Allows Alternate Care-of-address support to be added at LMA to
separate signaling and control plane traffic.
Exec > Global Configuration > Context Configuration > LMA
configure > context
Entering the above command sequence results in the following prompt:
[ default | no ] alt-coa-allowed
Including this keyword with the command disables the feature. The
feature is disabled by default.
Disables the specified functionality.
This command allows Alternate Care-of-address support to be added at
LMA to separate signaling and control plane traffic.
The support of the extensions and functionality is defined in RFC
6275 and RFC 6463 for IPv6 and IPv4 transport respectively.
Proxy Mobile IPv6 is a network-based mobility management protocol. The
mobility entities involved in the Proxy Mobile IPv6 protocol, the Mobile Access
Gateway (MAG) and the Local Mobility Anchor (LMA), setup tunnels dynamically to
manage mobility for a mobile node within the Proxy Mobile IPv6 domain. There is
an extension to the Proxy Mobile IPv6 protocol to register an IPv4 or IPv6 data
plane address that is different from the Proxy Care-of Address with the LMA.
This allows separation of control and data plane. Some of the deployments of
Proxy Mobile IPv6 separated the control and data plane end points for Mobile
Access Gateway. There will be a separate IP address for the entity that sends
and received the Proxy Mobile IPv6 signaling messages. Similarly, there will be
a separate IP address for the entity that encapsulates and decapsulates the
data traffic to and from the mobile node.
In order to allow the separation of the control and data plane, the
address of the data plane traffic endpoint needs to be sent in a separate
extension to register two IP addresses with the LMA. The IP address used for
the signaling messages will continue to be called the Proxy Care-of-Address. A
separate IP address for the data plane is carried in the Proxy Binding Update
to indicate the tunnel end point for the data traffic.
The extension Alternate Care-of-Address Mobility Option defined in RFC
6275 should be used. When using IPv6 transport and IPv4 transport, Alternate
Ipv4 Care of Address Mobility Option defined in RFC 6463 should be used.
Normally, a binding update specifies the desired care-of-address in
the source address field of the IPv6 header. However, in some cases such as
when the mobile node wishes to indicate a Care-of Address that it cannot use as
a topologically correct source address or when the used security mechanism does
not protect the IPv6 header it is not possible.
The Alternate Care-of-Address option is for this type of situation.
This option is valid only in binding update. The Alternate Care-of Address
field contains an address to use as the care-of-address for binding rather than
using the source address of the packet as the care-of-address.
The following command disables Alternate Care-of-address support: