bird/proto/babel/config.Y
Toke Høiland-Jørgensen d9763bd7a0
babel: Add route metric smoothing
The Babel RTT extension employs metric smoothing to dampen route
oscillations in the face of varying RTT values between two peers[0].

This patch implements such dampening in Bird, roughly following the
implementation in babeld (i.e., using the same exponential function
definition). The main difference is that we calculate everything in the
native Bird microsecond time unit (and increase constants accordingly), and
that we split out the smoothed metric calculation in two function variants,
one that has no side effects and one that does.

  [0] https://arxiv.org/pdf/1403.3488.pdf

Signed-off-by: Toke Høiland-Jørgensen <toke@toke.dk>
2022-12-12 13:46:36 +08:00

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/*
* BIRD -- Babel Configuration
*
* Copyright (c) 2015-2016 Toke Hoiland-Jorgensen
* (c) 2016--2017 Ondrej Zajicek <santiago@crfreenet.org>
* (c) 2016--2017 CZ.NIC z.s.p.o.
*
* Can be freely distributed and used under the terms of the GNU GPL.
*/
CF_HDR
#include "proto/babel/babel.h"
#include "nest/iface.h"
CF_DEFINES
#define BABEL_CFG ((struct babel_config *) this_proto)
#define BABEL_IFACE ((struct babel_iface_config *) this_ipatt)
CF_DECLS
CF_KEYWORDS(BABEL, INTERFACE, METRIC, RXCOST, HELLO, UPDATE, INTERVAL, PORT,
TYPE, WIRED, WIRELESS, TUNNEL, RX, TX, BUFFER, PRIORITY, LENGTH, CHECK,
LINK, NEXT, HOP, IPV4, IPV6, BABEL_METRIC, SHOW, INTERFACES, NEIGHBORS,
ENTRIES, RANDOMIZE, ROUTER, ID, AUTHENTICATION, NONE, MAC, PERMISSIVE,
RTT, MIN, MAX, DECAY, SEND, TIMESTAMPS)
CF_GRAMMAR
proto: babel_proto ;
babel_proto_start: proto_start BABEL
{
this_proto = proto_config_new(&proto_babel, $1);
init_list(&BABEL_CFG->iface_list);
BABEL_CFG->hold_time = 1 S_;
BABEL_CFG->metric_decay = BABEL_SMOOTHING_DECAY;
};
babel_proto_finish:
{
if (BABEL_CFG->metric_decay)
BABEL_CFG->smooth_recp = BABEL_SMOOTHING_UNIT + BABEL_SMOOTHING_CONSTANT / BABEL_CFG->metric_decay;
};
babel_proto_item:
proto_item
| proto_channel
| INTERFACE babel_iface
| RANDOMIZE ROUTER ID bool { BABEL_CFG->randomize_router_id = $4; }
| METRIC DECAY expr_us { BABEL_CFG->metric_decay = $3; if ($3 && (($3 < BABEL_SMOOTHING_STEP) || ($3 > BABEL_SMOOTHING_DECAY_MAX))) cf_error("Metric decay must be 0, or between 1-180s"); }
;
babel_proto_opts:
/* empty */
| babel_proto_opts babel_proto_item ';'
;
babel_proto:
babel_proto_start proto_name '{' babel_proto_opts '}' babel_proto_finish;
babel_iface_start:
{
this_ipatt = cfg_allocz(sizeof(struct babel_iface_config));
add_tail(&BABEL_CFG->iface_list, NODE this_ipatt);
init_list(&this_ipatt->ipn_list);
reset_passwords();
BABEL_IFACE->port = BABEL_PORT;
BABEL_IFACE->type = BABEL_IFACE_TYPE_WIRED;
BABEL_IFACE->limit = BABEL_HELLO_LIMIT;
BABEL_IFACE->tx_tos = IP_PREC_INTERNET_CONTROL;
BABEL_IFACE->tx_priority = sk_priority_control;
BABEL_IFACE->rtt_min = BABEL_RTT_MIN;
BABEL_IFACE->rtt_max = BABEL_RTT_MAX;
BABEL_IFACE->rtt_decay = BABEL_RTT_DECAY;
BABEL_IFACE->rtt_send = 1;
BABEL_IFACE->check_link = 1;
};
babel_iface_finish:
{
if (BABEL_IFACE->type == BABEL_IFACE_TYPE_WIRELESS)
{
if (!BABEL_IFACE->hello_interval)
BABEL_IFACE->hello_interval = BABEL_HELLO_INTERVAL_WIRELESS;
if (!BABEL_IFACE->rxcost)
BABEL_IFACE->rxcost = BABEL_RXCOST_WIRELESS;
}
else
{
if (!BABEL_IFACE->hello_interval)
BABEL_IFACE->hello_interval = BABEL_HELLO_INTERVAL_WIRED;
if (!BABEL_IFACE->rxcost)
BABEL_IFACE->rxcost = BABEL_RXCOST_WIRED;
if (BABEL_IFACE->type == BABEL_IFACE_TYPE_TUNNEL && !BABEL_IFACE->rtt_cost)
BABEL_IFACE->rtt_cost = BABEL_RXCOST_RTT;
}
if (BABEL_IFACE->rtt_cost && !BABEL_IFACE->rtt_send)
cf_error("Can't set RTT cost when sending timestamps is disabled");
if (BABEL_IFACE->rtt_min >= BABEL_IFACE->rtt_max)
cf_error("Min RTT must be smaller than max RTT");
/* Make sure we do not overflow the 16-bit centisec fields */
if (!BABEL_IFACE->update_interval)
BABEL_IFACE->update_interval = MIN_(BABEL_IFACE->hello_interval*BABEL_UPDATE_INTERVAL_FACTOR, BABEL_MAX_INTERVAL);
BABEL_IFACE->ihu_interval = MIN_(BABEL_IFACE->hello_interval*BABEL_IHU_INTERVAL_FACTOR, BABEL_MAX_INTERVAL);
BABEL_CFG->hold_time = MAX_(BABEL_CFG->hold_time, BABEL_IFACE->update_interval*BABEL_HOLD_TIME_FACTOR);
BABEL_IFACE->passwords = get_passwords();
if (!BABEL_IFACE->auth_type != !BABEL_IFACE->passwords)
cf_error("Authentication and password options should be used together");
if (BABEL_IFACE->passwords)
{
struct password_item *pass;
uint len = 0, i = 0;
WALK_LIST(pass, *BABEL_IFACE->passwords)
{
/* Set default crypto algorithm (HMAC-SHA256) */
if (!pass->alg)
pass->alg = ALG_HMAC_SHA256;
if (!((pass->alg & ALG_HMAC) ||
(pass->alg == ALG_BLAKE2S_128) ||
(pass->alg == ALG_BLAKE2S_256) ||
(pass->alg == ALG_BLAKE2B_256) ||
(pass->alg == ALG_BLAKE2B_512)))
cf_error("Only HMAC and Blake2 algorithms are supported");
len += mac_type_length(pass->alg);
i++;
}
BABEL_IFACE->mac_num_keys = i;
BABEL_IFACE->mac_total_len = len;
}
};
babel_iface_item:
| PORT expr { BABEL_IFACE->port = $2; if (($2<1) || ($2>65535)) cf_error("Invalid port number"); }
| RXCOST expr { BABEL_IFACE->rxcost = $2; if (($2<1) || ($2>65535)) cf_error("Invalid rxcost"); }
| LIMIT expr { BABEL_IFACE->limit = $2; if (($2<1) || ($2>16)) cf_error("Limit must be in range 1-16"); }
| TYPE WIRED { BABEL_IFACE->type = BABEL_IFACE_TYPE_WIRED; }
| TYPE WIRELESS { BABEL_IFACE->type = BABEL_IFACE_TYPE_WIRELESS; }
| TYPE TUNNEL { BABEL_IFACE->type = BABEL_IFACE_TYPE_TUNNEL; }
| HELLO INTERVAL expr_us { BABEL_IFACE->hello_interval = $3; if (($3<BABEL_MIN_INTERVAL) || ($3>BABEL_MAX_INTERVAL)) cf_error("Hello interval must be in range 10 ms - 655 s"); }
| UPDATE INTERVAL expr_us { BABEL_IFACE->update_interval = $3; if (($3<BABEL_MIN_INTERVAL) || ($3>BABEL_MAX_INTERVAL)) cf_error("Update interval must be in range 10 ms - 655 s"); }
| RX BUFFER expr { BABEL_IFACE->rx_buffer = $3; if (($3<256) || ($3>65535)) cf_error("RX buffer must be in range 256-65535"); }
| TX LENGTH expr { BABEL_IFACE->tx_length = $3; if (($3<256) || ($3>65535)) cf_error("TX length must be in range 256-65535"); }
| TX tos { BABEL_IFACE->tx_tos = $2; }
| TX PRIORITY expr { BABEL_IFACE->tx_priority = $3; }
| CHECK LINK bool { BABEL_IFACE->check_link = $3; }
| NEXT HOP IPV4 ipa { BABEL_IFACE->next_hop_ip4 = $4; if (!ipa_is_ip4($4)) cf_error("Must be an IPv4 address"); }
| NEXT HOP IPV6 ipa { BABEL_IFACE->next_hop_ip6 = $4; if (!ipa_is_ip6($4)) cf_error("Must be an IPv6 address"); }
| 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; }
| RTT MIN expr_us { BABEL_IFACE->rtt_min = $3; }
| RTT MAX expr_us { BABEL_IFACE->rtt_max = $3; }
| RTT COST expr { BABEL_IFACE->rtt_cost = $3; if ($3 >= BABEL_INFINITY) cf_error("RTT cost must be < 65535"); }
| RTT DECAY expr { BABEL_IFACE->rtt_decay = $3; if (($3 < 1) || ($3 > 256)) cf_error("RTT decay must be between 1-256"); }
| SEND TIMESTAMPS bool { BABEL_IFACE->rtt_send = $3; }
| password_list
;
babel_iface_opts:
/* empty */
| babel_iface_opts babel_iface_item ';'
;
babel_iface_opt_list:
/* empty */
| '{' babel_iface_opts '}'
;
babel_iface:
babel_iface_start iface_patt_list_nopx babel_iface_opt_list babel_iface_finish;
dynamic_attr: BABEL_METRIC { $$ = f_new_dynamic_attr(EAF_TYPE_INT, T_INT, EA_BABEL_METRIC); } ;
CF_CLI_HELP(SHOW BABEL, ..., [[Show information about Babel protocol]]);
CF_CLI(SHOW BABEL INTERFACES, optproto opttext, [<name>] [\"<interface>\"], [[Show information about Babel interfaces]])
{ PROTO_WALK_CMD($4, &proto_babel, p) babel_show_interfaces(p, $5); };
CF_CLI(SHOW BABEL NEIGHBORS, optproto opttext, [<name>] [\"<interface>\"], [[Show information about Babel neighbors]])
{ PROTO_WALK_CMD($4, &proto_babel, p) babel_show_neighbors(p, $5); };
CF_CLI(SHOW BABEL ENTRIES, optproto opttext, [<name>], [[Show information about Babel prefix entries]])
{ PROTO_WALK_CMD($4, &proto_babel, p) babel_show_entries(p); };
CF_CLI(SHOW BABEL ROUTES, optproto opttext, [<name>], [[Show information about Babel route entries]])
{ PROTO_WALK_CMD($4, &proto_babel, p) babel_show_routes(p); };
CF_CODE
CF_END