CANOGA PERKINS L357 Gigabit Ethernet Service Unit - Manual (Page 18)

EdgeAccess Universal Chassis System
3.3.2 Link Loss Echo
Caution: To avoid a lockup condition, do not set LLE at both the local and remote ends of the
link.
Link Loss Echo (LLE) propagates a link loss to the device connected to an optical Extension or User
Port on the L357. See Figure 4. If a link loss is detected on the Extension Port Rx, the Extension
Port Tx is disabled, echoing the fault back to the source. LLE configures the L357 to not send data
until it receives data. Set this in the User Interface.
Figure 4. Link Loss Echo Detection
Note: LLE on the optical Extension Port is available only when SBMC is disabled; if you enable
SBMC, use LLF.
A UTP to fiber L357 ignores the LLE User Port setting.
3.3.3 Loopback
The L357 supports four loopback modes that you can set at the local site for both the Local and
Remote L357s. These modes loop the data through either the physical layer (PHY) on the User side
or the FPGA. For details on setting loopback in software, see Section 4.6.
• Local-Local mode loops the electrical data that the Local L357 receives on the local User Port Rx
through the FPGA to the User Port Tx. The data is not sent out the Extension Port Tx and
incoming data on the Extension Port Rx is ignored. See Figure 5. To set this mode at the
Diagnostics screen, set the Loopback State for the Local module to Local.
Figure 5. Local-Local Loopback Mode
L357 Gigabit Ethernet Service Unit 3-4