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Who's
MAE and Why's She So Slow?
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Q: What happened
yesterday? Our sysadmin said that MAE was having problems, so the East Coast
was unbearably slow. What is MAE and is it a router or a backbone node? What
gives?
Jon
A: Although it's a
sales mark of MFS Communications, the MAE
acronym has practically become a generic term for public network exchange
points and network access points (NAPs). But what are those, you ask? Well,
let me explain.
Network access points
were initially created by the National Science Foundation so ISPs could
connect to the NSF-funded backbone in the early commercial days of the Net.
Although used interchangeably with NAP, public network exchange point is a
more generic term that better describes the current purpose of these
entities: They are places where ISPs come to exchange traffic and routes
(tell each other who's on their networks), and no longer places ISPs come to
hook up to the Internet.
Physically, public
network exchange points are usually switched LANs, where
an ISP, for a fee, can acquire an Ethernet, FDDI, or ATM port, as well as some rack
space for a router. But
getting a connection to a network exchange point is only half the equation,
because it just puts you on a LAN with a bunch of other ISPs. There's no
guarantee they'll exchange traffic with you.
An agreement to
exchange traffic is known as peering, and they can be difficult to get -
especially with the bigger ISPs. Most of the larger ones demand that another
ISP have connections (all the same speed) to at least four or five different
public network exchange points before they'll consider a peering agreement.
This prevents an ISP from connecting a fairly cheap line to one exchange
point and getting a free ride off other ISPs with an expensive national backbone.
The original MAE, or Metropolitan Area
Ethernet, was an Ethernet set up by MFS and a few ISPs in the Washington, DC,
area to peer and exchange traffic in the early 1990s, when the National
Science Foundation was getting out of the Internet backbone business. The MAE
was very successful. At the time, the MAE was the center of the Internet
universe - the one place where everyone came together and exchanged routes.
After this success, MFS and NASA opened a similar facility in Silicon Valley and dubbed it MAE-West. There are several other notable exchange points, such as the Sprint NAP in New Jersey, the Pacific Bell NAP in San Francisco, and a whole passel of new MAEs in major metropolitan areas.
Public network exchange
points are a good thing, but they often suffer from traffic congestion. The
bottlenecks usually occur when an ISP has more data to get out of the
exchange point than its connection can handle. And with relatively few
exchange points in the world, data can travel great physical distances before
it gets to its ultimate destination. The most extreme example of this is
Europe, which effectively has no public exchange point, so MAE-East in the United
States must shoulder the burden. One way to solve this problem is to create
more public network exchange points in more places around the globe. This
would relieve the current load on many of the key NAPs, as well as utilize
bandwidth better by keeping local bandwidth local and avoiding expensive and
potentially overcrowded long-haul lines.
To avoid potentially congested NAPs, many ISPs currently rely on private network exchange points. Private network exchange points (or private peering points, as they are often called) are (as their name implies) invitation-only network exchange points. They're usually created when two ISPs conclude that they exchange a lot of traffic, and that it would be beneficial to both sides to avoid congestion at NAP points.
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Jon |