Another use for multiple network interfaces is to provide a backup in case of network failure. If a client is connected to a server via two networks, the client can establish a connection via the second network if the first one goes down.
To configure Adaptive Server for query port backup:
Install multiple “master” and “query” lines in a server entry in the interfaces file.
Adaptive Server listens for connections at both ports. Clients looking for a host name and a port number for a connection to an Adaptive Server will try the port on each “query” line in order, until they establish a connection.
The following example shows how to configure a backup network that will be used only if the normal connection fails. The second network is named “network2”.
# PRODUCTION server with two network listeners PRODUCTION<tab>3<tab>3<newline> <tab>master tli tcp /dev/tcp \x0002130a83d601f60000000000000000 <tab>master tli tcp /dev/tcp \x0002130a83d601f70000000000000000 <tab>query tli tcp /dev/tcp \x0002130a83d601f60000000000000000 <tab>query tli tcp /dev/tcp \x0002130a83d601f70000000000000000#PRODUCTION server with two network listeners PRODUCTION<tab>3<tab>3<newline> <tab>query tcp ether ZEPPO 6464 <tab>query decnet ether CHICO 150 <tab>master tcp ether ZEPPO 6464 <tab>master decnet ether CHICO 150# PRODUCTION server with two network listeners PRODUCTION<tab>3<tab>3<newline> <tab>master tcp ether SERV_CORPNET 4559 <tab>master tcp ether SERV_ENGNET 5479 <tab>query tcp ether SERV_CORPNET 4559 <tab>query tcp ether SERV_ENGNET 5479
Configure PC-client interfaces files with the appropriate multiple “query” entries, as described in the Open Client documentation. For client interfaces files in a homogeneous environment, you can copy the entire interfaces file entry for the Adaptive Server into the client interfaces file.
A connection on the secondary port occurs only if the corporate network is disabled, or if the corporate network interface on the host machine fails or is shut down due to a network-related failure.
