PRODUCT BRIEF
Plexxi In Depth
Instinctively Simple: Evaluating Complexity
There is no perfect measure for complexity; there is no scalar value that defines a Complexity Index in any
generally accepted way. There is, however, an overwhelming sense in IT generally and networking specifically that
architecting, deploying, and managing infrastructure is becoming increasingly complex. If complexity is not directly
measurable, how can anyone evaluate the complexity of competing systems?
In developing a basic model for understanding relative complexities, Plexxi has treated technology as individual layers, each of
which makes its own contribution to the overall system complexity. While layering ignores the inherent complications of various
technologies working in concert, it does establish a baseline that is relatively easy to formulate and compare. Evaluators can
create simple models, and then adjust accordingly if they believe that layer interaction significantly impacts the results.
Total Complexity = Tech1 Complexity + Tech2 Complexity + … + TechN Complexity
The overall complexity for the system is defined as the sum of the individual complexities for each of the constituent
technologies. Within each technology strata, complexity is a function of how difficult a task is, and over how many devices that
task must be repeated. For example, a 1-line configuration change might be very easy; replicating that change across 3,000
devices is more complex.
TechN Complexity = Difficulty of Task x Number of devices
It is challenging to assign a constant value to Difficulty of Task. Without an agreed upon way of measuring difficulty, such a
numeric value does not exist. However, it is useful to consider the rarity of skills required to complete a task as a proxy for overall
complexity. For instance, a task for which there are 1,000,000 capable people is likely less complex than a task for which there are
only 1,000 skilled individuals. Using this model, roughly speaking, the second task might be modeled as 1,000 times more
complex.
Using this framework, the key to establishing a baseline for difficulty is identifying the most common networking skill levels and
calculating the ratio of the networking populations within each. In networking, the most common measure for level of expertise
is certification level. Of the certifications, the most prevalent are the Cisco certifications: CCNA, CCNP, and CCIE.
To create the proportions, Plexxi has used publicly available information about the number of certifications. The challenge here
is to get data across multiple tracks within the same year. In 2005, the number of CCNA certifications was close to 700,000. That
same year, the number of CCIE certifications was roughly 13,500. The ratio of CCNA to CCIE in this case is 52:1.
The number of CCNP certifications for that year is not available, but knowing that CCNP falls somewhere between the two, Plexxi
estimates the ratio of CCNA to CCNP to be on the order of 20:1. These numbers form the foundation of Plexxi’s overall
complexity model.
To create the individual complexity scores for each technology area, the difficulty of that
technology (the certification required) is multiplied times the number of devices in the deployment that must be touched. If a different ratio between difficulty levels is warranted, simply change
the difficulty values. If there is an overarching complexity due to interrelationships between
technologies, architects might consider further adjustments up from this baseline.
COMPLEXITY SCORE OF COMMON TASKS
Technology
# of touch
points
Difficulty
Complexity
Score
Plexxi touch
points
Plexxi
Complexity
Score
MPLS / TE
4
Expert (52x)
208
1
0 (Automatic)
Multi-service QoS
20
Professional (20x)
400
1
0 (Automatic)
VLAN config
20
Associate (1x)
20
1
1 (Associate)
Shortest-Path
Bridging (SPB) or
TRILL
20
Professional (20x)
400
1
1 (Associate)
OTV + LISP
4
Expert (52x)
208
1
1 (Associate)
OSPF ECMP
(Leaf/Spine)
20
Professional (20x)
400
1
1 (Associate)
In the example that follows, two 432-access-port datacenters are connected to each other via two WAN
gateway devices in each datacenter. To provision an end-to-end service, users must configure technology across some or all of
the network nodes.
MULTIPLE STEPS TO PROVISION END-TO-END SERVICE
Time and complexity required to provision end-to-end
layer 2 services across DCs using MPLS WAN (VPLS)
and RSVP traffic engineering
Task
Complexity Score
Configure VLAN connectivity
16 devices @ 1x = 16
Configure QoS
(queueing and classification)
16 devices @ 20x = 320
Setup MPLS LSPs
4 devices @ 52x = 208
Configure MPLS services
4 devices @ 52x = 208
Total = 752 complexity score
Action
Complexity Score
Configure edge ports/vlan
1x device @ 1x = 1
Create Affinity and run “Fit”
1x device @ 20x = 20
Time and complexity required to provision end-to-end
layer 2 services across DCs using Plexxi Control and
inter-data center transport.
Total = 21 complexity score
While these numbers cannot be taken as a precise complexity measurement, they do begin to quantify the complexity difference between competing solutions. In this example, a traditional WAN gateway solution is about 36x more complex than the
Plexxi equivalent.
Put in different terms, the world’s tallest building, the Burj Khalifa in Dubai, stands an astonishing 2,722 feet tall and has 162
floors. If this represented the total complexity in the system, Plexxi would be the 7-story, 75-foot-tall building in its shadow.
Plexxi, Inc.
222 Third Street, Suite 1100
Cambridge, MA 02142
+1.888.630.PLEX (7539)
[email protected]
www.plexxi.com
Copyright © 2013 Plexxi, Inc. All rights reserved. This product is protected by U.S. and international copyright and intellectual property laws. Plexxi and the Plexxi logo are registered
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July 2014