▁Rel ations hip ▁to ▁Internet ▁Pro tocol ▁M PL S ▁works ▁in ▁conj unction ▁with ▁the ▁Internet ▁Pro tocol ▁( IP ) ▁and ▁its ▁routing ▁protocol s , ▁such ▁as ▁the ▁Inter ior ▁Gate way ▁Pro tocol ▁( IG P ). ▁M PL S ▁L SP s ▁provide ▁dynamic , ▁transparent ▁virtual ▁networks ▁with ▁support ▁for ▁traffic ▁engineering , ▁the ▁ability ▁to ▁transport ▁layer - 3 ▁( IP ) ▁V PN s ▁with ▁over la pping ▁address ▁spaces , ▁and ▁support ▁for ▁layer - 2 ▁pseud ow ires ▁using ▁Pseud ow ire ▁Em ulation ▁Edge - to - Edge ▁( P WE 3 ) ▁that ▁are ▁capable ▁of ▁transport ing ▁a ▁variety ▁of ▁transport ▁pay loads ▁( IP v 4 , ▁IP v 6 , ▁AT M , ▁Frame ▁Rel ay , ▁etc .). ▁M PL S - cap able ▁devices ▁are ▁referred ▁to ▁as ▁L SR s . ▁The ▁paths ▁an ▁L SR ▁knows ▁can ▁be ▁defined ▁using ▁explicit ▁hop - by - h op ▁configuration , ▁or ▁are ▁dynamically ▁rout ed ▁by ▁the ▁const rained ▁short est ▁path ▁first ▁( C SP F ) ▁algorithm , ▁or ▁are ▁configured ▁as ▁a ▁loose ▁route ▁that ▁avoid s ▁a ▁particular ▁IP ▁address ▁or ▁that ▁is ▁partly ▁explicit ▁and ▁partly ▁dynamic . ▁ ▁In ▁a ▁pure ▁IP ▁network , ▁the ▁short est ▁path ▁to ▁a ▁destination ▁is ▁chosen ▁even ▁when ▁the ▁path ▁becomes ▁con g ested . ▁Meanwhile , ▁in ▁an ▁IP ▁network ▁with ▁M PL S ▁Tra ffic ▁Engineering ▁C SP F ▁routing