how to get ipv6 address of cpe from cmts using snmp command?

[cisco cmts]

I have used snmp command to retrieve the ipv4 address of a cpe from cmts. Here is the command,

>snmpwalk  -c public -v 2c 10.130.82.12 1.3.6.1.4.1.9.9.116.1.3.1.1.3.1.14.23.221.56.134

The result is like,

SNMPv2-SMI::enterprises.9.9.116.1.3.1.1.3.1.14.23.221.56.134 = IpAddress: 10.31.93.64

here 

10.130.82.12 - cmts's ip

1.3.6.1.4.1.9.9.116.1.3.1.1.3 - the oid for the object, cdxCmCpeIpAddress

1.14.23.221.56.134 - cpe's mac address

10.31.93.64 - cpe's ip address

No problem for this. My question is how to retrieve ipv6 address of cpe if the cpe has one?

If Cisco supports it, what's the oid I can use?

I have tried some cmts from other brands, such as Arris C4, Casa, Hamonic, etc. They provide an oid to support ipv6 address retrieval of cpe.

[cisco cmts]

I found an oid to retrieve a list of ipaddresses for all cpes behind a modem from a cmts. The oid is,

1.3.6.1.4.1.9.9.116.1.3.8.1.3, and its name is, cdxCmToCpeInetAddress.

However, if the modem has more than one cpes, given a list of cpes' macAddresses, then there is no way to match ipaddesses with the cpes' macAddresses.