OSI/MHS Configuration and Management Manual

Planning Your OSI/MHS Subsystem

OSI/MHS Configuration and Management Manual—424827-003

3-11

Link Retries and Route Retries

If you want to define alternate routes, you must determine how to configure link retries,

route retries, and priorities. The following paragraphs describe these topics.

Link Retries and Route Retries

Links are defined by pairs of OSI addresses that are configured for each MTA. A pair

of OSI addresses is a set of local and remote address definitions in the MTA object

representing an adjacent MTA. When a link fails or is unavailable, all the other links for

that MTA are tried depending on (1) how you set the time available to establish the

association and (2) how you set the time to wait before an MR group can retry the

previously failed association. You set these times through the CLASS attributes LINK-

RETRY-TIME and LINK-RETRY-DELAY. This is called link retry. OSI/MHS can have

up to seven links to each adjacent MTA.

When an MTA initially attempts to establish an association, it tries the links in order of

priority: the order in which you list the addresses when you define the MTA object. If it

cannot establish an association on a higher-priority link, it retries on the next-lower

priority link. In the case of an association that fails during a transfer, the behavior is

slightly different: the MTA first tries the link of next higher priority (in relation to the

failed link), then the failed link again, then the link of next lower priority, and so on.

If, however, MTA2 is out of service, all attempts to retry the association fail. The retry

of different OSI addresses is done by the RTS process of the MR group. When there

Figure 3-4. Alternate Routes

Note. If an MTA fails to establish an association on a link, it tries another link right away

instead of retrying on the failed link.

029VS T .VS D

MTA

Country A Country B

PRMD 1 ADMD 1

Ro ute 1

Ro ute 2

(Alternate Route)