Digi TransPort/Sarian Support FAQ

FAQ

General Configuration

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Q: How can I reset my Digi TransPort or Sarian-branded router to it's factory defaults?
A: You can press and hold the 'User' button for 5 seconds to reset the router back to it's default configuration or use Flashwriter to return the router to a basic configuration.
Q: Can I use Internet Explorer to copy files to and from the Digi TransPort or Sarian-branded router?
A: Yes, either from a LAN connection or a Dial-Up Networking connection. See FTP with IE for full details.
Q: I want to connect to my Digi TransPort or Sarian-branded router via an ASY port with Dial-Up Networking but I get a 'Hardware Error' when it tries to dial.
A: This is usually due to modem speed being set incorrectly, check the speed of the ASY port and change it in both the Windows Control Panel > Phone and Modem Options and the DUN connection properties.
Q: When using FlashWriter I cannot access the device on a USB COM port device.
A: Unfortunately, many USB com port devices are lacking functionality or have bad flow control which is necessary for safe operation of FlashWriter, try using a hardware COM port instead.
Q: I want to use a Digi TransPort or Sarian-branded GPRS router as a backup to my main internet router. Can I use the Digi TransPort or Sarian-branded router to get access to the RS232 console port on the router and access it over GPRS?
A: Yes, connect the router's console port to the Digi TransPort/Sarian-branded's ASY port and set it to 'telnet mode' with Configure -> General -> ASY [port] Telnet mode: 'Telnet WITH null stuffing'. It can then be accessed by telneting to the GPRS Digi TransPort or Sarian-branded on port 400x (where x is the number of the ASY port). Note that a special cable is available from Digi International to connect directly to the special console port interface on Cisco devices.

Generic WAN

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Q: How do I configure a static IP address on a PPP interface?
A: To use a static IP address on the PPP interface:

You should configure the PPP parameters as shown here (configure >> ppp 1 > standard), replacing the IP address and subnet details with your own:

Then to turn off the DHCP client on the PPP interface, browse to PPP x > Advanced and set Request IPCP local address option: to NO.
The DNS server option is on the PPP x standard page, we only support 1 DNS server on the PPP interfaces so enter 1 address here:

The gateway address is configured in Configure > IP Routes > Default route 0
The Source address and mask should be left blank.

GPRS Connections

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Q: I am connecting by GPRS - what speed and response time should I expect?
A: A ping round-trip-time of <700ms is considered exceptional for GPRS you can expect ping times up to 1.5 seconds. Speed varies by operator but you can expect up to 20 44Kb/s downstream and 10 22Kb/s upstream. Speeds can be more than this where the operator supports higher coding schemes (e.g. CS3 or CS4) which typically relates to North American networks.
Q: Do any Sarian-branded routers support Enhanced Data rate for GSM Evolution (EDGE) mode?
A: The Sarian-branded ER series support EDGE with automatic fallback to GPRS, speeds of up to 177Kb/s have ben observed in tests. Check out the ER2110 details in the product section.
Q: I have a GPRS connection to the internet but cannot resolve any hostnames.
A: Check your PC's IP settings and make sure you have the Digi TransPort or Sarian-branded as the DNS host.
Q: I have a GPRS router but would like to back-up to GSM/CSD in the event of a GPRS failure - can this be done?
A: Yes, See Application Note 12 for full details.
Q: How can I tell the status of my GPRS connection?
A: From the web interface Status -> GPRS Module. Also see GPRS Status for full details.
Q: How can I get my GPRS router to answer GSM/CSD data calls?
A: You will need to add an initialization string to enable the data bearer under Configure -> GPRS -> Modem Init 0 -> at+cbst=71,0,1 then you can configure a PPP instance to answer the call.
Q: How can I find out the absolute speed of my GPRS connection?
A: Currently neither the GPRS modules used in the Digi TransPort or Sarian-branded routers nor the network itself makes this information available.
Q: How Do I reset my GPRS Connection?

A: GPRS connections are more likely to go stale than other PPP type connections. When this happens, the connection remains up, but no data is transmitted.

Fortunately, there is a mechanism for dealing with this issue. We have a very useful firewall which can inspect the state of the connection based off of ICMP or TCP traffic and then declare an interface OOS or Out Of Service. This involves turning the firewall for the PPP port on and making sure the correct firewall rules are in place. For example:

Pass out break end on PPP 1 proto TCP from addr-ppp 1 to any flags S!A inspect-state oos 60 t=10 c=5 d=10

This rule allows packets out, but it monitors the state of the TCP connections. If a TCP connection is not made, the interface is declared OOS for 60 seconds. It has 10 seconds to find a connection, has 5 connection attempts, and if after 10 connection attempts it still fails, the interface will be rebooted. In essence, you'll be turning the interface off and back on.

You'll want to follow that up with a second rule just allowing the rest of the traffic through like:

pass break end.

If you put these two lines in a file called fw.txt, upload it to the router and then turn the firewall on for PPP 1, you'll have the solution to your problem. If you like, you can adjust the C and D values down to 1 or 2 to cause them to reboot quickly.

Q: What do the RSSI Codes mean that appear in the Event log?

A: These are messages from the Siemens MC45 GPRS module, and are quite normal.

URC stands for Unsolicited Result Codes - these are mostly just informative messages generated by the module, and occur whenever the status of something changes in the module. The most common status change is when the signal strength changes (rssi = received signal strength indication). The event is CIEV:rssi and the values are in the range 0 .. 5, where:
0 = signal strength <= -112 dBm
1-4 = signal strength in 15 dBm steps
5 = signal strength >= -51 dBm

This would look like the following in the Event log:
14:26:35, 30 Jul 2008,GPRS URC CIEV: rssi,2

The CIEV:Signal events are a measure of estimated signal quality.
0 through to 7, 0=best...7=worst, 99 means unmeasurable.
13:13:03, 03 Jul 2007,GPRS URC CIEV: signal,3

ISDN

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Q: I keep seeing ISDN events in the trace F3->F7 what does this mean?
A: These are layer 1 status messages from the BRI interface, where F7 is the final working state of the line, see I.430 for more details. You would typically see this when connecting in your ISDN line, if you see F8 messages (loss of framing) then this can indicate a problem with the line.
Q: When trying to make an ISDN call it fails with 'no cct' in the trace.
A: 'no cct' means no circuit and usually indicates that both 'B' Channels on the BRI line are in use, if you share your channels with analogue phones (e.g. BT Highway) then each phone call will utilise a 'B' Channel.
Q: What do the different layer 1 state definitions mean?
A: The following codes will be displayed in the Sarian-branded's event log when using ISDN:
F1 - Inactive
In this inactive (powered-off) state, the terminal equipment (TE)1 is not transmitting and can not detect the presence of any input signals.
F2 - Sensing
This state is entered after the TE has been powered on but has not determined the type of signal (if any) that the TE is receiving. When in this state, a TE may go into a low power consumption mode.
F3 - Deactivated
This is the deactivated state of the physical protocol. Neither the network termination (NT)2 nor the TE is transmitting. When in this state, a TE may go to a low power consumption mode.
F4 - Awaiting Signal
When the TE wishes to initiate activation, it sends an Activation signal to the NT and awaits a response.
F5 - Identifying Input
At first receipt of any signal from the NT, the TE stops sending Activation signals and awaits the activation signal or synchronized frame from the NT.
F6 - Synchronized
When the TE has received an activation signal from the NT, it responds with a synchronized frame and is awaiting a synchronized frame from the NT.
F7 - Activated
This is the normal active state, with the protocol activated in both directions. Both the NT and the TE are transmitting normal frames. State F7 is the only state where B-channel and D-channel contain operational data.
F8 - Lost Framing
This is the condition when the TE has lost frame synchronization and is awaiting re-synchronization.

Wireless

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Q: What are the International APN's (Access Point Name) for wireless operators?
A: Please view this excel document.
Q: What do the signal indicators mean on my Digi TransPort or Sarian-branded router?
A:The signal strength is shown in negative dB, which means that the stronger the signal, the lower the number. As a guide -51dB would be a very strong signal, only normally obtained very close to a cell site. -115dB represents no signal. If your router reports -115dB try reorienting the antenna or consider adding an external antenna. On routers equipped with GPRS modules, there are three LED's on the front panel that will indicate the strength of the signal, as shown in the table below. The minimum recommended strength indication is 2 LED's. If you have no or 1 LED's lit, it is recommended that you fit an external antenna to the router.
LED's Lit Signal Strength
None Under -113 dBm (effectively no signal)
1 -112 dBm to -87 dBm (weak signal)
2 -86 dBm to -71 dBm (medium strength signal)
3 -70 dBm to -51 dBm (strong signal)
Q: Can I choose which network technology my wireless router uses?
A: A HSDPA/3G router can be configured to specifically connect to the desired Radio access technology:
The following initialization string may be used to control the radio access technology on the a router:
What you need to do is connect to the Digi TransPort or Sarian-branded router via the web interface and navigate to the following location,

Configure-> GPRS Module->SIM 1

Use the first available blank initialization string and enter the following:

NOVATEL only
$NWRAT=n,2

Where n is:
0 for automatic
1 for GSM only (GSM = GPRS / EDGE)
2 for WCDMA only (WCDMA = 3G / HSDPA)

OPTION only
_OPSYS=n,2

Where n is:
0 for GSM only (GSM = GPRS / EDGE)
1 for WCDMA only (WCDMA = 3G / HSDPA)
5 for automatic

SIERRA WIRELESS only
!SELRAT=n
Where n is:
00 for Automatic
01 for UMTS 3G only
02 for GSM 2G only
03 for UMTS 3G preferred
04 for GSM 2G preferred

ALL MODULES, continue here:
Save the changes and drop your PPP instance to initialize.
Sometimes the module requires a power cycle to initialize.
When reverting to automatic selection it is not enough to remove the initialization string you must specify the correct number for automatic.

NEW CLI parameter for OPTION modules, firmware 5.049 or later is required, this supersedes the _OPSYS parameter described above:
The command 'modemcc 0 psys n' (for SIM 1) and 'modemcc 0 psys_2 n'(for SIM 2) may be used to set the preferred system (GSM/WCDMA).
This command is only supported on Option 3G modules. Usage is: modemcc 0 psys n, where n is:
0 (module's factory default)
1 (GSM only),
2 (WCDMA only),
3 (Automatic),
4 (GSM first),
5 (WCDMA first),
99 (disables the feature, i.e. prevents any change occurring).
Use 'modemcc 0 psys_2 n' for SIM 2 settings.
Note that for the Option 3G modules, the module's factory default is 'WCDMA first'.
Note also that if one of the modem init strings is an '_OPSYS=...' command, then this setting does nothing so as to avoid any conflict with an existing configuration.

Please note that if you specify the chosen network technology and for whatever reason that technology is not available you will be left without any service at all.

Q: How fast are today's wireless networks?
A: Please see the table below for details:
  GPRS EDGE 3G HSDPA 3.6 HSDPA 7.2 HSUPA
Theoretical Max Upload Data rate kb/s 42.8 118.4 64 384 384 1.8Mb/s
Real Life Experience Data rate kb/s 10-20 80-100 50-60 200-300 200-300  
Theoretical Max Download Data rate kb/s 85.6 177.6 384 3.6Mb/s 7.2Mb/s 7.2Mb/s
Real Life Experience Data rate kb/s 30-40 130-160 180-230 600-900    

Serial

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Q: What Serial Port Settings should I have on my PC?

A: When making a serial connection from the Digi TransPort or Sarian-branded router to a PC or laptop, this can be done using a terminal emulator program such as Hyperterminal or Teraterm. Connect to the serial port using a straight through serial cable.

The following settings need to be made:

Port - Set this to match the PC port that the Digi TransPort or Sarian-branded router is connected to (eg COM2)
Baud rate - 115200
Data - 8 Bit
Parity - None
Stop - 1 bit
Flow control - None

Firewall

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Q: What Serial Port Settings should I have on my PC?
A: If you are using NAT then the Digi TransPort or Sarian-branded router will need to change the FTP-CNTL data going through it, this can be turned on using the firewall rule pass out proto ftp from any to any inspect-state.
Q: How do I NAT (Network Address Translate) the source and destination of a packet?

A: Both of the laptops need to be able to talk to each other, however they have no routes pointing at the Digi TransPort or Sarian-branded router.

The Digi TransPort or Sarian-branded router uses the following setup:

Use either Port Isolate mode or use the Group option to place Eth 1 in another Hub Group.

Eth 0 & 1:
Firewall turned on, NAT is off.

Firewall config:

pass in break end on eth 0 from 192.168.0.5 to addr-eth 0 -> addr-eth 1 to 192.168.20.5
pass out break end on eth 0

pass in break end on eth 1 from 192.168.20.5 to addr-eth 1 -> addr-eth 0 to 192.168.0.5
pass out break end on eth 1

Q: What ports do i need to open on the firewall to allow IPSec tunnels?

A: To allow IP Sec traffic through a firewall you will need to ensure the following ports / protocols are allowed.

IKE - TCP/UDP 500
IKE Float -TCP/UDP 4500
Compression if used - Protocols 4 & 108
ESP - Protocol 50
L2TP (windows Client VPN) - UDP 1701

Examples

pass break end proto udp from any port=1701 to any inspect-state

pass break end on PPP 1 proto udp from any to addr-ppp 1 port=500 inspect-state
pass break end on PPP 1 proto udp from any to addr-ppp 1 port=4500 inspect-state
pass in break end on eth 3 proto 50 from any to addr-eth 3 inspect-state
pass break end on eth 3 proto 4 from addr-eth 3 to any inspect-state
pass break end on eth 3 proto 108 from addr-eth 3 to any inspect-state

#This Last rule allows traffic over the Eroute, in the example the eroute number is 0
pass break end oneroute 0

Routing

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Q: Can I create a raw TCP connection from the command line to a remote host?
A: Yes, See Application Note 2 for full details.
Q: I would like to replace a modem-modem link with an IP connection - how can this be done?
A: The Digi TransPort or Sarian-branded router supports many modes of operation to 'spoof' modem commands, if the target host is IP enabled you can use TCPDIAL or Adaptive-rate over IP for end-to-end emulation.
Q: I would like to use a Digi TransPort or Sarian-branded GPRS router as a backup for my main internet router.
A: Digi TransPort or Sarian-branded GPRS devices support the VRRP protocol for redundant backups as well as advanced probing features (called VRRP+) that allow the Digi TransPort or Sarian-branded router to detect the loss of even a remote link and cause it to take over routing.
Q: I am using Microsoft DDNS service but the Sarain does not register its IP address.
A: The Digi TransPort or Sarian-branded routers can update to an RFC-compliant DDNS service, currently Microsoft's DDNS is proprietary.
Q: What are the default settings for the PPP instances on a Digi TransPort or Sarian-branded router?
A: In the standard shipping config for most products PPP 0 is set to answer incoming PPP calls and PPP 1 is set to dial out on ISDN/GPRS. The MW3520 PPP 1 is pre-configured for ADSL, PPP 2 is pre-configured for ISDN, PPP 3 is pre-configured for GPRS and PPP 4 is configured for internal PSTN modem.

VPN

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Q: I want to make an IPSEC tunnel but I have a dynamic client IP address.
A: Use IKE Aggressive Mode on the client, See Application Note 10 for full details.
Q: Can I create a VPN connection if I am getting an RFC1918 private address from my network provider?
A: Yes, Digi TransPort or Sarian-branded routers support IPsec Aggressive mode with version 3 NAT traversal, See Application Note 10 for full details.
Q: How can I make an IPSEC Main Mode/Aggressive mode connection when both my host and client get dynamic public addresses?
A: Use the Dynamic DNS feature and your own or an internet based dynamic DNS service (e.g. dyndns.org, no-ip.org) and use the hostnames as the peer ID's for your connection.
Q: Can I make a VPN connection from my Windows 2000/XP machine to a Digi TransPort or Sarian-branded router?
A: Yes, See Application Note 11 for full details.
Q: Can the Digi TransPort or Sarian-branded router make a VPN tunnel to a Cisco PIX?
A: Yes, please refer to Application Note 27 for full details.
Q: Will the Digi TransPort or Sarian-branded router pass through my L2TP/PPTP VPN client data?
A: Yes, although for PPTP you will need to enable GRE protocol on your interface.
Q: Can the Digi TransPort or Sarian-branded router make a VPN tunnel to a Cisco IOS Router?
A: Yes, See Application Note 9 for full details.
Q: Can the Digi TransPort or Sarian-branded router make a VPN tunnel to a Cisco 3000 Series VPN Concentrator?
A: Yes, this has been tested on numerous occasions.
Q: I have a Sarian-branded MR2110 and want to create a VPN using 3DES/DES/AES these options do not appear on the menus.
A: The encryption pack is an extra option for this model, please the contact sales for full details.
Q: What ports do i need to open on the firewall to allow IPSec tunnels?

A: To allow IP Sec traffic through a firewall you will need to ensure the following ports / protocols are allowed.

IKE - TCP/UDP 500
IKE Float -TCP/UDP 4500
Compression if used - Protocols 4 & 108
ESP - Protocol 50
PPTP (windows Client VPN) - UDP 1701

Examples

pass break end proto udp from any port=1701 to any inspect-state

pass break end on PPP 1 proto udp from any to addr-ppp 1 port=500 inspect-state
pass break end on PPP 1 proto udp from any to addr-ppp 1 port=4500 inspect-state
pass in break end on eth 3 proto 50 from any to addr-eth 3 inspect-state
pass break end on eth 3 proto 4 from addr-eth 3 to any inspect-state
pass break end on eth 3 proto 108 from addr-eth 3 to any inspect-state

#This Last rule allows traffic over the Eroute, in the example the eroute number is 0
pass break end oneroute 0

Firmware

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Q: Where can I download the latest version of Firmware for my Digi TransPort or Sarian-branded router?
A: Visit the Firmware page for full details.
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