This presentation includes a short overview of OLSR protocol.

1. OPTIMIZED
LINK STATE
ROUTING
(OLSR)
PROTOCOL
Prepared By:
Huda Abualola
Maha Kadadha
Hadi Otrok

2. A glimpse on OLSR
◦ Messages:
◦ HELLO
◦ Topology Control (TC)
◦ MultiPoint Relay (MPRs)
◦ Forward and Receive Packets for their MPR
Selectors
◦ Generate and Forward TC messages
◦ MPRs are selected based on uniqueness and
reachability to 2-hop neighbors

3. Packet Structure of OLSR Messages
◦ Each packet includes multiple OLSR
messages (could be different messages’
types)
◦ A header is added to each message
featuring
◦ The size of the OLSR message
◦ The Type
◦ The Sender IP Address
◦ Etc.
Reference: https://datatracker.ietf.org/doc/html/rfc3626

4. HELLO Message Structure
◦ In the HELLO message each Node includes the IPs of its 1-hop Neighbors.
◦ Each node Knows who are the 1-hop neighbors when it receives their HELLO message.
◦ HELLO message is not forwarded.
◦ HELLO message is shared with 1-hop neighbors only.
◦ HELLO message is periodically shared every 2 seconds.
◦ The selected MPR is announced through the HELLO message.
◦ All nodes in the network generate and share HELLO message.
0 16 31
Reserved Htime Willingness
Link Code Reserved Link Message Size
Neighbor Interface Address
…
Reference: https://datatracker.ietf.org/doc/html/rfc3626

5. HELLO Message Sharing Example
• Taking Vehicle 3 as an example
• Vehicle 3 announce itself to the 1-hop neighbors
by sharing the HELLO message
2
Hello message sharing
1
3
4
5
6
HELLO
HELLO
HELLO
MPR
Smart
Vehicle

6. Topology Control (TC) Message
◦ TC message is shared every change in the topology.
◦ Only MPRs generate and forward TC messages.
◦ TC message is used to build the routing table.
◦ An MPR generates a TC message containing the set of selectors from its 1-hop neighbors.
Reference: https://datatracker.ietf.org/doc/html/rfc3626

7. TC Message Sharing Example
◦ Taking this topology as an example
1
3
4
5
6
MPR
Smart
Vehicle
Vehicle 1 2 3 4 5 6
MPR 2 3 5 3 3 5
MPR 2 3 5
Selectors {1} {2,4,5} {3,6}
2

8. TC message generated by MPRs
2
0 16 31
ANSN Reserved
1
3
5
ANSN Reserved
2
4
5
ANSN Reserved
3
6
MPR
Selectors

9. 0 16 31
ANSN Reserved
1
TC Message Sharing Example
1
2
3
4
5
6
◦ Taking MPR 2 as an Example for TC message Flow
◦ MPR 3 Forwards the Message, since MPR 2 is a selector of MPR 3
◦ MPR 5 receives the TC message and Forwards it since MPR 3 is a
selector of MPR5
MPR 2 3 5
Selectors {1} {2,4,5} {3,6}
TC message
sharing from
originator MPR
MPR
Smart
Vehicle
TC message
Forwarding from
originator MPR

10. Related Research Papers