Nexus 5500 ASIC to port mapping
While assigning ports on a Cisco Nexus 5500 switch, it is a good practice to span out ports that belong to separate ASICs on board to uplink to upstream or downstream devices. For e.g. while connecting a 5500 to say a UCS FI, it is good practice to select 2 ports from one ASIC bay and 2 from another ASIC bay. The way you find out ASIC to port mapping is with the following CLI command : 'show hardware internal carmel asic <0-13>' where 0-13 are the ASIC numbers.
Here, Ports 9-16 are mapped to ASIC 1. On Nexus 5500 switches, 8 ports are mapped to each ASIC.
HP Moonshot
Despite my humble beginnings as a network engineer, I’m almost always including servers/virtualization/storage in my day-to-day work. If you’re not into building servers from scratch (not a bad venture) then the leaders in the server space might be a good fit for you - most are doing some pretty interesting things in the battle for the top spot in this space. Most folks would agree that HP is still the number one leader, even if only considering pure volume (I see c7000 chassis EVERYWHERE).HP Moonshot
Despite my humble beginnings as a network engineer, I’m almost always including servers/virtualization/storage in my day-to-day work. If you’re not into building servers from scratch (not a bad venture) then the leaders in the server space might be a good fit for you - most are doing some pretty interesting things in the battle for the top spot in this space. Most folks would agree that HP is still the number one leader, even if only considering pure volume (I see c7000 chassis EVERYWHERE).Crossbow on Big F#@!ing Webtone Switch
Back in the days of SUN Microsystem, Scott McNealy asked us to build a big F#@!ing Webtone Switch. At that time, the underlying pieces weren’t there but over last few years the possibilities have opened up. We now have the switch chips from Broadcom and Intel that switch at 1.2Tbps in H/W. From a OS view, 1.2 Tbps of switching at 300ns latency is great but the more amazing thing is PCIe as a control plane which allows 20-40Gbps of control plane B/W where you can change switch registers, L2/L3-tables, TCAMs, etc at nano-second rates.
So after more than three years of work and million lines of C code, the Pluribus Network’s engineering team has the switch chip under Crossbow control. For people who are not sure what I am talking about, in 2005 project Crossbow invented virtual switching inside a server hypervisor and introduced hardware based Virtual NICs and dynamic polling to get 40Gbps of bandwidth through a server OS. The details were published in “Crossbow: From Hardware Virtualized NICs to Virtualized Networks” in ACM Sigcomm VISA 09.
In the goal to benefit from merchent silicon ecosystem and orchestrate the entire infrastructure using Open source OS Continue reading
Show 155 – Integrating OTV, FabricPath & LISP – Sponsored
At Cisco Live 2013 in Orlando, Packet Pushers co-hosts Ethan Banks and Greg Ferro sat with Nexus 7000 champion Ron Fuller and network design expert Russ White to discuss how, when and why you might choose to deploy FabricPath, OTV, or LISP. In particular, we get into the specifics of what each protocol does, where […]
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The post Show 155 – Integrating OTV, FabricPath & LISP – Sponsored appeared first on Packet Pushers Podcast and was written by Ethan Banks.
IGP Metric Tweaks – Direction is Important
A while back I was responsible for setting up a group of switches and routers to serve as the internet distribution for a hospital, mainly the function of designing the IGP of choice to work given the hospital’s requirements and coordinating with the teardown of the old gear. The idea was to configure EIGRP so that one next-hop was preferred over another. We know this is possible through tweaking the various metrics for a given IGP, but in the process, I was reminded of something that’s quite important to think about when doing so.IGP Metric Tweaks – Direction is Important
A while back I was responsible for setting up a group of switches and routers to serve as the internet distribution for a hospital, mainly the function of designing the IGP of choice to work given the hospital’s requirements and coordinating with the teardown of the old gear. The idea was to configure EIGRP so that one next-hop was preferred over another. We know this is possible through tweaking the various metrics for a given IGP, but in the process, I was reminded of something that’s quite important to think about when doing so.IGP Metric Tweaks – Direction is Important
A while back I was responsible for setting up a group of switches and routers to serve as the internet distribution for a hospital, mainly the function of designing the IGP of choice to work given the hospital’s requirements and coordinating with the teardown of the old gear. The idea was to configure EIGRP so that one next-hop was preferred over another. We know this is possible through tweaking the various metrics for a given IGP, but in the process, I was reminded of something that’s quite important to think about when doing so.Healthy Paranoia Show 15: The Dudes of REN-ISAC
It’s the latest dudilicious episode of Healthy Paranoia! This time we’ll be covering the topic of information sharing and analysis centers (ISAC), specifically in the research and educational networking sector, aka REN-ISAC. Joining Mrs. Y on this adventure into the land of dudeness is Wes Young, REN-ISAC Principal Security Engineer and Architect (El Duderino), Keith […]
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The post Healthy Paranoia Show 15: The Dudes of REN-ISAC appeared first on Packet Pushers Podcast and was written by Mrs. Y.
Lessons Learned Writing a Custom Config Builder
A while back, I set about developing a modest configuration templating system for my employer. When I first joined the company, new network devices were being provisioned using configuration templates stored as Microsoft Word files, which, as you can imagine, was pretty painful. Each variable had to be identified and replaced by hand in a tedious and error-prone process. I wanted something better, but also cheap (or free) and simple. So I started building something.
To kick off my crazy project, I first decided to build a web application based on the Django Python framework (the same platform on which PacketLife.net runs). Django and similar frameworks handle most of the mundane tasks involved in writing a web application and allow for rapid prototyping. It also includes a built-in administration interface for creating and manipulating data independent of the front-end user interface. I spun up a modest internal VM running...
You got promoted, now what?
Leadership in most companies is not really something explicitly practiced. Generally, a few people who are naturally inclined kind of do their thing while the rest of the leadership ranks sort of ignore the finer points of people management. But why is that the case? And how do you avoid being one of those leaders […]
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The post You got promoted, now what? appeared first on Packet Pushers Podcast and was written by Michael Bushong.
Confusing The Familiar with The Superior
We all know the archetype of the fanboy (or fangirl of course, however I will forthwith use zealot as a gender-neutral term). They expound upon the superiority of their favorite… whatever, and lambaste the competing product or products, and will hear of nothing that would contradict their conclusions. The battle the zealots fight are well known: […]
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The post Confusing The Familiar with The Superior appeared first on Packet Pushers Podcast and was written by Tony Bourke.
PQ Show 30 – RPKI DNSEC and Internet Security with Ivan Pepelnjak
There are two proposals floating around that are trying to address BGP origination hijacks (aka Pakistan vs. YouTube): RPKI and DNSSEC-based system. Ivan Pepelnjak joins Greg Ferro to talk about what is means for Networking. This show was recorded in January 2013 and it’s been delayed publishing. Please accept my apologies. Show Links Opinionated background […]
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The post PQ Show 30 – RPKI DNSEC and Internet Security with Ivan Pepelnjak appeared first on Packet Pushers Podcast and was written by Greg Ferro.
Quality of Service (QoS) Congestion-Avoidance Notes
Congestion-avoidance tools are complementary to, and dependent upon, queuing algorithms. Queuing/scheduling algorithms manage the front of a queue, while congestion-avoidance mechanisms manage the tail of a queue.
Congestion-avoidance tools are designed for TCP traffic, because TCP has built-in flow-control mechanisms that operate by gradually increasing traffic flows until packet loss has occurred. Once packet loss has occurred, the transmission rate is reduced before slowly ramping up again. This means that if no mechanism is in place to control TCP, any particular flow has the ability to eat up all available bandwidth.
When there are no congestion-avoidance tools in place, and queues fill, tail drop occurs, which means all traffic is dropped.
In a constricted channel without congestion-avoidance tools, TCP connections eventually synchronize with each other – they ramp up together, lose packets together, and back off together. This is called global synchronization and basically results in “waves” of TCP traffic.
Congestion-avoidance tools has no real benefit or use for UDP traffic, because UDP traffic does not have any retry logic.
Random Early Detection (RED)
RED combats global synchronization by preemptively and randomly dropping packets before queues fill. Instead of waiting for the queues to fill, Continue reading
Calculating distances in meatspace
I'm working on an automated provisioning system for a very large VPN network. For each new VPN client, I need to select a headend site where VPN tunnels should land. The only data available is that which I can get from the sales and billing systems. This system offers me the zip code of the install site.Using the zip code of the install site, and the known zip codes of my various head-end sites, I'm able to select the destination for the primary and secondary VPN tunnels.
It's not perfect (physical location often has little to do with network path), but it's better than nothing. I haven't decided how to handle non-US sites yet.
I'm using a database of US zip codes found here, and a very dirty perl script. The script grabs the latitude and longitude of two zip codes from the database, and prints the mileage between them as calculated using the Haversine formula for great circle distance.
It runs like this:
Christophers-MacBook-Pro:scripts chris$ zipdistance.pl 95134 60614
1837 miles
Christophers-MacBook-Pro:scripts chris$
The script:
#!/opt/local/bin/perl
use GIS::Distance;
my $dbfile="/Users/chris/Downloads/zipcode.csv";
my $lat1,$lon1,$lat2,$lon2;
sub usage{
printf "Usage: $0 <zipcode> <zipcode>n";
exit;
}
if (@ARGV ! Continue reading
The value of Connectors in the workplace
In Malcolm Gladwell’s book The Tipping Point [affiliate link] the author identifies key roles that individuals play in spreading knowledge and ideas. Gladwell outlines two key roles, the maven and the connector. The maven is a person who accumulates subject matter expertise and is willing to distribute that knowledge on request. Think of a maven […]
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The post The value of Connectors in the workplace appeared first on Packet Pushers Podcast and was written by John Harrington.
CCIE Rack for Sale
I am selling my rack as I need to make some space and I am now using CCIE Rack Rentals all the time which I find are so much more convenient. Only for UK as it is collection only, but if you are in the market for a CCIE Rack based on the INE topology […]
The post CCIE Rack for Sale appeared first on Roger Perkin - Networking Articles.
Ageism and your career in I.T.
I recently decided to commit to my current company. I don’t mean work harder or focus more, though that’s implicit. I mean to consider being a “lifer.” For an independent personality like myself that’s a pretty tall leap. One of the reasons I got my CCIE was to avoid ever being the guy sweating when […]
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The post Ageism and your career in I.T. appeared first on Packet Pushers Podcast and was written by Keith Tokash.
Software Defined Data Centres and the blending of cultures
As some of you may know, I have spent a fair amount of my time in the last few years designing and improving multi-tennant hosting environments. Each revision attempts to learn from the mistakes of the previous iterations, as well as bundle in new features and “advancements” from each of the different vendors in the stack.
New offerings on the storage fronts, developments in the server space in the form of the boom of virtualisation, and the simple existence of the network amongst the fact that none of these technologies changed the existing/fundamental laws of networking.
Software-Defined Networking has sprung up as a way of providing both advancements in our current architectures and providing agility in changes needed in the future, but what is truly needed is a true abstraction of the entire data centre model that encompassed all of compute, storage, security and networking. The ability to define all of the requirements of your existing data centre and have them deployed and rolled out across which ever stack you are using (Private / Public / Hybrid / Tomorrows Favourite buzz.), in a consistent and definable manner.
Merging the requirements of each of the existing silos and describing Continue reading
AdaptingIT: Why I Started a Podcast Featuring Women in Tech
As a systems admin a few years back I decided that I needed to figure out a way to understand networking. I could do basic things, but how do you figure out what you don’t know? That’s when I started listening to podcasts. The first podcast I came across was Packet Pushers and I haven’t […]
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The post AdaptingIT: Why I Started a Podcast Featuring Women in Tech appeared first on Packet Pushers Podcast and was written by Lauren Malhoit.