Explicitly provide gNB IP address for E2 in gNB configuration

[HaoxinSEU]

Hi community,

We want to report one thing about the documentation for the E2 interface.

We hope to implement FlexRIC and srsRAN, so we follow all the instructions on the documentation page, and use the provided E2 configuration for gNB:

e2:
  enable_du_e2: true                # Enable DU E2 agent (one for each DU instance)
  e2sm_kpm_enabled: true            # Enable KPM service module
  addr: 10.16.0.77                   # RIC IP address
  port: 36421                       # RIC port

But we get the following errors when launching the gNB, and it cannot connect to FlexRIC.

Connecting to NearRT-RIC on 10.16.0.77:36421
Failed to connect SCTP socket to 10.16.0.77:36421. error="Connection refused" timeout=1ms
srsGNB ERROR: Failed to create SCTP gateway.

Finally we find that it's necessary to add the gNB IP address under the e2 field, and after adding it, gNB can successfully connect to FlexRIC. So our gNB configuration looks like this now:

e2:
  enable_du_e2: true
  e2sm_kpm_enabled: true
  addr: 10.16.0.77
  bind_addr: 10.16.0.73
  port: 36421

I believe this is a common problem for SCTP bind when running the gNB and FlexRIC on different machines. And it's really confusing because in the documentation this bind_addr field is not mentioned. Thus, it would be nice if you can add this bind_addr field in the RIC section of documentation.

Thanks.

[brendan-mcauliffe]

Hi @HaoxinSEU, I am currently updating the RIC tutorial and will add a section relating to this. Thanks for pointing it out.

[zzerodream]

@HaoxinSEU Thank you so much dude, I am facing the same issue when integrating oran-sc ric in k8s with E2 nodes. I really appreciate your sharing.