MPLS LSR. MPLS LSR LSR . , , , LSR, Label Edge Router (LER, ), LSR LSR. : LSR MPLS MPLS MPLS, LER MPLS , IP-, , . MPLS (X.25, FR ATM) . , , . .
MPLS . 15.3 MPLS-, (LER1, LER2) (LSR1, LSR2) . (LER1 1 IP 2 (L2), a LER2 4 IP). MPLS FEC, LER. LSP (Label-Switched Path) (LSR), . . LER1 1 LSR2 5. LSR2 LER2 4. , LER LSR , ATM, Frame Relay, X.25. 3 IP- IP- , MPLS MPLS MPLS. L2 2.
. 15.3.
, MPLS . LIB (Label Information Base). LIB . , LSR.
MPLS TCP/IP MPLS- LIB. LSR , IP-. MPLS- MPLS LS, , MPLS. , MPLS Ethernet, - , Ethernet, .
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MPLS , , () LSP . VPI/VPC, . .
LSP ( FEC ), LSP FEC, , . LSP. , . 15.4.
. 15.4. MPLS
MPLS 1 MPLS, , 2, 3, 4. (4,3,2,1). , . MPLS , S- TTL. 1 15.4 (S=1). MPLS : (push), (pop), (swap). 15.5 MPLS IP , , FEC. MPLS - . LER1 ( ) - LSP1 LSP2 (LSP1 IP1 LSP2 IP2 ). LER1 ( 305 14 - ) (push) , 256. , (256 272).
LSR2 (pop) . IP1 305, IP2 14 . LER2 LSP2 IP1, . LER2 IP1 . LER2 305 299 LER3 LER4 LER2 . .
, ( FEC ), () LSP , , , FEC, , . , . LSP1: LERl, LSRl, LSR2, LER2, LER3, LSR3, LER4 IP1 . LSP2: LER1, LSR1, LSR2, LER 2 IP2 . LSP, ( ).
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m LSP. LSP m , LSR, m ( m ), LSR, m LSR, m-1 ( MPLS, IP) . LSR (m-1), m LSR . LSR .
. 15.5. LSP1 LSP2, 1 2
. 15.6 LSP (m=4).
. 15.6. LSP
15.1 LSR1, LSR2, LSR3, LSR4.
15.1. LSP4
LSP | |
LSP1, LSP2, LSP3, LSP4 | |
LSP2, LSP3, LSP4 | |
LSP3, LSP4 | |
LSP4 |
LSP3, LSP2, LSP1 ( LSP3) ( LSP1 LSP2) LSP.