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Doc: SADR documentation

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Ondrej Zajicek (work) 2018-03-17 22:25:06 +01:00
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@ -293,6 +293,20 @@ routes are:
<item>Route next hops (see below) <item>Route next hops (see below)
</itemize> </itemize>
<sect1>IPv6 source-specific routes
<label id="ip-sadr-routes">
<p>The IPv6 routes containing both destination and source prefix. They are used
for source-specific routing (SSR), also called source-address dependent routing
(SADR), see <rfc id="8043">. Currently limited mostly to the Babel protocol.
Configuration keyword is <cf/ipv6 sadr/.
<itemize>
<item>(PK) Route destination (IP prefix together with its length)
<item>(PK) Route source (IP prefix together with its length)
<item>Route next hops (see below)
</itemize>
<sect1>VPN IPv4 and IPv6 routes <sect1>VPN IPv4 and IPv6 routes
<label id="vpn-routes"> <label id="vpn-routes">
@ -1239,6 +1253,12 @@ foot).
pair, and <cf/.len/, which separates prefix length from the pair. pair, and <cf/.len/, which separates prefix length from the pair.
So <cf>1.2.0.0/16.len = 16</cf> is true. So <cf>1.2.0.0/16.len = 16</cf> is true.
<cf/NET_IP6_SADR/ nettype holds both destination and source IPv6
prefix. The literals are written as <cf><m/ipaddress//<m/pxlen/ from
<m/ipaddress//<m/pxlen/</cf>, where the first part is the destination
prefix and the second art is the source prefix. They support the same
operators as IP prefixes, but just for the destination part.
<cf/NET_VPN4/ and <cf/NET_VPN6/ prefixes hold an IP prefix with VPN <cf/NET_VPN4/ and <cf/NET_VPN6/ prefixes hold an IP prefix with VPN
Route Distinguisher (<rfc id="4364">). They support the same special Route Distinguisher (<rfc id="4364">). They support the same special
operators as IP prefixes, and also <cf/.rd/ which extracts the Route operators as IP prefixes, and also <cf/.rd/ which extracts the Route
@ -1459,6 +1479,7 @@ foot).
lclists, with LCs instead of pairs as arguments. lclists, with LCs instead of pairs as arguments.
</descrip> </descrip>
<sect>Operators <sect>Operators
<label id="operators"> <label id="operators">
@ -1651,19 +1672,25 @@ cases desirable.
routes over the same IPv6 transport. For sending and receiving Babel packets, routes over the same IPv6 transport. For sending and receiving Babel packets,
only a link-local IPv6 address is needed. only a link-local IPv6 address is needed.
<p>BIRD does not implement any Babel extensions, but will coexist with <p>BIRD implements an extension for IPv6 source-specific routing (SSR or SADR),
implementations using extensions (and will just ignore extension messages). but must be configured accordingly to use it. SADR-enabled Babel router can
interoperate with non-SADR Babel router, but the later would ignore routes
with specific (non-zero) source prefix.
<sect1>Configuration <sect1>Configuration
<label id="babel-config"> <label id="babel-config">
<p>Babel supports no global configuration options apart from those common to all <p>The Babel protocol support both IPv4 and IPv6 channels; both can be
other protocols, but supports the following per-interface configuration options: configured simultaneously. It can also be configured with <ref
id="ip-sadr-routes" name="IPv6 SADR"> channel instead of regular IPv6
channel, in such case SADR support is enabled. Babel supports no global
configuration options apart from those common to all other protocols, but
supports the following per-interface configuration options:
<code> <code>
protocol babel [<name>] { protocol babel [<name>] {
ipv4 { <channel config> }; ipv4 { <channel config> };
ipv6 { <channel config> }; ipv6 [sadr] { <channel config> };
interface <interface pattern> { interface <interface pattern> {
type <wired|wireless>; type <wired|wireless>;
rxcost <number>; rxcost <number>;
@ -1683,8 +1710,8 @@ protocol babel [<name>] {
</code> </code>
<descrip> <descrip>
<tag><label id="babel-channel">ipv4|ipv6 <m/channel config/</tag> <tag><label id="babel-channel">ipv4 | ipv6 [sadr] <m/channel config/</tag>
The supported channels are IPv4 and IPv6. The supported channels are IPv4, IPv6, and IPv6 SADR.
<tag><label id="babel-type">type wired|wireless </tag> <tag><label id="babel-type">type wired|wireless </tag>
This option specifies the interface type: Wired or wireless. On wired This option specifies the interface type: Wired or wireless. On wired
@ -2124,7 +2151,7 @@ using the following configuration parameters:
but in such cases you need to tweak the BGP paths manually in the filters but in such cases you need to tweak the BGP paths manually in the filters
to get consistent behavior.) Optional <cf/ip/ argument specifies a source to get consistent behavior.) Optional <cf/ip/ argument specifies a source
address, equivalent to the <cf/source address/ option (see below). address, equivalent to the <cf/source address/ option (see below).
Optional </cf/port> argument specifies the local BGP port instead of Optional <cf/port/ argument specifies the local BGP port instead of
standard port 179. The parameter may be used multiple times with standard port 179. The parameter may be used multiple times with
different sub-options (e.g., both <cf/local 10.0.0.1 as 65000;/ and different sub-options (e.g., both <cf/local 10.0.0.1 as 65000;/ and
<cf/local 10.0.0.1; local as 65000;/ are valid). This parameter is <cf/local 10.0.0.1; local as 65000;/ are valid). This parameter is
@ -2745,16 +2772,17 @@ protocol device {
<p>The Direct protocol is a simple generator of device routes for all the <p>The Direct protocol is a simple generator of device routes for all the
directly connected networks according to the list of interfaces provided by the directly connected networks according to the list of interfaces provided by the
kernel via the Device protocol. The Direct protocol supports both IPv4 and IPv6 kernel via the Device protocol. The Direct protocol supports both IPv4 and IPv6
channels. channels; both can be configured simultaneously. It can also be configured with
<ref id="ip-sadr-routes" name="IPv6 SADR"> channel instead of regular IPv6
channel in order to be used together with SADR-enabled Babel protocol.
<p>The question is whether it is a good idea to have such device routes in BIRD <p>The question is whether it is a good idea to have such device routes in BIRD
routing table. OS kernel usually handles device routes for directly connected routing table. OS kernel usually handles device routes for directly connected
networks by itself so we don't need (and don't want) to export these routes to networks by itself so we don't need (and don't want) to export these routes to
the kernel protocol. OSPF protocol creates device routes for its interfaces the kernel protocol. OSPF protocol creates device routes for its interfaces
itself and BGP protocol is usually used for exporting aggregate routes. Although itself and BGP protocol is usually used for exporting aggregate routes. But the
there are some use cases that use the direct protocol (like abusing eBGP as an Direct protocol is necessary for distance-vector protocols like RIP or Babel to
IGP routing protocol), in most cases it is not needed to have these device announce local networks.
routes in BIRD routing table and to use the direct protocol.
<p>There is one notable case when you definitely want to use the direct protocol <p>There is one notable case when you definitely want to use the direct protocol
-- running BIRD on BSD systems. Having high priority device routes for directly -- running BIRD on BSD systems. Having high priority device routes for directly
@ -2829,8 +2857,10 @@ kernel protocols to the same routing table and changing route destination
(gateway) in an export filter of a kernel protocol does not work. Both (gateway) in an export filter of a kernel protocol does not work. Both
limitations can be overcome using another routing table and the pipe protocol. limitations can be overcome using another routing table and the pipe protocol.
<p>The Kernel protocol supports both IPv4 and IPv6 channels; only one of them <p>The Kernel protocol supports both IPv4 and IPv6 channels; only one channel
can be configured in each protocol instance. can be configured in each protocol instance. On Linux, it also supports <ref
id="ip-sadr-routes" name="IPv6 SADR"> and <ref id="mpls-routes" name="MPLS">
channels.
<sect1>Configuration <sect1>Configuration
<label id="krt-config"> <label id="krt-config">
@ -4281,6 +4311,7 @@ protocol rip {
<sect>RPKI <sect>RPKI
<label id="rpki">
<sect1>Introduction <sect1>Introduction