DMG1000/2000 - Three Common Configuration Issues

These are three important configuration settings when using a gateway from the Dialogic 1000 Media Gateway Series (DMG1000 gateway) or the Dialogic 2000 Media Gateway Series (DMG2000 gateway):  

• BOOTP

• Network RTP capture  

• Transport Type. 

This article identifies and discusses each of these configuration settings and provides recommendations for proper parameter values.

BOOTP

Description: 
When enabled, this parameter causes the DMG1000/DMG2000 gateway to issue a BOOTP request  on startup. 

A BOOTP/TFTP server may be configured to provide IP credentials, firmware upgrades, and a configuration INI file. The BOOTP parameter can be found under the "IP" menu (for both 5.x and 6.x software). 

Allowed Values: 

• Yes = Parameter enabled - DMG1000/DMG2000 gateway issues a BOOTP request on startup. 

• No = Parameter disabled - DMG1000/DMG2000 gateway does not issue a BOOTP request on startup.

By default, the BOOTP parameter is set to YES which causes the DMG1000/DMG2000 gateway to always issue a BOOTP request upon start up. 

Recommended usage:
Typically, users will want to disable BOOTP after initial configuration by setting the BOOTP enabled parameter to NO thus allowing the  DMG1000/DMG2000 gateway to always have a static IP address assigned. 

Possible issues associated with BOOTP = Yes:
Common symptoms when BOOTP is enabled are slower DMG1000/DMG2000 gateway reboot time and random IP address changing.

Open

Network RTP capture

Description: 
The Network Capture creates an in-memory log of Media Gateway IP traffic. Since there can be a great deal of traffic, the Network Capture control page allows filtering of IP packets. Filtering packets makes it easier to analyze problems by reducing the number of irrelevant messages.

The RTP filter can be found under the "Diagnostics" --> Network Capture" tab (5.x software) and "Trace/Logging" --> "Network Capture" configure button (6.x software) 

Allowed Values:

• Unchecked - gateway captures RTP data

• Checked - gateway filters out RTP data

By default, the RTP capture filter is CHECKED which means that no RTP is captured when tracing.  

Recommended usage:
The recommended state of this parameter is to for it to be UNCHECKED when the user is troubleshooting voice quality issues or any issues relating to RTP traffic. 

Possible issue related to this setting:
Users that are unaware of this filter setting and who look at the traces may report that no RTP traffic is being sent.

Open

Transport Type

Description: 
Defines the preferred transport protocol for call signaling packets. The Transport Type parameter can be found under the "SIP" menu (5.x software) and "VoIP" --> "General" menu (6.x software). 

Allowed Values: 

• TCP = Transmission Control Protocol is used as the transport protocol. 

• UDP = User Datagram Protocol is used as the transport protocol. 

By default, the Transport Type parameter  is set to UDP and this is the protocol that most end points will use, except for Microsoft®-based systems.

However, it is always recommended that the user confirms the protocol for which the receiving IP end point is configured for.

Note that both Microsoft® Office Communications Server and Microsoft® Exchange UM use TCP. 

A common symptom of a Transport Type mismatch is failure to establish calls - the receiving IP endpoint may reject the call because the DMG1000/DMG2000 gateway is misconfigured, so that it transmits using the wrong protocol. 

Note: while the DMG1000/DMG2000 gateway is configured for TCP transport, the gateway will still accept inbound requests on BOTH UDP and TCP. The Transport Type setting only controls what the gateway sends out on new requests.

Glossary of Acronyms / Terms

TCP - Transmission Control Protocol 
UDP - User Datagram Protocol
BOOTP - Bootstrap Protocol
RTP - Real Time Protocol