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Documentation update,

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Ondrej Zajicek 2012-07-24 20:12:14 +02:00
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@ -215,7 +215,27 @@ an <it/import/ filter checks routes in the opposite direction.
When the routing table gets a route from a protocol, it recalculates
the selected route and broadcasts it to all protocols connected to
the table. The protocols typically send the update to other routers
in the network.
in the network. Note that although most protocols are interested
in receiving just selected routes, some protocols (e.g. the <cf/Pipe/
protocol) receive and process all entries in routing tables (accepted
by filters).
<p><label id="dsc-sorted">Usually, a routing table just chooses a
selected route from a list of entries for one network. But if the
<cf/sorted/ option is activated, these lists of entries are kept
completely sorted (according to preference or some protocol-dependent
metric).
This is needed for some features of some protocols
(e.g. <cf/secondary/ option of BGP protocol, which allows to accept
not just a selected route, but the first route (in the sorted list)
that is accepted by filters), but it is incompatible with some other
features (e.g. <cf/deterministic med/ option of BGP protocol, which
activates a way of choosing selected route that cannot be described
using comparison and ordering). Minor advantage is that routes are
shown sorted in <cf/show route/, minor disadvantage is that it is
slightly more computationally expensive.
<chapt>Configuration
@ -354,11 +374,14 @@ protocol rip {
defaults are here for a compatibility with older versions
and might change in the future.
<tag>table <m/name/</tag> Create a new routing table. The default
routing table is created implicitly, other routing tables have
to be added by this command.
<tag>table <m/name/ [sorted]</tag>
Create a new routing table. The default routing table is
created implicitly, other routing tables have to be added by
this command. Option <cf/sorted/ can be used to enable
sorting of routes, see <ref id="dsc-sorted" name="sorted table">
description for details.
<tag>roa table [ { roa table options ... } ] <m/name/</tag>
<tag>roa table <m/name/ [ { roa table options ... } ]</tag>
Create a new ROA (Route Origin Authorization) table. ROA
tables can be used to validate route origination of BGP
routes. A ROA table contains ROA entries, each consist of a
@ -1270,8 +1293,10 @@ for each neighbor using the following configuration parameters:
mode is the behavior specified by the BGP standard. Direct
mode is simpler, does not require any routes in a routing
table, and was used in older versions of BIRD, but does not
handle well nontrivial iBGP setups and multihop. Default:
<cf/direct/ for singlehop eBGP, <cf/recursive/ otherwise.
handle well nontrivial iBGP setups and multihop. Recursive
mode is incompatible with <ref id="dsc-sorted" name="sorted
tables">. Default: <cf/direct/ for singlehop eBGP,
<cf/recursive/ otherwise.
<tag>igp table <m/name/</tag> Specifies a table that is used
as an IGP routing table. Default: the same as the table BGP is
@ -1317,6 +1342,16 @@ for each neighbor using the following configuration parameters:
attributes to be transparent (for example does not prepend its AS number to
AS PATH attribute and keeps MED attribute). Default: disabled.
<tag>secondary <m/switch/</tag> Usually, if an import filter
rejects a selected route, no other route is propagated for
that network. This option allows to try the next route in
order until one that is accepted is found or all routes for
that network are rejected. This can be used for route servers
that need to propagate different tables to each client but do
not want to have these tables explicitly (to conserve memory).
This option requires that the connected routing table is
<ref id="dsc-sorted" name="sorted">. Default: off.
<tag>enable route refresh <m/switch/</tag> When BGP speaker
changes its import filter, it has to re-examine all routes
received from its neighbor against the new filter. As these
@ -1422,7 +1457,9 @@ for each neighbor using the following configuration parameters:
This option enables a different (and slower) algorithm
implementing proper RFC 4271 route selection, which is
deterministic. Alternative way how to get deterministic
behavior is to use <cf/med metric/ option. Default: off.
behavior is to use <cf/med metric/ option. This option is
incompatible with <ref id="dsc-sorted" name="sorted tables">.
Default: off.
<tag>igp metric <m/switch/</tag> Enable comparison of internal
distances to boundary routers during best route selection. Default: on.