ozalp@aya.cs.cornell.edu (Ozalp Babaoglu) (08/06/88)
suppose a country (italy, to be precise) currently has a single internet site (in pisa) and has been registered as a top-level domain (domain .IT). there are three class C type IP addresses allocated to the country. what are some reasonable ways to structure subdomains in this country domain and incorporate LANs at other sites (cities) into the internet? the physical transport medium available is x.25 (both private and PDN run by the telephone company). what is the technology of choice for ethernet-x.25 gateway hardware and the software to do the routing and encapsulation (of IP packets over x.25)? any suggestions will be appreciated. ozalp babaoglu
lars@ACC-SB-UNIX.ARPA (Lars J Poulsen) (08/07/88)
> From lars@acc.arpa Sat Aug 6 09:35:15 1988 > Date: 5 Aug 88 20:29:51 GMT > From: ozalp@cu-arpa.cs.cornell.edu (Ozalp Babaoglu) > Organization: Cornell Univ. CS Dept, Ithaca NY > Subject: x.25 as an internet backbone > To: tcp-ip@sri-nic.arpa > > suppose a country (italy, to be precise) currently has a single > internet site (in pisa) and has been registered as a top-level domain > (domain .IT). there are three class C type IP addresses > allocated to the country. what are some reasonable ways to structure > subdomains in this country domain and incorporate LANs at other > sites (cities) into the internet? the physical transport medium > available is x.25 (both private and PDN run by the telephone company). > > what is the technology of choice for ethernet-x.25 gateway hardware > and the software to do the routing and encapsulation (of IP > packets over x.25)? any suggestions will be appreciated. > > ozalp babaoglu For each campus, assume an ethernet with its own network number. (class C may be adequate for a while). For each of these, nominate a router with an X.25 interface to be the gateway to the outside world. Suitable routers include Ultrix with ACC's ACP5250, SUN with SUNLINK, VMS with Wollongong TCP/IP and ACP5250, and many otehrs as well as standalone router boxes. The router must run EGP, ROUTE-D or similar gateway protocol to advertize reachability. If the private X.25 network has a DNIC and can communicate with the public data network, then you have one X.25 world, and all X.25 should use one network number. If not, get a network number for the X.25 network. Since X.25 has no ARP mechanism, all routers must share knowledge of IP address to X.25 address mappings. This means a centralized management of each X.25 IP network. CSNET does this on a commercial basis in the US, and it would be to your advantage to join them so that your PTT network is joined with the X.25 part of CSNET. However, I don't know if their fee schedule makes this practical. Another possibility is to declare your X.25 network to be its own IP network, and have a single gateway to the outside (via CSNET or AC.UK or via a private arrangement with a US site) but this means you have to have fairly sophisticated traffic analysis in the gateway in order to charge back the international X.25 charges to the member institutions (since they all will be charged to the gateway). I don't know of any router equipped to do this. Let me know how you arfe involved with the evangelism in Italy, and contact me if I can be of more help. / Lars Poulsen ACC Customer Service. P.S.: No slight is intended of any product not mentioned above. I have nothing against CMU TCP/IP or Hewlett-Packard. SRI MultiNet is a fine product, and so is the ACS4020... products mentioned above are for examples only. My employer does not know I'm sending this ... is that enough disclaimers ?