PQ Show 29 – How To Prepare for the CCDE

At Cisco Live US 2013 in Orlando, Packet Pushers co-host Ethan Banks was joined by CCDE program manager Elaine Lopes, CiscoPress author Russ White who was closely involved with the CCDE program creation, quad-CCIE & CCDE Scott Morris, and CCIE & CCDE Jeremy Filliben who instructs a CCDE bootcamp. We discuss (what else) how to […]

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

TwitterGoogle+LinkedIn

The post PQ Show 29 – How To Prepare for the CCDE appeared first on Packet Pushers Podcast and was written by Ethan Banks.

Quality of Service (QoS) Congestion Management Notes

Of all the tools within the QoS toolset, congestion management tools, also known as queuing tools, provide the biggest impact on application service levels.  Whenever packets enter a device faster than can exit it, congestion exists and this is where queuing tools come into play.  Queuing tools are only engaged when congestion exists, otherwise packets are sent as soon as they arrive.  When congestion does exist, packets must be buffered, or queued, to mitigate dropping.

Packet markings, or lack thereof, affect queuing policies, so queuing policies are complementary and have a dependence on classification and marking policies.

Scheduling vs. Queuing

These two terms are often incorrectly used interchangeably – they are two different things.  Scheduling determines how a frame or packet exits a device. Whenever packets enter a device faster than they can exit it, as is the case with speed mismatches (ex. Gigabit Ethernet traffic heading to a WAN interface), congestion can occur.  Devices have buffers that allow the temporary storing and subsequent scheduling of these backed-up packets, and this process is called queuing.

Inbound traffic > Queuing (During congestion) > Scheduling > Outbound traffic

• Queuing – orders packets in linked output buffers. Only Continue reading

Quality of Service (QoS) Classification and Marking Notes

The first part of building a QoS policy is to identify the traffic that you need to treat preferentially (give better priority), or differentially.  This is accomplished via classification and marking.

• Classification – sorts packets into different traffic types that policies can then be applied to.
• Marking (or re-marking) – establishes a trust boundary on which scheduling tools later utilize.  The edge of the network where markings are either accepted or rejected is known as the trust-boundary.
• Classifier tools – Inspect one or more fields in a packet to identify the type of traffic that is being carried. After being identified, it is passed to the appropriate mechanism to handle that type of traffic class.
• Marking tools – actually write a field within the packet (or frame, cell, label) to preserve the classification decision.  By marking traffic at a trust boundary, subsequent nodes do not have to perform the same in-depth analysis to determine how to treat the packet.

Classification Tools

These tools can examine a number of criteria within layers 1, 2, 3, 4, and 7.

• L1 – Physical interface, subinterface, PVC, port
• L2 – MAC, 802.1Q/p CoS, VLAN, MPLS EXP, ATM Cell Continue reading

Checksum Verification

Occasionally I have to install software that is no longer available for download via the official channels. This is due to us having pretty strict standards on which IOS versions are stable and suitable for use via a bug scrub process that Cisco are party to.

I could speak to our Cisco SE and ask for the image to be provided, but it’s simpler and quicker to find a similar piece of kit on the network and FTP/SCP the image across.

I did this today, and then realised that I couldn’t rely on CCO to give me the MD5 sum for the image. A quick google tells me that I can perform a checksum on the switch using this command:

verify /md5 <file-location>:<file-name>

Location choices are:

bs: File to be verified
cns: File to be verified
flash: File to be verified
ftp: File to be verified
http: File to be verified
https: File to be verified
null: File to be verified
nvram: File to be verified
rcp: File to be verified
scp: File to be verified
system: File to be verified
tar: File to be verified
tftp: File to be verified
tmpsys: File to be verified
xmodem: File to be Continue reading

Change your vocabulary, change your career

When people look at their careers, the focus pretty naturally falls to skills acquisition. Almost everyone believes that their future hinges on learning some skill or mastering some talent. Maybe you want to know more about business or strategy. Perhaps you think you need to read leadership books or find Harvard Business Review articles on […]

Author information

Michael Bushong

The post Change your vocabulary, change your career appeared first on Packet Pushers Podcast and was written by Michael Bushong.

Invest in great tools for your engineers

Can you remember your last newly hired engineer, all shiny and happy and new? Can you also remember the look on their face when they received their corporate craptop? Or maybe they received a decent laptop, but it came in a ten dollar laptop bag. The tech industry spends a lot of time and effort […]

Author information

John Harrington

John is an experienced data center engineer with a background in mobile telecoms. He works as a network test engineer for a large cloud service provider, and is gradually accepting that he's a nerd. He blogs about network technology and careers at theNetworkSherpa.com. You can reach him on twitter at: @networksherpa

The post Invest in great tools for your engineers appeared first on Packet Pushers Podcast and was written by John Harrington.

Don’t Alienate Your Co-Workers With Your Passion

We geeks love our tech. Really love it. I mean…really, really get down deep into a technology, decide it’s the best thing ever, and then wave the flag around high. Make the wallpaper. Wear the t-shirt. Evangelize the ignorant. Shout down the naysayers. Mock the competitors. Fan the flames of rivalry. Linux vs. Microsoft. Mac […]

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

TwitterGoogle+LinkedIn

The post Don’t Alienate Your Co-Workers With Your Passion appeared first on Packet Pushers Podcast and was written by Ethan Banks.

CDN activity and what it means for network monitoring

One of the more useful ways to find out what is happening in the real world of network monitoring and troubleshooting is to have a look through some of the many on line forums that exist. Spiceworks Community and SolarWinds Thwack are examples but there are many more. Here you can spot trends as to […]

Author information

Darragh Delaney

Technical Director at NetFort

Darragh Delaney is head of technical services at NetFort. As Director of Technical Services and Customer Support, he interacts on a daily basis with NetFort customers and is responsible for the delivery of a high quality technical and customer support service.

Darragh has extensive experience in the IT industry, having previously worked for O2 and Tyco. His User and Network Forensics blog. for Computer World focuses his experiences of network management and IT security in the real world. In his current role Darragh is regularly on site with network administrators and managers and this blog is a window into the real world of keeping networks running and data assets secure.

He shares network security and management best practices on the NetFort blog. Follow Darragh on Twitter @darraghdelaney and NetFort Technologies @netfort. You can also contact him Continue reading

eFSU on VSS (WS-6513, Sup2T)

Visibility, Debugging and Network Virtualization (Part 1)

[This post was written by Martin Casado and Amar Padmanahban, with helpful input from Scott Lowe, Bruce Davie, and T. Sridhar]

This is the first in a multi-part discussion on visibility and debugging in networks that provide network virtualization, and specifically in the case where virtualization is implemented using edge overlays.

In this post, we’re primarily going to cover some background, including current challenges to visibility and debugging in virtual data centers, and how the abstractions provided by virtual networking provide a foundation for addressing them.

The macro point is that much of the difficulty in visibility and troubleshooting in today’s environments is due to the lack of consistent abstractions that both provide an aggregate view of distributed state and hide unnecessary complexity. And that network virtualization not only provides virtual abstractions that can be used to directly address many of the most pressing issues, but also provides a global view that can greatly aid in troubleshooting and debugging the physical network as well.

A Messy State of Affairs

While it’s common to blame server virtualization for complicating network visibility and troubleshooting, this isn’t entirely accurate. It is quite possible to build a static virtual datacenter and, assuming the vSwitch Continue reading

The Value of Certifications

I hope to clear the air on what a vendor certificate (or any certificate, such as a degree/diploma/etc) is, and is not. Too many times have I heard/seen people place too little or too much stock in the single piece of paper. What a certificate is A certificate, simply put, is proof that on a […]

Author information

Ken Matlock

Ken Matlock is a networking veteran of 19 years. He has worked in many fields in the networking industry including Service Provider, Retail, and Healthcare. When he's not fixing the problems of the networking world, he can be found studying for his CCIE, spending time with his family, and trying to chase the ever-elusive sleep.

He can be found on twitter @KenMatlock , email at [email protected] , irc.freenode.net #PacketPushers, or the occasional blog or forum post.

The post The Value of Certifications appeared first on Packet Pushers Podcast and was written by Ken Matlock.

Cisco onePK: Now I Get It

I had an opportunity recently to sit in a Cisco onePK lab and it opened my eyes to exactly what Cisco is doing with onePK, why it’s going to be so important as Software Defined Networking (SDN) continues to gain traction, and why onePK is different than what anyone else is doing in the industry.

onePK is a key element within Cisco’s announced Open Network Environment SDN strategy. onePK is an easy-to-use toolkit for development, automation, rapid service creation and more. It enables you to access the valuable data inside your network via easy-to-use APIs.

Source: www.cisco.com/go/onepk

Since having my own eyes opened, I’ve been pondering how to explain my new found understanding in a way that others will grasp. In particular to business decision makers (BDMs) and technical decision makers (TDMs). I’m really, really, struggling to come up with a good analogy for BDMs. I’m still working on that one. Surprisingly, I’m also struggling to come up with a sound analogy that will work with the majority of TDMs that I know. Maybe I shouldn’t be so surprised at that since all the TDMs I deal with are on the infrastructure side of things (networks, storage, Continue reading

Show 153 – Cisco Live 2013 Roundtable Discussion with Tech Field Day

At Cisco Live US 2013, we were able to get together a nice group of folks to share their opinions on the announcements we found most interesting. You’ll know some of them from Tech Field Day, an event Greg and I have been a part of several times. This show is good conversation with smart […]

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

TwitterGoogle+LinkedIn

The post Show 153 – Cisco Live 2013 Roundtable Discussion with Tech Field Day appeared first on Packet Pushers Podcast and was written by Ethan Banks.

Cisco onePK: Now I Get It

I had an opportunity recently to sit in a Cisco onePK lab and it opened my eyes to exactly what Cisco is doing with onePK, why it's going to be so important as Software Defined Networking (SDN) continues to gain traction, and why onePK is different than what anyone else is doing in the industry.

onePK is a key element within Cisco's announced Open Network Environment SDN strategy. onePK is an easy-to-use toolkit for development, automation, rapid service creation and more. It enables you to access the valuable data inside your network via easy-to-use APIs.

Source: www.cisco.com/go/onepk

Since having my own eyes opened, I've been pondering how to explain my new found understanding in a way that others will grasp. In particular to business decision makers (BDMs) and technical decision makers (TDMs). I'm really, really, struggling to come up with a good analogy for BDMs. I'm still working on that one. Surprisingly, I'm also struggling to come up with a sound analogy that will work with the majority of TDMs that I know. Maybe I shouldn't be so surprised at that since all the TDMs I deal with are on the infrastructure side of things (networks, storage, Continue reading

Your Career – Enemies Within and Without

In the mood for some self analysis and reflection around your career and your employer? Good. I’ve strong feelings about employment in general and even stronger ones around balancing it with your personal life (I wouldn’t dare say private any more) and making work work for you. I’m definitely in the work to live camp. […]

Author information

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 Your Career – Enemies Within and Without appeared first on Packet Pushers Podcast and was written by Steven Iveson.

Heatsink Upgrade

Heatsink Upgrade

Network Security and the N00b Meter

This morning I read an article in which the writer thought that wireless security was too inconvenient and difficult, so he simply disabled it, leaving his network wide open. He was tired of his complex password being too hard for guests to use and made the comparison that they didn’t have to use these kinds […]

Author information

Mrs. Y

Snarkitecht at Island of Misfit Toys

Mrs. Y is a recovering Unix engineer working in network security. Also the host of Healthy Paranoia and official nerd hunter. She likes long walks in hubsites, traveling to security conferences and spending time in the Bat Cave. Sincerely believes that every problem can be solved with a "for" loop. When not blogging or podcasting, can be found using up her 15 minutes in the Twittersphere or Google+ as @MrsYisWhy.

TwitterLinkedIn

The post Network Security and the N00b Meter appeared first on Packet Pushers Podcast and was written by Mrs. Y.

Optimizing and Protecting Spanning Tree – Lab Testing

Unfortunately the equipment I was using didn’t support PVST+ (Sup2Ts in 6503 Catalyst Switches), so I skipped testing UplinkFast and BackboneFast as these are incorporated in 802.1w (RSTP) and 802.1s (MSTP, which is basically an extension of RSTP).

BPDU Guard

For this test, SwitchD will be treated as a Rogue Switch being attached to the network.  Initially, SwitchC’s port 2/1 is configured as an access port with only PortFast enabled.

1. 1. Disconnect link between SwitchC and SwitchD
2. 2. Configure SwitchC port 2/1 as an access port in VLAN 10 with PortFast enabled.
3. 3. Configure SwitchD port 2/1 as an access port in VLAN 10. Configure the priority on VLAN 10 to be 0.
4. 4. Reconnect link between SwitchC and SwitchD and check topology for VLAN 10. SwitchD should be the root for VLAN 10.
5. 5. Disconnect link between SwitchC and SwitchD
6. 6. Enable BPDU Guard on Switch C port 2/1
7. 7. Reconnect link between SwitchC and SwitchD. SwitchC port 2/1 should move to an err-disable state. Verify with sh interfaces status err-disabled. Verify SwitchD is no longer the root for VLAN 10.

*Jul  5 22:02:06.023: %SPANTREE-2-BLOCK_BPDUGUARD: Received BPDU on port GigabitEthernet2/1 with BPDU Guard enabled. Disabling Continue reading

Masterclass – Tcpdump – Expressions

This Masterclass article series aims to provide in-depth technical information on the installation, usage and operation of the classic and supremely popular tcpdump network traffic analysis program including alternatives, running tcpdump as a process, building expressions, understanding output and more. I’ve covered the Basics and Parameters previously and here I move on to filter Expressions; […]

Author information

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 Masterclass – Tcpdump – Expressions appeared first on Packet Pushers Podcast and was written by Steven Iveson.