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Hello
Hello messages are used as a form of greeting, to allow a router to discover other adjacent routers on its local
links and networks. The messages establish relationships between neighboring devices (called adjacencies)
and communicate key parameters about how OSPF is to be used in the autonomous system or area.
Database Description
Database Description messages contain descriptions of the topology of the autonomous system or area. They
convey the contents of the link-state database (LSDB) for the area from one router to another. Communicating
a large LSDB may require several messages to be sent by having the sending device designated as a master
device and sending messages in sequence, with the slave (recipient of the LSDB information) responding with
acknowledgements.
Link State Request
These messages are used by one router to request updated information about a portion of the LSDB from
another router. The message specifies exactly which link(s) about which the requesting device wants more
current information.
Link State Update
These messages contain updated information about the state of certain links on the LSDB. They are sent in
response to a Link State Request message, and also broadcast or multicast by routers on a regular basis. Their
contents are used to update the information in the LSDBs of routers that receive them.
Link State Acknowledgment
These messages provide reliability to the link-state exchange process, by explicitly acknowledging receipt of a
Link State Update message.
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4
D
D
D
D
N
N
S
S
DDNS (Dynamic DNS Free) allows you to create a hostname that points to your home or office IP address, providing an
easy-to-remember URL for quick access.
You must register for the service at one of the listed service providers. You can reach the service provider’s Web Site by
selecting them in the list. Apply for a domain name, and ensure it is allocated to you.
Details of your DDNS account (Host name, Name, password) must then be entered and saved on this screen.
The device will then automatically ensure that you current IP address is recorded by the DDNS service provider from