ated ▁from ▁Frame ▁Rel ay ▁to ▁M PL S ▁over ▁IP ▁or ▁E ther net , ▁which ▁in ▁many ▁cases ▁will ▁reduce ▁costs ▁and ▁improve ▁manage ability ▁and ▁performance ▁of ▁their ▁wide ▁area ▁networks . ▁ ▁AT M ▁( As ynchronous ▁transfer ▁mode ) ▁While ▁the ▁underlying ▁protocol s ▁and ▁techn ologies ▁are ▁different , ▁both ▁M PL S ▁and ▁AT M ▁provide ▁a ▁connection - orient ed ▁service ▁for ▁transport ing ▁data ▁across ▁computer ▁networks . ▁In ▁both ▁techn ologies , ▁connections ▁are ▁sign aled ▁between ▁end points , ▁the ▁connection ▁state ▁is ▁maintained ▁at ▁each ▁node ▁in ▁the ▁path , ▁and ▁enc aps ulation ▁techniques ▁are ▁used ▁to ▁carry ▁data ▁across ▁the ▁connection . ▁Ex cluding ▁differences ▁in ▁the ▁signal ing ▁protocol s ▁( R SV P / LD P ▁for ▁M PL S ▁and ▁P NN I : Private ▁Network - to - Network ▁Interface ▁for ▁AT M ) ▁there ▁still ▁remain ▁significant ▁differences ▁in ▁the ▁behavior ▁of ▁the ▁techn ologies . ▁ ▁The ▁most ▁significant ▁difference ▁is ▁in ▁the ▁transport ▁and ▁enc aps ulation ▁methods . ▁M PL S ▁is ▁able ▁to ▁work ▁with ▁variable ▁length ▁packets ▁while ▁AT M ▁trans ports ▁fixed - length ▁( 5 3 ▁bytes ) ▁cells . ▁Pack ets ▁must ▁be ▁segment ed , ▁transport ed ▁and ▁re - ass emble d ▁over ▁an ▁AT M ▁network ▁using ▁an ▁adaptation ▁layer , ▁which ▁adds ▁significant ▁complexity ▁and ▁overhead ▁to ▁the ▁data ▁stream . ▁M PL S , ▁on ▁the ▁other ▁hand , ▁simply ▁adds