. ▁ ▁Ro le ▁and ▁function ing ▁M PL S ▁is ▁scal able ▁and ▁protocol - in dependent . ▁In ▁an ▁M PL S ▁network , ▁data ▁packets ▁are ▁assigned ▁labels . ▁Pack et - forward ing ▁dec isions ▁are ▁made ▁sole ly ▁on ▁the ▁contents ▁of ▁this ▁label , ▁without ▁the ▁need ▁to ▁examine ▁the ▁packet ▁itself . ▁This ▁allows ▁one ▁to ▁create ▁end - to - end ▁circ uits ▁across ▁any ▁type ▁of ▁transport ▁medium , ▁using ▁any ▁protocol . ▁The ▁primary ▁benefit ▁is ▁to ▁eliminate ▁dependence ▁on ▁a ▁particular ▁O SI ▁model ▁data ▁link ▁layer ▁( layer ▁ 2 ) ▁technology , ▁such ▁as ▁As ynchronous ▁Transfer ▁Mode ▁( AT M ), ▁Frame ▁Rel ay , ▁S ynchronous ▁Opt ical ▁Network ing ▁( SON ET ) ▁or ▁E ther net , ▁and ▁eliminate ▁the ▁need ▁for ▁multiple ▁layer - 2 ▁networks ▁to ▁satisfy ▁different ▁types ▁of ▁traffic . ▁Mult ip ro tocol ▁label ▁switching ▁belongs ▁to ▁the ▁family ▁of ▁packet - switch ed ▁networks . ▁ ▁M PL S ▁oper ates ▁at ▁a ▁layer ▁that ▁is ▁generally ▁considered ▁to ▁lie ▁between ▁traditional ▁definitions ▁of ▁O SI ▁L ayer ▁ 2 ▁( data ▁link ▁layer ) ▁and ▁L ayer ▁ 3 ▁( network ▁layer ), ▁and ▁thus ▁is ▁often ▁referred ▁to ▁as ▁a ▁layer ▁ 2 . 5 ▁protocol . ▁It ▁was ▁designed ▁to ▁provide ▁a ▁un ified ▁data - car ry ing ▁service ▁for ▁both ▁circuit - based ▁clients ▁and ▁packet - switch ing ▁clients ▁which ▁provide ▁a ▁dat agram