPv6, Linux uses a more classic radix tree (or Patricia trie). There are three reasons for not sharing:
- The IPv6 implementation (introduced in Linux 2.1.8, 1996) predates the IPv4 implementation based on LPC-tries (in Linux 2.6.13, commit 19baf839ff4a).
- The feature set is different. Notably, IPv6 supports source-specific routing1 (since Linux 2. Continue reading
TextFSM Getting Started
TextFSM installation and basic usage.TextFSM Getting Started
Textfsm is a text parsing library written in python to turn plain text into structured data. Originally created by Google, the project seemed largely abandoned until recently being added to github and receiving a small update. This post will show how to extract interesting data from the...Cisco Nexus 9000v Vagrant Box Install
How to install a Cisco Nexus 9000v Vagrant box.Cisco Nexus 9000v Vagrant Box Install
This blog covers how to install Cisco Nexus 9K boxes for use with Vagrant. Great news.. if you have followed my other posts around creating Vagrant boxes from Cisco post and post images, this will not be quite as involved. Cisco has provided a Nexus vagrant box for download from...Louisiana Moves the State’s IT Infrastructure to Software-Defined
It’s using Dell, Nutanix, VMware, and CA Technologies.