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was received. The link set is then updated as follows:
If no link entry exists for the tuple (originating IP, IP of received interface) then such an entry is created. The originating IP is fetched from the IP header of the received packet. Whenever a link entry is created a corresponding neighbor entry is created as well if no such entry exists.
An asymmetric timer is then updated according to the validity time received. This timer decides for how long the link entry is to be considered asymmetric if the symmetric timer times out.
If the address of the receiving interface is located in the received HELLO message, the symmetric timer is updated and the status of the link is updated if necessary. The status of the neighbor entry according to this link entry is also updated if necessary.
Finally the actual holding time for this entry is set to be the maximum of the asymmetric timer and the symmetric timer.

3.5.2 Neighbor detection

Neighbor detection populates the 1-hop neighbor repository and only uses the main addresses of nodes. As seen in the previous section, the neighbor entries are closely related to the link entries. Whenever a link entry is created, the neighbor table is queried for a corresponding neighbor entry. Note that this neighbor entry must be registered on the main address of the node. If no such entry can be located, then a new neighbor entry is created. This means that while a node can have several link-entries describing different links to the same neighbor, only one neighbor entry exists per neighbor.

The status of the neighbor entries is also updated according to changes in the link-set. A neighbor is said to be a symmetric neighbor if there exists at least one link-entry in the link set connecting a local interface to one of the neighbor’s interfaces where the symmetric timer is not timed out. When a link-entry is deleted, the corresponding neighbor entry is also removed if no other link entries exist for this neighbor.

3.5.3 MPR Selector detection

The MPR flooding scheme is based on the requirement that nodes have registered what neighbors have chosen them as a MPR. Nodes mark their selected MPR neighbors in HELLO messages by setting the Neighbor Type to be MPR_NEIGH.

Upon receiving a HELLO message, a node checks the announced neighbors in the message for entries matching one of the addresses used by the local node. If an entry has a matching address and the neighbor type of that entry is set to MPR_NEIGH then an entry is updated or created in the MPR selector set using the main address of the sender of the HELLO message.

3.6 Link state declaration:

Link state routing protocols are based on nodes flooding the network with information about their local links. In protocols like ISIS this information is mostly links to subnets, since these protocols are highly based on aggregation of networks. OLSR uses host based flat routing, so the link state emitted describes links to neighbor nodes. This is done using Topology Control (TC) messages. The format of a TC message is shown in figure 3-9.

Figure: 3-9, the OLSR Topology Control Message Format.

TC messages are flooded using the MPR optimization. This is done on a regular interval, but TC messages are also generated immediately when changes are detected in the MPR selector set. In OLSR the floodin本论文由英语论文网提供整理，提供论文代写，英语论文代写，代写论文，代写英语论文，代写留学生论文，代写英文论文，留学生论文代写相关核心关键词搜索。