Mobility with ICE (MICE)
draft-wing-mmusic-ice-mobility-00
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft whose latest revision state is "Expired".
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|---|---|---|---|
| Authors | Dan Wing , Prashanth Patil , Tirumaleswar Reddy.K | ||
| Last updated | 2012-07-09 | ||
| RFC stream | (None) | ||
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| Consensus boilerplate | Unknown | ||
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draft-wing-mmusic-ice-mobility-00
MMUSIC D. Wing
Internet-Draft P. Patil
Intended status: Standards Track T. Reddy
Expires: January 10, 2013 Cisco
July 9, 2012
Mobility with ICE (MICE)
draft-wing-mmusic-ice-mobility-00
Abstract
This specification describes how endpoint mobility can be achieved
using ICE. Two mechanisms are shown, one where both endpoints
support ICE and another where only one endpoint supports ICE.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on January 10, 2013.
Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
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described in the Simplified BSD License.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Notational Conventions . . . . . . . . . . . . . . . . . . . . 3
3. Mobility using ICE . . . . . . . . . . . . . . . . . . . . . . 3
4. Mobility using TURN . . . . . . . . . . . . . . . . . . . . . . 4
4.1. Creating an Allocation . . . . . . . . . . . . . . . . . . 5
4.1.1. Sending an Allocate Request . . . . . . . . . . . . . . 5
4.1.2. Receiving an Allocate Request . . . . . . . . . . . . . 5
4.1.3. Receiving an Allocate Success Response . . . . . . . . 5
4.1.4. Receiving an Allocate Error Response . . . . . . . . . 5
4.2. Refreshing an Allocation . . . . . . . . . . . . . . . . . 6
4.2.1. Sending a Refresh Request . . . . . . . . . . . . . . . 6
4.2.2. Receiving a Refresh Request . . . . . . . . . . . . . . 6
4.2.3. Receiving a Refresh Response . . . . . . . . . . . . . 7
4.3. New STUN Attributes . . . . . . . . . . . . . . . . . . . . 7
4.3.1. MOBILITY-REQUEST . . . . . . . . . . . . . . . . . . . 7
4.3.2. MOBILITY-TICKET . . . . . . . . . . . . . . . . . . . . 7
4.4. New STUN Error Response Codes . . . . . . . . . . . . . . . 7
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
6. Security Considerations . . . . . . . . . . . . . . . . . . . . 7
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8
7.1. Normative References . . . . . . . . . . . . . . . . . . . 8
7.2. Informative References . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8
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1. Introduction
When moving between networks, an endpoint has to change its IP
address. This change breaks upper layer protocols such as TCP and
RTP. Various techniques exist to prevent this breakage, all tied to
making the endpoint's IP address static by using tunnels (Mobile IP,
Proxy Mobile IP, LISP). Other techniques exist, which make the upper
layer protocol ambivalent to IP address changes (e.g., SCTP). The
mechanisms described in this document are in that last category.
To overcome NAT and Firewall traversal issues, hosts may choose to
use the services of a TURN server that acts as a relay to exchange
packets with other hosts [RFC5766]. Relaying is also used for IPv6
privacy. Clients allocate an IP address and port on the TURN server,
called the relayed transport address, for a specific client IP
address and port. Both the client and the server remember the
5-tuple used in the Allocate request and all subsequent transactions
between the client and the server use the same 5-tuple. When an IP
address of a client changes because of movement to a new network, the
existing allocation on the TURN server cannot be re-used and the
client will have to allocate a second relayed transport address by
creating a second allocation using a different 5-tuple. This will
break connection between the client and its peer. Communication
between the client and its peer can only continue when the new
relayed transport address is signaled to the peer.
This document proposes two mechanisms to achieve RTP mobility: a
mechanism where both endpoints support ICE, and a mechanism where
only one endpoint supports ICE. When both endpoints support ICE, ICE
itself can be used to provide mobility. When only one endpoint
supports ICE, a TURN server provides mobility. Both mobility
techniques work across and between network types (e.g., between 3G
and wired Internet access), so long as the client can still access
the remote ICE peer or TURN server.
2. Notational Conventions
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 [RFC2119].
This note uses terminology defined in [RFC5245].
3. Mobility using ICE
When both endpoints support ICE, ICE itself can provide mobility.
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[[more text will be written here.]]
4. Mobility using TURN
To achieve mobility, a TURN client should be able to retain an
allocation on the TURN server across changes in the client IP address
as a consequence of movement to other networks.
When the client sends the initial Allocate request to the TURN
server, it will also include a new STUN attribute MOBILITY-REQUEST
which indicates that the client is a mobile node. The TURN server
provisions a ticket that is sent inside a new STUN attribute
MOBILITY-TICKET in the Allocate Success response to the client. The
ticket will be used by the client when it wants to refresh the
allocation but with a new client IP address and port. It also
ensures that the allocation can only be refreshed this way by the
same client. When a client's IP address changes due to mobility, it
presents the previously obtained ticket in a Refresh Request to the
TURN server. If the ticket is found to be valid, the TURN server
will retain the same relayed address/port for the new IP address/port
allowing the client to continue using previous channel bindings. Any
data from external peer will be delivered by the TURN server to this
new IP address/port of the client. The TURN client will continue to
send application data to its peers using the previously allocated
channelBind Requests.
TURN TURN Peer
client server A
|-- Allocate request --------------->| |
| + MOBILITY-REQUEST | |
| | |
|<--------------- Allocate failure --| |
| (401 Unauthorized) | |
| | |
|-- Allocate request --------------->| |
| + MOBILITY-REQUEST | |
| | |
|<---------- Allocate success resp --| |
| + MOBILITY-TICKET | |
... ... ...
(changes IP address)
| | |
|-- Refresh request ---------------->| |
| + MOBILITY-TICKET | |
| | |
|<----------- Refresh success resp --| |
| + MOBILITY-TICKET | |
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| | |
4.1. Creating an Allocation
4.1.1. Sending an Allocate Request
In addition to the process described in Section 6.1 of [RFC5766], the
client includes the MOBILITY-REQUEST attribute indicating that the
client is a mobile node.
4.1.2. Receiving an Allocate Request
In addition to the process described in Section 6.2 of [RFC5766], the
server does the following:
If the MOBILITY-REQUEST attribute is included and the TURN session
mobility is forbidden by local policy, the server MUST reject the
request with a TBD (Mobility Forbidden) error. Following the rules
specified in [RFC5389], if the server does not understand the
MOBILITY-REQUEST attribute, it generates an Allocate error response,
which includes an ERROR-CODE attribute with 420 (Unknown Attribute)
response code. This response will contain an UNKNOWN-ATTRIBUTE
attribute listing the unknown MOBILITY-REQUEST attribute.
If the server can successfully process the request create an
allocation, the server replies with a success response that includes
a STUN MOBILITY-TICKET attribute. TURN server stores it's session
state, such as 5-tuple and NONCE, into a ticket that is encrypted by
a key known only to the TURN server and sends the ticket in the STUN
MOBILITY-TICKET attribute as part of Allocate success response.
The ticket is opaque to the client, so the structure is not subject
to interoperability concerns, and implementations may diverge from
this format. TURN Allocation state information is encrypted using
128-bit key for Advance Encryption Standard (AES) and 256-bit key for
HMAC-SHA-256 for integrity protection.
4.1.3. Receiving an Allocate Success Response
In addition to the process described in Section 6.3 of [RFC5766], the
client will store the MOBILITY-TICKET attribute, if present, from the
response. This attribute will be presented by the client to the
server during a subsequent Refresh request to aid mobility.
4.1.4. Receiving an Allocate Error Response
If the client receives an Allocate error response with error code TBD
(Mobility Forbidden), the error is processed as follows:
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o TBD (Mobility Forbidden): The request is valid, but the server is
refusing to perform it, likely due to administrative restrictions.
The client considers the current transaction as having failed. The
client MAY notify the user or operator and SHOULD NOT retry the same
request with this server until it believes the problem has been
fixed.
All other error responses must be handled as described in [RFC5766].
4.2. Refreshing an Allocation
4.2.1. Sending a Refresh Request
If a client wants to refresh an existing allocation and update its
time-to-expiry or delete an existing allocation, it will send a
Refresh Request as described in Section 7.1 of [RFC5766]. If the
client wants to retain the existing allocation in case of IP change,
it will include the MOBILITY-TICKET attribute received in the
Allocate Success response. If a Refresh transaction was previously
made, the MOBILITY-TICKET attribute received in the Refresh Success
response of the transaction must be used.
4.2.2. Receiving a Refresh Request
In addition to the process described in Section 7.2 of [RFC5766], the
client does the following:
If the STUN MOBILITY-TICKET attribute is included in the Refresh
Request then the server will not retrieve the 5-tuple from the packet
to identify an associated allocation. Instead TURN server will
decrypt the received ticket, verify the ticket's validity and
retrieve the 5-tuple allocation from the contents of the ticket. If
this 5-tuple obtained from the ticket does not identify an existing
allocation then the server MUST reject the request with an error.
If the source IP address and port of the Refresh Request is different
from the stored 5-tuple allocation, the TURN server proceeds with
checks to see if NONCE in the Refresh request is the same as the one
provided in the ticket. The TURN server also uses MESSAGE-INTEGRITY
validation to identify the that it is the same user which had
previously created the TURN allocation. If the above checks are not
successful then server MUST reject the request with a 441 (Wrong
Credentials) error.
If all of the above checks pass, the TURN server understands that the
client has moved to a new network and acquired a new IP address. The
source IP address of the request could either be the host transport
address or server-reflexive transport address. The server then
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updates it's 5-tuple with the new client IP address and port. TURN
server calculates the ticket with the new 5-tuple and sends the new
ticket in the STUN MOBILITY-TICKET attribute as part of Refresh
Success response.
4.2.3. Receiving a Refresh Response
In addition to the process described in Section 7.3 of [RFC5766], the
client will store the MOBILITY-TICKET attribute, if present, from the
response. This attribute will be presented by the client to the
server during a subsequent Refresh Request to aid mobility.
4.3. New STUN Attributes
4.3.1. MOBILITY-REQUEST
This attribute is used by the client to indicate to the TURN server
that it is a mobile node. This attribute has no value part and thus
the attribute length field is 0.
4.3.2. MOBILITY-TICKET
This attribute is used to retain an Allocation on the TURN server.
It is exchanged between the client and server to aid mobility. The
value is encrypted and identifies identifies session state such as
5-tuple and NONCE. The value of MOBILITY-TICKET is a variable-length
value.
4.4. New STUN Error Response Codes
This document defines the following new error response codes:
TBD (Mobility Forbidden): Mobility request was valid but cannot be
performed due to administrative or similar restrictions.
5. IANA Considerations
This note requests of the IANA to add attributes MOBILITY-REQUEST and
MOBILITY-TICKET to the TURN attribute registry. The note also
requires reservation of a new error code for error Mobility
Forbidden.
6. Security Considerations
TURN server MUST use strong encryption and integrity protection for
the ticket to prevent an attacker from using a brute force mechanism
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to obtain the ticket's contents or refreshing allocations.
Security considerations described in [RFC5766] are also applicable to
this mechanism.
7. References
7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5245] Rosenberg, J., "Interactive Connectivity Establishment
(ICE): A Protocol for Network Address Translator (NAT)
Traversal for Offer/Answer Protocols", RFC 5245,
April 2010.
[RFC5389] Rosenberg, J., Mahy, R., Matthews, P., and D. Wing,
"Session Traversal Utilities for NAT (STUN)", RFC 5389,
October 2008.
[RFC5766] Mahy, R., Matthews, P., and J. Rosenberg, "Traversal Using
Relays around NAT (TURN): Relay Extensions to Session
Traversal Utilities for NAT (STUN)", RFC 5766, April 2010.
7.2. Informative References
[RFC2663] Srisuresh, P. and M. Holdrege, "IP Network Address
Translator (NAT) Terminology and Considerations",
RFC 2663, August 1999.
[RFC5768] Rosenberg, J., "Indicating Support for Interactive
Connectivity Establishment (ICE) in the Session Initiation
Protocol (SIP)", RFC 5768, April 2010.
Authors' Addresses
Dan Wing
Cisco Systems, Inc.
170 West Tasman Drive
San Jose, California 95134
USA
Email: dwing@cisco.com
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Prashanth Patil
Cisco Systems, Inc.
Cessna Business Park, Varthur Hobli
Sarjapur Marthalli Outer Ring Road
Bangalore, Karnataka 560103
India
Email: praspati@cisco.com
Tirumaleswar Reddy
Cisco Systems, Inc.
Cessna Business Park, Varthur Hobli
Sarjapur Marathalli Outer Ring Road
Bangalore, Karnataka 560103
India
Email: tireddy@cisco.com
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