SUNYNet Technology Services

SUNYNet Current Architecture

Case 1:  Intranet on a single line (T1, DS3)
combined with general Internet as a lower priority
(see drawing, below)

Listing of Cases

Method of delivering Internet and intranet:
SUNYNet intranet service is built on a line to AT&T's Internet. The line terminates on campus in a router (the blue, cross-shaped box) that is owned and operated by AT&T. SUNYNet Operations also operates a router (tan, cross-shaped box) on campus. The line is capable of handling both intranet traffic (red dotted line) and Internet traffic (blue dotted line) simultaneously and can be configured to give preferred handling to the intranet traffic. Some campuses choose to keep general Internet traffic off the SUNYNet intranet link, (as in Case 3),but in this case, the campus has chosen to merge the two types of traffic on one line. AT&T offers a new feature that helps make this merging feasible. The feature, called CoS (Class of Service) tells the routers on both ends of the campus-to-AT&T link to give priority to specially identified traffic in both directions. This allows the line to run near capacity all the time without hurting response time on high priority (intranet) applications. This feature carries an additional monthly fee, which is cost-effective on a T1, but not a DS3, so we have two sub cases to describe:

Sub Case 1a, Physical Line is a T1: in this case, the campus uses AT&T's CoS feature, which is much less expensive than getting a separate T1 for intranet, even one that is clocked at the lowest port speed (128K). Also, it allows the intranet line to be used for small, but important subnets, such as the Administration building, library, or some classrooms, giving them consistent response times. When traffic outgrows a single T1, additional lines will be added, moving the campus into Case 2 or Case 3.

Sub Case 1b, Physical Line is a DS3: This is very similar to Case 4 which uses multiple T1s. In this case, the campus has a physical DS3, perhaps with a sub-45 MB port speed. The campus line to AT&T is sufficiently well-managed and generous enough in bandwidth to accommodate its intranet traffic. The campus has chosen not to use AT&T's CoS because the charge for it on a DS3 line is greater than the cost of a separate T1. The campus has so much bandwidth that getting a separate line Case 2 or Case 3) is not warranted. When the DS3 starts to become congested, the campus will get a separate T1 for the intranet. Even without being a CoS subscriber, the campus may mark outgoing intranet packets to allow their traffic to receive priority as it traverses the access lines of campuses that do subscribe to CoS. SUNYNet can do this marking in its campus (tan) router.

Roles of the Routers:
IP traffic that is bound for off-campus destinations gets directed to the SUNYNet (tan) router. If the campus LAN administrators prefer, they may send their non-SUNY Internet traffic directly to the AT&T (blue) router to bypass processing by SUNYNet. The SUNYNet router marks authorized intranet traffic in one of three high priority categories. The top priority marking is applied to designated video and voice traffic, and the second highest to interactive applications such as business and library. Certain addresses or ports can be identified for better-than-average Internet performance if so desired. Wherever the application requires it, the router puts traffic into a "tunnel" (not shown graphically here) to make it secure (encrypted) or to control its flow over the AT&T network. Also, tunnels will be used for SUNY-to-SUNY DECNet traffic. The SUNYNet router hands packets to AT&T's campus router over an Ethernet cable. The AT&T campus router sends traffic into its core network (blue cloud) which delivers it to SUNY destinations, or to other AT&T Internet subscribers and Internet Service Providers worldwide.

All of the public IP address space for the campus will be announced to the Internet by AT&T.