INTERNET DRAFT                                                   M. Ohta
draft-ietf-dnsop-shared-root-server-01.txt Tokyo Institute of Technology
                                                               June 1999

      Distributing Root Name Servers via Shared Unicast Addresses

Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
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Abstract

   This memo describes an operational guideline for root name servers to
   share unicast addresses.

. Motivation

   For the stability of the Internet, it is critical that there are
   sufficiently many DNS root servers operating at various places of the
   Internet.

   For the stability of the domestic Internet, it is critical for each
   country that there are sufficiently many DNS root servers operating
   at various places of the Internet in the country.

   However, the number of unicast IP addresses of root servers is
   limited.  Thus, for the internationally fair operation of DNS, the
   number of root servers in each country (including US) must be equal
   to the number of unicast IP addresses of root servers divided by the

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   number of countries (some weight may be given according to the number
   of Internet hosts in each country).

   Given the current number of countries and IP addresses of root
   servers, each country (again, including US) will be able to have 1/20
   root servers, which definitely is not sufficiently many.

   Thus, it is necessary to somehow increase the number of root servers.
   This memo proposes administrative scoping of the routing ranges of
   unicast addresses of root servers.

   With administratively scoped unicast addresses, any entity, including
   a country, can use the addresses for its local root servers and set
   the scope of the routing ranges of the addresses appropriately.

   Note that operations similar to that described in this memo are
   possible today locally without global coordination by any operator
   who may be irritated by the lack of his control on (sufficiently
   many) root servers, which may be a source of some operational
   problems. This memo is an attempt to document the way to solve the
   problem in a least harmful manner.

   Similar operation described in this memo may be applicable to gTLD
   servers but it is outside the scope of this memo.

. Suggested Operation

   As is demonstrated by the proliferated private use addresses, it is
   easy to set up routers to let unicast addresses have local scopes. It
   is also easy to let the unicast addresses have nested local scopes.
   The important difference between the addresses for privae use and
   root servers is in their semantics that the root servers sharing an
   address share the globally unique semantics of the address. The root
   servers may share a globally unique DNS host name, too.

   A possible problem of such addresses is that the shared addresses can
   not be used for global communication. So, it is suggested that the
   root name servers with the administratively scoped shared unicast
   addresses have additional globally unique unicast addresses, which
   may be used for global communication such as zone transfer.

   The other possible problem of such addresses is that the shared
   addresses are not managed by a single entity that the mapping from
   the shared address of a root server to some operational entity is
   impossible. However, if the routers near the root server has a global
   addresses, it is possible to map from the global address to an
   operational entity, which is expected to be operating the root
   server.  That is, tools like traceroute works to find the operational

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   entity of the root servers.

   To be compatible with the current practice that a single address
   belong to a single AS, each administratively scoped shared unicast
   address is assigned its own AS number. There will be multiple ASes of
   the AS number containing the same address ranges.

   ASes, still, can be identified by adjacent ASes.  For example,
   network operators may choose their favorite root server based on the
   AS numbers of the next hop ASes with, for example, AS path and BGP
   policy.

   It is required that operators of an AS adjacent to the root servers'
   AS be fully responsible to the operation of the root servers.  If a
   root server's AS is adjacent to multiple ASes, operators of all the
   ASes must be fully responsible to the operation of the root server.
   Thus, if there is a routing problem related a root server, operators
   of the next hop AS(es) should be contacted.

. Assignment

   Considering that each country is likely to need a considerable number
   of root servers, it is reasonable to make most, if not all, of the IP
   addresses of the root servers administratively scoped and shared.

   Note that given the large number of root servers in the Internet, it
   is impossible that all the servers use a single server as the primary
   source of zone transfer. That is, the name and the IP address of the
   current primary server may also be shared.

   Considering the huge effort to change the file containing the IP
   addresses of the root servers all around the Internet, the IP
   addresses of the root servers should better stay same as that of
   today.  Organizations running the current root servers are requested
   to release the current class B or C address blocks containing the
   current IP addresses of the root server for the public use.

   The AS numbers assigned to root server addresses are:

      Name                 IP Address/Mask     AS Number

      A.ROOT-SERVERS.NET   198.41.0.4/8        (to be assigned by IANA)
      B.ROOT-SERVERS.NET   128.9.0.107/16      (to be assigned by IANA)
      C.ROOT-SERVERS.NET   192.33.4.12/8       (to be assigned by IANA)
      D.ROOT-SERVERS.NET   128.8.10.90/16      (to be assigned by IANA)
      E.ROOT-SERVERS.NET   192.203.230.10/8    (to be assigned by IANA)
      F.ROOT-SERVERS.NET   192.5.5.241/8       (to be assigned by IANA)
      G.ROOT-SERVERS.NET   192.112.36.4/8      (to be assigned by IANA)

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      H.ROOT-SERVERS.NET   128.63.2.53/16      (to be assigned by IANA)
      I.ROOT-SERVERS.NET   192.36.148.17/8     (to be assigned by IANA)
      J.ROOT-SERVERS.NET   198.41.0.10/24      (to be assigned by IANA)
      K.ROOT-SERVERS.NET   193.0.14.129/24     (to be assigned by IANA)
      L.ROOT-SERVERS.NET   198.32.64.12/24     (to be assigned by IANA)
      M.ROOT-SERVERS.NET   202.12.27.33/24     (to be assigned by IANA)

. Security Considerations

   This memo describes just an operational guideline with no protocol
   change. As such, the guideline does not introduce any security issues
   of the protocol level.

   As the route forgery to the root servers can be implemented today
   without this memo by anyone including local intruders, the guideline
   does not introduce any security issues of the operational level,
   either.

   A guideline to track down and verify valid or forged route or AS path
   to the root servers is described in section 2.

. Authors' Addresses

   Masataka Ohta
   Computer Center
   Tokyo Institute of Technology
   2-12-1, O-okayama, Meguro-ku
   Tokyo 152-8550, JAPAN

   Phone: +81-3-5734-3299
   Fax: +81-3-5734-3415
   EMail: mohta@necom830.hpcl.titech.ac.jp


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