Logical boy in a logical world


There always has been to the idea of thinking in the logical headspace. Since the inception of Virtual Local Area Networks the wizards of the ether, Network Administrators, have had a notion of a logical and physical representation of the network. A layer 2 domain could span multiple switches and have a routed gateway. This may be partitioned by a transparent firewall or another appliance. This thought process has evolved with Virtual Route Forwarding (VRF) and can be seen used in conjunction with MPLS which abstracts the data plane and the control plane.

Traditional application stacks that reside in data centres generally consist on three tiers. These are the web front end, an application engine and the data base tiers. These tiers generally consist of security policies that separate zones. These can be enforced by logical constructs such as ACL’s, Rule sets, NAT, VLANs and physical barriers such firewalls (generally multiple!) or physical isolation.

In application stacks that reside in Data Centers today that deliver our business critical applications there has been a shift from a handful of devices delivering to a service to thousands upon thousands at each tier. This generates a vast amount of east west traffic generally built upon old three-tier network styles. Unfortunately as applications have evolved our network architectures have been stagnant and rather physical.

With the strong presence of virtualization within modern data centres we have brought a new capabilities traditionally found in hardware into the hypervisor. Once in the hypervisor, network functionality capability has the same feature set as any physical counterpart. With services such as switching, routing, fire walling, load balancing and VPN functions to name a few now residing in software constructs, administrators need to start thinking about how this all maps together. The logical landscape is vastly different to the physical landscape and getting the mindset into gear requires some thinking.

So I put it to you my network colleagues – think about drawing out your logical networks. Consider an entire network that is virtualized that leverages the physical network as IP transport. Picture a reduction in inane traffic hairpins and sub-optimal packet walks. Program yourself to think logically and you will have taken your first step into a larger world. A logical boy in a logical world!

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