In a broadcast network a DIS is formed which in turn elects a pseudonode
All the routers exchanges information with the pseudonode
There are seperate DIS elected for both L1 and L2 updates the election of DIS is premptive the one with the highest priority wins if the priorities are equal the one with the highest mac address wins
DIS creates the pseudonode, it creates and updates the pseudonode
Conduct flooding over the lan
A priority of 0 does not mean the router is ineligible for becoming the DIS
In the above slide the router with the lowest mac address is elected as DIS as they have the same priority.
CSNP is sent every 10 seconds
If a CSNP is received which advertises a newer LSP, a PSNP request is sent requesting for the new LSP
If a newer lsp is received it is updated in the database and it is then flooded to other isis nodes
If the sequence number is same the LSP is ignored
If the sequence number is older athen what is locally present an updated LSP is sent.
The last point in the above figure suggests that the CSNP acts as an implicit acknowledgement
All the routers exchanges information with the pseudonode
There are seperate DIS elected for both L1 and L2 updates the election of DIS is premptive the one with the highest priority wins if the priorities are equal the one with the highest mac address wins
DIS creates the pseudonode, it creates and updates the pseudonode
Conduct flooding over the lan
In the above slide the router with the lowest mac address is elected as DIS as they have the same priority.
CSNP is sent every 10 seconds
If a CSNP is received which advertises a newer LSP, a PSNP request is sent requesting for the new LSP
If a newer lsp is received it is updated in the database and it is then flooded to other isis nodes
If the sequence number is same the LSP is ignored
If the sequence number is older athen what is locally present an updated LSP is sent.
The last point in the above figure suggests that the CSNP acts as an implicit acknowledgement
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