Network Working Group T. Sanda
Internet Draft T. Ue
Expires: August 2004 Panasonic
February 2004
Pre CRN discovery from proxy on candidate new path
draft-sanda-nsis-mobility-qos-proxy-01.txt
Status of this Memo
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Abstract
NSIS WG has been discussing the ways to minimize/avoid QoS
interruption during handover. One solution is to install new
path before MN's move (fast state installation).
This document proposes a procedure of pre CRN discovery for fast
state installation by using proxies on candidate new paths. An
example of fast state installation is shown.
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 [2].
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Table of Contents
1. Introduction................................................2
1.1 Terminology.............................................2
1.2 Assumption..............................................3
2. Proxy for Fast State Installation...........................3
3. Proxy discovery.............................................3
4. Pre CRN Discovery...........................................4
5. New path installation.......................................7
5.1 Fast state installation for downlink data flow..........7
5.2 Fast state installation for uplink data flow............8
6. Signaling messages for fast CRN discovery...................9
7. Security Considerations....................................10
References....................................................10
Author's Addresses............................................11
1. Introduction
When a MN performs L3 level handover with a QoS state, it is
required to establish new QoS paths before handover to
avoid/minimize QoS interruption in new subnetwork. Discussions
on this topic are taking place in the NSIS WG and some drafts
are proposing "Fast State Installation", by which new QoS paths
are established in advance [3][5][6][8].
The goal of this draft is to initiate discussion on concrete
solutions for Fast State Installation. An example is provided of
a procedure that includes crossover node (CRN) discovery. This
procedure utilizes a proxy entity on the candidate new path, to
perform CRN discovery and QoS state installation along the new
path prior to the MN's move to the new subnetwork.
Terminology definitions and assumptions in this document are
described in the following section.
1.1 Terminology
Uplink data flow:
data flow from MN to CN
Downlink data flow:
data flow from CN to MN
UCRN and DCRN:
The same as defined in [6]
mQNE:
The NSIS aware node supporting QoS and mobility
functionalities
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1.2 Assumption
o Signaling messages are path-coupled [8]. Signaling messages
from MN to CN are routed only through NEs that are in the Uplink
data path, and signaling messages from CN to MN are routed only
through NEs that are in the Downlink data path
o Network supports Mobile IPv6 [13]
o Only optimized route case is discussed in this document
although several routes are possible such as triangle route,
tunnel between OAR and NAR established by FMIP, and so on.
o MN and CN are mQNE
2. Proxy for Fast State Installation
MN cannot directly initiate resource reservation signaling on
candidate new paths before it actually moves. Therefore NSIS
proxy utilization will be necessary for fast state installation,
as described in [3].
The proxy can be used for preparing new path installation, e.g.
discovering CRN in advance of the MN's move(pre CRN discovery).
Additionally the proxy may install the new path on behalf of the
MN.
The following section describes a procedure for pre CRN
discovery followed by fast state installation.
3. Proxy discovery
Either old (current) or candidate new adjacent mQNEs of MN (see
Figure1) can act as a proxy.
An example of the former case is described in an appendix of [5].
Here we aim to consider the latter case, i.e. new adjacent mQNE
acts as a proxy and prepares new path creation.
If candidate NAR(s) has mQNE functionalities, the NAR(s) acts as
a proxy.
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new
adjacent
mQNE
+..+ +---+ +----+
.MN.---|NAR|---|mQNE|---...--------
+..+ +---+ +----+ |
^ |
| |
+--+ +---+ +-+ +----+ +----+ +--+
|MN|===|OAR|==|R|==|mQNE|==...==|mQNE|==...==|CN|
+--+ +---+ +-+ +----+ +----+ +--+
old (current)
adjacent
mQNE
=== current path
--- expected new path
R: Router or NE (not QNE)
Figure1: New and old adjacent mQNE
If MN and network support suitable mobility protocol, such as
CARD [12], MN can obtain proxies information through the CARD
server.
When the network does not support CARD, the MN may have to rely
on pre-stored information. This information could be in the form
of tables contains mapping information between APs and their
connecting ARs, and neighboring mQNEs (proxies) of the ARs. The
MN would then be able to associate the information on candidate
APs to mQNEs that will likely be on the new path and would be
able to act as proxies. Given though that determining whether an
mQNE router will be on a data path to an arbitrary CN is
difficult, it is proposed that only access routers with mQNE
capabilities are used as proxies as described in [6]. This has
the added advantage that these routers will be able to perform
DAD on prospective new CoAs which would enable them to also
perform the state installation on behalf of the MN.
4. Pre CRN Discovery
The idea of pre CRN (both UCRN and DCRN) discovery is as follows.
a. After determining proxies, MN sends PROXY_INIT message to
the proxies. The PROXY_INIT message is a NSLP signaling
message and contains current flow identifier and session
identifier (for both uplink and downlink, or either)
information.
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b. On receipt of PROXY_INIT message, each proxy sends a
DCRN_DISCOVERY message to CN. A DCRN_DISCOVERY is NSLP
signaling message and containing the flow identifier and
session identifier received from the MN. An IP address of CN is
contained in flow identifier.
c. Each QNE belonging to the signaling path from proxy to CN
intercepts DCRN_DISCOVERY, and checks if any interface has
resource reservation for the pair of flow identifier and
session identifier for uplink. If one of interface has the
reservation, the QNE appends IP address of the interface to
DCRN_DISCOVERY.
When DCRN_DISCOVERY message arrives to CN, DCRN_DISCOVERY
message contains the information of all overlapping interfaces
belonging to current uplink QoS path (from MN to CN) and
expected new uplink path (from proxy to CN) in order.
current path
=======================>
IF1 IF2
+--+ +----+ +----+ +----+ +----+ +--+
|MN|>>>>|mQNE|>>>|mQNE|>>>|mQNE|>>>|mQNE|>>>>|CN|
+--+ +----+ +----+ >+----+>>>+----+>>>>+--+
^
^ ----->
^ |
+-----+ +----+ ^ |
|Proxy|>>>>>|mQNE|>>>> |
+-----+ +----+ |
|
-------------------
DCRN_DISCOVERY
IF=Interface to be appended
to the message
Figure2: Interfaces' information collected by DCRN_DISCOVERY
d. On receipt of DCRN_DISCOVERY message, CN sends a
UCRN_DISCOVERY to the proxy. A UCRN_DISCOVERY message is NSLP
signaling message and containing the flow identifier and
session identifier received from MN via DCRN_DISCOVERY message.
A UCRN_DISCOVERY message also contains the information of IP
addresses appended to DCRN_DISCOVERY message.
e. Each QNE belonging to the signaling path from CN to proxy
intercepts UCRN_DISCOVERY, and checks if any interface has
resource reservation for the pair of flow identifier and
session identifier for downlink. If one of interface has the
reservation, the QNE appends IP address of the interface to
UCRN_DISCOVERY.
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When UCRN_DISCOVERY message arrives to proxy, UCRN_DISCOVERY
message contains the information of all overlapping interfaces
belonging to current uplink QoS path (from MN to CN) and
expected new downlink path (from proxy to CN) in order.
current path
<=======================
IF4 IF3
+--+ +----+ +----+ +----+ +----+ +--+
|MN|<<<<|mQNE|<<<|mQNE|<<<|mQNE|<<<|mQNE|<<<<|CN|
+--+ +----+ +----+ <+----+<<<+----+<<<<+--+
v
v ------
v |
+-----+ +----+ v |
|Proxy|<<<<<|mQNE|<<<< |
+-----+ +----+ |
|
<------------------
UCRN_DISCOVERY
IF=Interface to be appended
to the message
Figure3: Interfaces' information collected by UCRN_DISCOVERY
f. The proxy receiving UCRN_DISCOVERY from CN checks appended
information in UCRN_DISCOVERY and decides CRN(s). The first
interface IP address appended to DCRN_DISCOVERY (and set into
UCRN_DISCOVERY) is DCRN, and the last interface IP address
appended to UCRN_DISCOVERY is UCRN.
collected by collected by
DCRN_DISCOVERY UCRN_DISCOVERY
<===============> <===============>
+------+--------+--------+------+--------+--------+
|up- |IP addr.|IP addr.|down- |IP addr.|IP addr.|
|stream| of IF1 | of IF2 |stream| of IF1 | of IF2 |
+------+--------+--------+------+--------+--------+
^ ^
| |
DCRN UCRN
Figure4: collected information and DCRN/UCRN
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The proxy sends PROXY_INIT_ACK message to the MN. PROXY_INIT_ACK
message is NSLP message and used for informing whether pre CRN
discovery is successfully done or failed.
5. New path installation
DCRN/UCRN discovered by proxy can be used for fast state
installation. For this purpose, it is required that RESERVE
message contains IP addresses of DCRN/UCRN. When the RESERVE
message reaches the DCRN, it is also required for the DCRN to
translate the RESERVE (create) message into RESERVE (update)
message and vice versa for UCRN in order to avoid duplicate
reservation of common QoS path (CN-UCRN/DCRN).
This section describes an example of fast state installation.
5.1 Fast state installation for downlink data flow
The following scenario assumes that the data flow is downlink
only.
a. When the MN listens to neighboring AP's beacons, MN refers a
proxy table (see Chapter 3). This table has mapping information
between APs and their connecting ARs, and whether the ARs have
mQNE functionalities. MN selects target subnetwork of which AR
has mQNE (proxy) functionalities.
b. MN configures NCoA from the AR's information in the table,
i.e. AR's IP address and prefix length.
c. MN sends PROXY_INIT message with NCoA to the new AR (NAR).
This PROXY_INIT message may contain IP address of MN's old
(current) mQNE as well.
d. The NAR executes DAD for NCoA.
e. Simultaneously with d., the NAR performs pre CRN discovery
as described in Chapter 4 and discovers UCRN.
f. If the NCoA is valid, the NAR send RESERVE message with UCRN
to CN. QSpec information may be obtained form mQNE in old
(current) path such as MN or old adjacent mQNE of MN.
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MN NAR CN
(Proxy)
| | |
+--------+ | |
|HO | | |
|Decision| | |
+--------+ | |
+-------------+ | |
|NCoA | | |
|Configuration| | |
+-------------+ | |
| | |
|PROXY_INIT | |
|------------------->| |
| | |
| +-------+ |
| |DAD for| |
| |NCoA | |
| +-------+ |
| | |
| |DCRN_DISCOVERY |
| |------------------->|
| | |
| | UCRN_DISCOVERY|
| |<-------------------|
| | |
| +---------+ |
| |Obtaining| |
| |UCRN | |
| +---------+ |
| | |
| |RESERVE |
| |------------------->|
| | |
| | |
Figure5: An example of Fast state installation for downlink
5.2 Fast state installation for uplink data flow
If data flow is uplink only or duplicate, the following
procedure can be used in addition to downlink case.
o DCRN_DISCOVERY message contains NCoA (which is valid).
o The CN receiving DCRN_DISCOVERY message performs RESERVE
message to NAR (proxy) for uplink, as it can obtain DCRN and
MN's NCoA.
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MN NAR CN
(Proxy)
| | |
+--------+ | |
|HO | | |
|Decision| | |
+--------+ | |
+-------------+ | |
|NCoA | | |
|Configuration| | |
+-------------+ | |
| | |
|PROXY_INIT | |
|------------------->| |
| | |
| +-------+ |
| |DAD for| |
| |NCoA | |
| +-------+ |
| | |
| |DCRN_DISCOVERY |
| |------------------->|
| | |
| | +---------+
| | |Obtaining|
| | |DCRN and |
| | |NCoA |
| | +---------+
| | |
| | RESERVE|
| |<-------------------|
| | |
| | UCRN_DISCOVERY|
| |<-------------------|
| | |
| | |
Figure6: An example of Fast state installation for uplink
6. Signaling messages for fast CRN discovery
PROXY_INIT, DCRN_DISCOVERY, UCRN_DISCOVERY and PROXY_INIT_ACK
may be extended existing QoS NSLP message, such as QUERY,
RESPONSE and NOTIFY [7]. If DCRN_DISCOVERY and UCRN_DISCOVERY
are QUERY and RESPONSE respectively, proxy can obtain downlink
path information simultaneously with UCRN discovery.
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7. Security Considerations
Security issues are addressed in section 12 of [6] but they are
not covering candidate proxies (mQNEs) which are described in
this document. Proper security handling must be provided in
candidate proxy discovery. It is also required to consider the
issues caused by sending PROXY_INIT which includes session and
flow identifiers from MN to candidate proxies, such as
session/reservation ownership.
Future draft will include these issues.
References
1. Bradner, S., "The Internet Standards Process -- Revision 3",
BCP 9, RFC 2026, October 1996.
2. Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997
3 X. Fu, et al., "Mobility Issues in Next Steps in Signaling
(NSIS)", Internet Draft (work in progress),
draft-fu-nsis-mobility-01.txt, October 2003
4 H. Chaskar, et al., "Requirements of a Quality of Service
(QoS) Solution for Mobile IP", RFC3583, September 2003
5 S. Lee, et al., "Mobility Functions in the QoS-NSLP",
Internet Draft (work in progress), draft-lee-nsis-mobility-nslp-
01.txt, October 2003
6 Roland Bless, et al., "Mobility and Internet Signaling
Protocols", Internet Draft (work in progress), draft-manyfolks-
signaling-protocol-mobility-00.txt, January 2004
7 Sven Van den Bosch (Editor), "NSLP for Quality-of-Service
signaling", Internet Draft (work in progress), draft-ietf-nsis-
qos-nslp-01.txt, October 2003
8 Robert Hancock et al., "Next Step in Signaling: Framework",
Internet Draft (work in progress), draft-ietf-nsis-fw-05.txt,
October 2003
9 R. Hancock, et al., "Interactions of Routing and Mobility on
NTLP and NSLP", Internet Draft (work in progress), draft-
hancock-nsis-routing-mobility-00.txt, October, 2003
10 S. Jeong, et al., "Mobility Functions in the NTLP", Internet
Draft (work in progress), draft-jeong-nsis-mobility-ntlp-01.txt,
October 2003
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11 H. Schulzrinne, et al., "GIMPS: General Internet Messaging
Protocol for Signaling", Internet Draft (Work in progress),
draft-ietf-nsis-ntlp-00, October 2003
12 M. Liebsch, et al., "Candidate Access Router Discovery",
Internet Draft (work in progress), draft-ietf-seamoby-card-
protocol-06.txt, December 2003
13 D.Johnson, C. Perkins and J. Arkko, "Mobility Support in
IPv6", Internet Draft (work in progress), draft-ietf-mobileip-
ipv6-24.txt, June 2003
Author's Addresses
Takako Sanda
Panasonic (Matsushita Electric Industrial Co., Ltd.)
5-3, Hikarino-oka, Yokosuka City, Kanagawa 239-0847, Japan
Phone: (+81) 46 840 5764
Email: sanda.takako@jp.panasonic.com
Toyoki Ue
Panasonic (Matsushita Electric Industrial Co., Ltd.)
5-3, Hikarino-oka, Yokosuka City, Kanagawa 239-0847, Japan
Phone: (+81) 46 840 5816
Email: ue.toyoki@jp.panasonic.com
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