Commit 8cc5bb09 authored by Ondrej Zajicek (work)'s avatar Ondrej Zajicek (work)
Browse files

Filter: Add 'weight' route attribute 

Add 'weight' route attribute that allows to get and set ECMP weight of
nexthops. Similar to 'gw' attribute, it is limited to the first nexthop,
but it is useful for handling BGP multipath, where an ECMP route is
merged from multiple regular routes.
parent 24658677

doc/bird.sgml

+9 −0
Original line number Diff line number Diff line
@@ -1674,6 +1674,15 @@ Common route attributes are: 
	creation/removal. Zero is returned for routes with undefined outgoing

	interfaces. Read-only.



	<tag><label id="rta-weight"><m/int/ weight</tag>

	Multipath weight of route next hops. Valid values are 1-256. Reading

	returns the weight of the first next hop, setting it sets weights of all

	next hops to the specified value. Therefore, this attribute is not much

	useful for manipulating individual next hops of an ECMP route, but can

	be used in BGP multipath setup to set weights of individual routes that

	are merged to one ECMP route during export to the Kernel protocol

	(with active <ref id="krt-merge-paths" name="marge paths"> option).



	<tag><label id="rta-igp-metric"><m/int/ igp_metric</tag>

	The optional attribute that can be used to specify a distance to the

	network for routes that do not have a native protocol metric attribute

filter/config.Y

+2 −1
Original line number Diff line number Diff line
@@ -278,7 +278,7 @@ CF_KEYWORDS(FUNCTION, PRINT, PRINTN, UNSET, RETURN, 
	SET, STRING, BGPMASK, BGPPATH, CLIST, ECLIST, LCLIST,

	IF, THEN, ELSE, CASE,

	TRUE, FALSE, RT, RO, UNKNOWN, GENERIC,

	FROM, GW, NET, MASK, PROTO, SOURCE, SCOPE, DEST, IFNAME, IFINDEX,

	FROM, GW, NET, MASK, PROTO, SOURCE, SCOPE, DEST, IFNAME, IFINDEX, WEIGHT,

	PREFERENCE,

	ROA_CHECK, ASN, SRC, DST,

	IS_V4, IS_V6,
@@ -750,6 +750,7 @@ static_attr: 
 | DEST    { $$ = f_new_static_attr(T_ENUM_RTD,   SA_DEST,	0); }

 | IFNAME  { $$ = f_new_static_attr(T_STRING,     SA_IFNAME,	0); }

 | IFINDEX { $$ = f_new_static_attr(T_INT,        SA_IFINDEX,	1); }

 | WEIGHT  { $$ = f_new_static_attr(T_INT,        SA_WEIGHT,	0); }

 ;



term:

filter/data.h

+1 −0
Original line number Diff line number Diff line
@@ -99,6 +99,7 @@ enum f_sa_code { 
  SA_DEST,

  SA_IFNAME,

  SA_IFINDEX,

  SA_WEIGHT,

} PACKED;



/* Static attribute definition (members of struct rta) */

filter/f-inst.c

+15 −0
Original line number Diff line number Diff line
@@ -516,6 +516,7 @@ 
      case SA_DEST:	RESULT(sa.f_type, i, rta->dest); break;

      case SA_IFNAME:	RESULT(sa.f_type, s, rta->nh.iface ? rta->nh.iface->name : ""); break;

      case SA_IFINDEX:	RESULT(sa.f_type, i, rta->nh.iface ? rta->nh.iface->index : 0); break;

      case SA_WEIGHT:	RESULT(sa.f_type, i, rta->nh.weight + 1); break;



      default:

	bug("Invalid static attribute access (%u/%u)", sa.f_type, sa.sa_code);
@@ -586,6 +587,20 @@ 
	}

	break;



      case SA_WEIGHT:

        {

	  int i = v1.val.i;

	  if (i < 1 || i > 256)

	    runtime( "Setting weight value out of bounds" );

	  if (rta->dest != RTD_UNICAST)

	    runtime( "Setting weight needs regular nexthop " );



	  /* Set weight on all next hops */

	  for (struct nexthop *nh = &rta->nh; nh; nh = nh->next)

	    nh->weight = i - 1;

        }

	break;



      default:

	bug("Invalid static attribute access (%u/%u)", sa.f_type, sa.sa_code);

      }

CRA Git | Maintained and supported by SUSTech CRA and CCSE