Coping with Byzantine Routing Failures

One of my readers sent me an interesting challenge:

We have two MPLS providers sending us default routes and it seems like whenever we have problem with SP1 our failover is not happening properly and actually we have to go in manually and influence our traffic to forward via another path.

Welcome to the wondrous world of byzantine routing failures ;)

Do We Have Too Many Knobs?

The last day of Interop New York found me sitting in the Speaker Center with a few friends pondering the hype and reality of SDN and brokenness of traditional network products. One of the remarks during that conversation was very familiar: “we have too many knobs to configure”, and I replied “and how many knobs do you think there are in Windows registry?" (or Linux kernel and configuration files).

Just Published: Overlay Virtual Networks in Software Defined Data Centers

Overlay virtual networks are one of my favorite topics – it seems I wrote over a hundred blog posts describing various aspects of this emerging (or is it reinvented) technology since Cisco launched VXLAN in 2011.

During the summer of 2014 I organized my blog posts on overlay networks and SDDC into a digital book. I want to make this information as useful and as widely distributed as possible – for a limited time you can download the PDF free of charge.

Learn more about the book

Reinventing the wheel (or RFC 1925 sect 2.11)

Simon Wardley is another old-timer with low tolerance for people reinventing the broken wheels. I couldn’t resist sharing part of his blog post because it applies equally well to what we’re seeing in the SDN world:

No, I haven't read Gartner's recent research on this subject (I'm not a subscriber) and it seems weird to be reading "research" about stuff you've done in practice a decade ago (sounds familiar). Maybe they've found some magic juice? Experience however dictates that it'll be snake oil […]. I feel like the old car mechanic listening to the kid saying that his magic pill turns water into gas. I'm sure it doesn't ... maybe this time it will ... duh, suckered again.

Meanwhile the academics already talk about SDN 2.0.

Viptela SEN: Hybrid WAN Connectivity with an SDN Twist

Like many of us Khalid Raza wasted countless hours sitting in meetings discussing hybrid WAN connectivity designs using a random combination of DMVPN, IPsec, PfR, and one or more routing protocols… and decided to try to create a better solution to the problem.

Viptela Secure Extensible Network (SEN) doesn’t try to solve every networking problem ever encountered, which is why it’s simpler to use in the use case it is designed to solve: multi-provider WAN connectivity.

Just Published: VXLAN 2.0 Videos

Last week I ran the second part of the updated (4-hour) VXLAN webinar. The raw videos are already online and cover these topics:

• VXLAN-related technologies, including encapsulation, IP multicast use, unicast VXLAN, and VXLAN-over-EVPN;
• VXLAN implementations, including Cisco Nexus 1000v, VMware vCNS, VMware NSX, Nuage VSP and Juniper Contrail;
• VXLAN gateways, including Arista, Brocade, Cisco and Juniper;
• Hardware VTEP integration with OVSDB and EVPN;
• VXLAN-based data center fabrics, including Cisco’s ACI.

Scaling the Cloud Security Groups

Most overlay virtual networking and cloud orchestration products support security groups – more-or-less-statefulish ACLs inserted between VM NIC and virtual switch.

The lure of security groups is obvious: if you’re willing to change your network security paradigm, you can stop thinking in subnets and focus on specifying who can exchange what traffic (usually specified as TCP/UDP port#) with whom.

A Month of SDN

My calendar for the following four weeks is jam-packed with SDN events:

• It starts today with a 3-hour SDN presentation in Ljubljana, Slovenia;
• I’m running a 2-day SDN-focused on-site workshop next week, followed by Scaling Overlay Virtual Networks webinar (register now, we’re slowly running out of space);
• The week of November 24th starts with an SDN meetup in Stockholm and continues with SDN/SDDC event in Rome;
• Finally, I’m running an OpenFlow Deep Dive webinar and another on-site NSX/SDN workshop in early December.

All the travel might affect my blogging frequency, but I still have a few podcasts in the editing queue, so you’ll have something to listen to in the meantime ;)

Handling the Bottom of MPLS Stack

MPLS bottom-of-stack bit confused one of my readers. In particular, he had a problem with the part where the egress MPLS Label Switch Router (LSR) should go from labeled (MPLS) to unlabeled (IPv4, IPv6) packets and has to figure out what’s in the packet.

Response: Midokura Open-Sources MidoNet

Last week Midokura decided to follow Juniper’s lead and make MidoNet an open-source product (after all, a similar move worked really well for Contrail, right?).

I may be too skeptical (again), but I fail to see how this could possibly work.

FlipIT Cloud: Orchestrating IT-as-a-Service on Software Gone Wild

Imagine being an IT administrator running a multi-tenant enterprise environment (example: an SMB business center). How many things would you have to configure to add a new tenant? How about adding a new user for an existing tenant?

The engineers behind the scenes of FlipIT cloud service ended up with a 40-page configuration guide when they started the service years ago… and obviously decided full-blown automation is the only way to go.

So You’re an Open Source Shop? Really?

I carried out an interesting quiz during one of my Interop workshop:

• How many use Linux-based servers? Almost everyone raised their hands;
• How many use Apache or Tomcat web servers? Yet again, almost everyone.
• How many run applications written in PHP, Python, Ruby…? Same crowd (probably even a bit more).
• How many use Nginx, Squid or HAProxy for load balancing? Very few.

Is there a rational explanation for this seemingly nonsensical result?

Just Published: HP and Dell Force10 Data Center Switches

Want to know how HP IRF works? What its limitations are? Which data center protocols HP 5900 supports? How Dell Force10 switches handle MLAG? How well are HP and Dell supporting OpenFlow?

You’ll get answers to all these questions in the videos recently published in the Data Center Fabric Architecture webinar (also available as part of yearly subscription).

Does a Cloud Orchestration System Need an Underlying SDN Controller?

A while ago I had an interesting discussion with a fellow SDN explorer, in which I came to a conclusion that it makes no sense to insert an overlay virtual networking SDN controller between cloud orchestration system and virtual switches. As always, I missed an important piece of the puzzle: federation of cloud instances.

2014-11-04 16:48Z: CJ Williams sent me an email with information on SDN controller in upcoming Windows Server release. Thank you!

Use a Disaster Recovery Project to Build Your New Cloud

It doesn’t make sense to build a new data center network to support legacy bare-metal server infrastructure. You’ll have to use relatively expensive 1G/10G ports to be able to connect the current and future servers, and once the server and virtualization engineers wake up and do hardware refresh you’ll end up with way too many ports (oh, and you do know that transceivers could cost more than the switching hardware, right?).

Make Rip-and-Replace a bit less Creepy

It was a dark and stormy Halloween night and a networking engineer was stuck in a data center facing a Mission Impossible project: replace a failing Cat6500 with a brand-new Nexus 7000. Shouldn’t have been a problem, if only the cables were labeled.

Overlay-to-Underlay Network Interactions: Document Your Hidden Assumptions

If you listen to the marketing departments of overlay virtual networking vendors, it looks like the world is a simple place: you deploy their solution on top of any IP fabric, and it all works.

You’ll hear a totally different story from the physical hardware vendors: they’ll happily serve you a healthy portion of FUD, hoping you swallow it whole, and describe in gory details all the mishaps you might encounter on your virtualization quest.

The funny thing is they’re all right (not to mention the really fun part when FUDders change sides ;).

Bad Ideas and Abominations

This post SHOULD have been published on April 1st, but I need to define the terminology for another upcoming post, so here it is ;)

RFC 2119 defines polite words to use when something really shouldn’t be done. Some network designs I see deserve more colorful terminology.

2014-11-02: Updated with reference to RFC 6919 (/HT to @LapTop006)

New Webinar: Scaling Overlay Virtual Networks

You can get an overlay virtual networking solution from almost every major hypervisor- and data center networking vendor. Do you ever wonder which one to choose for your large-scale environment? I’m positive you’d get all of them up and running in a one-rack environment, but what if you happen to be larger than that?

We’ll try to address scalability hiccups and roadblocks you might encounter on your growth path in Scaling Overlay Virtual Networks webinar (get your free ticket here).

Cumulus Linux in Real Life on Software Gone Wild

A year ago Matthew Stone first heard about Cumulus Linux when I ranted about it on a Packet Pushers podcast (which only proves that any publicity is good publicity even though some people thought otherwise at that time), and when his cloud service provider company started selecting ToR switches he considered Cumulus together with Cisco and Arista… and chose Cumulus.