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Category Archives for "Networking"

FusionIO Acquires Nexgen

For anyone keeping tabs on the storage industry these days, you might have noticed the news today regarding FusionIO’s acquisition of Nexgen - one of a myriad of storage startups that have cropped up in the past few years to address the ever-changing needs of the data center industry. After looking through some of the articles that were published today, I think we all understand the financial details behind the transaction.

Notes On AAA

Enabling aaa new model means the switch will try and match all login attempts using a aaa method.

First, define the TACACS or RADIUS server using:

tacacs-server host <IP-address> <optional key value>

There are some other values you can use, but I’ve never had to use these.

Now, give your authentication method a name:

aaa group server tacacs+ <method-name>
 server <IP-address>

Call the method for authenttication

aaa authentication login default group <method-name> group <fallback method name if configured> local

You should now be good to go!


DHCP client testing tool

DHCP is vastly growing in service provider networks for broadband subscribers, I had the chance to work lately with a some of these setups. The protocol is really easy to configure for broadband and provide many benefits.  It has lower overhead compared to PPPOE and it is much more suitable for Multicast services. For those [...] No related posts. Related posts brought to you by Yet Another Related Posts Plugin.

Programming 101 for Network Engineers – Preparation

Okay, let’s say you’re convinced you need to learn to programme and you don’t want to be left behind. The earlier you start, the more you can pick up (and the sooner you’ll become consciously competent) at a pace that suits you. Hopefully, you’ll be able to blend this into your schedule with whatever else you […]

Author information

Steven Iveson

Steven Iveson

Steven Iveson, the last of four children of the seventies, was born in London and has never been too far from a shooting, bombing or riot. He's now grateful to live in a small town in East Yorkshire in the north east of England with his wife Sam and their four children.

He's worked in the IT industry for over 15 years in a variety of roles, predominantly in data centre environments. Working with switches and routers pretty much from the start he now also has a thirst for application delivery, SDN, virtualisation and related products and technologies. He's published a number of F5 Networks related books and is a regular contributor at DevCentral.

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The post Programming 101 for Network Engineers – Preparation appeared first on Packet Pushers Podcast and was written by Steven Iveson.

Playing with event-scripts

Last week, I worked on 2 small projects in 11.4 Junos. I should: - Find a way to automatically disable a physical link when LACP "flapped" too many times during a given time. - Find a way to automatically disable a physical link when too many CRC errors...

Playing with event-scripts

Last week, I worked on 2 small projects in 11.4 Junos. I should: - Find a way to automatically disable a physical link when LACP "flapped" too many times during a given time. - Find a way to automatically disable a physical link when too many CRC errors...

DCI Series: Overlay Transport Virtualization

This is the third article in my series on Data Center Interconnection (DCI). In the first (Why is there a “Wrong Way” to Interconnect Data Centers?) I wrote about the risks associated with DCI when the method chosen is to stretch Layer 2 domains between the data centers. In the second article (DCI: Why is Stretched Layer 2 Needed?) I wrote about why the need exists for stretching Layer 2 domains between sites and also touched on why it's such a common element in many DCI strategies.

Routing iSCSI Traffic

This post was initiated by a side conversation I had about iSCSI. From time to time I’m required to implement an iSCSI-based solution, and this is not the first time I’ve heard the question: “So why can’t I route iSCSI traffic?” Most folks with any knowledge of storage protocols will have at some point picked up this informal best practice idea; some will vehemently defend this idea as the word of $deity and shun all those who contradict this truth.

Routing iSCSI Traffic

This post was initiated by a side conversation I had about iSCSI. From time to time I’m required to implement an iSCSI-based solution, and this is not the first time I’ve heard the question: “So why can’t I route iSCSI traffic?” Most folks with any knowledge of storage protocols will have at some point picked up this informal best practice idea; some will vehemently defend this idea as the word of $deity and shun all those who contradict this truth.

Arduino: Using my MelodyUtils library for R2-D2 style chirps

As part of a small robotics project I've been working on this weekend (affectionately called CoBe1, there will be a follow up blog on that soon) I decided to give by robot some personality in the form a a voice, and uploaded some of my code to GitHub.

While Arduino is capable of playing music and sounds from an SD Card I wanted something a little more authentic… something similar to R2-D2's chirps from Star Wars. I had a mini 8Ohm speaker lying around and following the tutorials here it was easy to get it hooked up to my Arduino Uno and start making sounds. By adjusting the default melody and timings I got part way to achieving my R2-D2 style attitude, but notes on their own just didn't cut it. What I needed was some articulations. I got coding and whipped up a library that makes it easy to use glissando and tremolo. Want to give it a try? Grab the code on GitHub Here's a simple example sketch:

#include <pitches.h>;

void setup()
{
MelodyUtils mel(8);
mel.Glis(NOTE_C3, NOTE_C4, 5);
delay(1000);
mel.Trem(NOTE_C3,  Continue reading

Multi-Vendor OSPF Cost Calculations

While on my current kick with virtual routing, I stumbled across an interesting concept regarding OSPF, and the flexibility that vendors have in determining the best path through an OSPF network. The following topology is what I’ve been staring at for the last few days Pretty simple, right? There’s a single network (192.168.123.0/24) down inside each virtual host where the VMs are to sit. Each host has a router on it (one Cisco CSR 1000v and the other Vyatta Core 6.

Multi-Vendor OSPF Cost Calculations

While on my current kick with virtual routing, I stumbled across an interesting concept regarding OSPF, and the flexibility that vendors have in determining the best path through an OSPF network. The following topology is what I’ve been staring at for the last few days Pretty simple, right? There’s a single network (192.168.123.0/24) down inside each virtual host where the VMs are to sit. Each host has a router on it (one Cisco CSR 1000v and the other Vyatta Core 6.

HP Route Preference (Administrative Distance)

When building networks leveraging a variety of products you need to consider interoperability and configuration consistency. When leveraging HP A-Series switches in a Cisco environment considerations need to be made in regards to administrative distance (Cisco's term) or route preference (HP's term). In order to ensure that you maintain consistent behavior it is recommended that you modify one or the other and make them consistent with each other. I would recommend following Cisco's administrative preference instead of HP's route preference.

HP's default route preference



Cisco's default administrative distance


Don't get caught with unexpected routing behaviors. Have fun!

What The Heck Is F5 Networks’ TMOS?

F5 Network’s Traffic Management Operating System (TMOS) is, first and foremost and for the sake of clarity, NOT an individual operating system. It is the software foundation for all of F5’s network or traffic (not data) products; physical or virtual. TMOS almost seems to be a concept rather than a concrete thing when you first try […]

Author information

Steven Iveson

Steven Iveson

Steven Iveson, the last of four children of the seventies, was born in London and has never been too far from a shooting, bombing or riot. He's now grateful to live in a small town in East Yorkshire in the north east of England with his wife Sam and their four children.

He's worked in the IT industry for over 15 years in a variety of roles, predominantly in data centre environments. Working with switches and routers pretty much from the start he now also has a thirst for application delivery, SDN, virtualisation and related products and technologies. He's published a number of F5 Networks related books and is a regular contributor at DevCentral.

TwitterLinkedIn

The post What The Heck Is F5 Networks’ TMOS? appeared first on Packet Pushers Podcast and was written by Steven Iveson.

Show 144 – Open EIGRP with Russ White + Cisco’s Donnie Savage

EIGRP is a distance vector routing protocol that for many years was unique to Cisco networking environments. Created and championed by Cisco, it didn’t get any traction in the standards bodies in the early days, because there were already enough interior gateway routing protocols around according to some. EIGRP just didn’t interest enough of the […]

Author information

Ethan Banks

Co-host at Packet Pushers

Ethan Banks, CCIE #20655, has been managing networks for higher ed, government, financials and high tech since 1995. Ethan co-hosts the Packet Pushers Podcast, which has seen over 3M downloads and reaches over 10K listeners. With whatever time is left, Ethan writes for fun & profit, studies for certifications, and enjoys science fiction. @ecbanks
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The post Show 144 – Open EIGRP with Russ White + Cisco’s Donnie Savage appeared first on Packet Pushers Podcast and was written by Ethan Banks.

[Virtual Routing] Part 2 – FHRP Issues in VMware vSphere

I was working on a topology for another post regarding interoperability between the recently released Cisco Cloud Services Router (CSR 1000v) and Vyatta when I ran into an issue regarding vSphere network security policies and First Hop Redundancy Procotols (FHRP) such as VRRP. This post will serve as a precursor to that overall post, but I want to point out a key configuration piece when performing redundant gateways with a FHRP like VRRP.
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