1-5
z
The system transforms the period of detecting errored frame period events into the maximum
number of 64-byte frames that a port can send in the specific period, that is, the system takes the
maximum number of frames sent as the period. The maximum number of frames sent is calculated
using this formula: the maximum number of frames = interface bandwidth (bps) × errored frame
period event detection period (in ms)/(64 × 8 × 1000)
z
If errored frames appear in a certain second, this second is called an errored frame second.
Remote fault detection
Information OAMPDUs are exchanged periodically among Ethernet OAM entities across established
OAM connections. In a network where traffic is interrupted due to device failures or unavailability, the
flag field defined in information OAMPDUs allows an Ethernet OAM entity to send error information to
its peer. In this way, you can keep track of link status in time through the log information and
troubleshoot in time,
Table 1-5
lists the critical link events and the transmission frequencies of the
corresponding OAMPDUs.
Table 1-5
Critical link error events
Ethernet OAM link events
Description
Link Fault
Peer link signal is lost.
Dying Gasp
An unexpected fault, such as power failure, occurred.
Critical event
An undetermined critical event happened.
The support of 3Com Switch 4500G family for information OAMPDUs carrying critical link events is as
follows:
z
3Com Switch 4500G family are able to receive information OAMPDUs carrying the critical link
events listed in
Table 1-5
.
z
Only the Gigabit optical ports are able send information OAMPDUs carrying Link Fault events.
z
3Com Switch 4500G family are able to send information OAMPDUs carrying Dying Gasp events
when the device is rebooted or relevant ports are manually shut down.
z
3Com Switch 4500G family are unable to send information OAMPDUs carrying Critical Events.
Remote loopback
Remote loopback is available only after the Ethernet OAM connection is established. With remote
loopback enabled, the Ethernet OAM entity operating in active Ethernet OAM mode sends
non-OAMPDUs to its peer. After receiving these PDUs, the peer does not forward them according to
their destination addresses. Instead, it returns them to the sender along the original path.
