jinhyeock choi, dongyun shin hppt://diffeo/frd

JinHyeock Choi, DongYun Shin

hppt://www.diffeo.com/FRD.ppt

Fast Router Discovery with L2 Support

draft-jinchoi-dna-frd-01.txt

BackgroundG2 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• 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.

1. PC AP with WLAN interface has FRD module.

AP

MN

RA2. AP scans incoming packets to cache an RA.

FRD Test Scenario

AR


AP

MN

3. At time T[0], MN establishes a new link layer connection with AP.

2. AP scans incoming packets to cache an RA.

4. After L2 association, AP immediately sends the cached RA in L2 unicast frame

FRD Test Scenario

AR

RA


3. At time T[0], MN establishes a new link layer connection with AP.

2. AP scans incoming packets to cache an RA.

4. After L2 association, AP immediately sends the cached RA in L2 unicast frame

FRD Test Scenario

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].

Min: 1.1msMax: 1.8msAverage 1.3ms

AP

MN

AR

RA

We gratefully acknowledge the generous assistance we received from Surekha Biruduraju for implementing and testing FRD scheme.

Internet

0. There is an RA which can properly represent link identity, for example an RA with LinkID.

AR

AP

RALinkID

RA Triggering, rough sketch

MN

1. MN moves in and establishes a link-layer 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.

Internet


AR

AP


MN



RALinkID

Internet


AR

AP


MN



RALinkID

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).


Internet

AR

AP

RALinkID

RA Proxying, rough sketch


Internet

AR

AP

1. AP caches an RA with LinkID, either manually or dynamically.

RALinkID

MN

2. MN moves in and establishes a link-layer connection (association) with AP.


Internet

AR

AP


RALinkID

MN


3. As soon as association is completed, AP immediately sends the cached RA to MN in unicast.


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).


Internet

AR

AP


RALinkID

MN


3. As soon as association is completed, AP immediately sends the cached RA to MN in unicast.

RA Proxying, rough sketch 0. There is an RA which can properly represent link identity, for example an RA with 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

AP

MN

6. MN receives RA and discovers new subnet.

1. MN arrives and sends Association Request

3. AP sends Association Response.

2. AP receives Association Request.

4. MN receives Association Response and association is made.

5. AR sends Unsolicited RA

AR sends RA periodically

Delay – RFC 2461 with Link UP

AR

AP

MN



3. AP sends Association Response.



7. AR sends RA after Random delay

5. MN sends RS after Random delay.

6. AR receives RS

AR

AP

MN


3. AP sends Association Response


4. AP send stored RA.



Delay – FRD

Continuous Scanning

It may cost too much to execute Scanning continuously.

RA arrival

RA arrival

RA arrival

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

ScanStart

Scan Stop

ScanStart

Scan Stop

ScanStart

ScanStop

RA arrival

RA arrival

RA arrival

With T value, We can decrease Scanning execution time.We assume a network administrator selects appropriate T value.

T T

jinhyeock choi, dongyun shin hppt://diffeo/frd

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