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SPAN Destination ports and VLAN Membership

Recently at work, a discussion sprouted up around how to handle/configure local session Switched Port Analyzer (SPAN) destination ports.  A suggestion was made to create a new VLAN just for these SPAN destination ports and place them there.  The justification was that they would be out of VLAN 1, and easily identifiable.  Personally I thought it was a waste of a VLAN for a few simple SPAN destination ports, as SPAN destination ports do not participate in spanning tree, and do not forward traffic.  However, ultimately in this case it was a good decision due to security requirements.
Some key characteristics to know about SPAN destination ports:

• A destination port can be a physical port that is assigned to an EtherChannel group, even if the EtherChannel group has been specified as a SPAN source. The port is removed from the group while it is configured as a SPAN destination port.
  
• The port does not transmit any traffic except that traffic required for the SPAN session unless learning is enabled.
  
• The state of the destination port is up/down by design. The interface shows the port in this state in order to make it evident that the port Continue reading

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Internets of Interest for 9th July 2014

  Collection of useful, relevant or just fun places on the Internets for 9th July 2014 and a bit commentary about what I’ve found interesting about them: Will Software Defined Networking Actually Happen? – Ethan Banks is blogging at cisco.com on SDN: I understand the cynicism. After all, for a long time, networking had lapsed […]

The post Internets of Interest for 9th July 2014 appeared first on EtherealMind.

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Summary Post – OSPF Network Statement Order and Matching

When you configure OSPF network statements, IOS orders them most-specific to least-specific then does a top-to-bottom match of the interfaces. It doesn’t matter which order you put them in, the configuration will always be ordered with the longest prefix matches first.  Lab time!

I have router R1 with these interfaces.

R1#sh ip int brief
Interface                  IP-Address      OK? Method Status                Protocol
FastEthernet0/0            10.0.0.1        YES manual up                    up
FastEthernet0/1            unassigned      YES unset  administratively down down
Loopback100                10.0.101.1      YES manual up                    up
Loopback200                10.2.101.1      YES manual up                    up

Let’s add the OSPF configuration where 10.0.0.0/8 is in area 2 then check what OSPF thinks is happening.

R1(config)#router ospf 1
R1(config-router)#network 10.0.0.0 0.255.255.255 area 2
...
R1#show ip ospf interface brief
Interface    PID   Area            IP Address/Mask    Cost  State Nbrs F/C
Lo100        1     2               10.0.101.1/24      1     LOOP  0/0
Lo200        1     2               10.2.101.1/24      1     LOOP  0/0
Fa0/0        1     2               10.0.0.1/24        10    WAIT  0/0

All the interfaces are in area 2 as expected. Now let’s add 10.0.0.0/16 into area 1 to see what happens.

R1(config-router)#network 10.0.0.0  Continue reading

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NSA: walk a mile in their shoes

While this is mostly a technical blog, our most popular posts deal with cyber-rights, supporting Snowden, Weev, and Swartz. Yet sometimes I appear to defend the NSA. People ask me why, so I thought I’d write up a response.

Most American schools force students to read the book To Kill a Mockingbird. It’s a great book for many reasons. Most people think it’s about racism, but it’s not – it’s about bigotry. Racism is just one of the forms of bigotry found in the book. The full message, repeated several times, is that we should get along with others by trying to understand their point of view.

Our society is improving with regards to racism, but other forms of bigotry are alive and well. Webster’s defines bigotry as: “obstinate and unreasoning attachment of one's own belief and opinions, with narrow-minded intolerance of beliefs opposed to them”. Our society praises such bigotry. Tolerance and understanding of other opinions is condemned.

People like Glenn Greenwald, Jacob Appelbaum, and others in the ‘activist’ movement are extreme bigots. There is good reason to oppose the NSA and its leaders who have egregiously mislead the public. Yet, this is still not justification for Continue reading

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SDN Started as a Customer Movement (Not a Vendor Innovation)

With the vast marketing budgets from big vendors and their well paid "evangelists", the startups vying to introduce new methods and the clamour of engineers trying to understand new technology it might be time to pause and remember that Software Defined Networking was a customer-driven initiative. Vendors had to be forced to accept that SDN was a necessary change.

The post SDN Started as a Customer Movement (Not a Vendor Innovation) appeared first on EtherealMind.

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Response: RFC 7045 – Transmission and Processing of IPv6 Extension Headers

IETF RFC  on the Standards Tracks that talks about the problem of chaining headers in IPv6. I’m getting a sense of deja-vu since this was also has issue with IPv4 and, ultimately, use of chained IPv4 headers died away. If they encounter an unrecognised extension header type, some firewalls treat the packet as suspect and drop it.  Unfortunately, […]

The post Response: RFC 7045 – Transmission and Processing of IPv6 Extension Headers appeared first on EtherealMind.

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What is Unidirectional Automation?

I was pleased as punch to wake up the other day and read Marten Terpstra’s blog post on getting over the fear of using automation to make changes on our network infrastructure. He illuminated a popular excuse that I’ve heard myself on multiple occasions – that automation is great for things like threshold alarms, or pointing out the percieved root cause of a problem, but not actually fixing the problem. The idea is that the problems that occur on a regular basis, or even performing configuration changes in the first place – is a specialized task that a warm-blooded human being absolutely, no-doubt must take total control of in order to be successful.

With the right implementation, this idea is, of course, rubbish. I asked a question on Twitter not too long ago in preparation for a presentation I was about to give. I have a decent amount of experience working with VMware vSphere, and knew there were some experienced server virtualization folks following me, so I asked about a feature that was thought of in similar light not too long ago:

For those running vSphere, do you have DRS enabled and set to something other than manual? If not, why not? Trying Continue reading

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What is Unidirectional Automation?

I was pleased as punch to wake up the other day and read Marten Terpstra’s blog post on getting over the fear of using automation to make changes on our network infrastructure. He illuminated a popular excuse that I’ve heard myself on multiple occasions - that automation is great for things like threshold alarms, or pointing out the percieved root cause of a problem, but not actually fixing the problem.

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What is Unidirectional Automation?

I was pleased as punch to wake up the other day and read Marten Terpstra’s blog post on getting over the fear of using automation to make changes on our network infrastructure. He illuminated a popular excuse that I’ve heard myself on multiple occasions - that automation is great for things like threshold alarms, or pointing out the percieved root cause of a problem, but not actually fixing the problem.

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Linking Purpose to Profits

Linking Purpose to Profits

---

by Andy McFarland, VP of Customer Care - July 8, 2014

Three bricklayers were working side by side. When asked, “What are you doing?” the first bricklayer replied, “I’m laying bricks.” The second bricklayer was asked and he answered, “Feeding my family.” The third bricklayer when asked the question, “What are you doing?” responded, “I’m building a cathedral.” 

This story illustrates the power of purpose. In a previous post I suggested that we are all in the customer service business, and I posed some questions to help teams see linkages between what they do and how that impacts customers and the company. The reason this is so important is because purpose leads to employee engagement, which leads to profitability. 

To maximize our personal satisfaction and employee engagement, we need three ingredients: purpose, autonomy, and mastery. (See Daniel Pink’s explanation in this video.) As leaders we must work relentlessly to break down barriers to allow our people the freedom to thrive. 

To help people understand the purpose of their work, leaders link tasks to outcomes and benefits. Some people see linkages naturally, while others require leaders to communicate Continue reading

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IP Subnetting Part 3: Understanding the Binary

I’ve often stated how simple subnetting really is. While each individual concept is rather simple, it is the combination that make the holistic process challenging. If we, as humans, could look at the process more like computers and network devices, subnetting would be a much simpler process. In short, some knowledge of binary is an important requirement prior to sharing more complex subnetting examples.

This article will demonstrate the process of converting binary to and from the more familiar decimal numbering system. This will establish the necessary baseline knowledge required to understand when applying subnet masks to IP addresses. The first question we need to answer is–

What is Binary?

Binary, also known as base-2, is a numbering system in which each position only has two possible values. We often represent one possible value as zero and the other possible value as one. Alternatively, it could be represented many other ways including: positive and negative voltage, black and white colors, voltage and no voltage present, or null and not null. This simplicity in representation is what makes the system so advantageous for a computer’s limited discreet capabilities.

In this article, we will represent binary digits using either a one or a Continue reading

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Raspberry Pi as a Deliciously Simple VPN Endpoint

Being the networking nerd I am, I have a pretty big network at home.  And as the denizens of the Packet Pushers IRC channel know, I do a lot of work with VPNs.  One of my use cases is sharing the resources on my home network.  My friends, family, and coworkers sometimes like to use my network […]

Author information

The post Raspberry Pi as a Deliciously Simple VPN Endpoint appeared first on Packet Pushers Podcast and was written by iggdawg.

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Show 195: HP – Real SDN and Virtual Application Networking

HP and Software Defined Networking. HP was one of the earliest supporters of OpenFlow and Software Defined Networking and have continued to build a portfolio of products. In this podcast we talk about SDN applications on security, application management and QoS management.

Author information

The post Show 195: HP – Real SDN and Virtual Application Networking appeared first on Packet Pushers Podcast and was written by Greg Ferro.

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Understanding IPv6: The Journey Begins

Why is IPv6 so difficult to understand? Denise Fishburne explains how she began unraveling this complex topic.

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Ansible Rapid Development Environment using Vagrant

First off, this post isn’t a straight-up networking post; although it does contain networking content (enabling Vagrant VMs to communicate over a physical data network) it’s more about constructing a rapid development environment for Ansible. Ansible is a configuration management tool that manages nodes over SSH, and only requires that Python 2.4 or later is […]

Author information

The post Ansible Rapid Development Environment using Vagrant appeared first on Packet Pushers Podcast and was written by Will Dennis.

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Community Show – Multicast Design and Deployment Considerations with Beau Williamson and Orhan Ergun

In this first part of the Multicast Design and Deployment Series, Orhan Ergun talks with Mr. Multicast Beau Williamson about many multicast concepts. They both start from the basic and deep dive many multicast concepts while giving real life examples.

The post Community Show – Multicast Design and Deployment Considerations with Beau Williamson and Orhan Ergun appeared first on Packet Pushers.

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Community Show – Multicast Design and Deployment Considerations with Beau Williamson and Orhan Ergun

In this first part of the Multicast Design and Deployment Series , Orhan Ergun talks with Mr.Multicast Beau Williamson about many multicast concepts. They both start from the basic and deep dive many multicast concepts while giving real life examples.   Why Multicast?. What are the general use cases in real life ? Layer 2 […]

Author information

The post Community Show – Multicast Design and Deployment Considerations with Beau Williamson and Orhan Ergun appeared first on Packet Pushers Podcast and was written by Orhan Ergun.

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Routing Considerations in DDoS Protection Environments

Lately I have done some studying for the CCDE and one of the things I was
looking at is how to protect against DDoS attacks. I’m not expecting it
to be a big topic for the CCDE but it has some interesting concepts relating
to routing. Take a look at the following topology:

There is an attacker at the top left. R1 is the edge device and then there are a
few more routers, all peering BGP with the RR, which is R5. The server of interest
is 100.100.100.100 and there is a scrubbing device to the far right. All routers
peer iBGP from their loopbacks to the RR, including the scrubbing device.

Normally traffic to 100.100.100.100 would flow through R1 to R4 and then to the
server.

The attacker now starts to flood the server with malicious traffic. This is detected
by the DDoS scrubbing device which starts to announce via BGP a more specific route
than the one advertised by R4. R4 normally advertises 100.100.100.0/24 but the
scrubbing device advertises 100.100.100.100/32. All the other routers will start
to forward traffic to 100.100.100.100 towards Continue reading

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Advertising a Default Route Into EIGRP

Let’s get an IPv4 default route into EIGRP.  There are a few methods to do it.  I hate most of them, though.  I think it will be obvious which one I like.

Here’s the lab I have set up to test everything.  I want R4 to generate the default in each case.

Default Network – Candidate default.  I don’t think I’ve ever used that all my years in networking, but here’s how to use it in EIGRP for a default route.  You basically say “If you don’t know where to send a packet, send it to where network X lives.”  We’re going to set the 192.168.1.0/24 as the default network, so, in our case X = 192.168.1.0. R4 will tag that route as a default candidate when it advertises it to the rest of the network.  The config is easy but requires a stateful (yes, stateful) network to beconfigured as the default.

R4 config:
R4(config)#ip default-network 192.168.1.0
!
R1 routes:
R1#sh ip route
...
     4.0.0.0/24 is subnetted, 1 subnets
D       4.4.4.0 [90/435200] via 192.0.2.3, 00:08:33, FastEthernet0/0
                [90/435200] via 192.0.2.2,  Continue reading

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Using Cisco’s DevNet “All-in-One VM” as a Free Router Lab

I know many have been [not so patiently] waiting for the arrival of a Cisco virtual lab. Although I haven’t heard any official release date for VIRL or CML, there is a small scale virtual router lab available today. This lab is the All-in-One Virtual Machine made available on the Cisco DevNet site.

While not a comprehensive lab, it is a quick and easy way to get some real command line experience or test smaller layer 3 challenges. This VM includes 3 routers with a total of 10 routed interfaces in use. There is no access to layer 2, so the topology can only be manipulated by shutting down interfaces on the routers.

Using the DevNet All-in-One Virtual Machine

1. Download the OVA File
2. Import into VMWare
3. Launch the Virtual Machine
4. Set Passwords
5. Access the Routers

This product downloads as an OVA file. The file is easily imported into VMWare. In my case, I used VMWare Fusion running on OSX. Once downloaded and imported, the VM is launched like any other virtual machine. As it boots, you will notice that this is running in Ubuntu. The initial credentials are cisco/cisco123 and the operating will prompt to change the password.

Once installed and logged in, you will be Continue reading