Huawei Commercial gNB - NG error indication ("id-RANNodeName" and "id-Extended-RANNodeName")

[fefer]

Hi,

I am trying to integrate a Huawei commercial gNB but I am getting an "error indication" after the ng setup request. I believe the error is caused because of mal functioning of parsing 2 fields of the ng setup request, the "id-RANNodeName" and "id-Extended-RANNodeName". Should I be able to parse both items? I am attaching the pcap too.

test.pcapng.zip

BR

[acetcom]

@fefer

There seems to be a problem with the asn1c compiler in open5gs. So, I manually created branch issues994 to handle this problem. You can find my patch code in this commit a3195bc. It's not a fundamental solution, but it work well at least in open5gs simulation environment.

And also, @riebl provided the following patch in the @mouse07410 vlm_master as below.
mouse07410/asn1c@c35ebd3

However, there is no APC_EXTENSION in RAN NodeName UTF8String of Extended RAN NodeName.

I'll try, but I'm not sure if I can fix it.

Thank you for sharing this issue.
Sukchan

[acetcom]

@fefer

I've fixed and updated it to the main branch. It was solved by manually modifying the code generated by asn1c.

The asn1c decoding/encoding does not work properly when UTF8String requires APC_EXTENSIBLE(...).

AMFNameUTF8String ::= UTF8String (SIZE(1..150, ...))
RANNodeNameUTF8String ::= UTF8String (SIZE(1..150, ...))

The following code shows that UTF8String is not a known multiplier and there is a bug where APC_EXTENSIBLE is lost in this case. For your reference, in PrintableString and VisibleString, APC_EXTENSIBLE is generated well. Because they are a known multiplier.

### libasn1parser/asn1p_expr.h

 87 #define ASN_STRING_KM_MASK  0x100   /* Known multiplier */
 88 #define ASN_STRING_NKM_MASK 0x200   /* Not a known multiplier */
 89 #define ASN_STRING_MASK     0x300   /* Every restricted string type */
 90     ASN_STRING_IA5String    = ASN_STRING_KM_MASK,
 91     ASN_STRING_PrintableString,
 92     ASN_STRING_VisibleString,
 93     ASN_STRING_ISO646String,    /* aka VisibleString */
 94     ASN_STRING_NumericString,
 95     ASN_STRING_UniversalString,
 96     ASN_STRING_BMPString,
 97     ASN_STRING_UTF8String   = ASN_STRING_NKM_MASK,
 98     ASN_STRING_GeneralString,
 99     ASN_STRING_GraphicString,
100     ASN_STRING_TeletexString,
101     ASN_STRING_T61String,

If you analyze the asn1c source code a little more, range->non_PER_visible is set to 1 in Not a known multipler.

### libasn1fix/asn1fix_crange.c

1022     /*
1023      * X.691, #9.3.6
1024      * Constraints on restricted character string types
1025      * which are not known-multiplier are not PER-visible.
1026      */
1027     if((expr_type & ASN_STRING_NKM_MASK))
1028         range->not_PER_visible = 1;
1029 

In this case, it is returned from line 2036 according to line 2034 of the code below. Lines 2098-2101 cannot be executed. So, APC_EXTENSIBLE is lost in UTF8String.

### libasn1compiler/asn1c_C.c

2032 static int
2033 emit_single_member_PER_constraint(arg_t *arg, asn1cnst_range_t *range, int      alphabetsize, const char *type) {
2034     if(!range || range->incompatible || range->not_PER_visible) {
2035         OUT("{ APC_UNCONSTRAINED,\t-1, -1,  0,  0 }");
2036         return 0;
2037     }
...
2098             OUT("{ APC_CONSTRAINED%s,%s% d, % d, ",
2099                 range->extensible
2100                     ? " | APC_EXTENSIBLE" : "",
2101                 range->extensible ? " " : "\t", (int)rbits, (int)ebits);

I haven't been tracking this issue anymore. I solved it manually as Open5GS only uses UTF8String in AMFNameUTF8String and RANNodeNameUTF8String.

Let me know if you have any further questions.

Thank you so much for sharing this issue.
Sukchan

[fefer]

Hi Sukchan,

Thanks a lot! With your update I was able to integrate the Huawei model is a BTS 5900 in case you want to add to your list. I was able to get up to 1Gbps (which is the max of my current interface) on a single device.

Best regards

[Matheus-Garbelini]

Hi, is BTS 5900 operating in 5G NSA or SA mode?
Could not find any official datasheet information of this product on google. Thanks