PacketBand-ISDN Technical FAQs

1. Q. Where can I download the DbManager software?
   
   
2. Q. Where can I find cable specifications?
   
   
3. Q. Where can I find the manual?
   
   
4. Q. How do I connect to the device?
   
   
5. Q. What does NT mean?
   
   
6. Q. What does TE mean?
   
   
7. Q. What do Patapsco’s different coloured cables mean?
   
   
8. Q. I can’t see some of the settings shown in the manual/they are grayed out. Why?
   
   
9. Q. When I upload to my device, I get an error message about commands not being accepted. Why?
   
   
10. Q. I am using an old version of DbManager. How can I upgrade?
    
    
11. Q. I only have one device node to connect to my units. How can I add more?
    
    
12. Q. How do I save the configuration to the device?
    
    
13. Q. Why can’t PacketBand clock from NT BRI ports?
    
    
14. Q. Why can’t I hear tones on my ISDN device?
    
    
15. Q. The tones my PacketBand generates sound very distorted!
    
    
16. Q. What is the difference between the switch types in the T1 PRI/US BRI options?
    
    
17. Q. How do I know if the BRI ports should be set to Point-to-point or Multipoint?
    
    
18. Q. Is there a way that I can look at how many calls are currently active?
    
    
19. Q. Should I use Pseudo-wire over IP or Pseudo-wire over IP including UDP/RTP?
    
    
20. Q. My call seems to route before I can dial all the digits, why?
    
    
21. Q. When I connect the BRI cables to PacketBand, the ports do not light up and my device shows no layer 1 activity. What is wrong?
    
    
22. Q. What is the difference between a Dynamic and fixed Logical Link?
    
    
23. Q. Can I break in/out of the PSTN public ISDN?
    
    
24. Q. What type of devices can I attach to a PacketBand-ISDN?
    
    
25. Q. What is the SIP Server option for?
    
    
26. Q. Can multiple ISDN users share the PSTN/ISDN network ports?
    
    
27. Q. Can I route in-coming ISDN calls from the network to specific ISDN ports?
    
    
28. Q. What is a Logical Link?
    
    
29. Q. What are the best Frames Per Packet settings to use?
    
    
30. Q. Can I use PacketBand on the public Internet and what are the issues?
    
    
31. Q. Can I use a satellite link?
    
    
32. Q. Will the link carry any traffic transparently?
    
    
33. Q. What is a Lost packet and a Late packet?
    
    
34. Q. What is the latency added by PacketBand?
    
    
35. Q. My PacketBands only have 1 Logical Link and I need more. How can I add more Logical Links?
    
    
36. Q. How do I know the best Jitter Buffer setting to use?
    
    
37. Q. How do I know where the clocking will come from for the system?
    
    
38. Q. I'm seeing a lot of packet loss on my link. What can I do about it?
    
    
39. Q. There are firewalls on the sites where PacketBand will be used. Can it still work?

Q1. Where can I download the DbManager software?

Please register at http://www.Patapsco.co.uk/Top_Level/LogIn_Register.asp for access to DbManager software. Back to top.

Q2. Where can I find cable specifications?

All cable specifications can be located in any Patapsco manual. Back to top.

Q3. Where can I find the manual?

All Patapsco product manuals and quick start guides can be located on the CD provided. They can also be found by signing in to www.patapsco.co.uk Back to top.

Q4. How do I connect to the device?

PacketBand can be initially connected to via the serial cable provided with the unit. Alternatively, the default IP address can be used for IP connection to the unit. Once a connection has been established with PacketBand, a new IP Address can be configured. All Patapsco devices have a default IP address of 192.168.0.1 Back to top.

Q5. What does NT mean?

The NT ports on a Patapsco device present as a Network, i.e. for connection to a piece of Terminal (TE) equipment. Back to top.

Q6. What does TE mean?

The TE ports on a Patapsco device present as a Terminal or User port, i.e. for connection to a Network (NT). Back to top.

Q7. What do Patapsco’s different coloured cables mean?

Green = E1/T1/PRI, BRI and Ethernet straight
Yellow = PRI crossover
Red = BRI crossover Back to top.

Q8. I can’t see some of the settings shown in the manual/they are grayed out. Why?

DbManager can be configured to run in two modes; Starter and Expert. Starter grays out or removes some of the more advanced options within DbManager, while Expert mode shows all available options. The mode can be switched by going to View - Properties - Device Configuring. Back to top.

Q9. When I upload to my device, I get an error message about commands not being accepted. Why?

If commands are not accepted on an upload, the most likely cause is that the version of DbManager in use is older than the firmware on the Patapsco unit. If you have a DbManager installation disk, please see the ‘Upgrade’ folder for information on how to upgrade, or contact Patapsco for instructions on how to upgrade. Back to top.

Q10. I am using an old version of DbManager. How can I upgrade?

If you have a DbManager installation disk, please see the ‘Upgrade’ folder for information on how to update, or contact Patapsco for instructions on how to upgrade. Back to top.

Q11. I only have one device node to connect to my units. How can I add more?

DbManager Lite only allows a single node to be configured for use. Once IP addresses are added to the IP list, the node can be configured to connect to each configured address as required. IP addresses can be configured in View - Properties - Terminal - Device IP Addresses, and the node can be reconfigured by right-clicking it (Ctrl + right-click for older DbManager versions) and going to Properties - IP List. Please contact Patapsco if multiple nodes are required. Back to top.

Q12. How do I save the configuration to the device?

All configuration changes must be uploaded to the device when finished. Changes to the configuration are made ‘offline’, and only take effect when uploaded. Go to File - Upload to load the changes to the device. Config files can be saved to disk by going to File - Save File, and loaded to devices by selecting ‘Load File’ followed by ‘Upload’. Back to top.

Q13. Why can’t PacketBand clock from NT BRI ports?

The architecture of ISDN BRI is such that clock must always be drawn from an NT (network) connection using a TE port. It is not possible to take clock from a TE connection using an NT port. This limitation should be considered when configuring and purchasing devices; TE BRI devices should be used at sites with ISDN network connections. Back to top.

Q14. Why can’t I hear tones on my ISDN device?

Tones are usually provided by the ISDN network. In situations where a network connection is not used, PacketBand has options for providing tones to local devices on a per-port basis. The tone settings can be found on the configuration settings for each BRI and PRI port. Back to top.

Q15. The tones my PacketBand generates sound very distorted!

The tone options allow configuration of two types of tone; A-law and µ-law. A-law tones are commonly used in most of the world except in North America and Japan, where μ-law is more common. If the tone type is set incorrectly for the connected device, the tone will sound distorted. Try switching the tone type if you are unsure whether the connected device is A-law or μ -law. Back to top.

Q16. What is the difference between the switch types in the T1 PRI/US BRI options?

There are three options under Switch Type: National ISDN 2, DMS-100 and AT&T 5E-SS. Each option forces the port to use different Numbering Plan and Numbering Type information elements:

When a call is routed out on a US BRI port, it will be sent on with the Type and Plan associated with that Switch Type. Back to top.

Q17. How do I know if the BRI ports should be set to Point-to-point or Multipoint?

All BRI ports default to Point-to-point mode, in which TEI values are dynamically assigned to calls as they arrive. Multipoint mode allows up to 8 devices to be connected to a single BRI interface, and should only be used if the BRI device or network connected supports it. Back to top.

Q18. Is there a way that I can look at how many calls are currently active?

If a ‘full’ version of DbManager is in use, the current status of calls can be checked by selecting the Connected to Device window and going to View - Call Status. In recent versions of DbManager (including Lite versions), this option can also be found under the Terminal port settings on the device. The Outstanding Events window within DbManager can also be used to determine the status of current active calls. Back to top.

Q19. Should I use Pseudo-wire over IP or Pseudo-wire over IP including UDP/RTP?

PacketBand’s Pseudo-wire over IP protocol is compatible with most types of IP network, and is the default layer 3 protocol setting. The UDP/RTP protocol type can be used for applications which require port number mapping, such as in applications involving firewalls. Back to top.

Q20. My call seems to route before I can dial all the digits, why?

In some scenarios where the overlap dialling method is in use, it may be required for the Liberator to only forward the call after all the required digits have been dialled. In this case, you can set a “call forwarding timer”. This timer is located on the ports advanced configuration button and is called “Overlap wait enable”. Back to top.

Q21. When I connect the BRI cables to PacketBand, the ports do not light up and my device shows no layer 1 activity. What is wrong?

The LEDs on the front of PacketBand represent the two B-channels used for calls. They do not indicate the layer 1 status of the PacketBand. Layer 1 will remain disabled until calls are made/received by the PacketBand. If required, the ports can be configured to constantly hold up layer 1 on the interface. To enable this setting, go to BRIX - Setup Network Port - Advanced Settings - Permanent Link Establish. Enable the option, upload (File - Upload) and reboot PacketBand for the setting to take effect. Back to top.

Q22. What is the difference between a Dynamic and fixed Logical Link?

A fixed Logical Link may only be used when both PacketBand devices are aware of each other’s IP addresses. A fixed Logical Link must have the IP address of the destination device configured, and so the Logical Link can only be used to go to that device.

A Dynamic Logical Link is not aware of the source or destination of the call traffic, and is used dynamically as a vessel for the communication. Destination IP addresses are specified in IPMT listings in the Call Routing Profiles, which can be selected from the Destination drop down menu.

Dynamic Logical Links allow for easier expansion of an existing system, as source IP addresses need not be explicitly configured on units which will receive calls.

Configure a Logical Link with the IP address 0.0.0.0 to enable dynamic operation. Back to top.

Q23. Can I break in/out of the PSTN public ISDN?

PacketBand may be fitted with TE interface PRI or BRI ports, which may be connected to ISDN lines to interface with the PSTN. PacketBand can route calls out to/in from the PSTN based on DDI, CLI, Subaddress, port, channel number and call type. PacketBand will take clock from the network interface which it will use to clock all of its transmissions. Back to top.

Q24. What type of devices can I attach to a PacketBand-ISDN?

Any Euro-ISDN E1 PRI or NET3 BRI device will work with PacketBand. Typically these devices include Phones, Faxes, Routers, PABXs, Video Conferencing units, Codecs, Secure/encryption devices and IVRs. Back to top.

Q25. What is the SIP Server option for?

The call routing for a PacketBand system can be centralized using a SIP server unit. PacketBands route all of their call traffic to the SIP server and the SIP server has routing profiles configured to handle the traffic and route to the correct destination. A Patapsco ‘SIP Manager’ application is available for configuring a SIP server. Please contact Patapsco for more information. Back to top.

Q26. Can multiple ISDN users share the PSTN/ISDN network ports?

PacketBand has support for multipoint connections on BRI ports. This means that up to eight users could connect to the S-Bus on a single BRI port. Also, PacketBand ISDN can be fitted with up to eight BRI ports or four PRI ports. These ports can be distributed between a group of devices, and calls can be routed to and from each port based on the on DDI, CLI, Subaddress, port, channel number and call type. Back to top.

Q27. Can I route in-coming ISDN calls from the network to specific ISDN ports?

Yes. PacketBand has a comprehensive suite of call routing functions, allowing routing based on DDI, CLI, Subaddress, port, channel number and call type. Secondary and tertiary destinations for calls can also be configured, so as to have backup destinations for calls in the event that the primary destination is busy. ‘Hunt groups’ of ports or channels can also be configured for group sources or destinations. Schedules for routing profiles are available, so different routing profiles with different settings can be enabled or disabled at different times of day. Back to top.

Q28. What is a Logical Link?

A Logical Link is a connection between two PacketBand units across a packet switched network. A single Logical Link can support up to 32 "B" channels between these two units. If a unit has one timeslot going to each of two PacketBands it will require 2 Logical Links. Each Logical Link can be configured with different settings (QoS and VLAN tags for example). Logical Links are sometimes referred to as Switched Virtual Circuits (SVCs).
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Q29. What are the best Frames Per Packet settings to use?

The default value is 20, which is a good place to start unless bandwidth allocation is an issue. Generally speaking, the Frames per Packet value should be as low as possible where bandwidth will allow as this tends to deliver the best clock recovery. If the packet switched network is known to have an amount of packet loss, then a higher frames per packet value should be used so that a lost packet will not cause so much data to be lost. Please see the PacketBand Overhead Calculator to work out how much bandwidth a system will occupy. This can be found on the DbManager installation disk. Back to top

Q30. Can I use PacketBand on the public Internet and what are the issues?

PacketBand can be used on the public Internet, provided there is enough network capacity available (remember an ADSL link will have a slow direction which is the limiting capacity of the link and there may also be considerable contention).

PacketBand has no control over packet loss across the link and packet loss means lost data.

The unpredictable nature of the public Internet and lack of prioritisation and management can make stable, synchronous communications systems difficult to run. Having said that, Patapsco does have some good experience in running services across the Internet.

Some actions can be taken to maximise the service and these include using the same ISP at each end of the circuit and using an ISP with QoS (Quality of Service) offerings.

National links and links within a region such as Europe will perform better than long distance inter-continental/regional links. Back to top

Q31. Can I use a satellite link?

PacketBand has been proven to work on many satellite links with excellent results. The large amount of extra delay associated with satellite transmissions is no issue for PacketBand, provided the delay is reasonably stable. Back to top

Q32. Will the link carry any traffic transparently?

Yes, PacketBand ISDN delivers a clear channel for use by any traffic. Back to top

Q33. What is a Lost packet and a Late packet?

PacketBand uses a buffer to collect and reorganize packets as they arrive from the packet switched network. The buffer can be configured to a defined size in order to catch the disorganized and variable transit delayed packets, without adding an unnecessary amount of extra latency to the system in processing time.

Early and Late packets are packets which arrive outside the range of the Jitter Buffer due to being very late or very early (these are rare) in crossing the packet switched network.

Lost packets are gaps in the packet sequence numbers, indicating that the packet was never received, and so was lost within the packet switched network. Early, Late and Lost packets are all unusable by PacketBand and the attached device and therefore are counted as Underruns. Back to top

Q34. What is the latency added by PacketBand?

A. The main setting to take into account when considering the latency added by PacketBand is the length of the Jitter Buffer. The Jitter Buffer should be configured large enough that it will catch early and late packets, but not so large that an inordinate amount of latency is added to the system and not used. Please see the PacketBand manual for a full description of the Jitter Buffer settings. Some of the other Logical Link settings will affect the amount of extra latency imposed by PacketBand, and these are also explained in the manual. Back to top

Q35. My PacketBands only have 1 Logical Link and I need more. How can I add more Logical Links?

Logical Links can be usually added to an existing unit using a configuration number supplied by Patapsco. Please contact Patapsco to purchase extra Logical Links and see the Ordering Information documents. Back to top

Q36. How do I know the best Jitter Buffer setting to use?

Jitter is the variation in delay time across a packet switched network. It is sometimes referred to as Packet Delay Variation (PDV). A high quality, managed packet switched network will often have a defined or maximum amount of jitter. Please consult a network administrator and ask about jitter.

If the amount of Jitter is not already predetermined, it is possible to monitor the Jitter on the network using PacketBand. PacketBand monitors its Jitter Buffer, and will report when packets fall outside the Jitter Buffer range. These are reported as Late and Early packets, and indicate that the Jitter Buffer length should be extended. graphs of Jitter Buffer usage are also available on DbManager and alarms can be generated if the network starts to perform outside of a configured threshold.

Please see the PacketBand manual for more information or contact Patapsco. Back to top

Q37. How do I know where the clocking will come from for the system?

Correct clocking for a system is absolutely vital - without it you will experience lost data (at best). PacketBand-ISDN performs a number of "invisible" tasks to ensure the clocks are synchronised and recovered across the network, including negotiating with any connected peers to determine who has the best source or who has a network clock, and renegotiating this as calls are made/cleared between different devices. This process is automatic, not seen by the user, who does not experience any change or degradation in service whist this is happening. Back to top

Q38. I'm seeing a lot of packet loss on my link. What can I do about it?

Packet loss can be experienced on poor quality and/or heavily loaded packet switched networks. PacketBand has no control over packet loss. The connection can be improved if PacketBand traffic can be prioritised over other traffic on the network. PacketBand supports QoS, ToS, VLAN, Diffserv and VPN. There are some other factors which can cause packet loss:

1. Half duplex links - PacketBand must have a full duplex path to other PacketBand devices. Switches and Routers connected to the system should be set to auto-negotiate or fixed to full duplex. If they are not you may see periodic and quite regular packet loss as a result of collisions.

2. Protocol Type - Please check that PacketBand is set for the correct protocol type for the packet switched network.

PacketBand can be configured with a sniffer port, which can be used with packet tracing software to prove that packets are being lost within the network. Please contact Patapsco for more information.
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Q39. There are firewalls on the sites where PacketBand will be used. Will it still work?

Yes, PacketBand can be used provided the correct port numbers are opened on the firewall and port forwarded to the PacketBand. PacketBand uses the following port numbers:

The Logical Link port numbers can be changed. Please see the PacketBand manual for details. Back to top

Should you be unable to find the answer you seek, or are having difficulties, please contact us referencing any Support Agreement.