# OPMSS: Optimal Producer Mobility Support Solution for Named Data Networking
## 3 Design of Proposed Optimal Producer Mobility Support Solution
### Broadcast Strategy  
The mobility interest packets are designed to carry the producer's new location information and update the intermediate routers. Hence, the broadcasting strategy is designed in such a way that, when the content producer moves to the new location, the new CR that accommodates a connected mobile producer will configure the new prefix and set the mobility flag, tag the _MI_ packets, and broadcast to the available interface connections within the domain. Once _MI_ packets are received by the next router, the look-up is performed to check if there are any prefix records before handoff that need to be updated with the new prefix after handoff. Otherwise, the router will record the new prefix in the FIB table and forward it to available interface connections. Figure 3 shows the flowchart of how the broadcasting strategy utilizes _MI_ packets to update the intermediate routers. The aim of _MI_ packet broadcasting is to update the entire network about the mobility information or a new data name prefix of the mobile producer. These can be described in steps for a proper understanding of the operational processes of the proposed OPMSS. The following steps are described in three phases--the process before, during, and after the handoff.  
Figure 2: Mobility interest packet.  
Steps before the handoff, when the consumer is connected to CR5 and the producer is connected to CR1
* Step 1: Normally, a consumer sends an interest packet requesting data to CR5. CR5 then checks if the content is available; otherwise, it floods the NDN network with the interest packet.
* Step 2: The interest packet passes through routers until the content producer is reached. The producer then sends the requested data to the consumer in a breadcrumb style. The steps before handoff are normal behavior in NDN and are the same as in the Kite solution. Steps when handoff starts
* Step 3: The producer suddenly decides to disconnect from CR1 and search for strong signal and connect to CR2 in another domain.
* Step 4: The new content name prefix and the \(MI\) packet are configured after connection with CR2 for an update.
* Step 5: The CR2 broadcasts the \(MI\) packets within the domain to update all FIB tables, including the FIB table of the restricted domain router (RDR).
* Step 6: The RDR placed in each domain to control the broadcasting storm will check the old and new prefix information. If the prefix hierarchy contains a neighbor domain, the RDR will re-broadcast the \(MI\) packet to the neighboring domain.
* Step 7: The content consumer re-sends the pending interest packet to the network as a normal transmission. Steps after handoff
* Step 8: The routing plane of NDN uses the best route strategy to establish the optimal route and forward the pending interest packet to the new location of the mobile producer.  
Figure 3: Mobility update by broadcasting strategy.  
Step 9: The mobile producer replies to the consumer with the requested data packets via the optimal path. Steps 3-9 will be repeated when the producer moves to the next access point.