[RADIATOR] Negative Acct-Delay-Time from proxy RADIUS server

[Vangelis Kyriakakis]

Hello list,

     I have a RADIUS server which proxies RADIUS requests to another
RADIUS server (both RADIATOR servers).
    Sometimes I see that the Acct-Delay-Time in the packet that is
proxied to the final server has a value of -1 and the final server
interprets this as Acct-Delay-Time = 4294967295.

Example:

Packet that is sent from router to the proxy:

Wed Jan 17 09:28:59 2018: DEBUG: Packet dump:
*** Received from XXX.XXX.XXX.XXX port 21706 ....  
Code:       Accounting-Request
Identifier: 162
Authentic:  <244><143><28><160><194>7K<230>#<156>e<11>c<212>$R
Attributes:
        Acct-Session-Id = "0060DCF0"
                            .
                            .
                            .              
        Acct-Delay-Time = 0


Packet that is sent from proxy to the final server:

Wed Jan 17 09:28:59 2018: DEBUG: Packet dump:
*** Sending to YYY.YYY.YYY.YYY port 1813 ....
Code:       Accounting-Request
Identifier: 67
Authentic:  <12><229>0<244>j<225>h<131>M<142><27><213><5><172>(<29>
Attributes:
        Acct-Session-Id = "0060DCF0"
                        .
                        .
                        .
        Acct-Delay-Time = -1


Packet that is received by the final server:

Wed Jan 17 09:28:59 2018: DEBUG: Packet dump:
*** Received from ZZZ.ZZZ.ZZZ.ZZZ port 33850 ....
Code:       Accounting-Request
Identifier: 67
Authentic:  <12><229>0<244>j<225>h<131>M<142><27><213><5><172>(<29>
Attributes:
        Acct-Session-Id = "0060DCF0"
                        .
                        .  
                        .
        Acct-Delay-Time = 4294967295

Any ideas why is this happen?

       Regards
          Vangelis