Nortel 2000 User Manual page 43

Book B
The CLI hosts command displays all entries in the host table. The Annex
can build and update the host table from RWHO messages and from
responses to DNS and/or IEN-116 queries. Entries are updated according
to information received. Information for a host will be updated if new
information received is different from what is currently in the host table.
The Annex considers information from a DNS server the most reliable
source; it considers an IEN-116 as the next reliable source; and it
considers RWHO broadcasts as the least reliable source. Thus,
information from a DNS server always updates current information
received from either an IEN-116 server or an RWHO broadcast;
information from an IEN-116 server always updates current information
received from an RWHO broadcast.
IEN-116 servers are not supported in a Windows NT
As a result, an Annex in a Windows NT
considers host table information from an IEN-116 server.
The Annex also deletes entries. The criteria for deletion depend on the
source of the entry. Each DNS response includes a time to live (TTL).
When an entry reaches its full life (default=60 minutes), the DNS server
is queried again. If a DNS server recognizes the name, the entry is
re-entered in the host table; otherwise, it is deleted. The Annex keeps
track of how often each IEN-116 host table entry is referenced. If a name
server entry has not been used for 32 days, it is deleted.
The Annex expects to receive an RWHO message from a host at least
every six minutes; if no message is received in that time period, the host
table status entry for that host is changed to down?. If there is no message
for 12 minutes, the status is changed to down, and if no message is
received for 60 minutes, the entry is removed from the table.
If the host table acquires a new entry after it is full, the Annex deletes the
oldest, least-used entry to make room for the new one. If the host table
is too small, it frequently changes. Increasing the size of the host table
using the Annex parameter host_table_size reduces these changes.
Remote Annex Administrator's Guide for UNIX
Chapter 1 Network Administration
®
environment.
®
environment never
Book B-35