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TCP/IP Tutorial and Technical Overview - IBM Redbooks

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A generalized label only carries a single level of label; that is, it is<br />

non-hierarchical. When multiple levels of label (LSPs within LSPs) are required,<br />

each LSP must be established separately.<br />

Note: GMPLS uses signaling to reserve <strong>and</strong> set up routing or connection<br />

paths. The process is call signaling, which means that a separate control link<br />

is used to convey requests <strong>and</strong> parameters.<br />

A special control link carries the route control information. The separation of<br />

control <strong>and</strong> data paths gives the meaning of “outb<strong>and</strong>” signaling.<br />

GMPLS extends routing protocols to disseminate non-packet switch<br />

characteristics. For example, it uses a link descriptor for encoding <strong>and</strong><br />

transmission rate, available <strong>and</strong> reservable b<strong>and</strong>width, protection- <strong>and</strong><br />

restoration-related characteristics, <strong>and</strong> so on.<br />

GMPLS is a family of protocols including:<br />

► Link Management Protocol for neighbor discovery<br />

► Signaling protocol for route selection <strong>and</strong> path setup<br />

A.4.4 Link Management Protocol (LMP)<br />

LMP provides the following functions:<br />

► Neighbor identification <strong>and</strong> link verification<br />

► Shared link group<br />

► Fault isolation<br />

► Topology-aware networks<br />

Note: LMP allows GMPLS networks to obtain peer-to-peer awareness such<br />

that every participating Label Switch Router (LSR) sees the entire network<br />

design topology.<br />

The two core procedures of LMP are control channel management <strong>and</strong> link<br />

property correlation. In addition, fault management <strong>and</strong> control channel<br />

activation are necessary.<br />

Control channel management<br />

Control channel management is used to establish <strong>and</strong> maintain control channels<br />

between adjacent nodes. This is done using a “Config” message exchange <strong>and</strong> a<br />

944 <strong>TCP</strong>/<strong>IP</strong> <strong>Tutorial</strong> <strong>and</strong> <strong>Technical</strong> <strong>Overview</strong>

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