B.3 MS behaviour

3GPP44.318Generic Access Network (GAN)Mobile GAN interface layer 3 specificationRelease 17TS

B.3.1 Receiving of data

B.3.1.1 Outer IP packet

When the MS receives an encrypted IP packet, it shall store the DSCP value from the ‘outer’ IP header in the context of this IPSec SA for this inner DSCP value.

B.3.1.2 Inner IP packet

Furthermore, the MS shall perform the following actions when handling the received IP packet and UDP datagram or TCP data in the application layer (i.e. GA-RC, GA-CSR or GA-PSR layers):

– For a received RTP/UDP packet, read the DSCP value from the ‘inner’ IP header (i.e. using the UDP socket for the traffic channel). If this value is different from what is currently being used for this RTP/UDP stream, then save the received DSCP value and use it for all outgoing RTP/UDP packets for this traffic channel (one way to achieve this is to set the DSCP value for the UDP socket).

– For a received GA-PSR-UNITDATA message, read the DSCP value from the ‘inner’ IP header. If this value is different from what is currently being used for this flow within the GA-PSR TC, then save the received DSCP value and use it for all outgoing GA-PSR-UNITDATA messages on this flow within the GA-PSR TC.

– For a received GA-RC message, GA-CSR message or GA-PSR message containing signalling or SMS, read the DSCP value from the ‘inner’ IP header (i.e. using the TCP socket for the TCP connection to the GANC). If this value is different from what is currently being used for this TCP connection, then save the received DSCP value and use it for all outgoing GA-RC messages, GA-CSR messages and GA-PSR messages containing signalling or SMS (one way to achieve this is to set the DSCP value for the TCP socket).

B.3.2 Sending of data

When the MS is sending an IP packet to the GANC, it shall make sure that the DSCP (DiffServ Code Point) values for the ‘inner’ IP header are computed from the received IP packets, as described in B.3.1.2 above. Further, the DSCP value for the ‘outer’ IP header is obtained from the stored value in the IPSec SA context for this inner DSCP value, as described in B.3.1.1 above, before forwarding the packet to the GANC-SEGW using the established SA.

Annex C (normative):
(Source-RAT) Measurement Report for Handover and Cell Change Order to GAN