- mobile IPv4 traffic is asymmetric. The tunnel from the home agent to the mobile node is unidirectional. The return traffic from the mobile node back to the corresponding node is NOT tunnel. The source IP of the packets from the mobile node is the Home Address (HoA). Since many network edges perform source IP filter, this represent an issue.
- Where else for mobile IPv6. The tunnel between the Home Agent (HA) and the Mobile Node (MN) is bidirectional. This resolves the source IP packet filter the is present in Mobile IPv4.
- Because the traffic from the MN to the Corresponding Node (CN) transverses the HA, the routing is potentially sub-optimum. If the CN supports Mobile IPv6, it can then establish a direct tunnel with the MN for optimized routing.