Modern routers offer a bewildering array of routing arrangements and security (firewall) options. To adjust for all this complexity the address book mode provides a flexibility of defining access parameters separately for each entry in the list. This includes, apart from the IP-address, an *access method** and an access (command) port number .
Both parameters are set in the address book entry dialog (see editing the address book ).
The access method defines how the DS Manager communicates with the DS:
| • | When out-of-band UDP access method is selected the DS Manager communicates with the DS using command UDP datagrams sent to command port 65535 (or 32767) of the DS. Out-of-band UDP commands is a primary way of network programming that requires no preliminary setup on the DS side. In other words, it always works as long as the routers and firewall do not ban UDP traffic to port 65535 (32767). Therefore, we suggest you to always use this access method whenever possible. The DS Manager allows you to input any port number but actually only two UDP command ports are provided on the DS- 65535 and 32767 (either one can be used). |
| • | When inband TCP access method is selected the DS Manager communicates with the DS by sending commands through the TCP connection established to the data port of the DS (this is the port number defined by the Data Port Number (PN) setting). Inband TCP commandsprovide a secondary method of network programming that can be used in situations when out-of-band UDP access is impossible. You can use any access port number- this is an additional flexibility- just make sure that you program the same port number on the DS and in the address book entry. There are several limitations associated with inband access: |
| • | For "inband" address book entries the DS Manager does not automatically verify DS presence when the Refresh button is pressed. Therefore, after the Refresh button is clicked all Device Servers for which the inband access is defined initially appear in the list with the  icon. If you want to check if such a DS is accessible then attempt to execute the desired action: press Settings button or Buzz button and see the result (Upgrade, Initialize, and Routing Statusfunctions are not available for "inband" address book entries). At this point the DS Manager will attempt to establish a TCP connection to the DS and find out if the DS is accessible. This will be reflected in the device list. |
| • | It is not possible to access the DS using inband access method when the DS is already engaged in a data TCP connection with another application and/or network host. Since inband commands are, by definition, the commands that are passed within the data connection itself the DS Manager actually establishes a data TCP connection with the DS in order to program it (this is why this connection is made to the data port of the DS, not the command port). The DS only allows for a single data connection at a time, so if it is already engaged in a data connection with another application and/or network host the DS Manager will be rejected. |
| • | When telnet TCP access method is selected the DS Manager performs programming through a TCP connection established to port 23 of the DS (see telnet TCP programming). Unlike inband access method, this does not require any prior setup of the DS side but will only work with newer Device Servers that run on firmware V3.50 or higher. |
* Here we touch on a very complicated subject. Modern routers offer a bewildering array of setup options. We will attempt to cover this in details in our upcoming white papers.