When CDP doesn’t discover

Marko's myths of VLAN 1 post continues to drive a lot of traffic to my response about CDP, tagging and the magic properties of VLAN 1.

Today I was introduced to a related phenomenon that I found interesting.

Backstory
CDP messages sent by switches are always in VLAN 1. If something other than VLAN 1 is the native VLAN on a particular trunk, then the CDP frame will be tagged with "1".

Funny Business
According to the post linked above there are related conditions that break CDP altogether.

The required elements are:
  1. A switch sending tagged CDP frames, either because it's using something other than VLAN 1 as the native VLAN or it's been configured with vlan dot1q tag native
  2. A router-on-a-stick that does NOT have a subinterface configured with encapsulation dot1q 1
Apparently the router, having no subinterface configured to receive frames tagged with "1", will toss incoming CDP frames without bothering to look inside to find the CDP message, killing CDP operation altogether. Bummer. And kind of unexpected.

I haven't tested this behavior, nor do I even have an IOS-XR (where the problem was found) box available. I suspect that IOS and IOS-XE systems might have a similar Continue reading

The Next Generation in Cloud-Scale Networking: The Arista 7500E

Today we are announcing our new 7500E modular switch, the fastest and densest modular switching platform in the industry, enabling cloud networks to scale to over 100,000 servers and millions of virtual machines.

The Arista 7500E is a remarkable 3X better than its predecessor. It offers 3X the number of ports, 3X the fabric bandwidth, 3X the packet buffer, 3X the supervisor performance, and 3X the power-efficiency, without a chassis or power upgrade.

But the real story of the 7500E it that it enables customers to build a universal cloud networking infrastructure for the worldʼs largest data centers that can handle even the most demanding workloads with ease.

Letʼs take a look inside this remarkable new switch.

3X the Fabric Bandwidth

The 7500E has 3.84 Tbps fabric bandwidth per slot, or 30 Tbps per 8-slot chassis, three times the bandwidth of the first generation 7500.

3X the Port Density

The 7508E supports 1152 10G, 288 40G or 96 100G wire-speed ports in a 11U chassis, the highest port density in the industry and three times the number of ports of the first generation 7500.

3X the Packet Buffer

The 7500E comes with a world-record 144 GByte of packet buffer per 8-slot chassis, Continue reading

VMware VCDX Lab: The Hardware

I have to admit I’m a big VMware fanboy. Wanting to master the art of virtualization, I’ve set out to build out a personal lab. My primary goal is to work my way up to the VCDX certification. The curious thing about building a VMware lab is that all parts need to be on the […]

Author information

Douglas Hanks

Douglas Hanks

Douglas Hanks is a Data Center Architect with Juniper Networks and focuses on solution architecture for service provider and enterprise. He is certified with Juniper Networks as JNCIE-ENT #213 and JNCIE-SP #875. He is the author of the Juniper MX Series by O'Reilly and several Day One books published by Juniper Networks. Douglas is also the co-founder of the Bay Area Juniper Users Group (BAJUG).
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Email: [email protected]
Twitter: @douglashanksjr
LinkedIn: http://www.linkedin.com/in/dhanks
My words are my own.
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The post VMware VCDX Lab: The Hardware appeared first on Packet Pushers Podcast and was written by Douglas Hanks.

Show 145 – Talking OpenDaylight and SDN

A community show where we get Brent Salisbury and Ivan Pepelnjak to talk about the events of the last few weeks. In the end, the only thing we seemed to cover was OpenDaylight, ONS and various SDN topics. Open Networking Summit – Brent reports in. Talking SDN and OpenDaylight Ivan asks “will you install open […]

Author information

Greg Ferro

Greg Ferro is a Network Engineer/Architect, mostly focussed on Data Centre, Security Infrastructure, and recently Virtualization. He has over 20 years in IT, in wide range of employers working as a freelance consultant including Finance, Service Providers and Online Companies. He is CCIE#6920 and has a few ideas about the world, but not enough to really count.

He is a host on the Packet Pushers Podcast, blogger at EtherealMind.com and on Twitter @etherealmind and Google Plus.

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The post Show 145 – Talking OpenDaylight and SDN appeared first on Packet Pushers Podcast and was written by Greg Ferro.

Nexus 7000 IO Module SKU Cheat Sheet

Wow the title of this post is a mouthful.

Similar to my previous post on the Nexus 2000 (Nexus 2000 Model Number Cheat Sheet), this post will explain what the letters and numbers mean in the Nexus 7000 IO module part numbers. This will allow you to quickly identify the characteristics of the card just by looking at the part number which in turn should help you out as you're building BOMs and picking the right card for the job.

Update July 2, 2013: Updated to reflect release of the Nexus 7700 and F3 modules.

IGP Route Multipathing

In preparation for an upcoming post, I was reminded about a commonly referred to feature in most IGPs - the concept of Equal-Cost Multipath, or simply ECMP. This is the idea that multiple routes with the same cost to a remote network should get placed in the routing table alongside each other and packets should load-balance over them to use the additional available paths. After all, it’s the same cost, so why not?

IGP Route Multipathing

In preparation for an upcoming post, I was reminded about a commonly referred to feature in most IGPs - the concept of Equal-Cost Multipath, or simply ECMP. This is the idea that multiple routes with the same cost to a remote network should get placed in the routing table alongside each other and packets should load-balance over them to use the additional available paths. After all, it’s the same cost, so why not?

A Data Center Delivers Apps – So Shouldn’t We Monitor App Delivery?

Dinner with His Toadishness, Derick Winkworth, the other night rolled into a 3+ hour discussion of avant garde ways to do networking. One of the adjunct topics that came up was that of ownership within IT. Ownership is a complex problem in the data center, because there’s many complex technologies at work. No one single […]

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 A Data Center Delivers Apps – So Shouldn’t We Monitor App Delivery? appeared first on Packet Pushers Podcast and was written by Ethan Banks.

Machine Fragile

Yesterday, a “breaking news” tweet at 1:07 PM EDT from the Associated Press reported that two explosions had occurred at the White House and President Obama had been injured. The news immediately sent the Dow Jones Industrial Average down 143 points, as this graph at the London Telegraph shows. There’s also a lovely animated display […]

Author information

Russ White

Principal Engineer at Ericsson

Russ White has scribbled a basket of books, penned a plethora of patents, written a raft of RFCs, taught a trencher of classes, nibbled and noodled at a lot of networks, and done a lot of other stuff you either already know about — or don't really care about. You can find Russ at 'net Work, the Internet Protocol Journal, and his author page on Amazon.
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The post Machine Fragile appeared first on Packet Pushers Podcast and was written by Russ White.

It Works and It Should Be Better

You say, “It works – don’t fix it.” I hear, “It works – don’t touch it.” I’m also thinking that if you don’t touch it, then it’s never upgraded or changed. Is a static, unchanged network the best you can do to support your business ? Are you happy with just doing more of the same […]

Author information

Greg Ferro

Greg Ferro is a Network Engineer/Architect, mostly focussed on Data Centre, Security Infrastructure, and recently Virtualization. He has over 20 years in IT, in wide range of employers working as a freelance consultant including Finance, Service Providers and Online Companies. He is CCIE#6920 and has a few ideas about the world, but not enough to really count.

He is a host on the Packet Pushers Podcast, blogger at EtherealMind.com and on Twitter @etherealmind and Google Plus.

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The post It Works and It Should Be Better appeared first on Packet Pushers Podcast and was written by Greg Ferro.

What can you learn in 5 minutes a day !

I  believe in minimalism and what small focused actions can make for a person and small steps is what Juniper learning bytes is all about. Learning bytes is an online learning resource launched last year by Juniper education services organization as a free service. The nice thing about the learning bytes is that they are focused, [...] No related posts. Related posts brought to you by Yet Another Related Posts Plugin.

Your Job Hunt is YOUR Responsibility

Earlier this week, I read the article below. This article took a strong stance that a recruiter works for the employer, not those seeking employment. I think there are some valid points made. However, my views are a little less extreme than that of the author. NEWSFLASH: A Recruiter is Not a Job Finder!. Frankly, […]

Author information

Paul Stewart

Paul is a Network and Security Engineer, Trainer and Blogger who enjoys understanding how things really work. With nearly 15 years of experience in the technology industry, Paul has helped many organizations build, maintain and secure their networks and systems. Paul also writes technical content at PacketU.

The post Your Job Hunt is YOUR Responsibility appeared first on Packet Pushers Podcast and was written by Paul Stewart.

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.

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...
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