MAE-east: what *is* a MAE anyway?
OK, so I have my cable modem, personal domain, mail server, etc...
I even back up my files to tape. I discovered recently I'm my
own personal mini-ISP to myself. How scary.
So then, I discover that my packets are taking 1/4 second to get
from my house to work when I can drive there in 15 minutes. This
might see OK but if you do the math and remember how fast the
speed of light is, it should take a lot less than 1/4 second or
250 milliseconds (we say "250ms" in the trade).
So, I do some probing (it turns out that 250ms is *very* noticeable
if you are typing in a telnet session) and found out that my packets
went from Boston to San Francisco and then back to Boston then to my
office. Nothing like a little trip to the coast and back. This
little "mis-routing" was cause by a mis-configuration at a place
known as MAE-east. A "MAE" is a metropolitan area Ethernet. This
is an idea cooked up by a company know as MFS and now known as WorldCom.
Loosely it's a way to connect up a bunch of Ethernet speed LAN's
using fiber and routers. Think of it as a room in a building near
Washington DC with lots of routers and blinking lights. Anyway,
in this room many (but not all) ISP's connect their networks together.
When they connect them together they need a way to communicate who
and what is where on the combined network. These days we use
"routing protocols" to let routers speak to each other about what
is where. SO, if the routing protocol says the wrong thing, or
if one router misunderstands or misinterprets the routing protocol
information, your packets go to San Francisco instead of Billerica.
OK, that's complex stuff. Imaging if you understand it, but don't
work for a ISP. Imagine trying to explain to them that there is
a routing problem. I did this for 2 (yes, two) months before I got
my cable company to fix the problem. Ugg. Even the phone company
was not that slow. The eventually fixed the problem (one ISP
was emitting a BGP-4 MED which cause them to prefer a route to
MAE-west over a local route to MAE-east, for the routing geeks) and
now my packets take only 40ms to get to work (that's 5 times faster
and I am much happier).
I think the cable companies are much more at home dealing with
people who can not get to the ESPN web site, but this is complex
stuff at the bottom and not fully baked yet...