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Latency is the time it takes for your computer to communicate with the World of Wacraft server. A latency of 50ms means that it takes 50 milliseconds to send and receive a packet from the World of Wacraft server. For playing games online such as WoW, a low latency is desired as it means less communication time between control input and events happening on the player's screen. A high latency can become a hindrance for proper gameplay. Things that could be experienced are delayed messaging, out of sync battles and difficulty of performing tasks ingame that are required to advance. The terms "Lag" and "Ping" are often used when players refer to their current latency status.
What can affect latency
World of Warcraft requires clients to connect to the Blizzard Servers to play the game. There are four possible breaking points in the transmission of the required communications, which are: the client's computer, the client's router, the client's ISP and finally Blizzard's Servers. In a network such as this, one faulty point causes the whole game experience to suffer. When trying to identify the cause of high latency, consider the following things:
- The last time a piece of hardware was added to your computer.
- The last time new software was installed on your computer.
- The last time drivers have been updated on your computer.
- The last time your router/modem has been reconfigured.
- The last time a new patch has been installed for World of Warcraft.
- The last time settings of the firewall were changed.
Any changes applied can cause devices to function slighly different than before, and as such, be the cause of elevated latency. Most likely, if problems ever do arise, something was done to alter the setup from how it worked before. The official World of Warcraft forums have a Technical Problem section where help can be found to more specifically pinpoint the cause and solve it.
Remember to keep the computer free from adware, spyware and other malware. These would fall under the category of new software. Since these are applied to a computer without notification or permission of the user, it is easy to overlook these as a possible cause of higher latency.
Some ISPs punish users of file sharing software by lowering the quality of their connections, which can increase latency. However, this usually stops promptly once the software stops running. With Bell Canada at least, one can use the same connection for both a BitTorrent client and WoW, but not both at the same time.
In 4.0.6 Blizzard changed the way the latency is displayed. There is now a 'home' and a 'world' latency. The official explanation is the following.
The speculation regarding what these ratings mean has been very interesting and some of the guesses as to what the numbers actually refer to have been pretty imaginative. Some have speculated that 'Home' referred to your personal latency and 'World' was Blizzard's latency. This is incorrect.
In essence, 'Home' refers to your connection to your realm server. This connection sends chat data, auction house stuff, guild chat and info, some addon data, and various other data. It is a pretty slim connection in terms of bandwidth requirements.
'World' is a reference to the connection to our servers that transmits all the other data... combat, data from the people around you (specs, gear, enchants, etc.), NPCs, mobs, casting, professions, etc. Going into a highly populated zone (like a capital city) will drastically increase the amount of data being sent over this connection and will raise the reported latency.
Prior to 4.0.6, the in-game latency monitor only showed 'World' latency, which caused a lot of confusion for people who had no lag while chatting, but couldn't cast or interact with NPCs and ended up getting kicked offline. We hoped that including the latency meters for both connections would assist in clarifying this for everyone.
As is probably obvious based upon this information, the two connections are not used equally. There is a much larger amount of data being sent over the World connection, which is a good reason you may see disparities between the two times. If there is a large chunk of data 'queued' up on the server and waiting to be sent to your client, that 'ping' to the server is going to have to wait its turn in line, and the actual number returned will be much higher than the 'Home' connection.
"Well, great," you may say, "but what does that mean to me?!"
Not much, maybe, but I wanted to focus on how local (or network) factors can (and will!) affect these numbers.
Here are the most common causes of high pings/latency (on both Home and World):
- Packet loss
- Addons (yes, those wonderful UI modifications)
- Firewalls (some firewalls do interesting things to latency... try playing without it to see if it helps!)
- Mis-configured or defective home routers (please temporarily bypass before anything else)
- Quality of Service and Traffic Management Systems performing packet queuing of some sort.
- Net link saturation (not necessarily your ISP, but somewhere between you and Blizzard)
*As of July 2010, the 'official' definition of Broadband Internet (per the FCC) is '4Mbps downstream and 1Mbps upstream'. Anything lower than this is not 'officially' broadband.
Lowering video settings (especially view distance) has the added benefit of lowering the amount of data your connection is asked to convey, as well, so even that can be a valid troubleshooting step.
If your 'Home' connection latency is low and your 'World' connection latency is high, that frequently indicates that there is some sort of QoS congestion controls being applied to your internet connection, at either the micro (LAN) or macro (WAN) level. A common symptom would be that you would be able to chat, but not to cast.If both connections report high latency, that means your connection to our servers, in general, is almost completely saturated, or 'overflowing'. Without making any claims where that saturation lies, that seems to have been the most common case to date.