What is Proxy functionality in Relay Node?

Probably your question is - what is the meaning of proxy functionality of DeNB in LTE (correct me if I am wrong)

The donor eNB (DeNB) is enhanced to provide S1 and X2 proxy functionality between the RN and other network nodes (other eNBs, MMEs and S-GWs). The S1 and X2 proxy functionality includes passing UE-dedicated S1 and X2 signalling messages as well as GTP data packets between the S1 and X2 interfaces associated with the RN and the S1 and X2 interfaces associated with other network nodes. Due to the proxy functionality, the DeNB appears as an MME (for S1-MME), an eNB (for X2) and an S-GW (for S1-U) to the RN.

On behalf of Bart (https://www.facebook.com/groups/LTE.Professionals )
In general proxy is terminating and originating whatever comes to it.
When doing so it (proxy) has chance to originate with changed parameters - like source ip or in diameter source/dest realm