Internet DRAFT - draft-shyam-hipi
draft-shyam-hipi
INTERNET DRAFT S. Bandyopadhyay
draft-shyam-hipi-00.txt January 26, 2020
Intended status: Experimental
Expires: July 26, 2020
Host Identification with Provider Independent Address
draft-shyam-hipi-00.txt
Abstract
This is a protocol to identify a host with a provider independent
address. It is useful to identify a host uniquely in a multihomed
environment where each host gets associated with more than one
provider assigned addresses. By means of associating a host with a
provider independent address, customers/customer networks will be
able to retain their number even after changing their service
provider(s).
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
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Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on July 26, 2020.
Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved.
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1. Introduction
Provider independent (PI) addressing can be conceived as naming a
host with a number. It can be used by customer networks who would
like to retain their number even after changing their service
provider; also it is useful to designate a host uniquely if the
customer network is multihomed. Just like in name services, as an
address needs to be resolved corresponding to a name to initiate
communication, the same is required for PI addressing. Each globally
unique PI address will be associated to at least one global unicast
provider assigned (PA) address. For a host with single interface,
this number will be same as the number of service providers the
customer network is associated with. This protocol resolves PA
addresses associated with a PI address with the approach of DNS. Out
of the entire internet protocol addresses, it expects same size of
address space to be allocated to PI addresses as the address space
allocated for provider assigned unicast addresses. As specified in
section 3.2.1 of the architectural specification[1], it assumes
address space with prefix ``00" will be assigned for PA addresses and
address space with prefix ``01" will be assigned for PI addresses.
2. PI address resolution
This section tries to come up with a solution for PI address
resolution with the approach of DNS[2] with necessary differences.
Just like name space in DNS, entire address range with prefix 01 will
be the address space used by PI addresses. Servers that will hold the
information of mapping between PI addresses and corresponding PA
addresses will be called as PIMapServers and the programs that will
be used to resolve addresses will be called as PIMapResolvers.
In case of DNS where name is used in hierarchical format to resolve
the addresses, PI address resolution will be based on the prefix of
the PI address used for resolution. The prefix is determined based
on the architectural model used for the internet. Based on the prefix
information addresses of a list of servers can be found out that will
act as regional servers which will be used to resolve mapped PA
addresses corresponding to that PI address. A prefix will serve a
fixed address space within entire PI address space. Address space
belonging to a prefix will be distributed within customer networks of
heterogeneous sizes. Address space allocation and the mapping of
associated PA address(es) will be assigned by a regional authority.
The regional authority will be fully responsible for the operation of
regional servers in that region.
Like DNS, there are some root servers which will have some fixed
addresses, under which there are some prefixes which will act as top-
level-domains. In case of CIDR based hierarchy, these prefixes may be
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of different prefix lengths which are selected based on the
requirements. Each prefix in a top level domain can further be split
into number of prefixes with the approach of CIDR. This tree
structured hierarchy will be kept on growing till we get prefixes
associated with regional servers. Each prefix associated with a
regional server will be distributed amongst customer networks of
various sizes as well as prefixes that will again be associated with
some regional servers with the approach of CIDR. These regional
servers can be considered as equivalent to the authoritative name
servers of DNS which are associated with zones. As stated earlier,
prefixes starting with "00" will be assigned for provider assigned
addresses and prefix starting with "01" will be assigned for provider
independent addresses where as prefix starting with "1" will be
assigned for addresses of all other types.
As inherent hierarchy is involved in "Mesh structured hierarchy",
this hierarchy goes up to two levels. As usual, there will be some
root servers with fixed assigned addresses. Each root server will
have prefixes with "01.A" that will act like top level domain. Under
each top level domain, there will be entries with prefixes "01.A.B".
Within a region "A.B", every global PA address is represented as
"00.A.B.C.user-id". In order to support customer networks of
heterogeneous sizes with the approach of VLSM, the "user-id" portion
is further divided as "subnet-id.user-id". So, the effective network
prefix of a customer network in PA address space is "00.A.B.C.pa-
subnet-id". Within an "A.B", entire PI address space with prefix
"01.A.B" will be distributed within customer networks of
heterogeneous sizes. So, effective network prefix of a customer
network with PI address will be "01.A.B.pi-subnet-id". A particular
prefix "01.A.B.pi-subnet-id" will be mapped to at least one provider
assigned prefix of same prefix length. For a multihomed customer
network within "A.B" that receives services from two service
providers will have prefixes "00.A.B.C1.pa-subnet-id1" and
"00.A.B.C2.pa-subnet-id2". A PI address prefix "01.A.B.pi-subnet-id"
of same length will be mapped to both these prefixes of PA address
space. Every region "A.B" will have regional server and backup
server(s) with a maximum limit (say 4) with net addresses
"00.A.B.server1", "00.A.B.server2", "00.A.B.server3" and
"00.A.B.server4".
Each PIMapServer will have a database of records that will have
information to resolve PI addresses. In memory copy of a region will
have an array of records where each record will have the following
format:
+------------+---------+------+-----+-------+-----------+
| NetAddress | NetMask | Type | TTL | NAddr | Addr(1-4) |
+------------+---------+------+-----+-------+-----------+
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First two fields "NetAddress/NetMask" represents the PI address range
of a network. "Type" will be either Domain/Referral/Individual/
SingleEntry/Default based on which a query and rest of the fields of
a record have to be processed. A PI address can have maximum four
mapped PA addresses. "Addr1", "Addr2", "Addr3", "Addr4" will hold the
corresponding PA addresses and "NAddr" will hold the number of such
addresses. The field "TTL" is a 32 bit integer measured in seconds
which will hold same meaning and approach as defined in the
specification of DNS[2]. When a server receives a query for an
address "X", it extracts the record of the network based on
"NetAddress/NetMask" and "X" from its database. If no matching record
is found, a negative response is sent. Based on the "Type" of the
record, the query is processed in the following manner.
Type=Domain:
This is the most common type. If a customer network would not like to
maintain a map server opts for this option. In this case there will
be one to one mapping between a PI address and corresponding PA
addresses. The fields "Addr1"/"Addr2"/"Addr3"/"Addr4" will hold the
PA Net Addresses corresponding to the PI address of the network.
Server will send the matching record to the resolver with
Type=Domain. Resolver will extract the user-id portion of "X" and
find the corresponding mapped PA addresses based on
"Addr1"/"Addr2"/...etc.
Theoretically, "A.B" portion of a PI address need not match with the
"A.B" portion of the corresponding PA addresses. Consider a large
corporate that has its corporate office and a branch office within
the same region of a particular "A.B" and some other offices with
different values of "A.B". The corporate can maintain a contiguous
range of PI addresses for the ease of its operation. It needs to
split entire PI address range based on its offices and assign the
corresponding PA addresses. In order to minimize the path of a query
it is desirable that "A.B" of a PI address and its corresponding
mapped PA addresses belong to the same region.
Type=Referral:
This is used when an address within the domain "NetAddress"/"NetMask"
has to be processed by another map server. The map server may itself
be another regional server or a server within a customer network.
When a customer network would like to have a direct control for the
mapping of its addresses it needs to opt for this option.
"Addr1"/"Addr2"/"Addr3"/"Addr4" of the database entry will hold the
pointer to the information associated to each map server. "NAddr"
will hold the number of map servers that can be referred. Information
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of each server will hold the following values: PI address of the map
server + Number of PA addresses to reach the map server + PA
addresses of the map server. Any one of these map servers need to be
queried for further processing. A server may act either in recursive
mode or in iterative mode based on its implementation just like in
DNS. A large corporate may have different offices and each (or some
of them) may maintain a map server based on their policies.
When a server needs to handle a particular address separately, it
needs to set "NetAddress" with that particular address and all the
bits of "NetMask" will be set to "1". The "Type" field has to be set
as "SingleEntry"(which is similar to the Type Address(A) in terms of
DNS). If some of its addresses need to be handled separately but for
the rest common rule may apply (like Type=Domain), records of the
individual entries should be processed first and then for the rest.
In these cases "Type" has to be set as "Default". So, a server of a
customer network may have database entries with Type=Domain/Referral
/SingleEntry/Default. It makes sense for a server (or a master file)
to have entries with Type=Default, but from the point of a resolver,
it does not make any sense. So a server needs to extract the PA
addresses and form a record with Type=SingleEntry and send it back to
the resolver.
For a host having multiple interfaces, each interface may be assigned
PA addresses supplied by all the service providers, but it is
desirable that PI address gets mapped to only one of them (preferably
for a CE router, the interface which will have the shortest path will
be mapped PI address with the PA address associated with that CE
router).
Type=Individual:
This is meant for the individual users opting for services like
telephonic services that need to maintain PI address. With this
option a mobile user may maintain its PI address after changing its
service provider. A map server needs to maintain some networks with a
range of PI addresses in its database. When a query for an address
"X" is received, server needs to get the corresponding record where
"Addr1" will hold the pointer to a open file descriptor (or pointer
to the in memory copy) of a separate data file where there will be
one to one mapping between PI address and its corresponding PA
address of all the assigned PI addresses. These networks and
assignment of individual PI addresses have to be done by the regional
authority.
As with Type=Default, Type=Individual does not make any sense to a
resolver. So, server needs to extract PA address and form a record
with Type=SingleEntry and send it back to the resolver.
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As stated above, this solution is based on the approach of DNS. For
the ease of implementation and to make use of the existing source
code related to DNS (e.g. BIND) most of the features have been taken
from DNS. DNS supports multiple entry output, but they appear in a
sequential manner. In order to make processing easier, they are
arranged in a structured manner in this document.
IANA has assigned a port <IANA_TBD1> for its UDP/TCP based
implementation.
2.1. Record Format
Each record (the way they will appear in a master file or will be
used for communication) will have the following format:
NetAddress/NetMask + Type (8 bit unsigned int) + <TTL> + RDATA (Type
specific information)
Record types are primarily the types of records as described above
along with three other types: SOA (Start of a zone of authority), MPS
(host with Type=SingleEntry that acts as a Map server for this zone)
and DFL (Data File). These types are mainly useful in the context of
processing AXFR/IXFR/NOTIFY/DFAXFR/DFIXFR messages.
Types are defined as follows:
Types values comments
-----------------------------------------------------------
SEN (SingleEntry) 1 same as type A(address) in DNS
MPS (MapServer) 2 Map server
DMN (Domain) 3
DEF (Default) 4
REF (Referral) 5
SOA (Start of a zone) 6
IND (Individual) 7
DFL (Data File) 8
-----------------------------------------------------------
RDATA of different types will appear as follows:
Type=SOA:
PI address of server+SERIAL+REFRESH+RETRY+EXPIRE+MINIMUM (meaning and
values of SERIAL/REFRESH/RETRY/EXPIRE/MINIMUM are same as they were
defined in section 3.3.13 of RFC 1035[3])
Type=(SEN/MPS):
NAddr(Number of addresses) + corresponding PA addresses
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Type=(DMN/DEF):
NAddr(Number of addresses) + corresponding Net addresses
Type=REF:
NAddr(Number of map server) + for each map server (PI address of map
server + NAddr(Number of addresses of map server) + corresponding PA
addresses))
Type=IND:
NAddr(=1) + full path name of the data file
Type=DFL:
Data file name + SERIAL + Number of records in the data file(32 bit
unsigned int)
While used in communication data file name is used as its length (8
bit unsigned int) followed by the octets of the string.
TTL value of a record has to be set to 0 if it is not relevant or to
accept the value associated with the record of SOA.
2.2. Messages
In order to support most of the features of DNS, message format has
been retained almost same as that of DNS. So, all the relevant fields
will be processed exactly in the same manner as that have been done
in DNS and all the irrelevant issues have to be ignored. Rest of this
section describes where and how changes have to be made.
As defined in RFC 1035, the top level format of message is divided
into 5 sections (some of which are empty in certain cases) shown
below:
+---------------------+
| Header |
+---------------------+
| Question | the question for the name server
+---------------------+
| Answer | answering part of the question
+---------------------+
| Authority | authoritative map server
+---------------------+
| Additional | additional information
+---------------------+
The header section has been retained as defined in RFC 5395[4] as
follows:
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0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| ID |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
|QR| OpCode |AA|TC|RD|RA| Z|AD|CD| RCODE |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| QDCOUNT/ZOCOUNT |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| ANCOUNT/PRCOUNT |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| NSCOUNT/UPCOUNT |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| ARCOUNT |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
The question section will have two parts:
QType(one octet unsigned int)+QData.
Query types are defined as follows:
QTypes values comments
-----------------------------------------------------------
SEN 1 query for mapped PA address
SOA 6 query information related to SOA
DFL 8 query information related to data file
DFXFR 249 data file transfer
DFIXFR 250 incremental data file transfer
IXFR 251 incremental authoritative data file xfr
AXFR 252 authoritative data file transfer
-----------------------------------------------------------
QData will hold values based on QType.
Following section describes issues related to QType=SEN. Issues
related to all other QTypes (i.e. related to file transfer) will be
discussed afterwords.
For QType=SEN(1): QData=PI address that needs to be resolved.
The answer section, authority section and additional section will
have a number of resource records where the number will be specified
in the header.
On receiving a query, map server will return the matching record from
its database. If response is address, the answer section will hold
the record of any one of these two types: SEN/DMN.
If Type=DMN, resolver needs to extract the mapped addresses as
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described in section 2.
If Type=DMN, entire address range will appear in the form of
NetAddress/NetMask. This will have advantages while catching data for
any particular address, but getting the information of the entire
address range.
If the response is referral, answer section will be empty and the
authoritative section will hold the record with Type=REF.
If server supports recursion, for each iterative process that it
receives a record with Type=REF, it needs to push the record to the
additional section of the message that needs to be sent to the
resolver. So, additional section will hold the records of Type=REF of
the chain of the tree through which PA addresses have been resolved.
2.3. Master file and data file
Section 5 of RFC 1035 states:
"Master files are text files that contain RRs in text form. Since
the contents of a zone can be expressed in the form of a list of RRs
a master file is most often used to define a zone, though it can be
used to list a cache's contents."
Section 5.1 of RFC 1035 states:
"The format of these files is a sequence of entries. Entries are
predominantly line-oriented, though parentheses can be used to
continue a list of items across a line boundary, and text literals
can contain CRLF within the text. Any combination of tabs and spaces
act as a delimiter between the separate items that make up an entry.
The end of any line in the master file can end with a comment. The
comment starts with a ";" (semicolon)."
Master files follow the same approach and format in the line of DNS
as described in section 5 of RFC 1035 with necessary differences.
An example master file may look like as follows:
@ "PI NetAddr"/"Net Mask" SOA "PI address of primary server" (
20 ; SERIAL
7200 ; REFRESH
600 ; RETRY
3600000; EXPIRE
60) ; MINIMUM
"PI NetAddr"/"Net Mask" MPS 0 NAddr "PA addresses"
"PI NetAddr"/"Net Mask" SEN 0 NAddr "PA addresses"
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"PI NetAddr"/"Net Mask" DMN 0 NAddr "Net addresses"
"PI NetAddr"/"Net Mask" DEF 0 NAddr "Net addresses"
"PI NetAddr"/"Net Mask" IND 0 NAddr(=1) "Data file name"
A data file contains a sequence of entries where each entry appears
in a separate line. Each entry is a mapping between a PI address and
its associated PA address separated by space(s). Entries are
generally sorted with PI address. As in case of master file comments
can be inserted with the start of a ";" (semicolon) that will end at
the end of the line. Data files are commonly associated with the map
servers maintained by regional authority, but they are not generally
associated with the map servers maintained by individual customer
networks. A data file entry may appear to be as follows:
"PI Address" NAddr "PA Addresses"
A map server may have a number of data files. These files have to be
defined in another file (a supporting file, the way boot file
"named.boot" is used in BIND) that will have information of each of
them. An entry in that file will follow the same format of a record
(Type=DFL) and will have the following fields:
"PI NetAddr"/"NetMask" Type(DFL) TTL "Data File Name" SERIAL "Number
of records".
This file will be used to process message with QType=DFL which will
be used to support data file transfer/incremental data file transfer.
For QType=DFL(8): QData="PI NetAddr"/"NetMask" of the desired network
For QType=SOA(6): QData="PI NetAddr"/"NetMask" of the desired zone
A map server will return a record of Type=DFL on receiving a query
with QType=DFL where as it will return a record of Type=SOA on
receiving a query with QType=SOA.
2.4. Zone maintenance and transfers
Section 4.3.5 of RFC 1034 states:
"The general model of automatic zone transfer or refreshing is that
one of the name servers is the master or primary for the zone.
Changes are coordinated at the primary, typically by editing a master
file for the zone. After editing, the administrator signals the
master server to load the new zone. The other non-master or
secondary servers for the zone periodically check for changes (at a
selectable interval) and obtain new zone copies when changes have
been made.
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To detect changes, secondaries just check the SERIAL field of the SOA
for the zone. In addition to whatever other changes are made, the
SERIAL field in the SOA of the zone is always advanced whenever any
change is made to the zone."
Section 1.2 of RFC 5936 states:
"A DNS implementation is not required to support AXFR, IXFR, and
NOTIFY, but it should have some means for maintaining name server
coherency. A general-purpose DNS implementation will likely support
AXFR (and in the same vein IXFR and NOTIFY), but turnkey DNS
implementations may exist without AXFR."
Zone maintenance and transfer will follow the same approach as DNS
with few minor updates. Frequency of update of data files will be
high compared to the frequency of update of master file. That is why
transfer(/incremental transfer) of data file has been treated
separately from the transfer(/incremental transfer) of master file.
For all the messages of QType=AXFR/DFXFR/IXFR/DFIXFR, QData="PI
NetAddr"/"NetMask" of the desired zone or the desired network. NOTIFY
message needs to include which file has been updated followed by the
related information. So, if master file has been changed, NOTIFY
message with query type SOA will be sent and query type DFL will be
sent if a data file has been changed.
Transfer of master file will be same as transfer of master file in
DNS followed by transfer of all the data files. i.e. processing of
AXFR will have the same approach as DNS followed by DFXFR for all the
data files. In order to make this happen, at the end of transferring
the contents of the master file, server (of AXFR message) needs to
send NOTIFY message for all of the data files belonging to that zone
to the client(i.e. the secondary server). Processing of NOTIFY of a
data file by the secondary server needs to send DFIXFR to the primary
if data file already exist; otherwise it needs to send DFXFR.
Incremental update of master file (IXFR) will be same as IXFR in DNS
with a minor update. If client of IXFR finds a new data file gets
introduced, it calls DFXFR corresponding to that data file. Similarly
if an entry of a data file gets deleted, client deletes corresponding
data file.
Processing of DFXFR will have same approach of AXFR in DNS.
Similarly processing of DFIXFR will have same approach as IXFR in
DNS. While transferring a data file record, an equivalent record of
type SEN needs to be sent with the values of PI address and mapped PA
address(es) from the record of data file. Where ever a record of type
SOA is sent while processing AXFR/IXFR in case of DNS, record of type
DFL needs to be sent while processing DFXFR/DFIXFR.
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For AXFR, IXFR and NOTIFY in DNS, one needs to follow RFC 5936[5],
RFC 1995[6] and RFC 1996[7] respectively.
3. IANA Consideration
IANA has assigned a port number <IANA_TBD1> and service name
<IANA_TBD2> for PI address resolution for both TCP and UDP.
4. Security Consideration
This document does not include any security related issues.
5. Normative References
[1] S. Bandyopadhyay, "An Architectural Framework of the Internet
for the Real IP World" <draft-shyam-real-ip-framework-61.txt>
(work in progress).
[2] P.V. Mockapetris., "Domain names - concepts and facilities",
RFC 1034, November 1987.
[3] P.V. Mockapetris, "Domain names - implementation and
specification", RFC 1035, November 1987.
[4] D. Eastlake 3rd, "Domain Name System (DNS) IANA
Considerations", RFC 5395, November 2008.
[5] E. Lewis, A. Hoenes, Ed., "DNS Zone Transfer Protocol (AXFR)",
RFC 5936, June 2010.
[6] M. Ohta, "Incremental Zone Transfer in DNS", RFC 1995,
August 1996.
[7] P. Vixie, "A Mechanism for Prompt Notification of Zone Changes
(DNS NOTIFY)", RFC 1996, August 1996.
6. Author's Address
Shyamaprasad Bandyopadhyay
HL No 205/157/7, Kharagpur 721305, India
Phone: +91 3222 225137
e-mail: shyamb66@gmail.com
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