Most Important Skills in Networking

It’s easy to get blinded these days by all the talk about cloud, SDN and automation leading both new and existing people in networking to make decisions in their career which may not be the best ones long term. I’ve had the pleasure of interacting and working together with a lot of prominent people in the industry. Based on this I have identified some skills that all of these people have to some degree and that I believe to be crucial to succeeding in the IT industry.

Ability to write – Many of the successful people in the industry like Ivan Pepelnjak, Russ White, Nick Russo and so on have either authored books, write blogs or both. The ability to put your thoughts down into writing is critical. For someone like me that is working in network design, it is probably the most important skill, not only to write technical documents but to interact with customers, colleagues, managers and so on. It doesn’t matter if you are a technical savant if you can’t put a brief document together describing why and how a certain technology should be implemented.

Ability to speak – A lot of people in IT are a Continue reading

The Network Architect Part 2

I got some great comments from my readers on the first part of this post. I love engaging with readers! So I thought I would write a part two to explain some of my thinking which I described in some of the comments.

Does a network architect need to be technical?

Yes, he/she needs to be technical but what does that mean? Let’s say that two datacenters need to be connected. Layer two needs to be stretched between the two DCs. The architect should be able to know different solutions to the problem such as using fibres between the two DCs, clustering technologies, TRILL, OTV and so on. Does the architect need to be able to configure OTV off the bat? Nope. Does the architect need to know what different timers OTV uses? Nope. Those are not things that need to be considered at that point in time. Now, often the architect is involved in the actual design as well and in that case the architect is involved in creating the design and documenting what commands are needed and so on. So the architect needs to be technical but not super technical.

Does the network architect need operational experience?

Preferably Continue reading

The Network Architect

What’s the difference between a network architect and a network designer? What is network architecture and what is network design? These are questions I asked myself a couple of years ago and that I get asked frequently from others. The reason I wanted to write this post is to help people that want to be network architects understand what it is about. I also wanted to help people that are studying for the CCDE to get into the right mindset. If you go in to the practical with the mindset of a designer, you will fail. You need to think like an architect.

This post is not about if an architect is more advanced than a designer. They are both needed and often they are the same person. I work as both but my title is network architect. Some people use the title to indicate it’s a senior role although the role might not be heavily geared towards design.

So what does a network architect do? And how is that different from the network designer?

The network architect is the one that is fronting the business. What does this mean? The network architect is the one that is meeting stakeholders Continue reading

General – Taking the Long Road

As we start the new year, I started thinking about something. Why do people think it’s acceptable to take shortcuts in their IT career? Is it because people don’t see the true effect of their work? Or is the cheating as prevalent in law and medicine but we working in IT aren’t aware of it?

Trust me, I understand that some people live really tough lives, they want to put food on the table for their family, find a better living, perhaps start a new life in a new country. The competition is fierce. Some countries have more engineers coming out of universities every year than we have people living in Sweden.

The thing is though, if you cheat your way to a CCIE, sooner or later you will be caught. But regardless of that. How would you feel if a power plant goes down due to your mistake? Having a heart monitoring unit fail because of your mistake? Having people’s private information leaked due to your mistake? We all make mistakes but we shouldn’t be making them because we pretend that we are something that we aren’t, experts. Networking is a critical part of everyones life now. Most of Continue reading

General – Merry Christmas And A Little Gift

Hi all,

I had some issues with the site and I haven’t blogged as much lately as I would have hoped but I wanted to wish you a Merry Christmas and send you a little gift from Martin Duggan.

Martin recently released part two of his CCDE Practical Scenarios. Like the last time he is giving you, my readers a discount when you buy it from Leanpub. It’s a really good scenario and you have to stay focused and do your best even if you are not comfortable with the scenario. This is very much how the real scenarios are. You may not be comfortable working with say a cable provider but that might be the scenario you are given. Focus on what is important and find the requirements and constraints and answer as best you can.

Follow this link to receive a discount on the scenario.

Merry Christmas!

The post General – Merry Christmas And A Little Gift appeared first on Daniels Networking Blog.

General – Advice on Numbering Policies in Networking

There are several situations where we need to write some form of policy such as QoS, routing policies used in for example redistribution, filtering and policy-based routing, dot1x and so on. Lately I had to update a policy used by the master controller (MC) in an IWAN design. What are some important things to consider when writing the policy?

The number to start with – If you start with the number one then it won’t be possible to insert anything above this line at a later time. How certain are you that you will never have to put anything before the starting line? My recommendation is to start with a higher number such as 100.

Space between each line – Don’t number your lines 100, 101, 102, 103 and so on. Leave some more space between each line in case you have to insert something later between two lines. A spacing of 10 should be fine for most situations.

Go from most granular to least granular – The policy should go from as granular as possible to the least granular at the end. If you have a statement that is too broad you may catch more than you expected even Continue reading

General – Challenges in Load Balancing Traffic

For the last year I have been working a lot with IWAN which is Cisco’s SD-WAN implementation (before Viptela acquisition).

One of the important aspects of SD-WAN is to be able to load balance the traffic. Load balancing traffic is not trivial in all situations though. Why not?

If you have a site where you have two MPLS circuits or two internet circuits and they both have the same amount of bandwidth, then things are simple. Or at least, relatively simple. Let’s say that you have a site with two 100 Mbit/s internet circuits. This means that we can do equal cost multi pathing (ECMP). If a flow ends up on link A or link B doesn’t matter. The flow will have an equal chance of utilizing as much bandwidth as it needs on either link. Now, there are still some things we need to consider even in the case of ECMP.

The size of flows – Some flows are going to be much larger than others, such as transfering files through CIFS or other protocols, downloading something from the internet versus something like Citrix traffic which is generally smaller packets and don’t consume a lot of bandwidth.

The number Continue reading

General – My Packing List for CLUS and Advice for International First Timers

It’s almost time for Cisco Live in Las Vegas. It’s Friday morning here and I have 95% of the packing done and I leave on Saturday. If this is your first time going to CLUS or even going to the US it can be challenging to know what to pack and if you need to bring cash etc. Here are some of my recommendations for packing. Make a list so that you don’t forget to pack things.

Essentials

Make sure to pack your passport. This is pretty obvious. Hopefully you already made sure that the passport is up to date as well.

I bring a copy of my approved ESTA. This is not mandatory but it’s nice having it there in case a security officer asks you. Depending where you are from you might not be part of the ESTA program.

I always print a copy of my booking for the flight and hotel etc. While not something you need when you have electronic check-in etc. I still like to keep a copy so that I have all of the info about my flight and hotel in case I can’t get on my phone.

Electronic Devices

Bring a power bank. Continue reading

CCNA Wireless – CCNA Wireless Notes Chapter 6

802.11 Frame Format

In a wired Ethernet network, the switch is not an active participant in communication at L2. In a wireless LAN, the AP is an active participant unless something like 802.11z, Extension to Direct Link Setup (DLS) is used.

To direct frames through the AP, the radio must have a MAC address, known as the BSSID.

802.11 frames can carry a maximum payload of 2304 bytes.

To support wireless communication, the Ethernet frame format is quite different compared to wired networks. The Ethernet frame starts out with a 2-byte Frame Control field, identifying the frame type, the direction the frame is traveling in and more.

In a common scenario with multiple clients associated with an AP that is connected to an DS, frames travel from clients towards the DS or from the DS towards the clients.

The frame motion is indicated by two bits, To DS and From DS, in the Frame Control field.

Frames sent by a wireless client will Continue reading

Certification – Major News for Expert Level Recertification

Certification – Major News for Expert Level Recertification

Everyone holding an expert level Cisco certification knows the pain of recertifying. Recertification today is achieved by taking any expert level written exam which means you can take the written in the track you are already certified in (the “safe bet”) or in another track if you want to learn something new. The quality of these written exams have varied over the years. Some revisions have been very difficult to pass even for people that are masters of their trade due to the pool of questions not being as high quality as can be expected from an expert level exam. This has been debated for years.

Every two years the pain of recertifying kicks in. Taking the written exam costs around 400$ per attempt depending on local rates, VAT etc. Many people have had to go through multiple attempts to recertify and some have chosen other written exams than their own track because the written of that track was not up to par quality-wise.

Over the years we have been many that have suggested that there must be a better path to getting recertified. Many of us go to Cisco Live, write Continue reading

CCNA Wireless – CCNA Wireless Notes Chapter 5

Types of Wireless Networks

Wireless LANs are not the only type of wireless networks that exist.

Wireless Personal Area Network (WPAN)

WPAN uses low-powered transmitters to create a very short range network, usually 7 to 10 meters. Based on the 802.15 standard and includes technologies such as Bluetooth and ZigBee although ZigBee can have greater range. Unlicensed ISM frequencies are used including the 2.4 GHz band.

Wireless Local Area Network (WLAN)

Wireless service connecting multiple devices using IEEE 802.11 standard over medium-sized range, usually up to 100 meters. Uses unlicensed frequencies in 2.4 GHz and 5 GHz band.

Wireless Metropolitan Area Network (WMAN)

Wireless service over a large geographic area, such as all or portion of a city. One technology used is WiMAX, which is based on the 802.16 standard. Most commonly uses licensed frequencies.

Wireless Wide Area Network (WWAN)

Wireless data service for mobile phones offered over a very large geographic area, such as regional, national or even global by telecommunication carriers. Licensed frequencies are used.

Wireless LAN Topologies

Likelihood of interference increases as the number of wireless devices grows. Wireless devices use half duplex to avoid colliding with other Continue reading

CCNA Wireless – CCNA Wireless Notes Chapter 4

Antenna Characteristics

Different antennas are needed for different applications. An open office space is very different to to a strip of closed offices. How do you cover a large open area such as a lobby? Covering an outdoor area is different than an indoor one and so on.

Radiation Patterns

Antenna gain is normally measured against an isotropic antenna, measured in dBi. This antenna only exists in theory though. It’s shaped like a tiny round point that when alternating current is applied, radiates a signal equally in all directions, in the form of an ever-expanding sphere.

The relative signal strength around an antenna, showed on a plot, is known as the radiation pattern.

The radiation pattern can be shown in a three-dimensional plot in form of a sphere where XY plane lies flat along the horizon and the XZ plane lies vertically along the elevation of the sphere. The first plane is referred to as H plane, horizontal, or also as the azimuth plane. The second one is known as the E plane, elevation.

Polar plots can also be used where concentric circles represent relative changes in signal strength as measured at a constant distance from Continue reading

CCNA Wireless – CCNA Wireless Notes Chapter 3

Interference

Interference will exist if there are other transmitters on the same channel or adjacent channels. This will lead to loss of frames and the frames will then have to be retransmitted, using up air time. Interference can be caused by micro waves, DECT phones and other devices depending on the band used.

Co-Channel Interference

Co-Channel Interference occurs when two or more transmitters use the same channel. The signals completely overlap and the whole 20 or 22 MHz channel bandwidth is affected. This is only a problem if they transmit simultaneously though. However they will contend for the same airtime and a channel can become very congested. When two signals interfere, it causes data corruption, rentransmitting of frames and that in turn uses up even more airtime.

It is common practice to only place a transmitter on a specific channel where received signals are much weaker. A margin of 19 dB is recommended. The margin depends on the coding and modulation scheme. BPSK may need less than 10 db but 64-QAM will require 19 dB. More advanced modulation such as 256-QAM may require between 31 to 50 dB.

Neighboring Channel Interference

In the 2.4 GHz band neighboring Continue reading

CCNA Wireless – CCNA Wireless Notes Chapter 2

ITU-R

A telecommunications regulatory body that regulates or decides how different parts of the RF spectrum may be used. Countries can also have own regulatory bodies that regulate the spectrum within the country. Maintains spectrum in three different regions:

Region 1: Europe, Africa, Northern Asia
Region 2: North and South America
Region 3: Southern Asia and Australiasa

Most bands in the RF spectrum are tightly regulated and require a license. Using a frequency in a licensed range requires an organization to submit an application to the regulatory body.

ITU-R allocated two two ranges for Industrial, Scientific and Medical (ISM) use:

2.400 to 2500 GHz
5.725 to 5.825 GHz

ISM bands are unlicensed and anyone can use them.

Unlicensed bands are more vulnerable to interference and noise due to them being more accessible.

FCC

Federal Communications Commission (FCC) regulates RF frequencies, channels and transmission power within the US but other countries may also follow the rules of the FCC. FCC has allocated Unlicensed National Information Infrastructure (U-NII) in addition to the ISM band. Consists of four bands in the 5 GHz band.

U-NII-1 5.15 to 5.25 GHz
U-NII-2 5.25 to 5.35 GHz
U-NII-2 Extended Continue reading

One Month to Cisco Live Las Vegas

We’re down to just a month before it’s time for Cisco Live in Las Vegas 2017. I’m really looking forward to meeting with a lot of people and attending some great sessions. This will also be my first event as a Cisco Netvet I have a few focus areas for this year’s event.

Cisco IWAN

I have a few IWAN projects I’m working on and I’m going to deep dive into IWAN during CLUS. My plans here are to attend the techtorial on Sunday and meet with some of the prominent people behind IWAN. Those contacts are invaluable to have when you are working on complex scenarios. I also want to see what’s on the roadmap and if I can find out anything about how the acquisition of Viptela will affect IWAN, if at all. I also want to see if APIC-EM has matured to be more useful in brownfield scenarios. Another interesting thing I will try to learn more about is how to best do monitoring in an IWAN network.

Cisco ACI

We have a lot of customers moving to ACI right now. Many of them have “legacy” data centers based on the Catalyst 6500. Moving to a vendor Continue reading

CCNA Wireless – CCNA Wireless Notes Chapter 1

I’ve started studying for the CCNA wireless exam and thought I would put my notes online. I always learn better when writing and hopefully my notes can be of assistance to someone else. These notes are based on reading the official certification guide “CCNA Wireless 200-355 Official Cert Guide“.

Basic wireless theory

Wireless LANs are based on the 802.11 standard.

Wireless LANs is a lot about Radio Frequency (RF) and planning of the RF environment.

When alternating current is sent through the antenna electric and magnetic fields propagate out and away as traveling waves. They travel along each other and are at right angles to each other.

Electromagnetic waves do not travel in a straight line. They travel by expanding in all directions away from the antenna.

When the electromagnetic waves reach the receiver’s antenna, they induce an electrical signal.

Frequency

Frequency – The number of times a signal makes one complete up and down cycle in one second. Measured in Hertz (Hz)

The frequency range from 3 kHz to 300 GHz is commonly called RF. Types of devices in this frequency range is radar, radio, shortwave radio, television, FM radio, microwave etc. The main two frequency Continue reading

Python – Kirk Byers Course Week 4 Part 3

This post will describe the exercises and solutions for week four of Kirk Byers Python for Network Engineers.

The final exercise of week 4 is the following.

III. Create a program that converts the following uptime strings to a time in seconds.
uptime1 = 'twb-sf-881 uptime is 6 weeks, 4 days, 2 hours, 25 minutes'
uptime2 = '3750RJ uptime is 1 hour, 29 minutes'
uptime3 = 'CATS3560 uptime is 8 weeks, 4 days, 18 hours, 16 minutes'
uptime4 = 'rtr1 uptime is 5 years, 18 weeks, 8 hours, 23 minutes'

For each of these strings store the uptime in a dictionary using the device name as the key.

During this conversion process, you will have to convert strings to integers.  For these string to integer conversions use try/except to catch any string to integer conversion exceptions.

For example:
int('5') works fine
int('5 years') generates a ValueError exception.

Print the dictionary to standard output.

The first step is to import pretty print which we will use to print the dictionary.

# Import pretty print
import pprint

To do the conversion from years, weeks and days to seconds, we are going to need some constants. Constants are usually defined with the variable Continue reading

Python – Kirk Byers Course Week 4 Part 2

This post will describe the exercises and solutions for week two of Kirk Byers Python for Network Engineers.

Our next task is to parse data from show version from a device.

II. Parse the below 'show version' data and obtain the following items (vendor, model, os_version, uptime, and serial_number).  Try to make your string parsing generic i.e. it would work for other Cisco IOS devices. 

The following are reasonable strings to look for:
'Cisco IOS Software' for vendor and os_version
'bytes of memory' for model
'Processor board ID' for serial_number
' uptime is ' for uptime

Store these variables (vendor, model, os_version, uptime, and serial_number) in a dictionary.  Print the dictionary to standard output when done.
Note, "Cisco IOS Software...Version 15.0(1)M4...(fc1)" is one line.

>>>>> show version data <<<<<
Cisco IOS Software, C880 Software (C880DATA-UNIVERSALK9-M), Version 15.0(1)M4, RELEASE SOFTWARE (fc1)
Technical Support: 
Copyright (c) 1986-2010 by Cisco Systems, Inc.
Compiled Fri 29-Oct-10 00:02 by prod_rel_team
ROM: System Bootstrap, Version 12.4(22r)YB5, RELEASE SOFTWARE (fc1)

twb-sf-881 uptime is 7 weeks, 5 days, 19 hours, 23 minutes
System returned to ROM by reload at 15:33:36 PST Fri Feb 28 2014
System restarted at 15:34:09 PST Fri Feb  Continue reading

Python – Kirk Byers Course Week 4 Part 1

This post will describe the exercises and solutions for week four of Kirk Byers Python for Network Engineers.

The first exercise is the following:

I. Prompt a user to input an IP address.  

Re-using some of the code from class3, exercise4--determine if the IP address is valid. 

Continue prompting the user to re-input an IP address until a valid IP address is input.

Compared to our last script we want to keep asking the user for an IP address until they supply a valid one. This means that we need a loop that can run until some condition changes. This is where While loops come in handy. We will create a Boolean variable called not_done and set this to True.

not_done = True

while not_done:

The meaning of while not_done: is that the While loop will run as long as not_done is True.

The next step is to ask the user for an IP address. We use the built-in function input() to do this.

ip_add = input("\n\nPlease enter an IP address: ")

We use another Boolean variable called valid_ip which is set to True until we prove that the IP address is not valid.

valid_ip = True

We will split Continue reading

Python – Kirk Byers Course Week 3 Part 3

This post will describe the exercises and solutions for week three of Kirk Byers Python for Network Engineers.

The last exercise of the week is to create an IP address checker that checks the validity of an IP address. Here are the instructions:

IV. Create a script that checks the validity of an IP address.  The IP address should be supplied on the command line.
    A. Check that the IP address contains 4 octets.
    B. The first octet must be between 1 - 223.
    C. The first octet cannot be 127.
    D. The IP address cannot be in the 169.254.X.X address space.
    E. The last three octets must range between 0 - 255.

    For output, print the IP and whether it is valid or not.

The IP address will be supplied through the command line. Like we’ve done before we are going to check the number of arguments supplied and exit the script if the number of arguments is not two. We need to import sys so that we can use sys.argv.

import sys

if len(sys.argv) != 2:
	sys.exit("Usage: ./ip_checker.py <IP-ADDRESS>")

We’ll store the IP address as input as dotted decimal into the Continue reading