SUNYNet Technology Services

SUNYNet Current Architecture

Case 4:   Intranet on multiple AT&T T1s combined with general Internet
(see drawing, below)

Listing of Cases

Method of delivering Internet and intranet:
SUNYNet intranet service is built on lines to AT&T's Internet. The lines terminate on campus in routers (the blue, cross-shaped boxes) that are owned and operated by AT&T. SUNYNet Operations also operates a router (tan, cross-shaped box) on campus. The lines are capable of handling both intranet traffic (red dotted line) and Internet traffic (blue dotted line) simultaneously. 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. The feature would be useful for this campus, but AT&T currently offers it only on individual lines (T1 or DS3), not over the bundles of T1s, called NxT1 (pron. "N by T one") being used by this campus. Since this campus wants NxT1 service, it needs to get a separate line if it wants  CoS. It can do so, as in Case 2, simply by removing one of its T1s from NxT1 configuration and placing it on a separate router. This campus has chosen to forgo use of CoS and to transmit intranet traffic through one of its NxT1 bundles that has consistent and sufficient bandwidth utilization to accommodate intranet applications. 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. When AT&T eventually develops QoS on NxT1, the campus can revisit this question.

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.