abc Today's letter in the Networking ABC's is the letter "L".  "L" has it's last hops, layers 1-7, loopbacks, and load balancing methods.  But I opted for a word that is relates to something I despise: waiting in line.  Today's word is Latency.

"L" is for Latency



Pronounced: leyt-n-see

Latency is defined as the delay between the moment something is initiated and the moment its first effects begin.  In the networking world, this is the waiting you must deal with between the time a network connection is established and when your request can be processed.  As I mentioned in the letter "K" for Keep-Alive, websites with 10's to 100's of objects that are required for presentation is a risk for latency disaster.  Browsers can only request a certain number of parallel requests, so let's assume this number is 5.  And, let's assume for the sake of argument that the connection latency between your browser and website "X" is 200ms.  For 100 objects (images, scripts, etc), a delay of 4 seconds would be added to the browsed page. This is on top of time required to process the request by the application servers.  Keep-Alives help with latency in that it reduces the connection latency by combining requests within the same connection.  There are other network devices that can help with latency by manipulating things at the TCP layer such as window sizes to optimize the amount of round trips needed for the lower level protocol negotiation on each connection.