9 good questions and answers about "IS-IS Operation over Broadcast Links"

What are the selection criteria for a DIS?
-Router with highest interface priority
-In case of tie; Router with highest SNPA (Sub network Point of Attachment)
-In case SNPAs are not comparable (frame relay/ATM) Router with highest system ID.
What is the command to configure the DIS priority?
What are the priority values ?
What priority value is better?
router isis WORD

priority [level] 0 127
higher is better
What is the DIS responsible for?
-Helping routers on a broadcast segment to synchronize
-Representing the broadcast segment in the link-state database as a standalone object; the Pseudonode
What are the possibilities when a router recieves a CSNP packet from a DIS? 3
-Router has LSP with same LSPID in its linkstate database==> no action performed
-Router does not have an LSP with the indicated LSPID in its link-state database or sequence number on DIS is higher
-Router has an LSP with the same LSPID in its link-state database but its sequence number on the DIS is lower or the DIS not advertise this LSPID.
What is the action when a Router does not have an LSP with the indicated LSPID in its link-state database or sequence number on DIS is higher?
The router needs to download the LSP from the DIS by creating a PSNP requesting the LSP in question and forwarding it onto the segment. The DIS will recieve the PSNP and flood the requested LSP.
What is the action when the PSNP or LSP get lost during transmission?
It wil be send again.
Who is responsible to orginate and flood the Pseudonode LSP on a broadcast network?
What will happen when the DIS fails? 4
-Another router will be elected.
-No additional adjacency necessary ( all routers are fully adjacent)
-Pseudonode LSP will be replaced by the new elected DIS
-Routers will update their LSPs to point toward the new Pseudonode LSP
What is the difference between a network LSP or a router LSP?
-Network LSP or Pseudonode LSP, the System ID is the ID of the DIS and the Pseudonode ID is set to the LOCAL Circuit ID of the DIS's interface network.

-Router LSP , the System-ID carries the ID of the router and the Pseudonode is set to 0
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