From: Claudio Jeker <cjeker@diehard.n-r-g.com>
Subject: Re: bgpd: shorthand for DOWNGRADE community
To: Job Snijders <job@bsd.nl>
Cc: tech@openbsd.org
Date: Thu, 24 Sep 2026 13:34:43 +0200

On Thu, Sep 24, 2026 at 11:17:57AM +0000, Job Snijders wrote:
> For https://datatracker.ietf.org/doc/html/draft-ietf-grow-downgrade-bgp-community
> IANA assigned a new well-known BGP community. For now just provide
> shorthand like (just like is done for other WKC).
> 
> OK?

OK claudio@

Do you want to add the draft to bgpd.8?

The question is how do we signal the LE DSCP towards those networks?
 
> Index: bgpctl/bgpctl.c
> ===================================================================
> RCS file: /cvs/src/usr.sbin/bgpctl/bgpctl.c,v
> diff -u -p -r1.324 bgpctl.c
> --- bgpctl/bgpctl.c	24 Jul 2026 05:01:57 -0000	1.324
> +++ bgpctl/bgpctl.c	24 Sep 2026 11:16:49 -0000
> @@ -1034,6 +1034,8 @@ fmt_community(uint16_t a, uint16_t v)
>  			return "NO_PEER";
>  		case COMMUNITY_BLACKHOLE:
>  			return "BLACKHOLE";
> +		case COMMUNITY_DOWNGRADE:
> +			return "DOWNGRADE";
>  		default:
>  			break;
>  		}
> Index: bgpctl/parser.c
> ===================================================================
> RCS file: /cvs/src/usr.sbin/bgpctl/parser.c,v
> diff -u -p -r1.140 parser.c
> --- bgpctl/parser.c	7 May 2026 12:35:03 -0000	1.140
> +++ bgpctl/parser.c	24 Sep 2026 11:16:50 -0000
> @@ -1216,6 +1216,10 @@ parsecommunity(struct community *c, char
>  		setcommunity(c, COMMUNITY_WELLKNOWN,
>  		    COMMUNITY_BLACKHOLE, 0, 0);
>  		return;
> +	} else if (strcasecmp(s, "DOWNGRADE") == 0) {
> +		setcommunity(c, COMMUNITY_WELLKNOWN,
> +		    COMMUNITY_DOWNGRADE, 0, 0);
> +		return;
>  	}
>  
>  	if ((p = strchr(s, ':')) == NULL)
> Index: bgpd/bgpd.conf.5
> ===================================================================
> RCS file: /cvs/src/usr.sbin/bgpd/bgpd.conf.5,v
> diff -u -p -r1.258 bgpd.conf.5
> --- bgpd/bgpd.conf.5	18 Sep 2026 15:46:14 -0000	1.258
> +++ bgpd/bgpd.conf.5	24 Sep 2026 11:16:50 -0000
> @@ -1808,6 +1808,7 @@ to do wildcard matching.
>  Alternatively, well-known communities may be given by name instead and
>  include
>  .Ic BLACKHOLE ,
> +.Ic DOWNGRADE ,
>  .Ic GRACEFUL_SHUTDOWN ,
>  .Ic NO_EXPORT ,
>  .Ic NO_ADVERTISE ,
> Index: bgpd/bgpd.h
> ===================================================================
> RCS file: /cvs/src/usr.sbin/bgpd/bgpd.h,v
> diff -u -p -r1.548 bgpd.h
> --- bgpd/bgpd.h	21 Sep 2026 19:06:16 -0000	1.548
> +++ bgpd/bgpd.h	24 Sep 2026 11:16:51 -0000
> @@ -1203,9 +1203,10 @@ struct filter_peers {
>  #define	COMMUNITY_NEIGHBOR_AS		2
>  #define	COMMUNITY_LOCAL_AS		3
>  
> -/* wellknown community definitions */
> +/* well-known community definitions */
>  #define	COMMUNITY_WELLKNOWN		0xffff
>  #define	COMMUNITY_GRACEFUL_SHUTDOWN	0x0000  /* RFC 8326 */
> +#define	COMMUNITY_DOWNGRADE		0x000A	/* draft-grow-downgrade */
>  #define	COMMUNITY_BLACKHOLE		0x029A	/* RFC 7999 */
>  #define	COMMUNITY_NO_EXPORT		0xff01
>  #define	COMMUNITY_NO_ADVERTISE		0xff02
> Index: bgpd/parse.y
> ===================================================================
> RCS file: /cvs/src/usr.sbin/bgpd/parse.y,v
> diff -u -p -r1.505 parse.y
> --- bgpd/parse.y	21 Sep 2026 18:45:09 -0000	1.505
> +++ bgpd/parse.y	24 Sep 2026 11:16:53 -0000
> @@ -4460,6 +4460,10 @@ parsecommunity(struct community *c, int 
>  		setcommunity(c, COMMUNITY_WELLKNOWN,
>  		    COMMUNITY_BLACKHOLE, 0, 0);
>  		return (0);
> +	} else if (strcasecmp(s, "DOWNGRADE") == 0) {
> +		setcommunity(c, COMMUNITY_WELLKNOWN,
> +		    COMMUNITY_DOWNGRADE, 0, 0);
> +		return (0);
>  	}
>  
>  	if ((p = strchr(s, ':')) == NULL) {
> 

-- 
:wq Claudio