Some of you know I took on a new job earlier this year, where the challenge was (and is) to transform a globally distributed network for a growing company into an enterprise class operation. A major focus area has been eliminating single points of failure (SPOFs): single links, single routers, single firewalls, etc. If it can break and consequently interrupt traffic flow, part of my job is to design around the SPOF within the constraints of a finite budget.
The Scaling Limitations of Etherchannel -Or- Why 1+1 Does Not Equal 2
December 7, 2010 By Leave a Comment
Breaking The Network, One /24 At A Time
November 3, 2010 By Leave a Comment
I have been working on a project to migrate our remote office connectivity into a private WAN. Today, many of those sites are connected via a manual mesh of site-to-site IPSEC VPN tunnels. In the process of this conversion, I have been re-working the WAN cloud itself to leverage the vendor’s ability to peer with me via BGP.
Coping Mechanisms For A Lying ARP Cache
October 14, 2010 By 1 Comment
Caches can be guilty of storing bad data. When they first learned their data, they had learned truth. But as a cache’s data ages, the possibility increases that the cached data becomes stale: out of sync with reality. When cache gives you stale data, it’s lying: a stiff penalty we sometimes pay for performance.
Traveling East-West Might Get A Little Easier: Highlights from the TRILL RFC5556
October 11, 2010 By Leave a Comment
Don’t Drop The Baby: Data Center Bridging Wants Storage To Trust Ethernet
October 8, 2010 By 1 Comment
“Convergence” is a buzzword seen in the IT press constantly these days. All convergence means is placing communications that used to ride on its own network onto one unified network; Ethernet’s cheapness, ubiquity, and ever-growing link speeds makes it the network everything is moving towards. The first big convergence move was to combine voice networks with data networks, using IP telephony. The challenges of a converged voice/data network include prioritizing voice traffic over pretty much anything else during times of link congestion, and keeping call quality high by delivering datagrams in a predictable time with a predictable gap in between those datagrams.
Assembly Required: A Basic Spanning-Tree Design for a Two-Tier Data Center
September 8, 2010 By Leave a Comment
An important element in beating back network chaos is a well-ordered spanning-tree. Spanning-tree was mostly ignored and/or disabled (!) by my predecessors. Much unloved, spanning-tree is one of those protocols that networking folks are prone to turn their backs on, looking at it from a distance with a jaundiced eye. ”If I leave it alone, it can’t hurt me, ” seems to be the mantra, right up there with, “Don’t ask, don’t tell,” and “Let sleeping dogs lie.”
GestaltIT.com Seattle Tech Field Day July 2010 – Presentations Overview Part 2 of 2
July 26, 2010 By Leave a Comment
Presentation #3 was by F5 networks at the F5 Technology Center. Compellent presented to the Tech Field Day delegation about their automated storage solution which they call “Fluid Data”. View Compellent’s introductory video. The final Tech Field Day presentation was from NEC, on their HYDRAstor storage array.
GestaltIT.com Seattle Tech Field Day July 2010 – Presentations Overview Part 1 of 2
July 21, 2010 By Leave a Comment
The Seattle Tech Field Day was actually 2 days. Across those 2 days, the TFD delegates watched 5 presentations from 5 different vendors, plus had a mixer-style dinner with all the vendors. Most of these presentations were storage and virtualization related. Only one vendor, F5 Networks, would be considered to be a networking company, and even their presentation showed some of their fancy new integration with VMware.
Assembly Required – Interconnecting 2 Ethernet Chassis Switches
June 28, 2010 By Leave a Comment
You’ve been tasked with interconnecting two ethernet chassis switches. There are lots of reasons you might want to do this. The link you’re building might be between two core switches acting as your main data center routers. The link could be connecting a core switch and distribution or access layer switch. Here’s a brain stream of the pros and cons of various approaches I’ve seen in production environments.