Test implementation during the remote
loopback sessions is vendor specific and is not covered by the respective IEEE
standard. Additionally, since the loopback information is dropped by the link partner
initiating OAM exchange in accordance with the IEEE 802.3ah, measuring the two way
end-to-end packet delay is not possible. Moreover, measuring the single-ended packet
delay requires implementation of a timer and application at the looped site, which is
not specified by 802.3ah, thus further complicating OAM-level transmission quality
measurements.
MIB Variable Retrieval The management information base (MIB) stores a networklevel
accessible database of so-called manageable variables, while the OAM protocol
provides strictly read-only access to MIB variables describing a specific network branch.
In this way, a network administrator may store a set of parameters describing any
Ethernet network link, accessed remotely on-demand when link testing is underway.
The on-demand character of the variable retrieval process may be easily interleaved
with any OAM message exchange, resulting in flexible implementation of any measurement
functions for estimating the link capability to support a SLA (similar to IP ping
for measuring delay, jitter, and throughput).
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