Transcript PPT Version

Fast Router Discovery
with L2 Support
draft-jinchoi-dna-frd-01.txt
JinHyeock Choi, DongYun Shin
hppt://www.diffeo.com/FRD.ppt
Background
G2
When upper-layer protocol sessions are being
supported, DNA schemes should detect the identity of
an attached link rapidly, with minimal latency lest there
should be a service disruption.
• For fast DNA, a host needs to quickly receive a
suitable RA upon establishing a new link-layer
connection.
• This draft present a way to deliver an RA to a host
with minimal latency upon network attachment.
Key Idea
• Point of Attachment (PoA)
– The link endpoint on the link, such as 802.11 Access Point
(AP) or 802.16 Base Station (BS), where a host may be
connected.
• While a router doesn’t perceive the presence of a new
host, usually L2 entity, PoA (Point of Attachment),
does.
• PoA may either 1
– trigger an AR (Access Router) to immediately send an RA
“RA Triggering” or
– send such an RA for itself “RA Proxying”.
Overview
• When a host establishes a link-layer connection, in the process,
an L2 entity, PoA (Point of Attachment), can detect the new
attachment and get the necessary information to deliver an
unicast L2 frame to the host, such as 802.11 MAC address or
802.16 CID (Connection Identifier).
• The PoA may forward the information to an AR (Access Router)
and trigger the AR to immediately send in unicast a suitable RA.
• Or the PoA itself may cache such an RA beforehand and deliver
the cached RA to the host in unicast upon network attachment
• In this draft, we refer the first scheme "RA Triggering" and the
second "RA Proxying".
RA Triggering Operation
• PoA and AR in one box
– Link UP Event Notification
• PoA and AR in separate boxes
– MIES (Media Independent Event Service)
– RS by PoA
RA Proxing Operation
• RA Caching
– PoA gets a suitable RA and stores it.
• RA Delivery
– As soon as a host established link-layer connection with
a PoA, it immediately sends a stored RA to the host in
unicast.
RA Caching methods
• Manual Configuration
• Scanning
• MICS (Media Independent Comment Service)
Summary
• This draft present a way for a host to receive a suitable RA with
minimum latency.
– RA proxying delivers the RA in the earliest possible time.
• This draft provides an useful DNA scheme with some constraints.
– The scheme is suitable for network initiated DNA.
– The scheme is Mobile/ Cellular network friendly.
– The scheme depends on link-layer support.
– The scheme works very well in certain environments, especially Mobile/
Cellular network but may not generally applicable to all networks.
– We also plan to advance this scheme in WIMAX and IEEE.
• We ask WG to accept this draft as a WG item
- to facilitate its adoption to other standard bodies
- to help the scheme to be deployed in mobile/ cellular network.
Appendix
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FRD Test Results
RA Triggering, rough sketch
RA Proxying, rough sketch
Rate Control
Performance Evaluation
FRD (Fast Router Discovery)
Implementation & Test Result
HeeJin Jang
FRD Implementation
• Implemented the FRD code on Linux OS (Kernel 2.4.20)
– RA Proxying with Scanning
• AP side
– We adopted the PCI-type card to implement an AP (Access Point) on
a Linux Box (PC)
– We modified its driver module for FRD
• Part 1 : Catch the RA from upper layer and cache it in the buffer.
• Part 2 : Deliver the cached RA to an MN in unicast 802.11 frame
right after L2 association
– No. of code lines: 31 lines
• Test Results
– We measured the time from L2 association to RA arrival with Ethereal
– Average: 1.3 ms
– Maximum: 1.8 ms
– Minimum: 1.1 ms
FRD Operation
1. We implemented FRD module on drives modules of netgear AP.
2. FRD module caches a suitable RA with Scanning.
3. When an MN is attached, it sends Association Request message.
4. FRD module extracts the MN's MAC address from the the
Association Request message.
5. FRD module combines the MN's MAC address with the cached
RA to make an unicast L2 frame.
6. FRD module sends the unicast L2 frame to the MN.
7. The MN receives the cached RA (in the unicast L2 frame) in
average 1.3 ms after L2 association is made.
FRD Test Scenario
AR
RA
1. PC AP with WLAN interface has FRD module.
2. AP scans incoming packets to cache an RA.
AP
MN
FRD Test Scenario
1. PC AP with WLAN interface has FRD module.
AR
2. AP scans incoming packets to cache an RA.
AP
MN
RA
3. At time T[0], MN establishes a new link layer
connection with AP.
4. After L2 association, AP immediately sends the
cached RA in L2 unicast frame
FRD Test Scenario
1. PC AP with WLAN interface has FRD module.
AR
2. AP scans incoming packets to cache an RA.
3. At time T[0], MN establishes a new link layer
connection with AP.
AP
4. After L2 association, AP immediately sends the
cached RA in L2 unicast frame
5. At time T[1], MN receives the cached RA.
6. We measure the DNA delay, T[1] – T[0].
7. Measured value of T[1] – T[0].
MN
RA
Min:
1.1ms
Max:
1.8ms
Average 1.3ms
We gratefully acknowledge the generous assistance we
received from Surekha Biruduraju for implementing and
testing FRD scheme.
RA Triggering, rough sketch
0. There is an RA which can properly
represent link identity, for example an
RA with LinkID.
Internet
AR
RA
LinkID
1. MN moves in and establishes a linklayer connection (association) with AP.
2. AP module deliver Link UP Event
Notification to AR module.
2. AR module immediately sends a
suitable RA to MN in unicast.
AP
MN
RA Triggering, rough sketch
0. There is an RA which can properly
represent link identity, for example an
RA with LinkID.
Internet
2. AP module deliver Link UP Event
Notification to AR module.
AR
AP
1. MN moves in and establishes a linklayer connection (association) with AP.
2. AR module immediately sends a
suitable RA to MN in unicast.
RA
LinkID
MN
RA Triggering, rough sketch
0. There is an RA which can properly
represent link identity, for example an
RA with LinkID.
Internet
1. MN moves in and establishes a linklayer connection (association) with AP.
AR
2. AP module deliver Link UP Event
Notification to AR module.
AP
3. AR module immediately sends a
suitable RA to MN in unicast.
MN
RA
LinkID
4. With LinkID, MN determines
whether it remains at the same link
or not.
5. In case of a link change, MN
initiates a new IP configuration with
the information in the RA ( Router
address, prefix et cetra).
RA Triggering, rough sketch
0. There is an RA which can properly
represent link identity, for example an
RA with LinkID.
Internet
1. MN moves in and establishes a linklayer connection (association) with AP.
AR
2. AP module deliver Link UP Event
Notification to AR module.
AP
3. AR module immediately sends a
suitable RA to MN in unicast.
MN
RA
LinkID
4. With LinkID, MN determines
whether it remains at the same link
or not.
5. In case of a link change, MN
initiates a new IP configuration with
the information in the RA ( Router
address, prefix et cetra).
RA Proxying, rough sketch
0. There is an RA which can properly
represent link identity, for example an
RA with LinkID.
Internet
AR
AP
RA
LinkID
RA Proxying, rough sketch
0. There is an RA which can properly
represent link identity, for example an
RA with LinkID.
Internet
1. AP caches an RA with LinkID, either
manually or dynamically.
AR
AP
2. MN moves in and establishes a linklayer connection (association) with AP.
RA
LinkID
MN
RA Proxying, rough sketch
0. There is an RA which can properly
represent link identity, for example an
RA with LinkID.
Internet
1. AP caches an RA with LinkID, either
manually or dynamically.
AR
2. MN moves in and establishes a linklayer connection (association) with AP.
3. As soon as association is completed,
AP immediately sends the cached RA
to MN in unicast.
AP
MN
RA
LinkID
4. With LinkID, MN determines
whether it remains at the same link
or not.
5. In case of a link change, MN
initiates a new IP configuration with
the information in the RA ( Router
address, prefix et cetra).
RA Proxying, rough sketch
0. There is an RA which can properly
represent link identity, for example an
RA with LinkID.
Internet
1. AP caches an RA with LinkID, either
manually or dynamically.
AR
2. MN moves in and establishes a linklayer connection (association) with AP.
3. As soon as association is completed,
AP immediately sends the cached RA
to MN in unicast.
AP
MN
RA
LinkID
4. With LinkID, MN determines
whether it remains at the same link
or not.
5. In case of a link change, MN
initiates a new IP configuration with
the information in the RA ( Router
address, prefix et cetra).
Delay – RFC 2461 without Link UP
AR sends RA periodically
AR
AP
MN
1. MN
arrives and
sends
Association
Request
2. AP
receives
Association
Request.
4. MN
receives
Association
Response
and
3. AP sends association
Association is made.
Response.
5. AR
sends
Unsolicited
RA
6. MN
receives RA
and
discovers
new subnet.
Delay – RFC 2461 with Link UP
AR
AP
MN
1. MN
arrives and
sends
Association
Request
2. AP
receives
Association
Request.
4. MN
receives
Association
Response
and
3. AP sends association
Association is made.
Response.
5. MN
sends RS
after
Random
delay.
6. AR
7. AR
receives sends
RS
RA after
Random
delay
8. MN
receives RA
and
discovers
new subnet.
Delay – FRD
AR
AP
MN
1. MN
arrives and
sends
Association
Request
4. AP
2. AP
send
receives
Association stored
RA.
Request.
3. AP sends
Association
Response
4. MN
receives
Association
Response
and
association
is made.
5. MN
receives RA
and
discovers
new subnet.
Continuous Scanning
RA
arrival
RA
arrival
RA
arrival
It may cost too much to execute Scanning continuously.
Rate Control
• Execute Scanning in regular interval.
– It may cost too much to execute Scanning continuously.
– For this we set time value T.
– AP execute Scanning in every T time.
• If we set T as 0, scanning is executed continuously.
Effect of T value
RA
arrival
RA
arrival
T
Scan Scan
Start Stop
RA
arrival
T
Scan Scan
Start Stop
Scan Scan
Start Stop
With T value, We can decrease Scanning execution time.
We assume a network administrator selects appropriate T value.