diff options
Diffstat (limited to 'doc/bird.sgml')
| -rw-r--r-- | doc/bird.sgml | 38 |
1 files changed, 25 insertions, 13 deletions
diff --git a/doc/bird.sgml b/doc/bird.sgml index 65efebb8..0ee86c18 100644 --- a/doc/bird.sgml +++ b/doc/bird.sgml @@ -1616,6 +1616,7 @@ protocol babel [<name>] { interface <interface pattern> { type <wired|wireless>; rxcost <number>; + limit <number>; hello interval <number>; update interval <number>; port <number>; @@ -1632,23 +1633,34 @@ protocol babel [<name>] { <descrip> <tag><label id="babel-type">type wired|wireless </tag> - This option specifies the interface type: Wired or wireless. Wired - interfaces are considered more reliable, and so the default hello - interval is higher, and a neighbour is considered unreachable after only - a small number of "hello" packets are lost. On wireless interfaces, - hello packets are sent more often, and the ETX link quality estimation - technique is used to compute the metrics of routes discovered over this - interface. This technique will gradually degrade the metric of routes - when packets are lost rather than the more binary up/down mechanism of - wired type links. Default: <cf/wired/. + This option specifies the interface type: Wired or wireless. On wired + interfaces a neighbor is considered unreachable after a small number of + Hello packets are lost, as described by <cf/limit/ option. On wireless + interfaces the ETX link quality estimation technique is used to compute + the metrics of routes discovered over this interface. This technique will + gradually degrade the metric of routes when packets are lost rather than + the more binary up/down mechanism of wired type links. Default: + <cf/wired/. <tag><label id="babel-rxcost">rxcost <m/num/</tag> - This specifies the RX cost of the interface. The route metrics will be - computed from this value with a mechanism determined by the interface - <cf/type/. Default: 96 for wired interfaces, 256 for wireless. + This option specifies the nominal RX cost of the interface. The effective + neighbor costs for route metrics will be computed from this value with a + mechanism determined by the interface <cf/type/. Note that in contrast to + other routing protocols like RIP or OSPF, the <cf/rxcost/ specifies the + cost of RX instead of TX, so it affects primarily neighbors' route + selection and not local route selection. Default: 96 for wired interfaces, + 256 for wireless. + + <tag><label id="babel-limit">limit <m/num/</tag> + BIRD keeps track of received Hello messages from each neighbor to + establish neighbor reachability. For wired type interfaces, this option + specifies how many of last 16 hellos have to be correctly received in + order to neighbor is assumed to be up. The option is ignored on wireless + type interfaces, where gradual cost degradation is used instead of sharp + limit. Default: 12. <tag><label id="babel-hello">hello interval <m/num/</tag> - Interval at which periodic "hello" messages are sent on this interface, + Interval at which periodic Hello messages are sent on this interface, in seconds. Default: 4 seconds. <tag><label id="babel-update">update interval <m/num/</tag> |