17-Jun-83 21:55:06-PDT,6428;000000000001 Return-path: Mail-From: SMTP created at 17-Jun-83 21:53:10 Received: FROM SRI-NIC BY USC-ISIF.ARPA WITH TCP ; 17 Jun 83 21:53:15 PDT Date: 17 Jun 1983 2014-PDT From: NIC at SRI-NIC Subject: DDN Newsletter No. 27 To: DDN-MGT-LIST4: ; cc: NIC at SRI-NIC ====================================================================== DDN-NEWS 27 NETWORK INFO CENTER for 17 June 1983 DCA DDN Program Mgmt Office (415) 859-3695 (NIC@SRI-NIC) DEFENSE DATA NETWORK NEWSLETTER (Maximum Distribution Requested. The DDN Newsletter is published by the Network Information Center under DCA contract. For on-line subscription, contact NIC@SRI-NIC. Back issues obtainable by FTP from the directory at SRI-NIC [10.0.0.73].) ====================================================================== Section I. OFFICIAL Topic: - More Details on the MILNET/ARPANET Split ---------------------------------------------------------------------- FURTHER DETAILS ON THE ARPANET/MILNET SPLIT Introduction As previously discussed in DDN Newsletter 26, the existing ARPANET will soon be split into two separate networks - the experimental ARPANET and the operational MILNET. Hosts on the two networks will intercommunicate via mail bridges, using the internet gateway mechanisms to pass mail traffic between hosts on the two networks. The mail bridges will, on a controlled basis, provide full internet gateway services for MILNET hosts that request it. The Logical Split Because it takes a large amount of time and effort to physically split a network in a coherent manner, the ARPANET will initially, on 4 October 1983, be logically partitioned by the use of existing mechanisms in the IMPs to enforce segregation of hosts and TACs into separate communities of interest. Each community of interest (COI) becomes a virtual network, i.e., hosts (including TACS) in the same community can fully interoperate as is currently the case, while hosts in different communities cannot directly intercommunicate. This, in effect, transforms the ARPANET into an Internet in which the MILNET will assume a new class A network number, network 26, while the ARPANET remains network 10. (Details of the host renumbering procedures will be covered in a later newsletter from the Network Information Center (NIC).) Intercommunication between the MILNET and ARPANET is via mail bridges which use standard internet protocols and mechanisms to pass data between hosts in the two networks. This is why the conversion from NCP to TCP/IP is so important; any host with a fully working TCP/IP implementation (including ICMP, the host-gateway protocol), should see no loss in service because of the split. However, hosts using incomplete TCP/IP implementations (those that do not include ICMP as a part of IP, or have no provision for using gateways) will be restricted to communicating with other TCP/IP hosts in the same network. In particular, this means that they will not be able to send (or receive) mail traffic through the bridges to hosts in the other network. THERE CAN BE NO EXEMPTIONS TO THE SPLIT!! Unlike the NCP-to-TCP conversion which is still underway for a few hosts, once the split occurs, there is nothing that can be done to allow a host with an incomplete TCP/IP to fully intercommunicate with the other network other than helping them to convert to a fully working TCP/IP as soon as possible. Future DDN Newsletters will discuss in greater detail how the split affects the users and host software maintainers, and how the split will be tested before it is finally implemented in October. The Physical Split Concurrent with the logical split the network is being physically split as well. Many new trunks are being added to support each network, and a number of trunks will eventually be removed once replacement trunks have been installed. The first quarter of CY 1984 has been established as the goal for completion of the physical split, but this is dependent upon delivery of new circuits from the TELCOs, some of which have very long lead times (over a year in some cases). To complete the physical split, hosts and terminals which are homed on the wrong IMP or TAC must be rehomed. In some cases, a new IMP on the proper network will be used; in other cases, a host may need to use HDH (the HDLC-based replacement for VDH) in order to gain access to its network via a remote IMP. In either case, the host must change its network address, and the TAC users of these hosts must be made aware of the change. Both host and terminal rehoming will be kept to the absolute minimum possible. Sources of Additional Information To obtain additional copies of this or previous newsletters, - Invoke FTP at your local host - Connect to SRI-NIC (the NIC host, 10.0.0.73) - Login as 'anonymous', password = 'guest' - Do a 'get' on files with pathnames DDN-NEWS-27.TXT DDN-MGT-BULLETIN-3.TXT or DDN-NEWS-n.TXT DDN-MGT-BULLETIN-n.TXT where 'n' = the number of the newsletter or bulletin desired NOTE: Only those newsletters since issue 20 pertain to the network after the cutover to the TCP/IP protocols, or to the new Defense Data Network and the MILNET/ARPANET split. Most readers will no longer need the information contained in issues 1-19. A list outlining which IMPs and hosts will be on MILNET and which will be on ARPANET may be FTPed as outlined above using the pathname MILNET-ARPANET.LIST A list of network liaison for each host may be FTPed with pathname LIAISON.TXT The Network Information Center (NIC) at SRI International will be the primary repository for information concerning MILNET/ARPANET and the upcoming split. For further information contact NIC@SRI-NIC or (415) 859-3695 Network Information Center SRI International Room EJ232 333 Ravenswood Avenue Menlo Park, CA 94025 -------