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.
When we started planning a VMware NSX-focused podcast episode with Dmitri Kalintsev, I asked my readers what topics they’d like to see covered. Two comments that we really liked were “how do I get started with VMware NSX?” and “how do I troubleshoot this stuff?”
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?
Last spring I ran an IPv6 High Availability webinar which started (not surprisingly) with a simple question: “which network components affect availability in IPv6 world, and how is a dual-stack or an IPv6-only environment different from what we had in the IPv4 world?”
This part of the webinar is now available on ipSpace.net content web site. Enjoy the video, explore other IPv6 resources on ipSpace net, and if you’re from Europe don’t forget to register for the IPv6 Security Summit @ Troppers in mid-March.
In one of the discussions on v6ops mailing list Matthew Petach wrote:
The probability of us figuring out how to scale the routing table to handle 40 billion prefixes is orders of magnitude more likely than solving the headaches associated with dynamic host renumbering. That ship has done gone and sailed, hit the proverbial iceberg, and is gathering barnacles at the bottom of the ocean.
Is it really that bad? Is simple renumbering in IPv6 world just another myth? It depends.
After discussing the load sharing intricacies we briefly dabbled with the concept of entropy labels.
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 na├»ve 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.
Imagine you need a data center WAN edge router with multiple 10GE uplinks. You’d probably go for an ASR or a MX-series router, right? How about using a 2 Tbps ToR switch and an SDN solution to make it work with full Internet routing table?
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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.
Every major hypervisor and networking vendor has an overlay virtual networking solution. Obviously they’re not identical, and some of them work better than others in large-scale environments – an interesting challenge we tried to address in the Scaling Overlay Virtual Networks webinar. As always, we started by identifying the potential problems.
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.