The Gx specification Release 15 (3GPP doc 29.212) and the Rx specification (3GPP doc 29.214) define extended AVPs for higher bandwidth values which are used to accommodate the need for higher speeds offered to the subscribers in 5G-enabled networks.
The difference between the non-extended and extended AVPs carrying the bandwidth value is in their units. The bandwidth unit for non-extended bandwidth AVPs is defined in b/s, while extended bandwidth AVPs are in kb/s, increasing the upper limit of the supported bandwidth by a scale of 1000. The value for QoS rates carried in those AVPs is a 32-bit value. In b/s units, this amounts to a maximum supported rate of 232 - 1 = 4 294 967 295 b/s or approximately 4.3 Gb/s. In kb/s, this equals over 4 Tb/s.
Support for the extended AVPs that can carry rate information in kb/s is enabled through the negotiated Extended Bandwidth 5G New Radio (Extended-BW-NR) feature (ยง5.4.1, 3GPP doc 29212). This feature is negotiated during Gx session establishment phase (CCR-I/CCA-I), between the PCEF and PCRF.
Extended-BW-NR feature is defined as:
Vendor-Id = 10415 (3GPP)
Feature-List-Id = 2
Feature-List = bit 7 (bitmask 00000000 00000000 00000000 10000000 to 0x80) with the AVP flag rule set to O (Optional)
Feature-List-Id = 2 is included in the CCR-I message only if the following conditions are met:
Application is on Gx.
Extended-BW-NR feature is enabled.
config
subscr-mgmt
diam-appl-plcy
gx
features
extended-bw
Supported-Features AVP is enabled.
config
subscr-mgmt
diam-appl-plcy
gx
include-avp
supported-features
After the Extended-BW-NR feature is successfully negotiated, the following AVPs with units in kb/s are supported:
Extended-GBR-DL (AVP code 2850)
Extended-GBR-UL (AVP code 2851)
Extended-Max-Requested-BW-DL (AVP code 554)
Extended-Max-Requested-BW-UL (AVP code 555)
Extended-APN-AMBR-DL(AVP code 2848)
Extended-APN-AMBR-UL (AVP code 2849)