CCIE Pursuit Blog

August 30, 2007

Gigabit to the Desktop: User Perceptions vs. Reality

Filed under: Cisco,Switching,Work — cciepursuit @ 4:55 pm

I was just reading a great article by Michael Morris over at Network World.  I encourage you to read the entire article, but the basic summary is that once end users become aware that gigabit Ethernet is available, then will want to have it and will swear that they need it – even when it is obvious that they do not:

Yes, there are definitely servers, databases, and network storage in a Data Center than can fill and benefit from 1 Gbps ports, but not users. Any traffic over WAN links is going to be limited by lower WAN bandwidth and effect delay has on TCP. So, unless you’re sitting on the same LAN as the DC with a home-built, water-cooled super-PC running your own compiled version of Linux……YOU DON’T NEED A GIG PORT!

I have fought this very same battle.  My battle began with server owners adding gigabit Ethernet cards to their servers and then expressing dismay with “the network bottleneck” because we only offered them 10/100 ports (this was a few years ago).  Even when we showed the server owners that they very rarely (and most times – never) came close to the 100 megabit port speed, they insisted that they needed gig speed.  In their minds they had gigabit cards and they were being throttled back at the switchport.  We eventually built a gigabit switched network and then charged them twice as much per port (“We’re giving you 10 times the speed at only twice the cost.”).  Even when we were able to show statistics to the server owners that they were still running way under 100 megs, they consistently claimed that they were getting better throughput with the gigabit connection. [Again, this was a few years ago.  There are servers now that do use gigabit speeds, like SAN servers and also during backups.  This was not the case then.]

A collegue and I decided to do an experiment.  Since we couldn’t change the speed on the port connected to the server because they would notice it, we instead set the uplink to 100 megabits.  With only one device on the switch, that server could use the full 100 megs on the uplink to the core switch.  The setup looked like this:

Server NIC (1000 Meg)—–(1000 Meg) Switch Port | Uplink Port (100 Meg) —–(100 Meg) Core Switch Port

First we set the switch port to 100 Full and told the server owner to set their NIC to the same. 

“Can’t I get gig?”
“Sure, but our policy is only to give gig to servers that require it.”
“We need it.”
“Based on your traffic patterns, we don’t think that you do.  BUT… if you have response issues we can give you a gig.”

Sure enough, even though we never saw more than 30 Megs pumping through the switchport, the server owner was soon compaining of “slow response.”  We increased the port speed to 1 gig, BUT left the uplink to the core switch (well, actually one of the distribution switches) at 100 Meg.  To nobody’s surprise, the server owner claimed that his “slow response” issues were gone.  We never told him that the only gigabit connection was from his NIC to the switchport, because we did not want to get fired.  :-)

*Note:  looking back on this, the server owner may not have even perceived any slowness.  He may have lied about this in order to get the gig connection just because he was tweaked about initially being denied the connection.  Admittedly, this was not a perfect test. 

In another instance, my company bought a much smaller company and I was sent out to integrate the network.  The “network guy” had installed some HP switches and was balking at the cost/nescessity of replacing those with Cisco 3750s.  He bragged about the HP running gigabit to the desktop.  This was unfortunately not true.  The HP switches DID have gigabit capability (the 3750s that we were going to replace them with were 10/100) BUT none of the PCs had gigabit NICs.  Everyone was running at 100 Full.  I could not get it through his head that this was the case.  PLUS, the HPs did not sufficient backplane capacity to handles multiple machines at gigabit speed, NOR did they have uplink ports capable of handling more that gigabit speed.  The coup de grâce was that all of their servers were housed in a data center in another state that they connected to via a T1 line!  Even after trying to explain that no matter how fast the PC could speak to the switch, there was no way that it could communicate with one of the data center servers at anything more than 1.5 megabits per second.  No sale.  He was still convinced that installing the 3750s would cripple their network.  Unfortunately, he spread this rumor around the site.  Anytime that there was the slightest perceived “slowness” issue, I got a call claiming that the new switches were too slow.  ARRGGHHH!!!!

I’ve also seen this disconnect with home users.  Friends of mine SWEAR that thier “Pre-N” wireless access points give them “way faster” access to the Internet.  I try to tell them that no matter how fast they can communicate with their AP, their not going to access the Internet any faster than their cable/DSL modem allows them.  You can guess how this battle usually ends.  Sigh.

The moral to this story?  Once end users know that there is some faster, shinier, cooler technology available they will feel that they NEED it in order to do thier job -  even when it can be empirically shown that they don’t.

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