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Summit Technical Support Frequently Asked Questions
1. What is Auto Profile Selection and is it supported?A profile is a set of parameters that define the manner in which a client associates to a wireless LAN infrastructure. A profile contains information including the System Set Identifier (SSID or the "name" of the wireless LAN infrastructure) means of data encryption, authentication type, security credentials, etc. A client device that operates with more than one wireless LAN infrastructure (perhaps in different buildings) will tend to have more than one profile set up on the device.
Auto Profile Selection is a means whereby a client device will automatically scan the infrastructure for an SSID that matches an SSID found in a profile and then enables that profile on the device for association to that infrastructure without user intervention. As of Summit software version 1.3 Auto Profile Selection is not supported. Support for this capability is planned for a release in the first half of 2008. 2. What is an ad hoc network and is it supported?Typically, a wireless LAN-enabled client device will communicate with an access point rather than directly with another wireless LAN-enabled client in the same way as an Ethernet-enabled client will communicate with an Ethernet switch rather than directly with another Ethernet-enabled client.
However, some applications such as a sales demonstration will call for direct client to client communication which is referred to as an ad hoc network.
As of Summit software version 1.3, ad hoc networking is not supported. Support for this capability is planned for a release in the first half of 2008. In the meanwhile, users can configure their Summit-enabled client device for ad hoc operation by using the Windows Zero Config (WZC) utility found in Microsoft Windows CE, XP and Windows Mobile. To enable WZC, go to the Summit Client Utility (SCU) and on the Main tab, select "Third Party Config" from the drop down menu and power cycle the device. At this point, portions of the Summit radio's operation will be controlled by WZC and not SCU. You may then configure WZC for ad hoc operation (follow screen prompts, consult Windows Help or documentation) which will then cause the Summit radio to operate in ad hoc mode and allow for a direct connection to another client device. 3. What is Polled Mode and how do I enable it?By default, Summit device drivers operate in "Interrupt Mode" which provides for optimal performance. In some cases, however, interrupt conflicts can occur with other device (non-Summit) drivers that are present on the device. When this condition is present, the device will typically and consistently "lock-up". Setting the Summit driver to "Polled Mode" will often address device lock-ups that result from interrupt conflicts. When the Summit driver is set to Polled Mode, there will be a minimal and typically unperceivable decrease in WLAN performance.
Polled Mode can only be enabled through a registry setting. Polled Mode may be enabled when the below registry key is set to a non-zero value:
HLKM\Comm\SDCCF10G1\Parms\Configs\GlobalConfig\polledIRQ
To return the driver to Interrupt mode, set the above registry key to 0 and power cycle the unit.
4. What is a Limited Channel Set and how do I enable it?In the 2.4 GHz frequency band used for 802.11b and 802.11g, there are, depending upon regulatory domain, between 11 and 14 available channels. However, of these channels only 3 or 4 (again, depending upon regulatory domain) do not overlap with each other and are available for wireless LAN operation. When operating in the FCC regulatory domain (North and South America, parts of Asia and the Middle East) most wireless LAN infrastructures are configured to operate on channels 1, 6 and 11. In the ETSI regulatory domain (Europe, Africa and parts of Asian and the Middle East) most wireless LAN infrastructures are configured to operate on either channels 1, 6 and 11 or 1, 7 and 13.
By default, Summit's software is configured to scan all 2.4 GHz channels prior to initiating a roam. During a scan, a client device is unable to send or receive data meaning that the longer a scan period, the lower the client's performance.
Limiting the set of channels to be scanned prior to a roam to only those channels that are actually in use in the wireless LAN infrastructure is an effective means of decreasing scan time and thereby improving performance. A Limited Channel Set may be enabled in two ways:
Find the "bLRS" registry entry which is a bitmask with bit 0 corresponding to channel 1, bit 1 to channel 2 etc…. If a bit is set, that channel will be scanned prior to a roam and associations will be allowed on that channel. If the bit is not set, that channel will not be scanned and associations on that channel will not be allowed. By default the bitmask, in hex, is set to: HEX: F F F F
The binary equivalent of which is: 1111 1111 1111 1111 Meaning that all channels will be scanned and allow for associations. To limit the channel set, manually edit the bitmask to selectively enable and disable channels. For example, to manually set the channel set to enable channels 11, 6 and 1 (and disable all others) make the following entry HEX: 0 4 2 1
The binary equivalent of which is: 0000 0100 0010 0001 5. What is a Power Save Mode and which one should I use?Maximizing battery life to better provide for full shift operation is an important consideration for vendors and users of hand-held data terminals and similar devices. Summit provides a number of different power save modes that can significantly reduce the radio's power consumption and in so doing maximize the battery life of the host device. In short, when in power save mode the radio will "sleep" most of the time, "waking" only when it has data that needs to be sent to the infrastructure or at an interval determined between the client and the access point at which time the access point will deliver to the client any data that has been buffered during the client's sleep period.
There is a good white paper on 802.11 power management located here. The paper promotes UPSD, which is a part of the IEEE 802.11e standard. But it also provides a good explanation of the building blocks of power save polling (PSP). Here is an excerpt:
The 802.11 standard defines procedures that can be used to implement power management during inactive periods. In particular, three distinct building blocks are provided to support power savings: a Wakeup Procedure, a Sleep Procedure, and a Power-save Poll (PS-Poll) Procedure. A station (STA or client device) can combine these power management building blocks in various manners for different applications.
Wakeup Procedure: There are two reasons for the STA to wake up: to transmit pending data or to retrieve buffered data from an access point (AP). Waking up to transmit data is a straightforward operation, driven by the STA. The decision to wake up and receive data is also made by the STA after monitoring its pending data bit in a periodic beacon frame sent out by its AP. Once the STA decides to transition from sleep mode to active mode, it notifies the AP by sending an uplink frame with the power-save (PS) bit set to active. Following such transmission, the STA remains active so the AP can send any buffered downlink frames afterward.
Sleep Procedure: Similar to the wakeup procedure, a STA in the active mode needs to complete a successful STA-initiated frame exchange sequence with PS bit set to sleep to transition into the sleep mode. Following this operation, the AP buffers all the downlink frames to this STA.
PS-Poll Procedure: Instead of waiting for the AP to transmit the buffered downlink frames, a STA in sleep mode can solicit an immediate delivery from its AP by using a PSPoll frame. Upon receiving this PS-Poll, the AP can immediately send one buffered downlink frame (immediate data response) or simply send an acknowledgement message and response with a buffered data frame later (delayed data response). For the immediate data response case, the STA can stay in the sleep state after finishing this frame exchange since there is no need for the STA to transition to the active state given that the AP can only send a buffered downlink frame in response to the PS-poll from the STA. For the delayed data response case, the STA has to transition to the active state until receiving a downlink frame from the AP.
Other Notes on PSP: An 802.11 AP transmits any multicast or broadcast frames immediately unless at least one associated client is in Power Save Polling (PSP) mode. When PSP is in use by at least one client, then: · When it associates to an AP, a PSP client sends the AP a unicast powersave “listen interval” value, which is configured as x DTIM (Delivery Traffic Indication Map) · The AP maintains a list of PSP clients in its Traffic Indication Map (TIM) tables · The AP queues frames for PSP clients · Once every DTIM interval, the AP determines if there are packets cached · With a Cisco AP, the default DTIM interval is the beacon interval (100ms) x 2, which means that the client wakes up every 200 ms · If there are packets cached, the AP transmits a DTIM frame or beacon, which lists the MAC addresses of associated clients for which there is data queued · Every x DTIM intervals (i.e. every “listen interval”), a PSP client wakes up · If the client is using Fast PSP, then it checks the DTIM frame or beacon · If the client is using Max PSP, then it sends a power save poll to the AP · After sending the DTIM frame (or responding to the power save poll), the AP transmits all queued data frames · Each PSP client acknowledges the receipt of each packet · Before transmitting the last packet, the AP flips one of the bits on the frame to signal that it is the last packet · Upon receiving the last cached packet, goes back into PSP mode (i.e. back to sleep)
Summit supports the three following power save modes: CAM (Constantly Awake Mode): Keeps the client adapter powered up continuously so there is little lag in message response time. Consumes the most power but offers the highest throughput. Is recommended for desktop computers and devices that use AC power. Max PSP (Max Power Savings): Causes the access point to buffer incoming messages for the client adapter, which wakes up periodically and polls the access point to see if any buffered messages are waiting for it. The adapter can request each message and then go back to sleep. Conserves the most power but offers the lowest throughput. Is recommended for devices for which power consumption is the ultimate concern (such as small battery-powered devices). Fast PSP (Power Save Mode): Switches between PSP mode and CAM mode, depending on network traffic. This mode switches to CAM when retrieving a large number of packets and switches back to PSP after the packets have been retrieved. Is recommended when power consumption is a concern but you need greater throughput than that allowed by Max PSP.
6. What is Roaming, how does it work and how can I customize roaming behavior?As a client device moves throughout a facility, it will tend to move in and out of the range of the access points that make up the network infrastructure. In order to maintain constant connectivity and stable performance, a moving client device will disassociate from one access point and then reassociate to another access point that provides for better connectivity. Roaming is the term applied to this action. The "decision" to initiate a roam is based on a number of conditions and parameters. With Summit software release 1.02.20 and later, Summit provides two complementary sets of roaming algorithms to provide for more reliable connectivity. Those sets of algorithms are:
Standard, which manages roaming behavior under typical conditions. Users can adjust Standard Roaming parameters to customize roaming behavior for a particular environment. Aggressive, which manages roaming behavior when the client device is in areas of particularly low coverage and is in imminent jeopardy of losing its connection to the network infrastructure. Users may not adjust Aggressive Roaming parameters but may disable this feature.
Standard Roaming The standard roaming algorithm is employed when Summit-enabled client devices are operating in areas of relatively strong RF coverage. This roaming algorithm is based on the signal strength, or Received Signal Strength Indication (RSSI, which is measured in dBm) of the current AP (the Access Point to which the client is currently associated) and any other APs that are within range of the client. The Summit radio calculates a moving-average RSSI for the current AP and treats it as the “current RSSI”. This value is displayed on the Status tab of the Summit Client Utility (SCU).
The administrator can configure three parameters for the standard roaming algorithm: Roam Trigger, Roam Delta, and Roam Period. Here is a description of each of these parameters and how they operate:
Roam Trigger: When the RSSI value of the current AP is weaker than the Roam Trigger value, the client will initiate (trigger) a roam scan where it sends probes to all other APs within range of the client. These APs will reply to the probes which will allow the client to assess the RSSI values of these available APs. Higher Roam Trigger values will tend to result in more frequent roam scans, lower Roam Trigger values will tend to result in less frequent roam scans. Roam Trigger values can range from -50 dBm to -75 dBm, may be configured in SCU in 5-dBm increments, and has a default value of -70 dBm. In addition, any integer may be assigned as the Roam Trigger in the registry.
Roam Delta: As per the above, when the Roam Trigger is met, the client will initiate a scan of all other APs within range of the client. The client will disassociate from the current AP and reassociate to another AP (roam) only when the RSSI of the other AP is at least the Roam Delta value stronger than the RSSI value of the current AP. Lower Roam Delta values will tend to result in more frequent roaming, higher Roam Delta values will tend to result in less frequent roaming. The Roam Delta may be configured in SCU in 5-dBm increments between 5 dBm and 35 dBm and is set by default to 15 dBm. In addition, any integer may be assigned as the Roam Delta in the registry.
Roam Period: After association to a new AP or the conclusion of a roam scan (with no roam), the client device will maintain association to the current AP for the Roam Period value (in seconds) before initiating a new roam scan. The Roam Period may be configured in SCU in five-second increments between 5 seconds and 60 seconds and is set by default to 10 seconds. In addition, any integer may be assigned as the Roam Period in the registry.
A Standard Roam scenario would be as follows: A client that is associated to an AP sees the RSSI go below the -75 dB Roam Trigger value, e.g. it goes to -80 dB. This prompts it to initiate a roam scan looking for a better AP (“better” in terms of signal strength). If it finds one, it will roam to it if the RSSI on the target AP is greater than the current AP by the Roam Delta value and it has been associated to the current AP for at least the Roam Period value.
Changing these parameters allows users to customize the roaming behavior of the client for environments that might be somewhere on a continuum between two extremes: if an environment has under-coverage (i.e., relatively few APs for the size of the facility) then the user can set the Roam Trigger to look for a new AP sooner and set the Roam Delta and Roam Period to smaller values so that the client will roam more quickly when it finds an alternative to the current AP. On the other hand, if an environment has over-coverage (i.e., a relatively large number of APs for the size of the facility) the user can set the Roam Trigger to a high value so that the client will only start looking for a new AP if the current AP signal gets very low, the new AP has a much stronger signal (Roam Delta), and the client has been associated to the current AP for some larger amount of time (30 seconds perhaps). How a given customer will configure these settings will depend on their RF environment, but also on the types of devices they use (laptop vs. data terminal for example), how those devices are used (truck-mounted going 25 MPH (40 KPH) or carried on a belt and being walked around), and what types of data they handle (voice/video vs. low data rate/latency insensitive bar-code scanning).
Aggressive Roaming Aggressive Roaming is employed when Summit-enabled client devices are operating in areas of relatively weak RF coverage such as the edge of a coverage area. Aggressive roaming uses settings that are not configurable but have been determined in real customer environments to be optimal for reliable connectivity in areas of relatively weak coverage. Aggressive Roaming can, however, be disabled as per the below. Aggressive roaming is triggered when the radio misses too many of the beacons expected from the current AP during a defined interval. The number of expected beacons is determined from the AP’s beacon rate and DTIM interval.
Once aggressive roaming is triggered, the radio scans for a “better” AP every second. If Aggressive Roaming is triggered Aggressive Roaming will stop only when the client finds an AP with an RSSI that is stronger than that of the current AP and the client then roams to that AP. Aggressive Roaming will stop after a successful roam or if the number of received beacons returns to the expected number. If the client moves completely out of the coverage area for all APs, it will miss all beacons, determine that it no longer is associated to an AP, and will change its status to “Not Associated”. The client will then revert to Standard Roaming.
In some environments such as environments with more than enough RF coverage (and significant co-channel interference) it may be desirable to disable Aggressive Roaming. This may be done through the "Aggressive Scan" menu item on the Global Settings tab in the Summit Client Utility (SCU). Changing the Aggressive Scan value from "On" to "Off" will disable this feature.
Aggressive Scanning may also be disabled by adding the below DWord to the registry and setting it to all zeroes as per the below:
"aggScanTimer"=dword:00000000
7. Can I customize the locations into which the Summit software is installed?Yes. Version 1.2.24 and later versions of he Summit software support the ability to install and run our driver and other files from user-specified locations such as a secondary storage device like a flash drive. This can be useful for those customers that require the ability to update Summit software without having to rebuild the system's entire software image (inclusive of operating system). To install the Summit software suite to a custom location, copy all Summit files in a custom directory such as \Flash Disk. Register the driver and add all registry keys as outlined in the Summit User's Guide which may be found at http://www.summitdatacom.com/documentation.htm.
Certain applications within the Summit software suite "expect" to find other applications at their default location. When performing a custom installation, you will have to manually edit the registry to specify the custom locations. The SCUtray tray icon expects the SCU.exe application to be in \\Summit\\scu.exe in the device’s Programs folder (CSIDL_PROGRAMS). To change the SCU location, add an AppLocation key specifying the folder where SCU is located such as \Flash Disk. Add the AppLocation key to the GlobalConfig area - HKLM\\Comm\\SDCCF10G1\\Parms\\Configs\\GlobalConfig.
The default certificates folder (if using EAP-FAST, PEAP-MSCHAP, PEAP-GTC) is \\Summit\\Certs\\ in the Programs folder. You can change the certs location by changing the certPath registry key, also in the GlobalConfig area of the registry.
If your operating system specifies a folder where it searches for drivers, place the files in that folder and add all registry entries (using a REG file). Add an AppLocation key to the Global Config area to specify the path to the scu.exe. You may also use the SCU or edit the certPath registry key if using certificates. If you don't know this folder, the easiest way to test this is to build a CAB file that installs the files to your custom location and adds all necessary registry keys. Summit's Technical Services group (support@summitdatacom.com) can provide assistance with this if necessary.
To test your custom installation: --Check that WPA or any EAP/Encryption combos that use our supplicant works. --Make sure that SCUtray tray icon appears in the system tray and that clicking on it opens the SCU. --Power-cycle the device and make sure that SCUtray, supplicant, etc. are still working.
8. How do I create a Personal Certificate for EAP-TLS using CiscoSecure ACS?The following outlines the generation of a Personal Certificate for EAP-TLS using version 4.01 of CiscoSecure ACS and a Certificate Authority (CA) both of which are running on the same Windows 2003 server. Any Windows PC with Internet Explorer may be used to generate and retrieve the certificate from the CA. In this example, the certificate is then installed on the client, an HP iPAQ running Windows Mobile v5.0.
Note: The CA should be configured to automatically issue certificates upon request (rather than queue them up for the administrator).
Detailed Steps: 1. Generate the certificate From the IE browser on the PC browse to the CA. Then: Select “Request a certificate” Select “advanced certificate request” Select “Create and submit a request to this CA” Provide a name that matches a valid username account on the ACS Server. Then: Select “Client Authentication Certificate” Select Key Size of 1024 Check “Mark keys as exportable” Accept all other defaults Click on “Submit” Select “Yes” when prompted with “Potential Scripting Violation…Do you want to request a certificate now?” Select “Install this certificate”. Select “Yes” when prompted with “Potential Scripting Violation…Do you want to add the certificates now?”
2. Prepare the certificate for export From the IE browser on the PC go to Tools, Internet Options, Content tab, Certificates. Then: Select the certificate and click on “View” Go to the Details tab. Select “Copy to File” (this will initiate the Export Wizard) Select “Next” Select the radio button “Yes, export the private key” Select “Next” Select the radio button for “Personal Information Exchange - PKCS #12 (.PFX)” Select the checkbox “Include all certificates in the certification path if possible” Unselect the checkbox “Enable strong protection” Select “Next” Enter a password that will be used the first time the certificate is authenticated (e.g. ‘summit’) Select “Next” On the “File to Export” screen browse to a directory of your choice and enter a name. It will get .pfx added to it. Select “Next” Select “Finish” On the last page, Select “Ok” to complete the wizard
3. Install the certificate on the client NOTE: Be sure to update the date and time on the client device or the certificate will fail On the PC, copy the certificate onto a memory card (such as an SD or CF memory card depending upon your client device) Install the memory card into the client and copy the certificate into a local directory Use the PFXIMPRT utility to import the certificate into the iPAQ’s certificate store. When the utility runs, there are two fields to fill in The first field is for the certificate. Browse to the certificate on the device and select it. The second field is populated with the password assigned to the certificate as part of the export process (‘summit’ in this example). Tap the “Import certificate” button. It will show that 1 personal cert was installed and 1 root cert was installed. Tap “ok”. To verify that the certificate is installed properly on the client, go to Settings, System tab, Certificates. On the Personal tab will be the certificate and expiration date. On the Root tab will be the name of the Certificate Issuer (CA) that issued the certificate.
4. Configure an SSID to use the Certificate Using Windows Zero Config on the client, select the SSID from the list, edit its properties to use “Smart card or certificate”, and select the certificate from the available certificates in the store. You should get prompted for the password assigned to the certificate (summit). The client should authenticate.
9. How do I log into the Summit Client Utility as an Administrator?Summit radios are typically installed into devices such as data terminals and similar data collection devices that are often used by individuals with little technical expertise, the Summit Client Utility (SCU) by default restricts the ability to make configuration changes.
Administrators and those with the need to change radio configuration parameters can, however, "unlock" these capabilities by logging into SCU as an administrator. To do so, go the the Main tab of SCU and click or tap on the "Admin Login" button. At the next screen, type in the Admin password. By default, the admin password is "SUMMIT" (all capital letters, no quotation marks). After clicking or tapping "OK" you'll be returned to the Main tab-- note that the Admin Login button now reads "Admin Logout". Pressing Admin Logout will "re-lock" the ability to make configuration changes.
The admin password may be changed on the Global Settings tab of SCU while in admin mode. By default SCU does not hide passwords. Passwords may be hidden by selecting the "Hide Passwords" property also found in the Global Settings tab.
10. Why does Summit restrict software access?The types of devices into which Summit radios are typically installed are wide and varied with different processors, operating systems, applications and peripherals. As such, the possibility of a new software release causing unintended issues is far greater for Summit than is the case for a company that serves a less varied market.
As such, Summit works closely with OEM customers to make sure that new Summit releases operate as expected in their devices. Summit leaves it to the OEM to certify a Summit release for their particular products and then make it available to their customers and partners. As such, Summit does not provide software access to resellers, integrators or end users.
Summit does, however, make our software available to a limited number of distributors who serve "after market" customers such as those that are installing Summit radios into standard PDAs and PCs. The current list of Summit distribution partners may be found at: http://www.summitdatacom.com/how_to_buy.htm.
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