DNS load balancing
draft-sonoda-dnsop-dnslb-00

Domain Name System Operations                                Sonoda, Ed.
Internet-Draft                            Internet Initiative Japan Inc.
Intended status: Informational                          January 22, 2018
Expires: July 26, 2018

                           DNS load balancing
                      draft-sonoda-dnsop-dnslb-00

Abstract

   This document defines a new DNS base load balancing function.

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1.  Introduction and Background

   This document defines a new DNS load balance function that is able to
   transfer information in zone transfer and not need online signing.

   DNS base load balance is popluer technology.  It provides weight base
   response and location base response.  It have become an indispensable
   part of traffic engineering.

   However, DNS base load balance can't transfer load balance
   information in zone transfer and need online sigining because it is
   not standardized.

   This document defines a new DNS resource record called "LB" and new
   EDNS option bit called "LS".  LB RR provides the balancing
   information wieght, location and target domain name.  LS bit provides
   the change response mechanism in name servers.

2.  Mechanism

   1.  Stub resolver sends A or AAAA query to full resolver.

   2.  Full Resolver sends A or AAAA query with LS bit to authoritative
   server.

   3.  Authoritative Server responses LB RRset.

   4.  Full Resolver selects target domaoin name using location
   information and weight information.

   5.  Full Resolver resolv target domaoin name.

   6.  Full Resolver response target domaoin name and LB RRSet to stub
   resolver.

3.  The LB Resource Record

   The LB RR has mnemonic LB.  LB RR define load balancing information.

   LB format below.

         <owner> <ttl> <class> LB <weight> <location> <target>

   The format is not class-sensitive.  All fields are required.

   <weight> field is a 2 octets, 1 or more natural number.

   <location> field is a "<character-string>" [RFC1035].

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   <target> field is a "<domain-name>" [RFC1035].  It has A or AAAA RR
   or CNAME RR or DNAME RR.

3.1.  Define location

   <location> ::= "*" | <continental code> | <country code> |
   <subdivision code> | <asn code> | <private code>

   <continental code> ::= "AF" | "AN" | "AS" | "EU" | "NA" | "OC" | "SA"

   <country code> ::= ISO 3166-1 alpha-2 Country code.

   <subdivision code> ::= ISO 3166-2 Codes for the representation of
   names of countries and their subdivisions.

   <asn code> ::= "AS" <asn> [ ":" <asn>]

   <private code> ::= "+" <let>

   <ans> ::= <nonzero digit> <digit>

   <nonzero digit> ::= any one of the ten digits 1 through 9

   <digit> ::= any one of the ten digits 0 through 9

   <let> ::= any one of the 26 alphabetic characters A through Z in
   upper case or any one of the ten digits 0 through 9.

3.2.  Record example

   ; for any region.
   example.jp. 3600 IN LB 1 * www.example.com.
   ; for AP region.
   example.jp. 3600 IN LB 1 AP ap.example.com.
   ; for JP region, weight 1.
   example.jp. 3600 IN LB 1 JP jp1.example.jp.
   ; for JP region, weight 3.
   example.jp. 3600 IN LB 3 JP jp2.example.jp.
   ; for tokyo region. (JP-13 is tokyo region ISO 3166-2:JP)
   example.jp. 3600 IN LB 1 JP-13 tokyo.example.jp.
   ; for AS2497
   example.jp. 3600 IN LB 1 AS2496 as2497.example.jp.
   ; for AS2497
   example.jp. 3600 IN LB 1 AS2496:1 as2497.example.jp.
   ; private use
   example.jp. 3600 IN LB 1 +BEER beer.example.jp.

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4.  The LB Support Flag

   Defines a new "EDNS Header Flags" [RFC6891] call LB Support Flag(LS)
   using full resolver sends LB RR supported to authoritative server.

   LS bit provides change response mechanism in authoritative name
   server.  If LS bit is flagged, Authoritative name server can response
   LB RR for A,AAAA query.

5.  Authoritative name server Behavior

   When authoritative name server receives a query of type A or AAAA
   with LS bit and LB record is present at a sname, The authoritative
   server returns the LB RRSet in the answer section with LS bit.

5.1.  Example of authoritative name server behavior

   Example zone data:

   example.jp. 3600 IN SOA ( ns1.example.com.
                             postmaster.example.com.
                             1
                             3600
                             900
                             1814400
                             900 )
   example.jp. 3600 IN NS ns1.example.com.
   example.jp. 3600 IN NS ns2.example.com.
   example.jp. 3600 IN A 198.51.100.1
   example.jp. 3600 IN LB 1 * www.example.com.
   example.jp. 3600 IN LB 1 JP jp1.example.com.
   example.jp. 3600 IN LB 3 JP jp2.example.com.

   Incomming query with LS bit:

   query: qtype = example.jp. qtype=A, LS=1

   Response for include LS:

   query: qtype = example.jp. qtype=A
   response: LS=1
     answer:
       example.jp. 3600 IN LB 1 * www.example.com.
       example.jp. 3600 IN LB 1 JP jp1.example.com.
       example.jp. 3600 IN LB 3 JP jp2.example.com.
     authority:
       example.jp. 3600 IN NS ns1.example.com.
       example.jp. 3600 IN NS ns2.example.com.

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   Incomming query without LS bit (normal query):

   query: qtype = example.jp. qtype=A, LS=0

   Response for not include LS:

   query: qtype = example.jp. qtype=A
   response:  LS=0
     answer:
           example.jp. 3600 IN A 198.51.100.1
     authority:
           example.jp. 3600 IN NS ns1.example.com.
           example.jp. 3600 IN NS ns2.example.com.

6.  Full Service Resolver Behavior

   When a full resulver sends a query of type A or AAAA with LS bit and
   recives a response with a LB RRset in the answer section with LS bit,
   Full resolver MUST re-resolv the either LB <target> of type "STYPE"
   [RFC1034].  <target> be selected by <location> and <weight>.

6.1.  Location selection

   Location selection needs full resolver or stub resolver location
   information.  Full resolver location informations with priority value
   SHOULD gets from config file.  Full resolver MUST setting '*'
   location with lowest priority.  Full resolver select location that
   match either LB RR <location> and highest priority resolver location.
   if all LB RRs don't matche all resolver locations, resolver selects a
   location randomly.

6.2.  Weight selection

   Full resolver selects <target> using <weight> from LB RR whose
   location matches.

6.3.  Example

   1.  Full resolver's location is configured "JP-13" "JP" "AS" "*".

   2.  Stub resolver query comming:

       query: qtype = example.jp. qtype=A

   3.  Full resolver send query:

       query: qtype = example.jp. qtype=A, LS=1

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   3.  If response include LB RRSets:

       query: qtype = example.jp. qtype=A
       response: LS=1
         answer:
               example.jp. 3600 IN LB 1 * www.example.com.
               example.jp. 3600 IN LB 1 JP jp1.example.com.
               example.jp. 3600 IN LB 3 JP jp2.example.com.
         authority:
               example.jp. 3600 IN NS ns1.example.com.
               example.jp. 3600 IN NS ns2.example.com.

   4. select LB RR that's location include resolver location:

               example.jp. 3600 IN LB 1 JP jp1.example.com.
               example.jp. 3600 IN LB 3 JP jp2.example.com.

   5.  Select one <target> using <weight>:

               example.jp. 3600 IN LB 3 JP jp2.example.com.

   5.  Name resolution <target>:

       query: qtype = jp2.example.com. qtype=A, LS=1
       response:
         answer:
               jp2.example.com. 3600 IN A 192.0.2.2
         authority:
               example.com. 3600 IN NS ns1.example.com.
               example.com. 3600 IN NS ns2.example.com.

   6.  Make response message:

       query: qtype = example.jp. qtype=A, LS=1
       response:
         answer:
               example.jp. 3600 IN LB 1 * www.example.com.
               example.jp. 3600 IN LB 1 JP jp1.example.com.
               example.jp. 3600 IN LB 3 JP jp2.example.com.
               jp2.example.com. 3600 IN A 192.0.2.2
         authority:
               example.jp. 3600 IN NS ns1.example.com.
               example.jp. 3600 IN NS ns2.example.com.

   7.  Stub resolver uses 192.0.2.2

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7.  IANA Considerations

   IANA is requested to assign a DNS RR data type value for the LB RR
   type under the "Resource Record (RR) TYPEs" subregistry and a EDNS
   Header Flag value for the LB Support Flag under the "EDNS Header
   Flags (16 bits)" subregistry under the "Domain Name System (DNS)
   Parameters" registry.

8.  Security Considerations

   Both authoritative server and resolvers that implement LB SHOUD
   carefully check for loops.

9.  Normative References

   [RFC1034]  Mockapetris, P., "Domain names - concepts and facilities",
              STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987,
              <https://www.rfc-editor.org/info/rfc1034>.

   [RFC1035]  Mockapetris, P., "Domain names - implementation and
              specification", STD 13, RFC 1035, DOI 10.17487/RFC1035,
              November 1987, <https://www.rfc-editor.org/info/rfc1035>.

   [RFC6891]  Damas, J., Graff, M., and P. Vixie, "Extension Mechanisms
              for DNS (EDNS(0))", STD 75, RFC 6891,
              DOI 10.17487/RFC6891, April 2013,
              <https://www.rfc-editor.org/info/rfc6891>.

Author's Address

   Manabu Sonoda (editor)
   Internet Initiative Japan Inc.

   Email: manbabu-s@iij.ad.jp

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