QTECH
Software Configuration Manual
8-104
DD packet format
Major fields :
·
Interface MTU : Size in bytes of the largest IP datagram that can be sent out the associated interface,
without fragmentation.
·
I (Initial) The Init bit, which is set to 1 if the packet is the first packet of database description packets, and set
to 0 if not.
·
M (More) : The More bit, which is set to 0 if the packet is the last packet of DD packets, and set to 1 if
more DD Packets are to follow.
·
MS (Master/Slave) : The Master/Slave bit. When set to 1, it indicates that the router is the master during
the database exchange process. Otherwise, the router is the slave.
·
DD Sequence Number : Used to sequence the collection of database description packets for ensuring
reliability and intactness of DD packets between the master and slave. The initial value is set by the master.
The DD sequence number then increments until the complete database description has been sent.
8.1.5.4 LSR packet
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.
LSR packet format
Major fields :