[j-nsp] Ethernet OAM platform support

[Phil Mayers]

All,

Does anyone know off the top of their heads which platforms have 
802.1ah/ag support? Juniper docs exist giving examples on the MX 
platform, but it seems to be absent from lower-end platforms (e.g. 
J-series, SRX2xx). This is JunOS 10.4R2.7.

We're vaguely interested in using it to detect link failure of some 
ethernet circuits we have which don't do link-state passthrough; these 
circuits are all plugged into J-series routers.