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Evolving Provider L2VPN Services with E-VPN

A team of us at Cisco has been working, together with industry colleagues, on defining and standardizing a new Layer 2 VPN solution known as Ethernet Virtual Private Network or E-VPN. In this post, I will discuss the key requirements that helped shape this solution, and attempt to shed some light on the drivers for the technology and how it enables the evolution of Service Provider L2VPN offerings. Read More »

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Why onePK is Better

This is the first in a series of posts about network based software development for “typical”  enterprise developers, and how onePK can help.

Network based software development is special. The main interfaces are based on CLI interactions and SNMP, not to mention using RADIUS as a RPC mechanism, various forms of XML/HTTP found nowhere else, and additional innovations. For a typical enterprise or script developer these kinds of interfaces are unusual, to say the least. Read More »

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Overlays, Underlays and the New World Order

The networking industry has recently developed a renewed interest in virtual overlays, often wrapped in an “SDN as the controller” context. Amidst the promise, the hope and the hype, the following questions present themselves:

  • What exactly is an overlay?
  • What distinguishes an overlay from a VPN?
  • How decoupled can an overlay be from the underlay network and what are the tradeoffs?
  • What are the advantages of overlays and will they emerge as the new networking world order? Read More »

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EIGRP vs OSPF – Take 2

September 13, 2012 at 8:01 am PST

First a bit of disclosure.  I have worked for Cisco over 15 years, much of that time as the lead developer for EIGRP. I think I understand its strengths and weakness’ very well, and have spent a great deal of energy minimizing them.

I often find comparing protocols similar to the old “tab vs spaces” or “emacs vs vi” wars.  There are valid reasons to choose one over the other and in the grand scheme of things it comes down to a wash; often preference or ‘religion’.  EIGRP seems to victim to this .  I mean where are the “ISIS vs OSPF” debates?  With EIGRP, network engineers that love it – love it. Those that don’t, well they don’t. Arguing its merits often results in an equally long list of “yea but” demerits.

For example, most everyone would agree eigrp is “simple to deploy”, but detractors would argue that simplicity leads to sloppy designs and only though complexity can we force network engineers to “do their job” and design the network properly. Read More »

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A Unified L2/L3 IP Based Overlay for Data Centres: another use-case for The Location Identity Separation Protocol

It is amazing how the data centre world has changed in the last few years.  A Data Centre used to be a collection of network elements to interconnect static servers (and their associated storage), with traffic patterns that were highly predictable and mostly north-south.  Cloud and virtualization have changed all of this: a data centre is now a collection of compute and storage resources which can be securely sliced up into virtual networks and placed anywhere according to real time needs, interconnected by a fabric.  The virtualization of servers, network services such as firewalls and load balancers, and even network devices such as switches and routers, has created a very dynamic landscape in terms of how fast you could configure a virtual network, in a way where location shouldn’t really matter, and where compute and storage resources can be added on the fly, based on demand.  Multi-tenant Data Centres, such as the one to deploy Virtual Private Clouds, need to support 10000’s of these virtual networks.  And every one of these virtual networks needs a lot of different service instances to stitch together the virtual network across virtual servers, virtual switches, virtual firewalls, virtual load-balancers, and virtual routers.  Traffic patterns have shifted to East-West, because of the new applications which spread processing across many hosts, and because of the ‘location freedom’ that virtualization allows.  Network infrastructure needs to be cost-effective to handle all this traffic, while the increased lookup-table size caused by the any to any traffic patterns often led to increased cost.  Read More »

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