[PATCH 2/2] Babel: Add option to control ecmp nexthop weight

[dxld at darkboxed.org]

Hi Toke,

On Sun, May 08, 2022 at 09:09:13PM +0200, Toke Høiland-Jørgensen wrote:
> Daniel Gröber <dxld at darkboxed.org> writes:
> 
> > ---
> >  doc/bird.sgml        | 21 ++++++++++++++-------
> >  proto/babel/babel.c  |  1 +
> >  proto/babel/babel.h  |  2 ++
> >  proto/babel/config.Y |  2 ++
> >  4 files changed, 19 insertions(+), 7 deletions(-)
> >
> > diff --git a/doc/bird.sgml b/doc/bird.sgml
> > index 5e85d8ec..1fdda7bc 100644
> > --- a/doc/bird.sgml
> > +++ b/doc/bird.sgml
> > @@ -1865,6 +1865,7 @@ protocol babel [<name>] {
> >  	ipv4 { <channel config> };
> >  	ipv6 [sadr] { <channel config> };
> >          randomize router id <switch>;
> > +	ecmp <switch> [limit <num>];
> >  	interface <interface pattern> {
> >  		type <wired|wireless>;
> >  		rxcost <number>;
> > @@ -1879,7 +1880,7 @@ protocol babel [<name>] {
> >  		check link <switch>;
> >  		next hop ipv4 <address>;
> >  		next hop ipv6 <address>;
> > -		ecmp <switch> [limit <num>];
> 
> Just add this in the right place the first time around? Or fold this
> into the first patch entirely; doesn't really need to be a separate
> patch...

Fixed.

> > +		ecmp weight <num>;
> >  		authentication none|mac [permissive];
> >  		password "<text>";
> >  		password "<text>" {
> > @@ -1910,6 +1911,13 @@ protocol babel [<name>] {
> >        router ID every time it starts up, which avoids this problem at the cost
> >        of not having stable router IDs in the network. Default: no.
> >  
> > +      <tag><label id="babel-ecmp">ecmp <m>switch</m> [limit <m>number</m>]</tag>
> > +
> > +      Determines whether babel will emit ECMP (equal-cost multipath)
> > +      routes, allowing to load-balancing traffic across multiple paths. If
> > +      enabled the maximum number of next-hops to allow can be specified,
> > +      defaulting to 16.
> > +
> >        <tag><label id="babel-type">type wired|wireless </tag>
> >        This option specifies the interface type: Wired or wireless. On wired
> >        interfaces a neighbor is considered unreachable after a small number of
> > @@ -1984,12 +1992,11 @@ protocol babel [<name>] {
> >        source for Babel packets will be used. In normal operation, it should not
> >        be necessary to set this option.
> >  
> > -      <tag><label id="babel-ecmp">ecmp <m>switch</m> [limit <m>number</m>]</tag>
> > -
> > -      Determines whether babel will emit ECMP (equal-cost multipath)
> > -      routes, allowing to load-balancing traffic across multiple paths. If
> > -      enabled the maximum number of next-hops to allow can be specified,
> > -      defaulting to 16.
> > +      <tag><label id="babel-ecmp-weight">ecmp weight <m>number</m></tag>
> > +      This specifies the relative weight used for nexthops going through
> > +      the iface when ECMP is enabled. Larger weight values relative to other
> > +      nexthops attract more traffic. Valid values are 1-256. Default value
> > +      is 1.
> >  
> >        <tag><label id="babel-authentication">authentication none|mac [permissive]</tag>
> >        Selects authentication method to be used. <cf/none/ means that packets
> > diff --git a/proto/babel/babel.c b/proto/babel/babel.c
> > index 4d9c657c..83d9a1d0 100644
> > --- a/proto/babel/babel.c
> > +++ b/proto/babel/babel.c
> > @@ -639,6 +639,7 @@ babel_nexthop_insert(
> >  {
> >    nh->gw = r->next_hop;
> >    nh->iface = r->neigh->ifa->iface;
> > +  nh->weight = r->neigh->ifa->cf->ecmp_weight;
> >  
> >    /*
> >     * If we cannot find a reachable neighbour, set the entry to be onlink. This
> > diff --git a/proto/babel/babel.h b/proto/babel/babel.h
> > index 3868dcb2..2ad1ded0 100644
> > --- a/proto/babel/babel.h
> > +++ b/proto/babel/babel.h
> > @@ -145,6 +145,8 @@ struct babel_iface_config {
> >    int tx_tos;
> >    int tx_priority;
> >  
> > +  u8 ecmp_weight;
> > +
> >    ip_addr next_hop_ip4;
> >    ip_addr next_hop_ip6;
> >  
> > diff --git a/proto/babel/config.Y b/proto/babel/config.Y
> > index 8f18c790..6f03482a 100644
> > --- a/proto/babel/config.Y
> > +++ b/proto/babel/config.Y
> > @@ -70,6 +70,7 @@ babel_iface_start:
> >    BABEL_IFACE->tx_tos = IP_PREC_INTERNET_CONTROL;
> >    BABEL_IFACE->tx_priority = sk_priority_control;
> >    BABEL_IFACE->check_link = 1;
> > +  BABEL_IFACE->ecmp_weight = 0;
> >  };
> >  
> >  
> > @@ -149,6 +150,7 @@ babel_iface_item:
> >   | AUTHENTICATION NONE { BABEL_IFACE->auth_type = BABEL_AUTH_NONE; }
> >   | AUTHENTICATION MAC { BABEL_IFACE->auth_type = BABEL_AUTH_MAC; BABEL_IFACE->auth_permissive = 0; }
> >   | AUTHENTICATION MAC PERMISSIVE { BABEL_IFACE->auth_type = BABEL_AUTH_MAC; BABEL_IFACE->auth_permissive = 1; }
> > + | ECMP WEIGHT expr { BABEL_IFACE->ecmp_weight = $3 - 1; if (($3<1) || ($3>256)) cf_error("ECMP weight must be in range 1-256"); }
> >   | password_list
> >   ;
> >  
> > -- 
> > 2.30.2

--Daniel