3com S7906E Manuel De Montage

 

1-13 

After exchanging DD packets, any two routers know which LSAs of the peer routers are missing from 

the local LSDBs. In this case, they send LSR (link state request) packets, requesting the missing LSAs. 

The packets contain the digests of the missing LSAs. The following figure shows the LSR packet format. 

Figure 1-12 LSR packet format 

 

 

Major fields: 

z 

LS type: Type number of the LSA to be requested. Type 1 for example indicates the Router LSA. 

z 

Link State ID: Determined by LSA type. 

z 

Advertising Router: ID of the router that sent the LSA. 

LSU (Link State Update) packets are used to send the requested LSAs to peers, and each packet 

carries a collection of LSAs. The LSU packet format is shown below.  

Figure 1-13 LSU packet format 

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