New label switcher can beef up a private network
We've noticed that a steadily increasing number of users on our network need
high-speed network access in their homes. Until recently, only one solution was
available to them: href="http://www.adsl.com/adsl_tutorial.html">ADSL service from GTE.
Our ADSL service from GTE is unique because we don't use GTE's Internet offerings.
Our users connect to an ADSL cloud that terminates via a DS-3 on our campus
backbone. Boot up a machine that's connected through the ADSL service and you'll get a
Duke University IP address and domain name. It's just like working from your office.
Unfortunately, ADSL coverage is spotty. We only get a 35 percent qualification rate;
that's not good enough. You can't base an enterprise solution on a service that's
available to only 35 percent of those who want it.
We've been looking for an alternative for some time, with little success. Time
Warner and Road Runner have a strong presence in the Raleigh-Durham-Chapel Hill area,
but they've only been offering consumer-grade service: network access with all the
bells and whistles, including an email account, channel content, and portals.
We are our own ISP and provide our users with email accounts. We don't want the
bells and whistles, just the bandwidth and a Duke IP address. And therein lies the rub;
Road Runner only provides Road Runner IP addresses and domain names.
Road Runner couldn't provide a Duke IP address to folks using its service, as GTE
could for ADSL. But suddenly that's changed, thanks to a new offering called target="new" href="http://www.mplsrc.com/">Multi Protocol Label Switching (MPLS)
MPLS is a direct descendant of several different label-switching schemes, including
tag switching. MPLS uses label edge routers and label switch
routers to assign 20-bit labels to each incoming packet and route them
How does this help us solve our residential broadband problems?
By labeling each packet and using the routers to direct the packets to their final
destination, we're able to build a "private" Duke University network that's layered
over the Road Runner commercial offering.
When customers request the Duke Road Runner service, they'll be given a cable modem
assigned to the Duke MPLS path. The DHCP request from the user's PC will be forwarded
to Road Runner's MPLS DHCP server, which will assign an IP address from a block of
numbers we've delegated to Road Runner. MPLS will work its magic and label all of the
packets from that machine as Duke packets. They'll then be passed through the Road
Runner core and handed off to an edge router on our campus.
Users will receive Duke IP addresses and domain names and will, for all intents and
purposes, be directly connected to the campus network. And, best of all, users can be
located anywhere that Road Runner provides service in this area. If you can get Road
Runner service, you can have MPLS-based Duke networking.
We're still in the early design phases of this project. MPLS is a new technology and
is still evolving. This is the first time Road Runner has offered such a service. I
suspect we'll have more than a few hurdles to clear before we can go to production with
MPLS-based cable modem service. But I think it will be worth the trouble. An easily
managed, secure, ubiquitous residential broadband offering is an enterprise network
For a more in-depth look at MPLS, take a look at these resources:
120s/120s5/mpls_te.htm">Cisco's MPLS configuration guide
- Juniper's MPLS overview