DXS-3326GSR Gigabit Layer 3 Switch
Checksum
A standard IP checksum that includes all of the packet’s contents
except for the 64-bit authentication field.
Authentication Type
The type of authentication to be used for the packet.
Authentication
A 64-bit field used by the authentication scheme.
Hello Packet
Hello packets are OSPF packet type 1. They are sent periodically on all interfaces, including virtual links, in order to
establish and maintain neighbor relationships. In addition, Hello Packets are multicast on those physical networks having a
multicast or broadcast capability, enabling dynamic discovery of neighboring routers.
All routers connected to a common network must agree on certain parameters such as the Network Mask, the Hello
Interval, and the Router Dead Interval. These parameters are included in hello packets, so that differences can inhibit the
forming of neighbor relationships. A detailed explanation of the receive processing for Hello packets, so that differences
can inhibit the forming of neighbor relationships.
The format of the Hello packet is shown below:
Hello Packet
1
Packet Length
Router ID
Area ID
Version No.
Checksum Authentication Type
Authentication
Authentication
Network Mask
Hello Interval
Options Router Priority
Router Dead Interval
Designated Router
Backup Designated Router
Neighbor
Figure 7- 19. Hello Packet
Field Description
Network Mask The network mask associated with this interface.
Options The optional capabilities supported by the router.
Hello Interval The number of seconds between this router’s Hello packets.
Router Priority This router’s Router Priority. The Router Priority is used in the
election of the DR and BDR. If this field is set to 0, the router is
ineligible to become the DR or the BDR.
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