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https://github.com/nplrkn/alsoran

5G gNodeB Centralized Unit written in Rust
https://github.com/nplrkn/alsoran

5g e1ap f1ap gnb-cu gnb-cu-cp gnb-cu-up gnbcu gnodeb ngap o-ran openran ran rrc

Last synced: 17 days ago
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5G gNodeB Centralized Unit written in Rust

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README 

          
# Alsoran



*** This project is no longer active, but much of it lives on in [QCore](http://www.github.com/nplrkn/qcore) ***

  

Alsoran is a Rust implementation of the gNodeB Centralized Unit (gNB-CU) of the 5G Radio Access Network (RAN).



The gNodeB is the component that manages the radio access of 5G User Equipment (UEs) and connects them to a 5G Core. 



This project is currently a proof of concept and not yet a fully functional gNB-CU.



## Quickstart

```

cargo build

./target/debug/gnb-cu --mcc 111 --mnc 11 --amf-ip 5.5.5.5

```



## Current support

- UE registration demo against free5GC.

- PDU session setup and release (TS 23.502, figures 4.3.2.2.1-1 and 4.3.4.2-1).

- Relay of userplane packets between GNB-DU and UPF.

- Separate CU-CP and CU-UP communicating using E1.

- Scale-out of GNB-CU-CP workers using multiple TNLAs.

- ASN.1 libraries for NGAP, E1AP, F1AP and RRC.

- Rust ASN.1 autogenerator (written in Python).

- UE state in Redis datastore.

- [Triangular redirection](documentation/design/triangular-redirection.md)

- SCTP connection management stack 



Generally only the success cases are covered, and there are a lot of 'To Dos'.



### Procedure support

#### CU-CP

-  NG Setup

-  RAN Configuration Update

-  F1 Setup

-  E1 Setup

-  Initial Access

-  Uplink NAS

-  Downlink NAS

-  Initial Context Setup

-  Pdu Session Resource Setup

-  Pdu Session Resource Release

-  AMF Status Indication

-  GNB CU Configuration Update

-  GNB DU Configuration Update

-  GNB CU CP Configuration Update.

#### CU-UP

-  E1 Setup

-  Bearer Context Setup

-  Bearer Context Modification

-  Bearer Context Release

-  GNB CU CP Configuration Update

-  Downlink user data

-  Uplink user data



## What's different about Alsoran?



It's written in Rust and it has a "scale-out single hop" design.



"Scale-out" means that it has multiple interchangeable stateless worker processes.  A request can be processed by any worker and no worker is a single point of failure.  A Coordinator process coordinates the interface management exchanges of the workers when the topology changes.  The motivation is scalability and fault tolerance.



"Single hop" means that, in the mainline case, a message is processed by a single worker (rather than chained through multiple microservices or load balancers).  Each Alsoran CU-CP worker has its own SCTP connection to the AMF, the DU and the CU-UP.  The motivation is speed and system simplicity.



Rust is an attractive choice of language for new O-RAN development.  The main barrier to entry is the ASN.1 and SCTP based protocols.  This project attempts to prove that this barrier is surmountable.



## Building and running integration tests



The build relies on `lld` to reduce linker memory needs.  You will either need to install LLD (`sudo apt install lld` or similar), or edit .cargo/config to remove the `target.x86_64-unknown-linux-gnu` config, which reverts to plain `cc` linking.



`cargo test` runs the integration test suite, minus the live Redis test.  



To run the live Redis test, `cargo test live_redis -- --ignored`.  For this to pass, you need to have `redis-server` in your path.  Get Redis here: https://redis.io/docs/getting-started/.



## A quick tour



The following test shows the Alsoran CU-CP and CU-UP carrying out UE registration, session establishment and userplane forwarding.

```sh

RUST_LOG=info cargo test successful_pdu_session_setup --test pdu_session -- --nocapture

```



This test shows two workers starting up, and the Coordinator instructing the workers how to initialize their NGAP, E1AP and F1AP interfaces.

```sh

RUST_LOG=info cargo test two_workers_base --test two_workers -- --nocapture

```



You can packet capture during these tests by running the following in parallel. 

```sh

sudo tcpdump -w alsoran.pcap -i lo port 38472 or port 38412 or port 38462 or port 38462 or port 2152

```

...then Ctrl-C at the end of the test and open alsoran.pcap in Wireshark.



To run the live registration against free5GC takes a bit more setup - see the [demo instructions](documentation/howto/free5GC-testing.md).



Finally you might want to browse the design notes in documentation/design, which give an idea of the design thinking that has gone into Alsoran so far.



## Contributing



If you would like to contribute, start by creating a Github issue or discusion to propose the change you want to make.



The [backlog](documentation/backlog.md) shows the main items being worked on and also tracks areas of tech debt. 



The instructions for regenerating the two OpenAPI interfaces are in [OpenAPI generation](documentation/howto/OpenAPI%20generation.md).



## 3GPP and O-RAN specifications



Alsoran protocol handling and workflow logic is based on the following specifications.  



-  3GPP TS23.501 - System architecture for the 5G System

-  3GPP TS23.502 - Procedures for the 5G System

-  3GPP TS29.281 - General Packet Radio System (GPRS) Tunnelling Protocol User Plane (GTPv1-U)

-  3GPP TS37.324 - Service Data Adaptation Protocol (SDAP) specification

-  3GPP TS38.300 - NR and NG-RAN Overall Description

-  3GPP TS38.323 - Packet Data Convergence Protocol (PDCP) Specification

-  3GPP TS38.331 - Radio Resource Control (RRC) protocol specification

-  3GPP TS38.401 - NG-RAN; Architecture description 

-  3GPP TS38.412 - NG signalling transport 

-  3GPP TS38.413 - NG Application Protocol (NGAP)

-  3GPP TS38.414 - NG data transport

-  3GPP TS38.415 - PDU Session User Plane Protocol

-  3GPP TS38.462 - E1 signalling transport

-  3GPP TS38.463 - E1 Application Protocol (E1AP)

-  3GPP TS38.472 - F1 signalling transport

-  3GPP TS38.473 - F1 Application Protocol (F1AP)

-  3GPP TS38.474 - F1 data transport

-  O-RAN.WG5.C.1 - NR C-plane profile