ETX link quality estimation algorithm is useful for link types other than
wireless,
especially when using babel with tunnels where packet losses do occur.
Changes since v2:
- change option type from bool to enum
- document the properties of the two algorithms
Changes since v1:
- fix missing reference to link quality in example configuration
- fix mishandling of default configuration
---
doc/bird.sgml | 10 ++++++++++
proto/babel/babel.c | 8 +++-----
proto/babel/babel.h | 8 ++++++++
proto/babel/config.Y | 8 +++++++-
4 files changed, 28 insertions(+), 6 deletions(-)
diff --git a/doc/bird.sgml b/doc/bird.sgml
index 8041faa9..269a5de9 100644
--- a/doc/bird.sgml
+++ b/doc/bird.sgml
@@ -1929,6 +1929,7 @@ protocol babel [<name>] {
rx buffer <number>;
tx length <number>;
check link <switch>;
+ link quality <none|etx>;
next hop ipv4 <address>;
next hop ipv6 <address>;
extended next hop <switch>;
@@ -2032,6 +2033,15 @@ protocol babel [<name>] {
hardware drivers or platforms do not implement this feature. Default:
yes.
+ <tag><label id="babel-link-quality">link quality none|etx </tag>
+ This option specifies the link quality estimation algorithm for computing
+ costs based on Hello history: none or etx. The none (k-out-of-j)
algorithm
+ is suitable for wired links that are either up, in which case they only
+ occasionally drop a packet, or down, in which case they drop all packets.
+ The Expected Transmission Cost algorithm, or etx, is suitable for
wireless
+ links that exhibit continuous variation of the link quality. Default:
etx for
+ wireless interfaces, none otherwise.
+
<tag><label id="babel-next-hop-ipv4">next hop ipv4 <m/address/</tag>
Set the next hop address advertised for IPv4 routes advertised on this
interface. Default: the preferred IPv4 address of the interface.
diff --git a/proto/babel/babel.c b/proto/babel/babel.c
index 7f0cca73..eb0f50ef 100644
--- a/proto/babel/babel.c
+++ b/proto/babel/babel.c
@@ -593,10 +593,9 @@ babel_update_cost(struct babel_neighbor *nbr)
if (!rcv || !nbr->ifa->up)
goto done;
- switch (cf->type)
+ switch (cf->link_quality)
{
- case BABEL_IFACE_TYPE_WIRED:
- case BABEL_IFACE_TYPE_TUNNEL:
+ case BABEL_IFACE_LINK_QUALITY_NONE:
/* k-out-of-j selection - Appendix 2.1 in the RFC. */
/* Link is bad if less than cf->limit/16 of expected hellos were received
*/
@@ -606,8 +605,7 @@ babel_update_cost(struct babel_neighbor *nbr)
rxcost = cf->rxcost;
txcost = nbr->txcost;
break;
-
- case BABEL_IFACE_TYPE_WIRELESS:
+ case BABEL_IFACE_LINK_QUALITY_ETX:
/*
* ETX - Appendix 2.2 in the RFC.
*
diff --git a/proto/babel/babel.h b/proto/babel/babel.h
index edde4cab..6a2968f1 100644
--- a/proto/babel/babel.h
+++ b/proto/babel/babel.h
@@ -118,6 +118,13 @@ enum babel_iface_type {
BABEL_IFACE_TYPE_MAX
};
+enum babel_iface_link_quality {
+ BABEL_IFACE_LINK_QUALITY_UNDEF = 0,
+ BABEL_IFACE_LINK_QUALITY_NONE = 1,
+ BABEL_IFACE_LINK_QUALITY_ETX = 2,
+ BABEL_IFACE_LINK_QUALITY_MAX
+};
+
enum babel_ae_type {
BABEL_AE_WILDCARD = 0,
BABEL_AE_IP4 = 1,
@@ -145,6 +152,7 @@ struct babel_iface_config {
u8 type;
u8 limit; /* Minimum number of Hellos to keep
link up */
u8 check_link;
+ u8 link_quality;
uint port;
uint hello_interval; /* Hello interval, in us */
uint ihu_interval; /* IHU interval, in us */
diff --git a/proto/babel/config.Y b/proto/babel/config.Y
index b8af0267..285a3f33 100644
--- a/proto/babel/config.Y
+++ b/proto/babel/config.Y
@@ -26,7 +26,7 @@ CF_KEYWORDS(BABEL, INTERFACE, METRIC, RXCOST, HELLO, UPDATE,
INTERVAL, PORT,
TYPE, WIRED, WIRELESS, RX, TX, BUFFER, PRIORITY, LENGTH, CHECK, LINK,
NEXT, HOP, IPV4, IPV6, BABEL_METRIC, SHOW, INTERFACES, NEIGHBORS,
ENTRIES, RANDOMIZE, ROUTER, ID, AUTHENTICATION, NONE, MAC, PERMISSIVE,
- EXTENDED, TUNNEL, RTT, MIN, MAX, DECAY, SEND, TIMESTAMPS)
+ EXTENDED, TUNNEL, RTT, MIN, MAX, DECAY, SEND, TIMESTAMPS, QUALITY, ETX)
CF_GRAMMAR
@@ -84,6 +84,8 @@ babel_iface_finish:
BABEL_IFACE->hello_interval = BABEL_HELLO_INTERVAL_WIRELESS;
if (!BABEL_IFACE->rxcost)
BABEL_IFACE->rxcost = BABEL_RXCOST_WIRELESS;
+ if (!BABEL_IFACE->link_quality)
+ BABEL_IFACE->link_quality = BABEL_IFACE_LINK_QUALITY_ETX;
}
else
{
@@ -93,6 +95,8 @@ babel_iface_finish:
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->link_quality)
+ BABEL_IFACE->link_quality = BABEL_IFACE_LINK_QUALITY_NONE;
}
if (BABEL_IFACE->rtt_cost && !BABEL_IFACE->rtt_send)
@@ -156,6 +160,8 @@ babel_iface_item:
| TX tos { BABEL_IFACE->tx_tos = $2; }
| TX PRIORITY expr { BABEL_IFACE->tx_priority = $3; }
| CHECK LINK bool { BABEL_IFACE->check_link = $3; }
+ | LINK QUALITY NONE { BABEL_IFACE->link_quality =
BABEL_IFACE_LINK_QUALITY_NONE; }
+ | LINK QUALITY ETX { BABEL_IFACE->link_quality =
BABEL_IFACE_LINK_QUALITY_ETX; }
| 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"); }
| EXTENDED NEXT HOP bool { BABEL_IFACE->ext_next_hop = $4; }
--
2.41.0
