Support Neighbor Address Resolution over PCUIF IPA multiplex

While NACC was initially developed, it became clear there was need for
a way to interact PCU<->BSC in order resolve ARFCN+BSIC into CGI-PS
for later RIM usage.
Hence, this resolution was first (until today) implemented using an out
of bands RPC system using the CTRL interface, which required specific
config to be written and matches in osmo-pcu and osmo-bsc VTY (ip+port
of the CTRL interface to use).
However, this has several shortcomings:
* As explained above, specific configuration is required
* Since recently, we do support BSC redundancy in osmo-bts. Hence the BTS
  may switch to a BSC other than first one. If that happened, that'd mean
  the CTRL interface would still point to the initially configured one,
  which may not be the same currently serving the PCU.

During recent development of ANR related features, a similar need for
PCU<->BSC was required, but this time it was decided to extend the IPA
multiplex of the Abis OML connection to pass PCUIF messages,
transparently forwarded to each side by the BTS.
This has the advantage that connection PCU<->BTS is handled by BTS and
both sides send messages transparently.

Let's switch by default to using this new interface, while still
maintaing the old way for a while (announcing them as deprecated) to
avoid breaking existing deployments until they are upgraded to new
versions of osmo-pcu and osmo-bsc.

Related: SYS#4971
Change-Id: I6ad33c7ab10202840cf804dea9ba595978d0e920

1 files changed, 2 insertions, 0 deletions

diff --git a/src/pcu_l1_if.h b/src/pcu_l1_if.h
index 2a4f0ead..7d48febe 100644
--- a/src/pcu_l1_if.h
+++ b/src/pcu_l1_if.h
@@ -160,6 +160,8 @@ extern "C" {
 #endif
 struct gprs_rlcmac_bts;
 
+int pcu_tx_neigh_addr_res_req(struct gprs_rlcmac_bts *bts, const struct neigh_cache_entry_key *neigh_key);
+
 int pcu_rx(struct gsm_pcu_if *pcu_prim, size_t pcu_prim_length);
 int pcu_l1if_open(void);
 void pcu_l1if_close(void);