Containers enable portability across cloud environments, but cloud predictability remains a challenge.
I’m doing a webinar over at IP Space next week—
Most modern data centers are still using vendor-driven “future proof” routers and switches with offering lots of (often unnecessary) capabilities. To build large, however, it is often better to build simple—radically simple. This webinar will cover the design components involved in building a data center or cloud fabric using a single, disaggregated device—the way some hyperscale and web scale operators build their networks. The first live session of the webinar will consider the benefits of disaggregated switch, focusing on the components, sources, and challenges in using disaggregated hardware and software in data center fabrics. The second live session will focus on the topologies and design concepts used in large scale data center fabrics using a single switching device as a leaf, spine and superspine switch.
This should be a fun time, and a good introduction to the disaggregation space.
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One of my readers sent me this question (slightly rephrased):
Assume you have A,B and C connected in a triangle (with an alternate longer path to C). What happens if C loses its links to A and B? Won’t the traffic to C loop between A and B for a while?
As always, it depends.
Read more ...It came around again: CCIE renewal. Last time I renewed, I wasn’t sure if I should do it again. But I gave in, passed the CCIE R&S Written Exam, and moved one step closer to Emeritus. Turns out it wasn’t that bad, and I should not have put it off for so long.
Cisco certifications below Expert level have a 3-year renewal cycle. You can renew your CCNA or CCNP certifications at any time by sitting an exam at the same level. Your 3-year cycle restarts from the day you pass that exam.
CCIE is a little different. A CCIE certification remains valid for two years from your lab date. You can sit any CCIE-level written exam to renew your CCIE certification. At that point your validity date gets extended for another two years - note that it is another two years based upon your lab date, not the date you passed your most recent re-cert exam.
If you don’t pass a written exam during the two-year period, your status goes to “Suspended.” You then have another 12 months to pass the exam, or you completely lose your CCIE status.
My renewal date was last Continue reading
VXLAN is an overlay network to encapsulate Ethernet traffic over an existing (highly available and scalable, possibly the Internet) IP network while accomodating a very large number of tenants. It is defined in RFC 7348. For an uncut introduction on its use with Linux, have a look at my “VXLAN & Linux” post.
In the above example, we have hypervisors hosting a virtual machines from different tenants. Each virtual machine is given access to a tenant-specific virtual Ethernet segment. Users are expecting classic Ethernet segments: no MAC restrictions1, total control over the IP addressing scheme they use and availability of multicast.
In a large VXLAN deployment, two aspects need attention:
A typical solution for the first point is using multicast. For the second point, this is source-address learning.
BGP EVPN (RFC 7432 and draft-ietf-bess-evpn-overlay for its application with VXLAN Continue reading