Notes on Cell Administration

Establishing Intercell Communication

Establishing Intercell Communication

The information in this section supplements the information in the OSF DCE Administration Guide — Core Services, and describes how intercell communication should be configured in an HP-UX environment.

Communication between DCE cells is facilitated by the gdad daemon, which implements the Global Directory Agent (GDA). When a client in a local cell wants to access another cell that the local cell does not already recognize, the request is passed to gdad, which looks up and returns information about how to find the remote cell. This information is cached, so that gdad is not asked repeatedly for the same information.

gdad finds information about the remote cell by querying a Domain Name Service (DNS) database. DNS is not part of DCE; it is a widely used distributed naming service, implemented on HP-UX by the named daemon, and documented in named (1M) man page and in Internet RFCs 1032, 1033, 1034, and 1035.

These procedures describe configuring GDA so that it can find the DNS server or servers where cell information is stored, creating DNS “resource records” that describe the cells you want GDA to be able to locate, and establishing peer-to-peer trust between two cells.

Specifying DNS Servers that GDA Should Query

GDA must be told which DNS name servers (such as instances of named) to query for information about foreign cells. The name server at localhost is usually preferred, as only localhost provides recursive query service—if localhost doesn’t have the requested data, localhost will query other name servers until it either finds the requested data or exhausts the list of name servers that it knows about.

Using localhost reduces the requirement to keep GDA informed when name server configurations change, and allows GDA to always receive a response with a single query. In some environments, however, you may want to point GDA at a non-local server or servers, rather than at localhost.

gdad uses the following algorithm to identify which name server or name servers to query:

Planning and Configuring HP DCE 1.7

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