# Comparative Analysis of Producer Mobility Management Approaches in Named Data Networking
## 3 Analysis of Scheme Designs
### Kite  
The Kite scheme works by setting up a forwarding path from an immobile anchor to a mobile producer. The Kite scheme uses a specific namespace design to make sure interests which cross paths with the trace path (the path between the anchor and the mobile producer) are directed to the mobile producer instead of the anchor to eliminate path stretch. A namespace design was proposed to implement the logic required for scheme operation as described below:  
* **Scheme Operation** 1. Namespace Design The prefix announced by the anchor is in the form /routingPrefix, and it notifies the network that this prefix is only reachable through this anchor. The prefix of the data packet generated by the mobile producer is /routingPrefix/tracingPrefix. The control packets (trace interest (TI) and trace data (TD)) have the prefixes /routingPrefix/\"trace\"/tracingPrefix/verificationInfo. The routing prefix is used to direct TIs toward the anchor, and the trace tag is used to differentiate the TI or TD from ordinary interest and data packets. Furthermore, they are easily detected and removed by the routers as necessary, and the verification information is for authenticating the communication between the anchor and the mobile producer. 2. Trace Set-up Every producer is associated with a dedicated anchor which announces the mobile producer's routing prefix in the routing plane. After handoff, the mobile producer sends a TI to its assigned anchor. A TI is an interest packet with a special \"/trace\" tag in the name field. This TI will be directed to the anchor based on the LPM. The anchor responds with a TD, which travels back to the mobile producer following the reverse path of the TI. The TD serves as an acknowledgment to the TI, since it has the same prefix of the earlier TI. In addition, in intermediate routers between the anchor and mobile producer, upon receipt of a TD, a forwarder treats it as a regular data packet, matches it against the PIT entries, and forwards it downstream if a match is found. The routers then search for the \"/trace\" tag in the TD's name field. If the tag is found, then the \"/trace\" prefix is extracted from the name. The router then updates the FIB using the prefix and the incoming face of the corresponding TI. The trace is in a soft state and will be purged if not refreshed, so the mobile producer needs to actively keep the trace alive by resending TIs. Consumers' interests are forwarded toward the anchor, unless they have reached a node in the trace path. In this case, the router's FIB will have two entries for the prefix: one for the announced prefix of the anchor and the other resulting from the TI or TD exchange. The entry set by the anchor announcement leads toward the anchor, and the entry set during the TI or TD exchanges leads toward the mobile producer, but since the latter will result in a longer prefix match, the consumer interest will be forwarded toward the mobile producer, thus eliminating unnecessary path stretch. After producer mobility from its current PoA, the intermediate routers in this trace will lead to the old location of the mobile producer (thus called a stale trace), which will result in a NACK sent back to the consumer. To avoid going to the stale trace again, a forwarding strategy is proposed to forward an interest to a face indicated by the shorter prefix match instead of the LPM, unless it results in the face from which the interest arrived to avoid looping. This will forward the interest to the anchor, which will direct the interest to the correct location of the mobile producer. Next, we provide an example of Kite's operation:
* **Kite Example** We show an example of Kite's operation in Figure 4. We assume two consumers: consumer1 attached to PoA C and consumer2 attached to D, as shown in Figure 4a. The anchor advertises for prefix /A, which is the routing prefix. Therefore, all routers in the network add an entry for /A in their FIB tables leading to the anchor.