! "#$%&'$&( "#%$&"#$%& )& * ! $& +, ( $%&$ (- # ! $& +, ( $%&$ .# -$ #()%$/0* %$/ #$%& & / $&/ && &! z & %$ # () %$ * %$- %% ! 0&% $& (& $& 0 %%& & ! * $%&$ % $& && ' z ! &(& %%%/ **$/%&$%%%% z &$+1/%%/ 2 /&/, z & $ +1 %%, * %(&- $& & %&& ' z * - %% &0 0 z (& && ( $ %% &- $ $ &0 / ( %$ $ $$0 z (&(&%%&- % $ &0 / ( % $ 0 z (& %% &- 00$ z "( (& ( %$%(- z 3& & & # $ ( $& / & 40 (5 %&/&(5%(& %! & 1 %! # 3 %% $! $/6&6 66 3 $&6-6-% * &$ && & %!0*0(&/ 6-76/ &$ $&%%0(&$( 6 &6/ && &- $ %! &(& &(& 3 &(& %! %! 0& - 3 &(& %! 6 &6 %(& &(& %% %! * 6 &6 0(&/ 6&76/ 6&6 6 &6 %(& %! (66&6 %(&& 8 0 %!/ % && ' 6&6$ 0 %!&(&&(&&(& %!/ 6 &6 # &- # &(& %%%&(&%!( %!%%/6&6 # &(&%! 8 / 6 &6 6 &6 %$$%"/$&.0-/9 :/;<! 6 &6 # (- #$%!6 #%%!&/%! 6&6 L2 switching L3 forwarding packets (&$$ & = & 3 *(& +3*,/ (& $ >+>,/ "#%& $>+">,3*(3 *(& 3"/ ?> +?%>0,/ >%>(&$/"> (& $ " 3 (& $%& &$ %!*>%(&% %>- A packet arrived Labeled Packet ? Yes No Push operation Swap / Pop operation PFT Push operation * &!% 3*4> (& 0&(&4&(&%! &(& %!/ 3* (& - %!6 3" + / %!6,>% 3* - ./ %! (- $ 8 / %$ &(& % % %! * / % %!&(&>-%(- >% 3*-/ $-( &(& ! % %! &(& % %% & >% > - .&&&(&%/ %! &-#(- >- &(&%!/&- ->-(-&(& # > (& */ %$ &(& % % %& %!6&(& &(&>- &(& && &(&/ $ %&$ % %%%/ %$ &(& %% % &(& % % / %$ &(& ! % %! >% >-.3&&-/%! &- # (- >- * "> (& !% &- $ " / 6 %% %! $% & %0&-(& "/ - $ >% "> - & ( 3*(& API Invocation LDPAgent LDPAgent LDPAgent API InvocationAPI Invocation !"# 20$/& & $/ & # / $/ #10 ( 3 2 0 $/ @$ && &$/&&&% (-@/ (&/ �$8 # $/ && @$ % # $ # *&& !' z z && z & && % &0 z & % 0 z &%$ &(&&&$ z & % $ z $!#%&(&" z $%& (& " z & & z %! z %! 0.1796 1: 0->8 U -1 Push(ingress) 3 1 32 4 0.1912 3: 0->8 L 1 Swap 5 1 31 4 0.1948 5: 0->8 L 1 Pop(penultimate) 7 0 30 0 $%&' 2 6$%&6 / #$%& &$%%33& $& $ + , 0 *#& % %! * # & %!6*# & 0 %! &(&+., &(&+, * # & $&(& 0& * # & % &(& %/%/ %*(1 & %!6 &(& * & & $ 6**A 3 ) #%$ 0$ $&( LSR4 LSR5 LSR2 LSR3 LSR6 LSR7 LSR8 (ingress) (egress) (egress) MPLS Domain : Direction of Packet Forwarding based on Shortest Path scheme (%&') 3)/ B// C/B / B B %! B C %! B. %! $ ( %/ %!$B&0&)DE/ %!$&0&F * && *& !(3) 3&&/20$&(5* $$&& ' z G $&H 3 (5 0 (5 && ' z BGIH z GIH z GIH z GIH z GIH z )GIH z DGIH z EGIH z FGIH z CGIH z BGIH *#&&!( " %&#&! ( (/&-B$/%*&1 z I %&#&! IB I ( B$ %*& z I %&#&! I I ( B$ %*& z I %&#&! I I ( B$ %*& z I %&#&! I I ( B$ %*& z I %&#&! I IF ( B$ %*& z I %&#&! I I) ( B$ %*& z I %&#&! I) ID ( B$ %*& z I %&#&! I) I ( B$ %*& z I %&#&! ID IE ( B$ %*& z I %&#&! ID IF ( B$ %*& z I %&#&! IE IF ( B$ %*& z I %&#&! IE IC ( B$ %*& z I %&#&! IF IB ( B$ %*& * # & && z I&%&&$%& * && % *& && &$-% z I&%1&(& z I&%$%%& z I&% &$ z I&%&& z I&%&-&& *#&$ (&$&0 z I(&&0 2&0$ &0*$$JI(&0J & && % 0 0$&/ && %' z I(&$ z I(&& *#&> $B / && $ CB z BG 4>H z IIBIB z IB%!A7)BB z IB0&7BBB z z G 4>H z III z I%!A7)BB z I0&7BBB z z BG 4&&H z IICIB z z G 4&&H z IIBI * * > 0 ( &&&& ' z IIBIB z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apping Messages +(,BB'(&(( &0 Egress LSR Ingress LSR Egress LSR +,BD'%! LDP Withdraw Messages LDP Withdraw Messages +,BB'(&2 &3"C 3"B Egress LSR Ingress LSR +,B'3& 3"C 3"B3"D CR-LDP Request Messages +,BEB'1 " CR-LDP Mapping Messages +,BED'%% " Egress LSR Ingress LSR +,BCE'! ( (&" E Egress LSR Ingress LSR Tunnel Ingress Point Tunnel Egress Point LSP Tunnel +, DC ' ! ( (&*& *'+!") 1.634000 2(0->9): U -1 Push(ingress) 3 11 32 4 1.648000 3(0->9): L 11 Swap 4 12 31 4 1.662000 4(0->9): L 12 Swap 8 11 30 4 1.662000 4(0->9): L 12 Push(tunnel) 5 12 32 8 1.676000 5(0->9): L 12 Swap 6 12 31 8 1.690000 6(0->9): L 12 Pop(penultimate) 8 0 30 4 1.704000 8(0->9): L 11 Pop(penultimate) 7 0 29 0 1.718000 7(0->9): U -1 L3 -1 -1 -1 0 ,*- ) 0 ! $& %% &- # $& 00#$%& ! $& . 2(0->9 ): U -1 Push(ingress) 3 11 32 4 1.648000 3(0->9 ): L 11 Swap 4 12 31 4 1.662000 4(0->9 ): L 12 Swap 8 11 30 4 1.662000 4(0->9 ): L 12 Push(tunnel) 5 12 32 8 1.676000 5(0->9 ): L 12. $&( LSR4 LSR5 LSR2 LSR3 LSR6 LSR7 LSR8 (ingress) (egress) (egress) MPLS Domain : Direction of Packet Forwarding based on Shortest Path scheme (%&') 3)/. %! z %! 0.1796 1: 0->8 U -1 Push(ingress) 3 1 32 4 0.1912 3: 0->8 L 1 Swap 5 1 31 4 0.1948 5: 0->8 L 1 Pop(penultimate) 7 0 30 0 $%&' 2