▁conce ived , ▁label ▁lookup ▁and ▁label ▁switching ▁were ▁faster ▁than ▁a ▁routing ▁table ▁or ▁R IB ▁( Rout ing ▁Information ▁Base ) ▁lookup ▁because ▁they ▁could ▁take ▁place ▁directly ▁within ▁the ▁switched ▁fabric ▁and ▁avoid ▁having ▁to ▁use ▁the ▁OS . ▁ ▁The ▁presence ▁of ▁such ▁a ▁label , ▁however , ▁has ▁to ▁be ▁indicated ▁to ▁the ▁router / switch . ▁In ▁the ▁case ▁of ▁E ther net ▁frames ▁this ▁is ▁done ▁through ▁the ▁use ▁of ▁E ther Type ▁values ▁ 0 x 8 8 4 7 ▁and ▁ 0 x 8 8 4 8 , ▁for ▁un ic ast ▁and ▁mult ic ast ▁connections ▁respectively . ▁ ▁Label ▁switch ▁router ▁An ▁M PL S ▁router ▁that ▁performs ▁routing ▁based ▁only ▁on ▁the ▁label ▁is ▁called ▁a ▁label ▁switch ▁router ▁( LS R ) ▁or ▁trans it ▁router . ▁This ▁is ▁a ▁type ▁of ▁router ▁located ▁in ▁the ▁middle ▁of ▁an ▁M PL S ▁network . ▁It ▁is ▁responsible ▁for ▁switching ▁the ▁labels ▁used ▁to ▁route ▁packets . ▁ ▁When ▁an ▁L SR ▁receives ▁a ▁packet , ▁it ▁uses ▁the ▁label ▁included ▁in ▁the ▁packet ▁header ▁as ▁an ▁index ▁to ▁determine ▁the ▁next ▁hop ▁on ▁the ▁label - switch ed ▁path ▁( L SP ) ▁and ▁a ▁corresponding ▁label ▁for ▁the ▁packet ▁from ▁a ▁lookup ▁table . ▁The ▁old ▁label ▁is ▁then ▁removed ▁from ▁the ▁header ▁and ▁replaced ▁with ▁the ▁new ▁label ▁before ▁the ▁packet ▁is ▁rout ed ▁forward . ▁ ▁Label ▁edge ▁router ▁A ▁label ▁edge ▁router ▁( L ER ,