Administrative Distance for Static Route is 1 or 0?
How does the internet work - We know what is networking
There are different documents and books which are claiming that Administrative distance for static routes configured using exit interface is 1 and for the static route configured using next-hop IP address Administrative distance is 0. R1(config)#ip route 20.0.0.0 255.255.255.0 10.10.2.1 R1(config)#ip route 20.0.0.0 255.255.255.0 fastEthernet 0/0 This is not true. Both of them are having AD […]
Difference between defining static routes with next-hop address or exit interface
How does the internet work - We know what is networking
There were a bit of confusion in my head about this case. It was not clear to me what is the difference between setting the static route using next hop interface IP address or using exit interface syntax. It seems that both methods are the same and that you have basically two different ways to […]
Difference between defining static routes with next-hop address or exit interface
Why ‘your’ project was outsourced
It’s easy to get upset when that cool new project you wanted is outsourced to an external VAR. The conversation usually goes something like, “You know the existing network and services really well so we’re going keep focused there. We’re going to engage ACME systems integrators for ‘project awesome’ and get them to give that […]
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The post Why ‘your’ project was outsourced appeared first on Packet Pushers Podcast and was written by John Harrington.
Quiz #18 – Cisco vs. Juniper – Filtering ICMP between BGP Peers
Your company uses multi-vendor routing platforms (Cisco and Juniper) and has multiple sites connected via MPLS from a service provider. Each remote site has a GRE tunnel with the Headquarter (HQ) and a BGP session over this tunnel. After some security change in the network, sites that are Juniper-based behave differently than the Cisco-based ones, creating outage for the customer. What's wrong?
Cisco Nexus 7000 Proxy Routing
In my previous blog - Data Center Design Constraints, I mentioned some of the design caveats involving M and F series line cards in the same VDC or 7K chassis. In this blog, I'll talk about design considerations with classical ethernet on a 7K. For a deep dive, refer Design Considerations for Classical Ethernet Integration if the Cisco Nexus 7000 M1 and F1 Modules.
What prompted me to write this blog was a design whiteboard session with a customer to order the right line cards for the 7K switch. We know the F1 series line cards are strictly for Layer 2 functionality only. They do not perform Layer 3 routing functions, they cannot. The M series line cards perform Layer 3 routing. Consider a Nexus 7009 switch populated with F1 and M1 series line cards. Say servers A and B connect to the 7K. Server A and B belong to VLANs A and B respectively. If Server A needs to talk to Server B, the switch requires inter VLAN routing to route between VLANs A and B. Without the M series, or a separate router on a stick device, this is not possible, right?
If this were a Catalyst Continue reading
Comcast filtering SMTP (TCP 25) for IPv6, but 587 still works!
Noticed this weekend that I couldn’t respond to emails on my personal hosted domains. I thought at first first they changed my PD prefix, but it was up to date in Postfix. Tried submission port and it worked just fine. So looks like Comcast finally caught up with “feature parity” in disallowing outbound SMTP connections on TCP 25.
Balancing Complexity and Simplicity
I’ve been in tech for several years. Over time, I’ve configured things that I’m proud of and I’ve built things that I’m not so proud of. Most of the things that I’m less proud of involve unnecessary or unwarranted complexity that has created operational challenges. In some cases this was a result of a small […]
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The post Balancing Complexity and Simplicity appeared first on Packet Pushers Podcast and was written by Paul Stewart.
Show 159 – Finding a Way To Test It
A welcome return to the Packet Pushers of old where we get where we get a bunch of engineers around the table to generally poke sticks into a box of networking problems and laugh at the noises. Topics What VMware do with networking at VMworld Mentoring in the Day Job – how and what you do to […]
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The post Show 159 – Finding a Way To Test It appeared first on Packet Pushers Podcast and was written by Greg Ferro.
Let Me Tell You…
In the last post in this series, I spent some time talking about the process of detecting a link failure (given down detection is always the more important issue in fast convergence); let’s continue by looking at notification. If a router discovers a down link, or a down neighbor, how does it tell all the […]
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DCI with LISP for Cold Migrations
Let’s step back for a minute. So far in this series of blog posts on DCI, I’ve been focusing on extending the Layer 2 domain between data centers with the goal of supporting hot migrations — ie, moving a virtual machine between sites while it’s online and servicing users.
Is that the only objective with DCI?
Well if it was, there wouldn’t be a need for this blog post :-) Cold migrations have valid use cases too. Cold migrations occur when the virtual machine is shut down in one site and then booted in a new site. As part of that operation, typically an orchestration layer (such as VMware’s Site Recovery Manager) will poke and prod the VM to make it ready for operation in the new site. Most notably, it takes care of changing the VM’s IP address and default gateway.
Cold migrations do not have a requirement for the same IP subnet in both sites. This is because there’s no need to maintain active user sessions during the migration. Different IP subnets in the sites means no stretched Layer 2 which means no risk of combining failure domains!
What if that orchestration layer didn’t have to poke Continue reading
DCI with LISP for Cold Migrations
Let's step back for a minute. So far in this series of blog posts on DCI, I've been focusing on extending the Layer 2 domain between data centers with the goal of supporting hot migrations — ie, moving a virtual machine between sites while it's online and servicing users.
Is that the only objective with DCI?
Healthy Paranoia Show 16: BSides DC Oktoberfest!
Willkommen, bienvenue, welcome! Meine Damen und Herren, Mesdames et Messieurs, Ladies and Gentlemen. Introducing the latest installment in that grand epic known as Healthy Paranoia. Where the nerds are a little nerdier, and the evil bit is always set on your packets. In this episode, we help launch the very first Security Oktoberfest, aka BSides DC. […]
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The post Healthy Paranoia Show 16: BSides DC Oktoberfest! appeared first on Packet Pushers Podcast and was written by Mrs. Y.
Understanding OTV
I took notes while reading up on OTV documentation. If you don't want to read through the OTV IETF or related Cisco documentation, this can be a quick deep dive into what OTV is and how it functions. Hopefully I'll implement this in a real network sometime soon to share actual configs.
Overlay Transport Virtualization (OTV)
OTV is a data center interconnect technology that routes mac based information by encapsulating mac addresses with IP addresses in an overlay transit network. As long as there is IP connectivity between two or more sites (DCs), OTV will function (ofcourse with the right hardware and configuration).
'MAC in IP' technique for supporting L2 VPNs over L2/L3 infrastructure.
Routing and forwarding states are maintained at the network edge devices between sites, not within the site or core.
There is no need to extend STP across sites, and STP topologies can be local to each site.
Hardware Requirements:
As of March 2013, from here.
Cisco Nexus 7000
M1/M2 line cards
NX-OS 5.0(3) or later, 5.2(3) or 6.2(2) are Cisco recommendations
Transport Services License
Cisco ASR 1000
IOS XE 3.5 or later
Adv IP Srvcs / Adv Ent Srvcs license
Late Night fun with a Meme Generator
I was watching a movie the other night with my wife and decided to hop on memegenerator.net and play around with memes. Thought I’d share my creations.
The Only Two Ok Responses to Valid Feedback
Earlier this week, I wrote over on the Plexxi blog that the most important thing to look for in a potential new hire is coachability. If being coachable is the most important contributor to sustained long-term growth in employees, then how do you make yourself more coachable? There are countless tips and tricks to being […]
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The post The Only Two Ok Responses to Valid Feedback appeared first on Packet Pushers Podcast and was written by Michael Bushong.
Show 158 – Avaya – Software Defined Data Centre & Fabric Connect
We’ve done many podcasts now on Software Defined Whatever. Most of those shows are focused on diving deep into SDN technology and how protocols such as OpenFlow are meant to work. Let’s face it - this is fascinating stuff to a bunch of engineers. But over and beyond just being cool technology – SDN must solve a problem.
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The post Show 158 – Avaya – Software Defined Data Centre & Fabric Connect appeared first on Packet Pushers Podcast and was written by Greg Ferro.
To Sit or Stand?
Unless you’ve been living under a rock for the last couple of years, I’m sure you’ve read the articles about how bad prolonged sitting is for your health. If you sit for a major part of your day (at work, in traffic and at home), your risk of diabetes and heart disease is doubled. The […]
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The post To Sit or Stand? appeared first on Packet Pushers Podcast and was written by Mrs. Y.
IPv6 Implementation beyond theory & How playing with RA messages may be issue-istic
How does the internet work - We know what is networking
Some of this things I read in books and some of them took me few days of troubleshooting and sweating to get to them so I give them for free here to save you fellow networker some time: SLAAC The mighty SLAAC is the prefered method of IPv6 allocation, but is it so mighty? Or it […]
IPv6 Implementation beyond theory & How playing with RA messages may be issue-istic