[apops] route mile and physical mile

["huaning\(bii\)" <nhua@biigroup.com>]

hi.
As for the carrier's network infrastructure,
there are two terms confused me, one is "route mile",
another is "physical mile". 
Can someone tell me the detail meaning and difference about
these two terms ?
Thanx in advance.
_________________________________________________
    Hua Ning
    Chief Engineer
    BII Group Holdings Ltd(Beijing Internet-networking Institute),
    110E 11F China Merchants Tower,
    No.2 Dong Huan Nan Lu, Chao Yang District,
    Beijing,China
    Zip Code: 100022
    Tel:+86-10-65660290-223
    Fax:+86-10-65660297
_________________________________________________
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