Internet DRAFT - draft-bharatia-mobileip-v6-dns-ext
draft-bharatia-mobileip-v6-dns-ext
Mobile IP Working Group Jayshree Bharatia
Internet Draft Kuntal Chowdhury
Category: Standards Track Nortel Networks
Expires on September 2002
<draft-bharatia-mobileip-v6-dns-ext-00.txt> March 2002
Mobile IPv6 Extension: Using DNS Servers Assigned by Home Agent
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 other groups may also distribute
working documents as Internet-Drafts.
Internet-Drafts are draft documents valid for a maximum of six
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The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt
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Abstract
This draft provides an extension to Mobile IPv6 protocol where the
Mobile Node (MN) obtains an information regarding DNS Servers from a
home agent. This is achieved by defining a new extension of a
Binding Acknowledgement message.
1 Introduction
Currently, There is no explicit mechanism defined in [MIPv6] for
assigning primary and secondary DNS servers in the IP network. In
any case, the MN has to obtain information of the DNS Servers. This
information can be passed to the MN by the IP network or it can be
obtained by some other means like the use of DHCP etc.
This draft basically considers a scenario where Mobile Node obtains
DNS addresses from the IP network. In this proposal, both primary
and secondary DNS servers are assigned by the Home Agent (HA) and
their information is passed to the MN after successful Mobile IPv6
Binding Update procedure. This proposed solution is more generic and
does not rely on the use of any specific link layer. Note that the
scope of this document is to emphasize on the mechanism by which the
Bharatia,Chowdhury Expires September 2002 1
information regarding DNS server addresses are relayed to MN. It
does not include discussion of how DNS server addresses are obtained
by the HA.
1.1 Glossary of Terms
FA Foreign Agent
HA Home Agent
MN Mobile Node
DNS Domain Name Server
2 Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in
this document are to be interpreted as described in RFC-2119.
3 Detailed Description of the Proposed Solution
This draft provides a mechanism to convey DNS addresses from the HA
to the MN. This information is passed to the MN during successful
Mobile IPv6 Binding Update procedure.
The message flow of the solution is shown in figure 1. Upon
successful Mobile IPv6 Binding Update, the HA appends IP addresses
of DNS servers in the Binding Acknowledgement message with new
Mobile IP extension (defined in section 4). The MN receives this
extension and sets the corresponding fields in the DNS lookup
accordingly.
MN HA
-- --
1. <----Router Advertisement-----
2. -----Binding Update---------->
3. <--Binding Acknowledgement----
(w/ Sub-Options for DNS)
Figure 1-Exchanges of DNS Servers Information
Figure 1 shows message exchanges between different Mobile IP
entities.
Step 1: As per procedure mentioned in [MIPv6], the Router
Advertisement is sent to the MN.
Step 2: The MN sends a Binding Update message to the HA. It is
recommended that the MN should set `A' bit in the Binding
Update message requesting the Binding Acknowledgement from
the HA.
Step 3: The HA appends Mobile IP Sub-Options (discussed in section
4) for primary and secondary DNS servers. When MN receives
this new Mobile IP Sub-Options, it sets the DNS lookup
accordingly.
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4 DNS Extension
The Mobile IP Sub-Optionsfor primary and secondary DNS servers shall
have the following format
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | DNS-Address_primary |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DNS-Address_primary (cont) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DNS-Address_primary (cont) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DNS-Address_primary (cont) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DNS-Address_primary (cont) | DNS-Address_secondary |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DNS-Address_secondary (cont) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DNS-Address_secondary (cont) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DNS-Address_secondary (cont) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DNS-Address_secondary (cont) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type
DNS-IPV6-EXT-TYPE=TBD. This Sub-Options value will be assigned
by IANA from the numbering space defined for Mobile IPv6
Binding Acknowledgement Sub-Options in [MIPv6]
Length
34
DNS-Address_primary
The DNS-Address_primary (16 octets) is the address of primary
DNS server to be used by the MN.
DNS-Address_secondary
The DNS-Address_secondary (16 octets) is the address of
secondary DNS server to be used by the MN.
5 IANA Considerations
This draft defines a new Mobile IPv6 Sub-Options of type DNS-IPV6-
EXT-TYPE as defined in section 4 of this document. The value will
be defined by IANA from the numbering space defined for Binding
Acknowledgement Sub-Options in [MIPv6].
6 Security Considerations
There are no additional security aspects imposed in this document in
addition to the one defined in [MIPv6].
7 References
[MIPv6] "Mobility Support in IPv6", draft-ietf-mobileip-ipv6-
15.txt, Work in progress, July 2001
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8 Acknowledgments
Authors like to thank Pete Wenzel, Tom Hussey and Glenn Morrow for
their valuable input to this work
9 Author's Address
Jayshree Bharatia
Nortel Networks
2221, Lakeside Blvd,
Richardson, TX-75082
Phone : 972-684-5767
jayshree@nortelnetworks.com
Kuntal Chowdhury
Nortel Networks
2221, Lakeside Blvd,
Richardson, TX-75082
Phone : 972-685-7788
chowdury@nortelnetworks.com
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