Cisco Mobile Networks Static Collocated Care-of Address

If a mobile node or mobile router determines that it is connected to a foreign network, it acquires a care-of address. This care-of address is the exit-point of the tunnel towards the mobile node. The care-of address is included in the Mobile IP registration request and is used by the home agent to forward packets to the mobile node in its current location. Two types of care-of addresses exist:

• Care-of address acquired from a foreign agent
• Collocated care-of address

A foreign agent care-of address is an IP address on a foreign agent that is advertised on the foreign network being visited by a mobile node. A mobile node that acquires this type of care-of address can share the address with other mobile nodes. A collocated care-of address is an IP address assigned to the interface of the mobile node itself. A collocated care-of address represents the current position of the mobile node on the foreign network and can be used by only one mobile node at a time.

For the Cisco Mobile Networks--Static CCoA feature, a static collocated care-of address is a fixed IP address configured on a roaming interface of the mobile router.

CCoA support using a dynamically acquired IP address will be available in a future release.

This feature allows a mobile router to roam to foreign networks where foreign agents are not deployed.

In general, static CCoA is intended for links where there are no foreign agents. If foreign agents are present, the interface will not support foreign agent care-of address roaming while the interface is configured for static CCoA. Any foreign agent advertisements detected on that interface will be ignored. A static CCoA interface will solicit advertisements if configured but will not automatically solicit advertisements when the interface comes up. This behavior overrides the default behavior--typically, in the Cisco Mobile Networks feature, when an interface goes down and comes back up, foreign agent advertisements are solicited automatically.

When the mobile router registers a CCoA with a home agent, a single HA-CCoA tunnel is created and is used for traffic to the mobile router and its mobile networks.

The static CCoA configured on the mobile router interface will become the endpoint of the HA-CCoA tunnel as the home agent tunnels packets to the mobile router. The mobile router will use this same tunnel to reverse tunnel packets back to the home agent if configured.

1.    enable

2.    configure terminal

3.    interface type number

4.    ip address ip-address mask

5.    ip mobile router-service roam

6.    ip mobile router-service collocated [gateway ip-address]

7.    ip mobile router-service collocated registration retry seconds

• Troubleshooting Tips

1.    show ip mobile router interface

2.    show ip mobile router agent

3.    show ip mobile router registration

4.    show ip mobile router

The following example shows a mobile router configured with a static CCoA address of 172.21.58.23 and a next-hop gateway address of 172.21.58.1.

interface loopback 0
! MR home address
 ip address 10.1.0.1 255.255.255.255
!
!Static CCoA
interface FastEthernet0/0
 ip address 172.21.58.23 255.255.255.0
 ip mobile router-service roam
 ip mobile router-service collocated gateway 172.21.58.1
 ip mobile router-service collocated registration retry 3
!
router mobile
!
ip mobile router
 address 10.1.0.1 255.255.255.255
 home-agent 1.1.1.1 
ip mobile secure home-agent 1.1.1.1 spi 100 key hex 12345678123456781234567812345678