Reliable flooding protocol 11 a The advertising router floods an lsa to all other interfaces a Other routers forward the lsa to all interfaces except the one that the lsa is received n To ensure reliability, all LSAs are positive acknowledged n a checksum is used to detect data corruption of an lSA, which covers the entire lSa except for some mutable fields. a The checksum is used both when the lsa is flooded and kept in the router 's database
Reliable flooding protocol 11 The advertising router floods an LSA to all other interfaces. Other routers forward the LSA to all interfaces except the one that the LSA is received. To ensure reliability, all LSAs are positiveacknowledged. A checksum is used to detect data corruption of an LSA, which covers the entire LSA except for some mutable fields. The checksum is used both when the LSA is flooded and kept in the router’s database
Packet storm prevention n To prevent packet storms from occurring, Use some information to differentiate new lsas from old lSas n Each router must keep the latest LSAs. d LSAs that are not newer are discarded a Differentiating between new and old lSas a Timestamps with local and global meanings (stamped by the advertising router A combination of sequence number (sn)and age
Packet storm prevention 12 To prevent packet storms from occurring, use some information to differentiate new LSAs from old LSAs. Each router must keep the latest LSAs. LSAs that are not newer are discarded. Differentiating between new and old LSAs Timestamps with local and global meanings (stamped by the advertising router). A combination of sequence number (SN) and age
LSAS' sequence numbers and ages o A new LSa is indicated by a larger SN (the advertising router increments the sn for every lsa it sends). a The age and other information may also be used when the sns are identica a Design of the sequence numbering a Circular Sn space(SN wraparounds a Linear SN space(no sn wraparounds)
LSAs’ sequence numbers and ages 13 A new LSA is indicated by a larger SN (the advertising router increments the SN for every LSA it sends). The age and other information may also be used when the SNs are identical. Design of the sequence numbering Circular SN space (SN wraparounds) Linear SN space (no SN wraparounds)
Linear sequence number space 14 n The sn starts from some value say o (this initial value may be negative). n The sn space should be large enough, say 32-bit SN space. a When attempting to increment the sn beyond the largest SN, n Prematurely age the lSa and reflooding it. n After receiving ACKs from all neighbor routers, send the LSA with the initial sn
Linear sequence number space 14 The SN starts from some value, say 0 (this initial value may be negative). The SN space should be large enough, say 32-bit SN space. When attempting to increment the SN beyond the largest SN, Prematurely age the LSA and reflooding it. After receiving ACKs from all neighbor routers, send the LSA with the initial SN