What is the 5800 Ethernet Peering Partner (EPP)?

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What is the 5800 Ethernet Peering Partner (EPP)?
The Ethernet Peering Partner (EPP) is a small companion device that is used for several Ethernet functions on 10/100/1000 electrical Ethernet connections. It works in conjunction with the 5800 cable diagnostics to verify wire mapping and shield ground continuity (requires a 5882 model to perform the shield test).  The EPP can also act as a layer 1 traffic reflector to perform Ethernet services testing such as RFC 2544 and Y.1564 on circuits that do not require mac swapping loops.