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Generic WAN
Q:
How do I configure a static IP address on a PPP interface?
GPRS Connections
Q:
I am connecting by GPRS - what speed and response time should
I expect?
Q:
Do any Sarian units support Enhanced Data rate for GSM Evolution
(EDGE) mode?
Q:
I have a GPRS connection to the internet but cannot resolve any
hostnames
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?
Q:
How can I tell the status of my GPRS connection?
Q:
How can I get my GPRS router to answer GSM/CSD data calls?
Q:
How can I find out the absolute speed of my GPRS connection?
Q:
How Do I reset my GPRS Connection?
Q:
What do the RSSI Codes mean that appear in the Event log?
ISDN
Q:
I keep seeing ISDN events in the trace F3->F7 what does this mean?
Q:
When trying to make an ISDN call it fails with 'no cct' in the
trace.
Q:
What do the different layer 1 state definitions mean?
Wireless
Q:
What are the International APN's (Access Point Name) for wireless operators?
Q:
What do the signal indicators mean on my Sarian?
Q:
Can I choose which network technology my wireless router uses?
Q:
How fast are today's wirless networks?
Generic WAN
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
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 donwstream 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 units support Enhanced Data rate for GSM Evolution
(EDGE) mode ?
A: The Sarian 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 Sarian 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 initialisation 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 Sarian units
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 quality changes (rssi = received signal strength indication). 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:
13:13:06, 03 Jul 2007,GPRS URC CIEV: signal,0
13:13:03, 03 Jul 2007,GPRS URC CIEV: signal,3
13:07:21, 03 Jul 2007,GPRS URC CIEV: signal,0
ISDN
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's even 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
Q:
What are the International APN's (Access Point Name) for wireless operators?
A: Please click on the attached excel document:
Q:
What do the signal indicators mean on my Sarian?
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 unit reports -115dB try reorienting the antenna or consider adding an external antenna. On units equipped with GPRS modules, there are three LEDs 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 LEDs. If you have no or 1 LEDs lit, it is recommended that you fit an external antenna to the unit.
| LEDs 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 unit can be configured to specifically connect to the desired Radio access technology:
The following initialisation string may be used to control the radio access technology on the a router:
What you need to do is connect to the Sarian via the web interface and navigate to the following location,
Configure-> GPRS Module->SIM 1
Use the first available blank initialisation 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
BOTH MODULES, continue here:
Save the changes and drop your PPP instance to initialise.
Sometimes the module requires a power cycle to initialise.
When reverting to automatic selection it is not enough to remove the initialisation string you must specify the correct number for automatic.
Please note that if you specify the chosen network technology and for whatever reason that technology is not avaialable you will be left without any service at all.
Q:
How fast are today's wirless 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 |
|
|
|
