Re: control characters in BGP shutdown communication(RFC 9003) messages and NETCONF

[Job Snijders via NANOG <nanog () lists nanog org>]

Dear Martin,

On Sun, Sep 07, 2025 at 01:25:34PM +0300, Martin Tonusoo via NANOG wrote:
> Meta(AS 32934) recently sent a cease NOTIFICATION message to its
> neighbors on AMS-IX and Piter-IX which had a "<0b>maintenance" string
> on the RFC 9003 "Shutdown Communication" field. In other words, the
> "Shutdown Communication" field contained "0b 6d 61 69 6e 74 65 6e 61
> 6e 63 65". At least on Junos(tested with versions 21.4R3-S3.4,
> 23.2R2-S4.5 and 25.2R1.9), calling the "get-bgp-summary-information"
> or "get-bgp-neighbor-information" RPCs using NETCONF returns the
> string containing the control character and this in turn means that
> libraries parsing the XML fail as 0x0b(vertical tab) is not in the
> allowed character range of XML 1.0:
> https://www.w3.org/TR/xml/#charsets
>
> Who is to blame here? Junos, for returning invalid characters in its
> NETCONF response?

Older versions of Junos incorrectly interpret the first byte of the
Shutdown Communication as a character in the message, instead as the
length field. The format is described here:
https://datatracker.ietf.org/doc/html/rfc9003#section-2

Try upgrading to a newer Junos. For more information go here:
https://prsearch.juniper.net/problemreport/PR1652786

Kind regards,

Job
- Author of RFC 8203 and RFC 9003
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