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

[Toke Høiland-Jørgensen]

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...

> +		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