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Case 7:   Intranet routing on Other ISP
(see drawing, below)

Listing of Cases

Method of delivering Internet and intranet:
Although SUNYNet intranet service is built on lines to AT&T's Internet, in this case the campus uses its existing, non-AT&T ISP in a modified, "virtual" intranet service. By using its existing Internet service, the campus avoids the cost of a separate AT&T service (as in Case 5). SUNYNet Operations operates an intranet router (tan, cross-shaped box) on campus to create tunnels and do encryption. Since the campus does not use AT&T, it will have more hops and some potentially serious points of congestion between the two core networks of the ISPs when communicating with the other campuses that use AT&T exclusively. Before choosing this arrangement, this campus has determined that their Internet connection has sufficient bandwidth to accommodate its time-sensitive applications and that traffic between the two ISPs does not usually get congested.

Roles of the Routers:
Most LAN traffic is directed to the campus's ISP router (the orange, cross-shaped box). Specially identified IP traffic, including all intranet traffic, is directed to the SUNYNet router. Wherever the application requires it, the SUNYNet router puts traffic into a "tunnel" (not shown graphically here) to make it secure (encrypted) or to control its flow over the two ISP's networks. Also, tunnels will be used for SUNY-to-SUNY DECNet traffic. Although the SUNYNet router could mark outgoing intranet packets in order to get priority handling when entering destination sites that use AT&T's CoS services, this will not work as long as AT&T does not accept such markings coming from other ISP's customers. The SUNYNet router hands packets to the campus ISP router over an Ethernet cable. The ISP campus router sends traffic into its core network (globe) which delivers it to SUNY destinations. For the SUNY sites using AT&T, data flows through peering arrangements between the campus's ISP and AT&T.

All of the public IP address space for the campus are being announced to the Internet by the campus's ISP.