Cisco GRS Configuration Manual page 22

Implementing NAT 64 over ISM
• Private IP6 subscribers – It denotes a private network.
• Interface/VLAN- It denotes a designated interface or VLAN which is associated with the VRF.
• Inside VRF – It denotes the VRF that handles packets coming from the subscriber network. It is known
as inside VRF as it forwards packets from the private network.
• App SVI- It denotes an application interface that forwards the data packet to and from the ISM. The
data packet may be sent from another line card through a backplane. Because the ISM card does not
have a physical interface, the APP SVI acts as a logical entry into it.
The inside VRF is bound to an App SVI. There are 2 App SVIs required; one for the inside VRF and
the other one for the outside VRF. Each App SVI pair will be associated with a unique "inside VRF"
and a unique public IP address pool. The VRF consists of a static route for forwarding packets to App
SVI1.
• Outside VRF- It denotes the VRF that handles packets going out to the public network. It is known as
outside VRF as it forwards packets from the public network.
• Public IPV4- It denotes a public network.
The following figure illustrates the path of the data packet from a private network to a public network in a
NAT64 implementation.
The packet goes through the following steps when it travels from the private network to the public network:
1 In the network shown in this figure, the packet travels from the host A (having the IP address
3001:DB8:E0E:E03::/40) in the private network to host B (having the IP address 11.11.11.2) in the public
network. The private address has to be mapped to the public address by NAT64 that is implemented in
ISM.
2 The packet enters through the ingress port on the Gigabit Ethernet (GigE) interface at Slot 3.
Cisco IOS XR Carrier Grade NAT Configuration Guide for the Cisco CRS Router, Release 5.2.x
12
Implementing Carrier Grade NAT on Cisco IOS XR Software
OL-32659-01