Mobile Ip - NetModule NB3710 User Manual

NB3710
User Manual for NRSW version 4.4

5.4.4. Mobile IP

Mobile IP (MIP) can be used to enable seamless switching between different kinds of WAN links (e.g.
WWAN/WLAN). The mobile node hereby remains reachable via the same IP address (home address)
at any time, independently of the WAN link being used. Effectively, any WAN link switch causes very
small outages during switchover while keeping all IP connections alive.
Moreover, NetModule routers also support NAT-Traversal for mobile nodes running behind a firewall
(performing NAT), which makes mobile nodes even there accessible from a central office via their
home address, and thus, bypassing any complicated VPN setups.
The home agent accomplishes this by establishing a tunnel (similar to a VPN tunnel) between itself
and the mobile node. WAN link switching works by telling the home agent that the WAN IP address
(called the care-of address in MIP terms) of the mobile node has changed. The home agent will
then encapsulate packets destined to a mobile node's home address into a tunnel packet containing
the current care-of address of the mobile node as its destination address.
To prevent problems with firewalls and private IP addressing, the MIP implementation always em-
ploys reverse tunneling, which means that all traffic sent by a mobile node is relayed via the tunnel
to the home agent instead of directly being conveyed to the final destination. This fact also empowers
MIP to be used as a lightweight VPN replacement (without payload secrecy).
The MIP implementation supports RFCs 3344, 5177, 3024 and 3519. For applications requiring vast
numbers of mobile nodes, interoperability with the Cisco 2900 Series home agent implementation has
been verified. However, since NetModule routers implement a mobile node as well as a home agent,
a MIP network with up to 10 mobile nodes can be implemented without requiring expensive third party
routers.
If MIP is run as a mobile node, the following settings can be configured:
Parameter
Primary home agent ad-
dress
Secondary home agent ad-
dress
Home address
SPI
Authentication type
Mobile IP Configuration
The address of the primary home agent
The address of the secondary home agent. The mobile node will try to
register with this home agent, if the primary home agent is not reach-
able.
The permanent home address of the mobile node which can be used
to reach the mobile router at any time
The Security Parameter Index (SPI) identifying the security context for
the mobile IP tunnel between the mobile node and the home agent.
This is used to distinguish mobile nodes from each other. Therefore
each mobile node needs to be assigned a unique SPI. This is a 32-bit
hexadecimal value.
The used authentication algorithm. This can be prefix-suffix-md5 (de-
fault for MIP) or hmac-md5.
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