rfc1347.ps

RFC 的详细文档！

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(Running TCP and UDP Over CLNP) h
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45.1 0 32 (TCP is run directly on top of CLNP \(i.e., the TCP packet is encapsulated directly inside a CLNP) W
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4.4 0 32 (packet ) W
4.4 0 32 (\002 the TCP header occurs directly following the CLNP header\). Use of TCP over CLNP is) W
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3.0 0 32 (straightforward, with the only non\255trivial issue being how to generate the TCP pseudo\255header \(for) W
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(use in generating the TCP checksum\).) h
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37.7 0 32 (Note that TUBA runs TCP over CLNP on an end\255to\255end basis \(for example, there is no intention) W
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65.7 0 32 (to translate CLNP packets into IP packets\). This implies that only "consenting updated systems") W
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58.3 0 32 (will be running TCP over CLNP; which in turn implies that, for purposes of generating the TCP) W
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54.1 0 32 (pseudoheader from the CLNP header, backward compatibility with existing systems is not an is\255) W
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206.1 0 32 (sue. There are therefore several options available for how to generate the pseudoheader. The) W
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111.4 0 32 (pseudoheader could be set to all zeros \(implying that the TCP header checksum would only be) W
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120.1 0 32 (covering the TCP header\). Alternatively, the pseudoheader could be calculated from the CLNP) W
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80.6 0 32 (header. For example, the "source address" in the TCP pseudoheader could be replaced with two) W
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35.7 0 32 (bytes of zero plus a two byte checksum run on the source NSAP address length and address \(and) W
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43.0 0 32 (similarly for the destination address\); the "protocol" could be replaced by the destination address) W
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170.6 0 32 (selector value; and the "TCP Length" could be calculated from the CLNP packet in the same) W
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58.8 0 32 (manner that it is currently calculated from the IP packet. The details of how the pseudoheader is) W
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(composed is for further study.) h
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4.7 0 32 (UDP is transmitted over CLNP in the same manner. In particular, the UDP packet is encapsulated) W
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155.0 0 32 (directly inside a CLNP packet. Similarly, the same options are available for the UDP pseudo\255) W
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(header as for the TCP pseudoheader.) h
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(RFC 1347) h
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(Updates to the Domain Name Service) h
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78.4 0 32 (TUBA requires that a new DNS resource record entry type \("long\255address"\) be defined, to store) W
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36.4 0 32 (longer Internet \(i.e., NSAP\) addresses. This resource record allows mapping from DNS names to) W
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40.9 0 32 (NSAP addresses, and will contain entries for systems which are able to run Internet applications,) W
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(over TCP or UDP, over CLNP.) h
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104.5 0 32 (The presence of a "long\255address" resource record for mapping a particular DNS name to a par\255) W
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29.4 0 32 (ticular NSAP address can be used to imply that the associated system is an updated Internet host.) W
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6.4 0 32 (This specifically does ) W
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6.4 0 32 (not) W
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6.4 0 32 ( imply that the system is capable of running OSI protocols for any other) W
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64.6 0 32 (purpose. Also, the NSAP address used for running Internet applications \(over TCP or UDP over) W
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178.1 0 32 (CLNP\) does not need to have any relationship with other NSAP addresses which may be as\255) W
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17.1 0 32 (signed to the same host. For example, a "dual stack" host may be able to run Internet applications) W
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5.7 0 32 (over TCP over CLNP, and may also be able to run OSI applications over TP4 over CLNP. Such a) W
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96.1 0 32 (host may have a single NSAP address assigned \(which is used for both purposes\), or may have) W
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119.2 0 32 (separate NSAP addresses assigned for the two protocol stacks. The "long\255address" resource re\255) W
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44.9 0 32 (cord, if present, may be assumed to contain the correct NSAP address for running Internet appli\255) W
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87.8 0 32 (cations over CLNP, but may not be assumed to contain the correct NSAP address for any other) W
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(purpose.) h
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136.1 0 32 (The backward translation \(from NSAP address to DNS name\) is facilitated by definition of an) W
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21.3 0 32 (associated resource record. This resource record is known as "long\255in\255addr.arpa", and is used in a) W
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(manner analogous to the existing "in\255addr.arpa".) h
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58.6 0 32 (Updated Internet hosts, when initiating communication with another host, need to know whether) W
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68.7 0 32 (that host has been updated. The host will request the address\255class "internet address", entry\255type ) W
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45.5 0 32 ("long\255address" from its local DNS server. If the local DNS server has not yet been updated, then) W
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65.2 0 32 (the long address resource record will not be available, and an error response will be returned. In) W
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115.9 0 32 (this case, the updated hosts must then ask for the regular Internet address. This allows updated) W
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(hosts to be deployed in environments in which the DNS servers have not yet been updated.) h
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88.6 0 32 (An updated DNS server, if asked for the long\255address corresponding to a particular DNS name,) W
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133.6 0 32 (does a normal DNS search to obtain the information. If the long\255address corresponding to that) W
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65.0 0 32 (name is not available, then the updated DNS server will return the resource record type contain\255) W
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62.4 0 32 (ing the normal 32\255bit IP address \(if available\). This allows more efficient operation between up\255) W
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(dated hosts and old hosts in an environment in which the DNS servers have been updated.) h
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29.7 0 32 (Interactions between DNS servers can be done over either IP or CLNP, in a manner analogous to) W
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17.2 0 32 (interactions between hosts. DNS servers currently maintain entries in their databases which allow) W
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79.6 0 32 (them to find IP addresses of other DNS servers. These can be updated to include a combination) W
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90.1 0 32 (of IP addresses and NSAP addresses of other servers. If an NSAP address is available, then the) W
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222.7 0 32 (communication with the other DNS server can use CLNP, otherwise the interaction between) W
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84.5 0 32 (DNS servers uses IP. Initially, it is likely that all communication between DNS servers will use) W
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22.7 0 32 (IP \(as at present\). During the migration process, the DNS servers can be updated to communicate) W
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(with each other using CLNP.) h
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(RFC 1347) h
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(June 1992) h
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(Other Technical Details) h
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(6.1 ) h
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(When 32\255Bit IP Addresses Fail) h
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138.8 0 32 (Eventually, the IP address space will become inadequate for global routing and addressing. At) W
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58.4 0 32 (this point, the remaining older \(not yet updated\) IP hosts will not be able to interoperate directly) W
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21.3 0 32 (over the global Internet. This time can be postponed by careful allocation of IP addresses and use) W
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66.2 0 32 (of "Classless Inter\255Domain Routing" \(CIDR [3]\), and if necessary by encapsulation \(either of IP) W
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155.6 0 32 (in IP, or IP in CLNP\). In addition, the number of hosts affected by this can be minimized by     ) W
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(aggressive deployment of updated software based on TUBA.) h
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5.4 0 32 (When the IP address space becomes inadequate for global routing and addressing, for purposes of) W
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18.1 0 32 (IP addressing the Internet will need to be split into "IP address domains". 32\255bit IP addresses will) W
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108.3 0 32 (be meaningful only within an address domain, allowing the old IP hosts to continue to be used) W
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74.0 0 32 (locally. For communications between domains, there are two possibilities: \(i\) The user at an old) W
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76.8 0 32 (system can use application layer relays \(such as mail relays for 822 mail, or by Telnetting to an) W
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125.6 0 32 (updated system in order to allow Telnet or FTP to a remote system in another domain\); or \(ii\)) W
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(Network Address Translation can be used [4].) h
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(6.2 ) h
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(Applications which use IP Addresses Internally) h
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85.8 0 32 (There are some application protocols \(such as FTP and NFS\) which pass around and use IP ad\255) W
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0.6 0 32 (dresses internally. Migration to a larger address space \(whether based on CLNP or other protocol\)) W
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81.5 0 32 (will require either that these applications be limited to local use \(within an "IP address domain") W
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81.8 0 32 (in which 32\255bit IP addresses are meaningful\) or be updated to either: \(i\) Use larger network ad\255) W
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23.4 0 32 (dresses instead of 32\255bit IP addresses; or \(ii\) Use some other globally\255significant identifiers, such) W
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(as DNS names.) h
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(6.3 ) h
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(Updated Hosts in IP\255Only Environments) h
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81.6 0 32 (There may be some updated Internet hosts which are deployed in networks that do not yet have) W
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25.3 0 32 (CLNP service, or where CLNP service is available locally, but not to the global Internet. In these) W
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25.8 0 32 (cases, it will be necessary for the updated Internet hosts to know to initially send all Internet traf\255) W
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52.6 0 32 (fic \(or all non\255local traffic\) using IP, even when the remote system also has been updated. There) W
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150.4 0 32 (are several ways that this can be accomplished, such as: \(i\) The host could contains a manual) W
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109.9 0 32 (configuration parameter controlling whether to always use IP, or to use IP or CLNP depending) W
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81.1 0 32 (upon remote address; \(ii\) The DNS resolver on the host could be "lied to" to believe that all re\255) W
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100.5 0 32 (mote requests are supposed to go to some particular server, and that server could intervene and) W
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(change all remote requests for long\255addresses into requests for normal IP addresses.) h
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(Local Network Address Translation) h
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12.4 0 32 (Network Address Translation \(NAT [4]\) has been proposed as a means to allow global communi\255) W
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83.8 0 32 (cation between hosts which use locally\255significant IP addresses. NAT requires that IP addresses) W
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64.6 0 32 (be mapped at address domain boundaries, either to globally significant addresses, or to local ad\255) W
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75.3 0 32 (dresses meaningful in the next address domain along the packet's path. It is possible to define a) W
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5.7 0 32 (version of NAT which is "local" to an addressing domain, in the sense that \(locally significant\) IP) W
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105.1 0 32 (packets are mapped to globally significant CLNP packets before exiting a domain, in a manner) W
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(which is transparent to systems outside of the domain.) h
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(TUBA: A Proposal for Addressing and Routing            ) h
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(June 1992) h
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20.1 0 32 (NAT allows old systems to continue to be used globally without application gateways, at the cost) W
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103.6 0 32 (of significant additional complexity and possibly performance costs \(associated with translation) W
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24.3 0 32 (or encapsulation of network packets at IP address domain boundaries\). NAT does not address the) W
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(problem of applications which pass around and use IP addresses internally. ) h
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(The details of Network Address Translation is outside of the scope of this document. ) h
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(Streamlining Operation of CLNP) h
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138.6 0 32 (CLNP contains a number of optional and/or variable length fields. For example, CLNP allows) W
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67.9 0 32 (addresses to be any integral number of bytes up to 20 bytes in length. It is proposed to "profile") W
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69.1 0 32 (CLNP in order to allow streamlining of router operation. For example, this might involve speci\255) W
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107.9 0 32 (fying that all Internet hosts will use an NSAP address of precisely 20 bytes in length, and may) W
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171.1 0 32 (specify which optional fields \(if any\) will be present in all CLNP packets. This can allow all) W
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41.9 0 32 (CLNP packets transmitted by Internet hosts to use a constant header format, in order to speed up) W
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(header parsing in routers. The details of the Internet CLNP profile is for further study.) h
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(References) h
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([1]    "The IAB Routing and Addressing Task Force: Summary Report", work in progress.) h
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([2) h
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(]     ) h
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("Protocol for Providing the Connectionless\255Mode Network Service", ISO 8473, 1988.) h
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( ) h
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([3]    "Supernetting: An Address Assignment and Aggregation Strategy", V.Fuller, T.Li, J.Yu, ) h
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651.0 0 32 ( ) W
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(         and K.Varadhan,  March 1992.) h
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([4]    "Extending the IP Internet Through Address Reuse", Paul Tsuchiya, December 1991.) h
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(Security Considerations) h
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(Security issues are not discussed in this memo.) h
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(Author's Address) h
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(Ross Callon) h
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(Digital Equipment Corporation) h
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(550 King Street, LKG 1\2552/A19) h
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(Littleton, MA  01460\2551289) h
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(Phone: 508\255486\2555009) h
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(Email: [e-mail]) h
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