Did you see the last changelog? This option was just added in this release.
*) ppp - added "enable-ipv6-accounting" option under PPP AAA menu (CLI only);
not present..... and the attribute also with your description is still not recognized
this is the log:
07:30:53 radius,debug,packet Unknown-Attribute(type=153) = 0x326130313a396138303a313031303a3a
07:30:53 radius,debug,packet 2f3634
07:30:53 radius,debug,packet Message-Authenticator = 0xa3a2726155160eb698779597ea83bcb4
07:30:53 radius,debug received reply for 1b:1b7d
07:30:53 radius,debug new request 1b:00 code=Accounting-Request service=ppp called-id=ULLPPPoE
07:30:53 radius,debug sending 1b:00 to xxx:1813
07:30:53 radius,debug,packet sending Accounting-Request with id 8 to xxx:1813
07:30:53 radius,debug,packet Signature = 0x5c7859434a129534ace69e4592476799
07:30:53 radius,debug,packet Service-Type = 2
07:30:53 radius,debug,packet Framed-Protocol = 1
07:30:53 radius,debug,packet NAS-Port = 15728644
07:30:53 radius,debug,packet NAS-Port-Type = 15
07:30:53 radius,debug,packet User-Name = "provaopen3"
07:30:53 radius,debug,packet Calling-Station-Id = "00:90:0B:BA:4C:B5"
07:30:53 radius,debug,packet Called-Station-Id = "ULLPPPoE"
07:30:53 radius,debug,packet NAS-Port-Id = "bonding-Network"
07:30:53 radius,debug,packet Acct-Session-Id = "81e00001"
07:30:53 radius,debug,packet Framed-IP-Address = yyy
07:30:53 radius,debug,packet Acct-Authentic = 1
07:30:53 radius,debug,packet Event-Timestamp = 1711089053
07:30:53 radius,debug,packet Acct-Status-Type = 1
07:30:53 radius,debug,packet NAS-Identifier = "FTTxAS1-test"
07:30:53 radius,debug,packet Acct-Delay-Time = 0
07:30:53 radius,debug,packet NAS-IP-Address = 192.168.12.196
07:30:53 pppoe,ppp,info,account provaopen3 logged in, yyy from 00:90:0B:BA:4C:B5