Envoy ACP/XF Configuration and Management Manual

WAN Subsystem Profiles and Modifiers for
EnvoyACP/XF
EnvoyACP/XF Configuration and Management Manual—429232-003
3-43
Optional Modifier Descriptions
NRM Protocol—Secondary Station
According to the NRM protocol standard, there is no timer for secondary stations;
however, EnvoyACP/XF does implement a timer for secondary stations (Figure 3-11).
When T1TIMER is configured for a secondary station, T1TIMER specifies the period
that a secondary station waits for a primary station to poll. This timer can indicate a
problem at the primary station: the absence of a poll for an extended period indicates
that the primary station is down. Set T1TIMER for a secondary station for a much
longer time than the regular T1TIMER; use minutes rather than seconds.
ABM Protocol
In ABM, T1TIMER has the same effect on both primary and secondary stations
(Figure 3-12). T1TIMER specifies the period that one station waits to receive a
response from the other station after sending an I-frame. If the transmitting station
does not receive a response before the specified timeout, it sends an RR frame with
the P-bit set. As in NRM, the configured time for T1TIMER also specifies the period
that the primary station waits to receive a response to its RR frame transmission from
the other station. The number of times that a station sends the RR frame is specified
by the L2RETRY modifier. For additional information on timeout and retries, refer to the
EnvoyACP/XF Application Programming Manual.
Figure 3-11. T1TIMER and NRM Secondary/Tributary Line
VST023.vsd
TITIMER specifies how long the tributary station waits to receive a poll
from the primary station before issuing a timeout error.
Tributary
Tributary
Tributary
NRM
Supervisor