Category: Data Center

I’m still convinced that architectures with centralized control planes (and that includes solutions relying on OpenFlow controllers) cannot scale. On the other hand, Big Switch Networks is shipping Big Cloud Fabric, and they claim they solved the problem. Obviously I wanted to figure out what’s going on and Andy Shaw and Rob Sherwood were kind enough to explain the interesting details of their solution.

Long story short: Big Switch Networks significantly extended OpenFlow.

A few days ago I completed the last chapter in the Data Center Design Case Studies book: building disaster recovery and active-active data centers. It focuses on application behavior and business needs, not on the underlying technologies; the networking technology part tends to be way easier to solve than the oft-ignored application-level challenges.

Cloud builders are often using my ExpertExpress service to validate their designs. Tenant onboarding into a multi-tenant (private or public) cloud infrastructure is a common problem, and tenants frequently want to retain the existing network services appliances (firewalls and load balancers).

The Combine Physical and Virtual Appliances in a Private Cloud case study describes a typical solution that combines per-tenant virtual appliances with frontend physical appliances.

Listening to some SDN pundits one gets an impression that SDN brings peace to Earth, solves all networking problems and makes networking engineers obsolete.

Cynical jokes aside, and ignoring inevitable bugs, is controller-based networking really more reliable than what we do today?

For whatever reason (subliminal messages from vendor marketing departments?), I’m constantly brooding about the vendor lock-in, its inevitability, and the way supposedly disruptive companies try to use the fear of lock-in to persuade naive customers to buy their products.

Brocade VCS fabric has one of the most flexible multichassis link aggregation group (LAG) implementation – you can terminate member links of an individual LAG on any four switches in the VCS fabric. Using that flexibility is not always a good idea.

2015-01-23: Added a few caveats on load distribution

Every time I write about unequal traffic distribution across a link aggregation group (LAG, aka Etherchannel or Port Channel) or ECMP fabric, someone asks a simple question “is there no way to reshuffle the traffic to make it more balanced?”

TL&DR summary: there are ways to do it, and some vendors already implemented them.

I got a lengthy email from one of my readers a while ago, essentially asking a simple question: assuming I want to go return to my studies and move further than CCIE I currently hold, should I go for CCDE or the new VMware’s VCIX-NV?

Well, it’s almost like “do you believe in scale-up or scale-out?” ;) Both approaches have their merits.

Olivier Hault sent me an interesting challenge:

I cannot find any simple network-layer solution that would allow me to use total available bandwidth between a Hypervisor with multiple uplinks and a Network Attached Storage (NAS) box.

TL&DR summary: you cannot find it because there’s none.

A few months ago I described how bandwidth limitations shatter the dreams of spread-out application stacks with elements residing (or being dynamically migrated) between data centers. Today let’s focus on bandwidth’s ugly cousin: latency.

TL&DR Summary: Spreading the server components of an application across multiple locations (multiple data centers or hybrid cloud deployments) can easily result in dismal performance even when there’s plenty of bandwidth available.