Lectures notes for 2010 - KTH

Hello packet
0 7 8 15 16 23 24 31
Version Type = 1 Message length
Source Router IP Address
Area Identification
Checksum
Authentication type
Authentication (64 bits)
Network Mask
Hello interval (seconds) All zeros E T Priority
Dead interval (seconds)
Designated router IP address
Backup designated router IP address
Neighbor IP address
…
Neighbor IP address
Figure 6: OSPF Link state update packet (see Forouzan figure 14.44 pg. 419)
• E = 1 indicates a stub area
• T = 1 indicates router supports multiple metrics
• priority = 0 indicates that this router should not be considered as a designated or backup
designated router
• Dead interval is the time before a silent neighbor is assumed to be dead
• list of neighboring routers (of the router which sent the hello packet)
Maguire Hello packet 7: 30 of 70
maguire@kth.se 2010.03.21 Internetworking/Internetteknik