From 7a7c1d9f34b95263d3bc100dec6cf3b94f1a9802 Mon Sep 17 00:00:00 2001 From: Pavel Machek Date: Mon, 20 Dec 1999 19:14:06 +0000 Subject: Few more entries for bird documentation --- doc/bird.html | 61 ++++++++++++++++++++++++++++++++++++++++++++++++----------- 1 file changed, 50 insertions(+), 11 deletions(-) diff --git a/doc/bird.html b/doc/bird.html index 2401ede..b45ecdd 100644 --- a/doc/bird.html +++ b/doc/bird.html @@ -17,6 +17,8 @@

Introduction

+

What is bird

+

You may wonder what 'bird' means. It is acronym of 'Basic Internet Routing Daemon', and we think that's cool name. Its task is similar to what firmware of Cisco routers does, or what gated does. However, you can not run Cisco's firmware on "normal" computer and @@ -60,6 +62,8 @@ protocol rip {

Filters

+

Introduction

+

Bird contains rather simple programming language. (No, it can not yet read mail :-). There are two objects in this language: filters and functions. Filters are called by bird core when route is being passed between protocol and main routing table, and filters may call functions. Functions may @@ -98,7 +102,7 @@ pairs type name;, where each pair defines one local variabl several statments into one by { statments } construction, that is usefull if you want to make bigger block of code conditional. -

Variables

+

Data types

Each variable and each value has certain type. Unlike C, filters distinguish between integers and booleans (that is to prevent you from shooting in the foot). @@ -154,31 +158,66 @@ booleans (that is to prevent you from shooting in the foot).

Rip

+

Introduction

+

Rip protocol (sometimes called Rest In Pieces) is simple protocol, where each router broadcasts distances to all networks he can reach. When router hears distance to other network, it increments it and broadcasts it back. Broadcasts are done in regular intervals. Therefore, if some network goes -unreachable, routers keep telling each other that distance is old distance plus 1. After some time, -distance reaches infinity (that's 15 in rip) and all routers know that network is unreachable. Rip -tries to minimize situations where counting to infinity is neccessary, because it is slow. Due to -infinity being 15, you can not use rip on networks where maximal distance is bigger than 15 -hosts. You can read more about rip at rfc1234. +unreachable, routers keep telling each other that distance is old distance plus 1 (actually, plus +interface metric, which is usually one). After some time, distance reaches infinity (that's 15 in +rip) and all routers know that network is unreachable. Rip tries to minimize situations where +counting to infinity is neccessary, because it is slow. Due to infinity being 16, you can not use +rip on networks where maximal distance is bigger than 15 hosts. You can read more about rip at rfc1234.

Configuration

In addition to options generic to other protocols, rip supports following options:

-
port number -
selects IP port to operate on, default 520. - -
authentication none|password|md5 +
authentication none|password|md5
selects authenticaion method to use. None means that packets are not authenticated at all, password means that plaintext password is embedded into each packet, and md5 means that packets are authenticated using md5 cryptographics hash. See rfc1234. If you set authentication to non-none, it is good idea to add - passwords { } section. + passwords { } section. +
+ +

There are two options that can be specified per-interface. First is metric, with +default one. Second is mode broadcast|quiet|nolisten|version1, it selects mode for +rip to work in. If nothing is specified, rip runs in multicasts mode. version1 is +currently equivalent to broadcast, and it makes rip talk at broadcast address even +through multicast mode is possible. quiet option means that rip will not transmit +periodic messages onto this interface and nolisten means that rip will talk to this +interface but not listen on it. + +

Following options generally override specified behaviour from rfc. If you use any of these +options, bird will no longer be rfc-compatible, which means it will not be able to talk to anything +other than equally (mis-)configured bird. I warned you. + +

+
port number +
selects IP port to operate on, default 520. (This is usefull when testing bird, if you + set this to address >1024, you will not need to run bird with uid==0). + +
infinity number +
select value of infinity, default 16. Bigger values will make protocol convergence + even slower. + +
period number +
specifies number of seconds between periodic updates. Default is 30 seconds. Lower + number will mean faster convergence but bigger network load. + +
timeouttime number +
specifies how old route has to be to be considered unreachable. Default is 4*period. + +
garbagetime number +
specifies how old route has to be to be discarded. Default is 10*period.
+

In addition, rip defines two filter variables, both of type it. rip_metric is rip +metric of current route, rip_tag is tag of current route. + 

 
 protocol rip MyRIP_test {
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