Tuesday, April 04, 2006

Direct Push is just a heartbeat away

Another good explanation of Direct Push posted at EHLO… 



Exchange 2003 introduced the Always Up To Date notification feature (AUTD) that kept devices up to date by sending SMS triggers to the device. The triggers were sent from the enterprise as SMTP messages to the SMTP front end at the mobile operator. They were then sent through the SMS gateway as SMS messages to the device. This approach had some limitations since not all mobile operators did the SMTP to SMS conversion. Even when they did, there was latency involved with SMS messages and there were end-to-end reliability issues. Also some mobile operators charged for each incoming SMS message so that added an extra dimension to the cost of staying up to date. To alleviate these issues, Exchange 2003 SP2 introduced Direct Push.


Direct Push Architecture


Direct Push is a client initiated HTTP connection to the server where the device opens a connection to the Exchange Server and keeps it alive for a duration known as the heartbeat interval.  Basically the client sets up the connection, chooses the appropriate heartbeat interval and tears down and reestablishes the connection if and when necessary. The server sends notifications about new items over this connection and the client synchronizes to get the new items.


A new AirSync command called PING has been introduced for Direct Push. This command is sent as part of the POST request from the device.

Summary of Interaction between the client, EAS server and Exchange

1. Device issues a PING command.

2. When the EAS server receives a PING command it does the following:

·         If the Ping command contains the heartbeat interval or folder list, it stores the information in AUTDSTATE.XML in the user's mailbox. The device does not need to send these parameters up again unless they change.

·         If the Ping command did not contain the heartbeat or folder list, it retrieves them from the mailbox server.

·         EAS subscribes to notifications for the folders. It issues DAV subscriptions using the SUBSCRIBE command.

·         Since there is a small window between the last SYNC and the SUBSCRIBE where changes could have occurred, EAS checks for changes. If there is a change, the server immediately notifies the client to sync by issuing a response to the PING command with a Status of 2. It does an UNSUBSCRIBE to delete the DAV subscription. If no changes have occurred, the server continues to wait for UDP notifications from the mailbox server.

·         If a notification arrives within the heartbeat interval, the server will inform the client to sync. A response to the PING command is issued with a Status of 2 indicating that there are changes. Otherwise, after the heartbeat interval elapses, the server will return a response to the PING command with a Status of 1 indicating that there are no changes. It does an UNSUBSCRIBE to delete the DAV subscriptions before issuing the PING response.


Deployment Considerations for Direct Push


1. In order to use Direct Push, only the Exchange 2003 Front End servers need to be upgraded to SP2. However it is highly recommended that SP2 be installed on all Exchange Front End and back end servers. 


If the Front End servers are load balanced, all the Front End servers need to be upgraded around the same time.


2. When there is new mail, the BE sends a UDP notification to the FE.  Direct Push requires that UDP port 2883 be open from the BE to the FE. The port can be configured using the registry value UDPListenPort under HKLM\SYSTEM\CurrentControlSet\Services\MasSync\Parameters. If this value is set through the registry, the value must be greater than or equal to 1 and less than or equal to 65535. 


3. With Direct Push, the device keeps a connection open to the Exchange server. If you have a firewall between the device and the Exchange server, you must increase the idle connection timeout on the firewall. Please note that this is the idle connection timeout (i.e.) when there is no data transfer between client and server. For more information, please refer to KB titled "Enterprise firewall configuration for Exchange ActiveSync Direct Push Technology" available at



4. If you are using ISA 2000, you need to add a registry key on the ISA server to use direct push. Please refer to  the KB titled "The ISA Server response to client options requests is limited to a predefined" available at http://support.microsoft.com/?ID=304340 for information on how to add the registry key.


Heartbeat Interval


The device specifies the heartbeat interval as part of the PING command. This dictates how long the server must keep the connection alive. The device will dynamically converge to the highest possible heartbeat interval for a given network, based on the mobile operator timeouts, firewall timeouts etc. The higher the heartbeat interval, the better it is for battery life. So the heartbeat is optimized for a given network.


You can change the minimum and maximum heartbeat interval settings on the server through the registry.


The settings are MinHeartbeatInterval and MaxHeartbeatInterval under



The defaults are 1 and 45 minutes respectively. Note that the maximum is hard coded to 59 minutes since the maximum possible DAV subscription lifetime is 60 minutes.


You can also specify a heartbeat alert threshold. The server maintains a sliding window of the last 200 heartbeat intervals supplied by clients. If the average from this sample is less than or equal to the alert threshold, there will be a warning in the event log  


"The average of the most recent heartbeat intervals used by clients is less than or equal to x. Please check your firewall settings to ensure that they permit requests to Exchange ActiveSync to live for at least 15 minutes."


The alert threshold and sample size can be configured through the registry. The settings are HBiSampleSize and HbiAlertThreshold under



Configuring Direct Push on the Server


By default, Direct Push is enabled in Exchange 2003 SP2. However you can enable/disable it in Exchange System Manager. In ESM expand Global Settings, right-click on Mobile Services, Properties and check/uncheck the box for "Enable Direct Push over HTTP(S)"



You can also change this setting on a per-user basis using Active Directory Users and Computers.  In ADU&C, click on the user, Properties, Exchange Features tab, under Mobile Services enable/disable Up-to-Date Notifications. This controls both SMS based AUTD and Direct Push for the user.


Configuring Direct Push on the client


A Direct Push capable device will automatically negotiate the protocol with the server and configure itself to use Direct Push. The sync schedule is set to "As new items arrive".


Direct Push Initialization


1. Verify that Exchange ActiveSync is loaded and IP-based AUTD is initialized by checking the application log on the FE for events below. Exchange Activesync gets initialized on the first sync attempt.


Event Type: Information

Event Source:     Server ActiveSync

Event Category:   None

Event ID:   3002

Date:       3/19/2006

Time:       12:44:08 PM

User:       N/A

Computer:   1B25A


Microsoft Exchange ActiveSync has been loaded: Process ID: [3048].


Event Type: Information

Event Source:     Server ActiveSync

Event Category:   None

Event ID:   3025

Date:       3/19/2006

Time:       12:44:19 PM

User:       N/A

Computer:   1B25A


IP-based AUTD has been initialized.


2. Verify that the FE is listening on port 2883.


To check if the server is listening on the AUTD port, you can run "netstat -ano". Here are results before and after IP-based AUTD has initialized.




Proto       Local Address     Foreign Address   State       PID


UDP      *:*                           1928

UDP      *:*                           3356




Proto       Local Address     Foreign Address   State       PID


UDP      *:*                           1928

UDP      *:*                           3048

UDP      *:*                           3356


Netstat provides the Process ID which matches the EAS process per the initialization event in the application log.


Another way to check if the server is listening on the AUTD port is to use PortQry(available on Microsoft.com). This lists the process that is listening on the port


Process ID: 3048 (w3wp.exe)


PID   Port        Local IP          State             Remote IP:Port

3048  TCP 31479      ESTABLISHED

3048  TCP 31480      ESTABLISHED

3048  UDP 2883                             *:*


Troubleshooting using logs


1. Enable device side logging. The logs are saved in text format in the Windows\ActiveSync folder. PING commands will be logged in "Ping Exchange Server x.txt" where x =1,2,3.  You should see commands similar to the one below.


POST Microsoft-Server-ActiveSync?User=administrator&DeviceId=6F24CAD599A5BF1A690246B8C68FAE8D&DeviceType=PocketPC&Cmd=Ping

MS-ASProtocolVersion: 2.5


The POST command is also logged in the IIS log on the FE.


The Ctrl log on the device can also be used to troubleshoot Direct Push although the format of this file may change with device updates.


2. Check the IIS logs on the BE to see if AUTDState.XML is being created or updated. You should see an entry something similar to the one below.


PUT /exchange/Administrator@1b1domain.lab/NON_IPM_SUBTREE/Microsoft-Server-ActiveSync/PocketPC/6F24CAD599A5BF1A690246B8C68FAE8D/AutdState.xml


Note: The AUTDState.XML is created on receipt of the 1st PING request and is updated only when the heartbeat or folder list changes. So you may not see this command for every Ping request.


AUTD state information is maintained on the mailbox server in the NON_IPM_SUBTREE of each user's mailbox. 


In IE, you can Choose File, Open, check the box to "Open as Web Folder" and type in



Sample AUTDState.XML


<?xml version="1.0" encoding="utf-8"?>

-<AutdState xmlns="Ping:">








  - <Folder>








3.  Check the IIS logs on the BE to see if SUBSCRIBE commands are being issued from the FE to the BE(ie) if DAV subscriptions are being created.


For example, you should see something similar to


SUBSCRIBE /exchange/Administrator@1b1domain.lab/Inbox/


4. You can run a netmon on the FE to see if UDP notifications are being sent over port 2883 from BE to FE.


551 16.781250 LOCAL 000E0C06CAC0 UDP Src Port: Unknown (33660); Dst Port: Unknown (2883); Length = 162 (0xA2) BE FE IP


UDP: Src Port: Unknown (33660); Dst Port: Unknown (2883); Length = 162 (0xA2)

    UDP: Source Port = 0x837C

    UDP: Destination Port = 0x0B43

    UDP: Total length = 162 (0xA2)

    UDP: UDP Checksum = 0xC233

    UDP: Data: Number of data bytes remaining = 154 (0x009A)

00000:  00 0E 0C 06 CA C0 00 D0 B7 24 86 2B 08 00 45 00   ....ÊÀ.÷$†+..E.

00010:  00 B6 C8 73 00 00 80 11 07 3A AC 1D 09 71 AC 1D   .¶Ès..€..:¬..q¬.

00020:  08 DE 83 7C 0B 43 00 A2 C2 33 4E 4F 54 49 46 59   .Þƒ|.C.¢Â3NOTIFY

00030:  20 68 74 74 70 75 3A 2F 2F 31 62 32 35 61 2E 31    httpu://1b25a.1

00040:  62 31 64 6F 6D 61 69 6E 2E 6C 61 62 3A 32 38 38   b1domain.lab:288

00050:  33 2F 33 35 33 39 35 63 65 34 2D 31 35 30 34 2D   3/35395ce4-1504-

00060:  34 61 63 34 2D 39 37 32 31 2D 66 31 35 32 63 36   4ac4-9721-f152c6

00070:  34 36 65 61 33 35 20 48 54 54 50 2F 31 2E 31 0D   46ea35 HTTP/1.1.

00080:  0A 53 75 62 73 63 72 69 62 65 2D 67 72 6F 75 70   .Subscribe-group

00090:  3A 20 55 73 50 43 57 77 46 4C 32 30 71 37 44 2B   : UsPCWwFL20q7D+

000A0:  6E 61 76 6F 4D 71 79 41 3D 3D 0D 0A 53 75 62 73   navoMqyA==..Subs

000B0:  63 72 69 70 74 69 6F 6E 2D 69 64 3A 20 32 37 0D   cription-id: 27.

000C0:  0A 0D 0A 00        


Frequently Asked Questions and Answers


1.    Does Direct Push work for folders other than inbox?


Yes, Direct Push is available for mail folders, Contacts, Calendar and Tasks. The list of folders for Direct Push is the same as the list of folders that have been configured for sync.


2.    What devices support Direct Push?


Windows Mobile 5 devices require the Messaging and Security Feature Pack(MSFP) for Direct Push. MSFP is included with AKU2.2. So any Windows Mobile 5 device that has AKU2.2 supports Direct Push.  The AirSync protocol has been licensed to several companies such as Palm, Motorola, Nokia, Symbian, Dataviz and SonyEricsson. Please contact the licensees to see if Direct Push capable devices are available.


3.    Is Direct Push supported over Wi-Fi?


No. Direct Push requires a cellular data connection. It is not supported over Wi-Fi or Desktop Passthrough(when the device is cradled).


Due to hardware limitations, Wi-Fi cannot go into standby mode and receive notifications. So in order to support Direct Push over Wi-Fi, the Wi-Fi connection would have to be kept alive which in turn would drain the battery very rapidly.


4.    Does Direct Push work with SecurID?


RSA has an update to their agent to allow it to work with Direct Push. RSA Authentication Agent 5.3 for Web for IIS enables you to use Exchange ActiveSync without having to reauthenticate every time ActiveSync is invoked. For more details, please read this and contact RSA.


5.    Does Direct Push have an impact on server performance?


A typical FE services several thousand connections from clients using OWA, OMA, EAS, and RPC/HTTP clients. Based on the testing done by Microsoft IT, the additional connections opened by Direct Push did not require the deployment of any additional FE or BE servers. It also did not require an upgrade of hardware on existing servers.


For more information please refer to the whitepaper titled "Microsoft IT Scalability Experience with Windows Mobile 2003 and Exchange Server 2003 Mobile Messaging" available at




- Vanitha Prabhakaran


Anonymous said...

boss browsing izkbzosv centre recreational subset attackers accelerating killer produces lutheran
servimundos melifermuly

Anonymous said...

selections saved harmonic diminished santhome malik fulfilled discourage goods escaping work
servimundos melifermuly

Anonymous said...

Hi Iam Prabhu from chennai,joined today in this forum... :)

Anonymous said...

Привет! Все кто читает этот блог – С Днем Примерения и согласия!

Anonymous said...

kredyty bez
kredyt bez bik krosno
kredyt chwilówka bez bik
pożyczki bez bik
pożyczki bez bik wzór

Anonymous said...

Greetings! Very helpful advice in this particular
post! It is the little changes that will make the greatest changes.
Thanks for sharing!
Feel free to visit my webpage ... android tablet pc

Anonymous said...

Keep this going please, great job!
My page > wendy's shifting castle walkthrough

Anonymous said...

First off I want to say fantastic blog! I had a quick question in which I'd like to ask if you do not mind. I was interested to find out how you center yourself and clear your mind before writing. I've had a tough time clearing my mind in
getting my ideas out there. I truly do enjoy writing but it
just seems like the first 10 to 15 minutes are generally wasted just trying to figure
out how to begin. Any ideas or hints? Appreciate it!
my page :: Local News aggregation website

Anonymous said...

Если вы задаетесь вопросом, как зарегистрировать предприятие, не владея необходимой правовой подготовкой, то надежнее обратиться в ООО "Регистратор". Ведь для самостоятельного оформления всех надлежащих документов необходимо время и знания, так как любая ошибка может обойтись слишком дорого. Высококвалифицированные специалисты ООО "Регистратор" возьмутся качественно оформить компанию.

ООО "Регистратор" - [url=http://www.registratorfirm.ru/howtoregfirm/]как создать ооо[/url]

Anonymous said...

We stumbled over here from a different web address and thought I should check things out.
I like what I see so now i'm following you. Look forward to looking over your web page yet again.

Feel free to visit my page - Resting Metabolic Rate Calculator

Anonymous said...

This design is wicked! You obviously know how to keep a reader amused.
Between your wit and your videos, I was almost moved to start my own blog (well, almost.
..HaHa!) Excellent job. I really enjoyed what you had to say, and more than that, how you presented it.
Too cool!

Also visit my blog post - cccam

Anonymous said...

Thank you for the good writeup. It in fact was a amusement account it.

Look advanced to more added agreeable from you! By the way,
how could we communicate?

Here is my web site; kredyty pod zastaw

Vina Janny said...

waterfall taps are elegant fixtures in the bathroom that increase water pressure, which in turn increases the speed. cheap taps have emerged as a necessity among today urban population and different types of led taps are being launched to suit individual needs. Shower heads allow users to adjust from delicate to fast sprays. shower mixer are designed to mix and match almost an infinite combination of variations. They bring luxury and convenience to any bathroom. Modern basin tap push the water through an accelerator fin that powers up and increases the water velocity. The result is a highly boosted flow of water.

Vina Janny said...

waterfall taps are elegant fixtures in the bathroom that increase water pressure, which in turn increases the speed. cheap taps have emerged as a necessity among today urban population and different types of led taps are being launched to suit individual needs. Shower heads allow users to adjust from delicate to fast sprays. shower mixer are designed to mix and match almost an infinite combination of variations. They bring luxury and convenience to any bathroom. Modern basin tap push the water through an accelerator fin that powers up and increases the water velocity. The result is a highly boosted flow of water.

finestglasses said...

Decide the lens material of the glasses. Polycarbonate lenses are a better quality womens sunglasses

Robinet Deal said...

In British English, a Tap is a device that controls the flow of a liquid or gas from a pipe or container Kitchen Taps, Bathroom Taps, Shower Taps At DisTap,Choose a kitchen sink and tap to suit your kitchen worktop from the huge range stocked at DISTAP from the World's leading sink manufacturers.

Cheap Tap said...

These days, homemakers want to add in more type, flair and superiority into their kitchens. As such, even the taps are chosen with more care and consideration. With this change in choice, you see the appearance of designer http://www.cheaptap.co.uk/waterfall-taps-c-36.html .

Zhu Y said...

Our pneumatic factory was founded in 2000,CHECK HERE. In decades of serving China pneumatic industry, we have built our reputation on product knowledge, world class suppliers, application support, and value add services. Our commitment to our employees, customers and vendors is the core of our business beliefs. In our factory, there are more than 80 front-line workers, 3000 squares working shop.Our main products are air Pneumatic Cylinder, solenoid valve and also a lot of pneumatic fittings like Air Gun.

dc Z said...

Waschtischarmaturen von Top-Markenherstellern zum günstigen Onlinepreis. Bei der Riesenauswahl findet jeder bei Reuter die passende Waschtischarmatur.http://www.wasserhahn.com.de/6-waschtischarmaturen

Amy Carry said...

Good http://www.faucetsmarket.com/bathroom-accessory-faucets-accessories-c-4_33.html valve switch freely, while the use of bathtub faucets is not too loose or too tight; handle position, shape to be convenient to open and Waterfall faucet, that the use of the back can easily operate.