Internet Engineering Task Force L. Song
Internet-Draft Beijing Internet Institute
Intended status: Standards Track W. Liao
Expires: April 25, 2019 Tencent
October 22, 2018
Client Dualstack Subnets in DNS Queries
draft-song-dnsop-dualstack-ecs-00
Abstract
During the period of IPv6 transition, IP-based Geolocation (GeoIP)
applications are identified as a challenge and speed bump for ICPs
(Internet Content Providers) to migrating their service to IPv6.
Some studies and operational experiences show that the accuracy of
IPv6 GeoIP is relatively poor in comparison to their IPv4
counterparts. This memo proposed to include client's dualstack
subnets into DNS queries to provide better IPv6 GeoIP.
REMOVE BEFORE PUBLICATION: The source of the document with test
script is currently placed at GitHub [Dualstack-ECS-GitHub].
Comments and pull request are welcome.
Status of This Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. GeoIP and its Challenge in IPv6 . . . . . . . . . . . . . . . 3
3. Methodology and targeted Senarios . . . . . . . . . . . . . . 4
4. Dual-stack EDNS Client Subnet . . . . . . . . . . . . . . . . 5
5. Security Considerations . . . . . . . . . . . . . . . . . . . 5
6. IANA considerations . . . . . . . . . . . . . . . . . . . . . 5
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 5
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction
During the period of IPv6 transition, IP-based Geolocation (GeoIP)
applications are identified as a challenge and speed bump for ICPs
(Internet Content Providers) to migrating their service to IPv6. The
key issue on GeoIP is the accuracy which however vary between IPv4
and IPv6. Some studies and operational experiences [ipv6geo] show
that the accuracy of IPv6 GeoIP is relatively poor in comparison to
their IPv4 counterparts.
One typical example of GeoIP application in DNS field is that many
authoritative nameservers today return different and tailored
responses based on the perceived topological location of the users.
If IPv6 GeoIP is not precise enough, the performance of topology-
sensitive authoritative nameserver is poorer in IPv6 than IPv4.
Users' experience is impacted , and it may end up with hesitation for
the authoritative DNS operator to update its DNS to Dual Stack. It
is a problem.
To provide a better IPv6 tailored DNS response in dual-stack
environment, this memo proposes to enable recursive server and Client
to include their IPv4 and IPv6 subnets into ECS Option [RFC7871] in
DNS queries. Authoritative nameservers can make a better use of this
dual-stack subnet information for a tailored response.
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2. GeoIP and its Challenge in IPv6
Knowing where your customer access your Internet service is very
important in modern Internet. It can be used for geolocation-aware
application to achieve service efficiency such as Ads pushing and
service recommendation. It is useful for Global Server Load Balance
(GSLB) such as DNS-based Content Distribution to achieve better
network utilization and users experience. It is also vital for
security policy and service access control usually referred as to
Geoblocking.
One important geolocation used in Internet is IP-based Geolocation
(GeoIP) which is usually collected and maintained by RIRs and ISPs
when IP address block are registered, deployed and even traded.
Generally there are mainly two categories of GeoIP: location of
physical geography and location of network topology (or ISP network
information). The former usually includes the country, region, city
ZIP code, longitude and latitude of a particular IP. The later is
mainly network information attached to a IP address like ISP
registration information and AS number. Usually they are combined to
generate a appropriate result for location-based application. For
example, only knowing the ISP information of a IP address is not
enough. GSLB application may have many servers located in the same
ISP network but in different physical location. Precise physical
location like city or street is of great help for this case.
The network information of IP address is accurate and deterministic
which can be easily learnt from Whois database, route reviews and
CIDR reports. However, the accuracy of physical location vary
between IPv4 and IPv6 based on our experience. Since IPv4 has been
used for many years, IPv4 GeoIP is relatively more accurate
especially in the aspect of accuracy of physical geography location.
In contrast IPv6 is newly deployed. The network information of a new
IPv6 block may not be well documented or updated. Some evidence and
study shows [ipv6geo] that the accuracy of IPv6 GeoIP is relatively
poor in comparison to their IPv4 counterparts.
In addition, the huge space of IPv6 address, as the major merit of
IPv6, however makes it impossible to gain precise location of each IP
block by tracing them (tracert on each IP subnet). This approach is
very common and efficient in IPv4 network for GSLB of large Internet
company.
To the best knowledge of the authors, no evidence shows the available
open GeoIP service providers take advantage of connection between
IPv6 and IPv4 GeoIP , or try something like translating IPv6 GeoIP
lookup to IPv4 GeoIP queries. Some GeoIP providers (like Maxmind)
only go with IPv6 addresses that contain an embedded IPv4 address.
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It is most likely that the Regional Whois Registry, online lookup
services(like IP2Location.com) and off-line database (MaxMind GeoIP2)
build separate systems between IPv4 and IPv6 without any reference or
mapping.
3. Methodology and targeted Senarios
It is a intuition that if IPv6 GeoIP is not as good as IPv4 GeoIP
especially in terms of accuracy of physical location, why not take
the physical location of client's IPv4 subnet into consideration for
the client's IPv6 GeoIP purpose?
There are two valid assumptions for this approach. One is that the
lack of accurate physical location of IPv6 address is the main cause
for poor IPv6 GeoIP. The second assumption is that the dual-stack
host assigned with both IPv6 and IPv4 addresses has only one physical
location which should be tied to its IPv4 and IPv6 GeoIP. Since IPv4
GeoIP database is relatively stable and more accurate, it is wise to
map IPv6 and IPv4 subnet, and take IPv4 subnet as a certain key to
search the IPv4 GeoIP database (especially for physical location) to
deliver a better result as one optional result of IPv6 GeoIP
information.
To take advantage of IPv4 GeoIP for IPv6 GeoIP purposed, the basic
approach is to make IPv4 subnet visible for IPv6 geolocation-based
applications. Existing practice shows that a topology-sensitive
authoritative nameservers may receive a AAAA query from IPv4
transport, or receive a AAAA query with a ECS option FAMILAY=1. It
can utilize the perceived IPv4 subnet to response a appropriate AAAA
record according to client's geolocation information based on IPv4
GeoIP database. However, when authoritative server received a AAAA
query from IPv6 transport or a AAAA query with ECS option FAMILAY=2,
it can only rely on less accurate IPv6 GeoIP available.
Multihoming is a issue for client using dual-stack ECS, because IPv4
and IPv6 addresses of a client or a site may be assigned by different
upstream ISPs. However the physical location of IPv4 still
informative and useful to enhance the accuracy of IPv6 GeoIP. For
example, Client lived in city_1 (or street_1) may have two upstream
ISP, ISP_1 for IPv6 network and ISP_2 for IPv4 network. The
authoritative server can generate tailored AAAA response according to
the location of ISP1 and city_1 (or street_1) which are retrieved
from both IPv4 and IPv6 GeoIP database.
Different from ECS mainly applied on public DNS, the scenarios of
Dual-stack ECS are mainly on stub-resolver and ISP's resolver who are
able to include their IPv4 and IPv6 subnet into DNS queries.
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4. Dual-stack EDNS Client Subnet
Note that Dual-stack ECS is to be define, extend existing ECS or
defined a new one. More effort should also be put on the behavior of
authoritative server if the community think dual-stack ECS is a good
idea.
5. Security Considerations
TBD
6. IANA considerations
No IANA considerations for this memo
7. Acknowledgments
8. References
[Dualstack-ECS-GitHub]
BII, "GitHub Repository of Dual-stack ECS",
<https://github.com/songlinjian/dualstack-ECS>.
[ipv6geo] "Comparing the Accuracy of IPv4 and IPv6 Geolocation
Databases", January 2016, <https://pdfs.semanticscholar.or
g/0705/1014673302f97a762e74b795b70efdd74a1c.pdf>.
[RFC7871] Contavalli, C., van der Gaast, W., Lawrence, D., and W.
Kumari, "Client Subnet in DNS Queries", RFC 7871,
DOI 10.17487/RFC7871, May 2016,
<https://www.rfc-editor.org/info/rfc7871>.
Authors' Addresses
Linjian Song
Beijing Internet Institute
2nd Floor, Building 5, No.58 Jing Hai Wu Lu, BDA
Beijing 100176
P. R. China
Email: songlinjian@gmail.com
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Weijian Liao
Tencent
9th Floor, Fiyta Building, Nanshan District
Shenzhen, Guangdong 518000
P. R. China
Email: jewforice@gmail.com
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