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authorLeonid Voronkin <bullet85@yandex.ru>2021-01-17 01:45:07 +0400
committerGitHub <noreply@github.com>2021-01-16 22:45:07 +0100
commitb6c5493342c7b2124cd754279eb8685b753bb629 (patch)
tree5135ba8901ee75a73ece753a54d0a47add07feb6 /docs
parent694628045ffc125deacd2d272c7d7f92aa95c9ce (diff)
downloadvyos-documentation-b6c5493342c7b2124cd754279eb8685b753bb629.tar.gz
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bgp: change comand order, add route filterig
* bgp: change comand order, add route filterig Placed upper more often used commands; Add route filtering; Add confederation commands; Add route dampening.
Diffstat (limited to 'docs')
-rw-r--r--docs/configuration/protocols/bgp.rst633
1 files changed, 405 insertions, 228 deletions
diff --git a/docs/configuration/protocols/bgp.rst b/docs/configuration/protocols/bgp.rst
index ae7eb795..27858224 100644
--- a/docs/configuration/protocols/bgp.rst
+++ b/docs/configuration/protocols/bgp.rst
@@ -28,7 +28,9 @@ From :rfc:`1930`:
Each AS has an identifying number associated with it called an :abbr:`ASN
(Autonomous System Number)`. This is a two octet value ranging in value from 1
to 65535. The AS numbers 64512 through 65535 are defined as private AS numbers.
-Private AS numbers must not be advertised on the global Internet.
+Private AS numbers must not be advertised on the global Internet. The 2-byte AS
+number range has been exhausted. 4-byte AS numbers are specified in
+ :rfc:`6793`, and provide a pool of 4294967296 AS numbers.
The :abbr:`ASN (Autonomous System Number)` is one of the essential elements of
BGP. BGP is a distance vector routing protocol, and the AS-Path framework
@@ -156,200 +158,11 @@ connection.
BGP Router Configuration
========================
-ASN and Router ID
------------------
-
-.. cfgcmd:: set protocols bgp <asn>
-
- First of all you must configure BGP router with the :abbr:`ASN (Autonomous
- System Number)`. The AS number is an identifier for the autonomous system.
- The BGP protocol uses the AS number for detecting whether the BGP connection
- is internal or external.
-
-.. cfgcmd:: set protocols bgp <asn> parameters router-id
-
- This command specifies the router-ID. If router ID is not specified it will
- use the highest interface IP address.
-
-Route Selection
----------------
-
-.. cfgcmd:: set protocols bgp <asn> parameters always-compare-med
-
- This command provides to compare the MED on routes, even when they were
- received from different neighbouring ASes. Setting this option makes the
- order of preference of routes more defined, and should eliminate MED
- induced oscillations.
-
-.. cfgcmd:: set protocols bgp <asn> parameters bestpath as-path confed
-
- This command specifies that the length of confederation path sets and
- sequences should be taken into account during the BGP best path
- decision process.
-
-.. cfgcmd:: set protocols bgp <asn> parameters bestpath as-path multipath-relax
-
- This command specifies that BGP decision process should consider paths
- of equal AS_PATH length candidates for multipath computation. Without
- the knob, the entire AS_PATH must match for multipath computation.
-
-.. cfgcmd:: set protocols bgp <asn> parameters bestpath as-path ignore
-
- Ignore AS_PATH length when selecting a route
-
-.. cfgcmd:: set protocols bgp <asn> parameters bestpath compare-routerid
-
- Ensure that when comparing routes where both are equal on most metrics,
- including local-pref, AS_PATH length, IGP cost, MED, that the tie is
- broken based on router-ID.
-
- If this option is enabled, then the already-selected check, where
- already selected eBGP routes are preferred, is skipped.
-
- If a route has an ORIGINATOR_ID attribute because it has been reflected,
- that ORIGINATOR_ID will be used. Otherwise, the router-ID of the peer
- the route was received from will be used.
-
- The advantage of this is that the route-selection (at this point) will
- be more deterministic. The disadvantage is that a few or even one lowest-ID
- router may attract all traffic to otherwise-equal paths because of this
- check. It may increase the possibility of MED or IGP oscillation, unless
- other measures were taken to avoid these. The exact behaviour will be
- sensitive to the iBGP and reflection topology.
-
-.. cfgcmd:: set protocols bgp <asn> parameters bestpath med confed
-
- This command specifies that BGP considers the MED when comparing routes
- originated from different sub-ASs within the confederation to which this
- BGP speaker belongs. The default state, where the MED attribute is not
- considered.
-
-.. cfgcmd:: set protocols bgp <asn> parameters bestpath med missing-as-worst
-
- This command specifies that a route with a MED is always considered to be
- better than a route without a MED by causing the missing MED attribute to
- have a value of infinity. The default state, where the missing MED
- attribute is considered to have a value of zero.
-
-.. cfgcmd:: set protocols bgp <asn> parameters default local-pref
- <local-pref value>
-
- This command specifies the default local preference value. The local
- preference range is 0 to 4294967295.
-
-.. cfgcmd:: set protocols bgp <asn> parameters deterministic-med
-
- This command provides to compare different MED values that advertised by
- neighbours in the same AS for routes selection. When this command is enabled,
- routes from the same autonomous system are grouped together, and the best
- entries of each group are compared.
-
-Administrative Distance
------------------------
-
-.. cfgcmd:: set protocols bgp <asn> parameters distance global
- <external|internal|local> <distance>
-
- This command change distance value of BGP. The arguments are the distance
- values for external routes, internal routes and local routes respectively.
- The distance range is 1 to 255.
-
-.. cfgcmd:: set protocols bgp <asn> parameters distance prefix <subnet> distance
- <distance>
-
- This command sets the administrative distance for a particular route. The
- distance range is 1 to 255.
-
- .. note:: Routes with a distance of 255 are effectively disabled and not
- installed into the kernel.
-
-Network Advertisement
----------------------
-
-.. cfgcmd:: set protocols bgp <asn> address-family <ipv4-unicast|ipv6-unicast>
- network <prefix>
-
- This command is used for advertising IPv4 or IPv6 networks.
-
- .. note:: By default, the BGP prefix is advertised even if it's not present
- in the routing table. This behaviour differs from the implementation of
- some vendors.
-
-.. cfgcmd:: set protocols bgp <asn> parameters network-import-check
-
- This configuration modifies the behavior of the network statement. If you
- have this configured the underlying network must exist in the routing table.
-
-.. cfgcmd:: set protocols bgp <asn> neighbor <address|interface> address-family
- <ipv4-unicast|ipv6-unicast> default-originate [route-map <name>]
-
- By default, VyOS does not advertise a default route (0.0.0.0/0) even if it is
- in routing table. When you want to announce default routes to the peer, use
- this command. Using optional argument :cfgcmd:`route-map` you can inject the
- default route to given neighbor only if the conditions in the route map are
- met.
-
-Route Aggregation
------------------
-
-.. cfgcmd:: set protocols bgp <asn> address-family <ipv4-unicast|ipv6-unicast>
- aggregate-address <prefix>
-
- This command specifies an aggregate address. The router will also
- announce longer-prefixes inside of the aggregate address.
-
-.. cfgcmd:: set protocols bgp <asn> address-family <ipv4-unicast|ipv6-unicast>
- aggregate-address <prefix> as-set
-
- This command specifies an aggregate address with a mathematical set of
- autonomous systems. This command summarizes the AS_PATH attributes of
- all the individual routes.
-
-.. cfgcmd:: set protocols bgp <asn> address-family <ipv4-unicast|ipv6-unicast>
- aggregate-address <prefix> summary-only
-
- This command specifies an aggregate address and provides that
- longer-prefixes inside of the aggregate address are suppressed
- before sending BGP updates out to peers.
-
-Redistribution
---------------
-
-.. cfgcmd:: set protocols bgp <asn> address-family <ipv4-unicast|ipv6-unicast>
- redistribute connected
-
- Redistribute connected routes to BGP process.
-
-.. cfgcmd:: set protocols bgp <asn> address-family <ipv4-unicast|ipv6-unicast>
- redistribute kernel
-
- Redistribute kernel routes to BGP process.
-
-.. cfgcmd:: set protocols bgp <asn> address-family <ipv4-unicast|ipv6-unicast>
- redistribute ospf
-
- Redistribute OSPF routes to BGP process.
-
-.. cfgcmd:: set protocols bgp <asn> address-family <ipv4-unicast|ipv6-unicast>
- redistribute rip
-
- Redistribute RIP routes to BGP process.
-
-.. cfgcmd:: set protocols bgp <asn> address-family <ipv4-unicast|ipv6-unicast>
- redistribute static
-
- Redistribute static routes to BGP process.
-
-.. cfgcmd:: set protocols bgp <asn> address-family <ipv4-unicast|ipv6-unicast>
- redistribute <route source> metric <number>
-
- This command specifies metric (MED) for redistributed routes. The
- metric range is 0 to 4294967295.
-
-.. cfgcmd:: set protocols bgp <asn> address-family <ipv4-unicast|ipv6-unicast>
- redistribute <route source> route-map <name>
-
- This command allows to use route map to filter redistributed routes.
+First of all you must configure BGP router with the :abbr:`ASN (Autonomous
+System Number)`. The AS number is an identifier for the autonomous system.
+The BGP protocol uses the AS number for detecting whether the BGP connection
+is internal or external. VyOS does not have a special command to start the BGP
+process. The BGP process starts when the first neighbor is configured.
Peers Configuration
-------------------
@@ -360,7 +173,7 @@ Defining Peers
.. cfgcmd:: set protocols bgp <asn> neighbor <address|interface> remote-as
<nasn>
- This command creates a new neighbor whose remote-as is NASN. The neighbor
+ This command creates a new neighbor whose remote-as is <nasn>. The neighbor
address can be an IPv4 address or an IPv6 address or an interface to use
for the connection. The command it applicable for peer and peer group.
@@ -368,7 +181,7 @@ Defining Peers
internal
Create a peer as you would when you specify an ASN, except that if the
- peers ASN is different than mine as specified under the :cfgcmd:`protocols
+ peers ASN is different than mine as specified under the :cfgcmd:`protocols
bgp <asn>` command the connection will be denied.
.. cfgcmd:: set protocols bgp <asn> neighbor <address|interface> remote-as
@@ -391,9 +204,10 @@ Defining Peers
.. cfgcmd:: set protocols bgp <asn> neighbor <address|interface> update-source
<address|interface>
- Specify the IPv4 source address to use for the BGP session to this neighbour,
+ Specify the IPv4 source address to use for the BGP session to this neighbor,
may be specified as either an IPv4 address directly or as an interface name.
+
Capability Negotiation
^^^^^^^^^^^^^^^^^^^^^^
@@ -451,6 +265,7 @@ Capability Negotiation
Capability Negotiation. Please use :cfgcmd:`disable-capability-negotiation`
command to disable the feature.
+
Peer Parameters
^^^^^^^^^^^^^^^
@@ -489,22 +304,6 @@ Peer Parameters
advertisements sent to a peer or peer group.
.. cfgcmd:: set protocols bgp <asn> neighbor <address|interface> address-family
- <ipv4-unicast|ipv6-unicast> distribute-list <export|import> <number>
-
- This command applys the access list filters named in <number> to the
- specified BGP neighbor to restrict the routing information that BGP learns
- and/or advertises. The arguments :cfgcmd:`export` and :cfgcmd:`import`
- specify the direction in which the prefix lists are applied.
-
-.. cfgcmd:: set protocols bgp <asn> neighbor <address|interface> address-family
- <ipv4-unicast|ipv6-unicast> filter-list <export|import> <name>
-
- This command applys the AS path access list filters named in <name> to the
- specified BGP neighbor to restrict the routing information that BGP learns
- and/or advertises. The arguments :cfgcmd:`export` and :cfgcmd:`import`
- specify the direction in which the prefix lists are applied.
-
-.. cfgcmd:: set protocols bgp <asn> neighbor <address|interface> address-family
<ipv4-unicast|ipv6-unicast> maximum-prefix <number>
This command specifies a maximum number of prefixes we can receive
@@ -566,6 +365,12 @@ Peer Parameters
This command allows peerings between directly connected eBGP peers
using loopback addresses without adjusting the default TTL of 1.
+
+.. cfgcmd:: set protocols bgp <asn> neighbor <address|interface>
+ disable-send-community <extended|standard>
+
+ This command specifies that the community attribute should not be sent
+ in route updates to a peer. By default community attribute is sent.
.. cfgcmd:: set protocols bgp <asn> neighbor <address|interface> ebgp-multihop
<number>
@@ -598,6 +403,12 @@ Peer Parameters
Configures the BGP speaker so that it only accepts inbound connections
from, but does not initiate outbound connections to the peer or peer group.
+
+.. cfgcmd:: set protocols bgp <asn> neighbor <address|interface> password
+ <text>
+
+ This command specifies a MD5 password to be used with the tcp socket that
+ is being used to connect to the remote peer.
.. cfgcmd:: set protocols bgp <asn> neighbor <address|interface> ttl-security
hops <number>
@@ -608,6 +419,7 @@ Peer Parameters
become neighbors. The number of hops range is 1 to 254. This
command is mutually exclusive with :cfgcmd:`ebgp-multihop`.
+
Peer Groups
^^^^^^^^^^^
@@ -632,9 +444,100 @@ are treated as belonging to a default peer group, and will share updates.
This command bind specific peer to peer group with a given name.
-General configuration
+
+Network Advertisement Configuration
+-----------------------------------
+
+.. cfgcmd:: set protocols bgp <asn> address-family <ipv4-unicast|ipv6-unicast>
+ network <prefix>
+
+ This command is used for advertising IPv4 or IPv6 networks.
+
+ .. note:: By default, the BGP prefix is advertised even if it's not present
+ in the routing table. This behaviour differs from the implementation of
+ some vendors.
+
+.. cfgcmd:: set protocols bgp <asn> parameters network-import-check
+
+ This configuration modifies the behavior of the network statement. If you
+ have this configured the underlying network must exist in the routing table.
+
+.. cfgcmd:: set protocols bgp <asn> neighbor <address|interface> address-family
+ <ipv4-unicast|ipv6-unicast> default-originate [route-map <name>]
+
+ By default, VyOS does not advertise a default route (0.0.0.0/0) even if it is
+ in routing table. When you want to announce default routes to the peer, use
+ this command. Using optional argument :cfgcmd:`route-map` you can inject the
+ default route to given neighbor only if the conditions in the route map are
+ met.
+
+
+Route Aggregation Configuration
+-------------------------------
+
+.. cfgcmd:: set protocols bgp <asn> address-family <ipv4-unicast|ipv6-unicast>
+ aggregate-address <prefix>
+
+ This command specifies an aggregate address. The router will also
+ announce longer-prefixes inside of the aggregate address.
+
+.. cfgcmd:: set protocols bgp <asn> address-family <ipv4-unicast|ipv6-unicast>
+ aggregate-address <prefix> as-set
+
+ This command specifies an aggregate address with a mathematical set of
+ autonomous systems. This command summarizes the AS_PATH attributes of
+ all the individual routes.
+
+.. cfgcmd:: set protocols bgp <asn> address-family <ipv4-unicast|ipv6-unicast>
+ aggregate-address <prefix> summary-only
+
+ This command specifies an aggregate address and provides that
+ longer-prefixes inside of the aggregate address are suppressed
+ before sending BGP updates out to peers.
+
+.. cfgcmd:: set protocols bgp <asn> neighbor <address|interface> address-family
+ <ipv4-unicast|ipv6-unicast> unsuppress-map <name>
+
+ This command applies route-map to selectively unsuppress prefixes
+ suppressed by summarisation.
+
+
+Redistribution Configuration
+----------------------------
+
+.. cfgcmd:: set protocols bgp <asn> address-family <ipv4-unicast|ipv6-unicast>
+ redistribute <route source>
+
+ This command redistributes routing information from the given route source
+ to the BGP process. There are six modes available for route source: bgp,
+ connected, kernel, ospf, rip, static.
+
+.. cfgcmd:: set protocols bgp <asn> address-family <ipv4-unicast|ipv6-unicast>
+ redistribute <route source> metric <number>
+
+ This command specifies metric (MED) for redistributed routes. The
+ metric range is 0 to 4294967295. There are six modes available for
+ route source: bgp, connected, kernel, ospf, rip, static.
+
+.. cfgcmd:: set protocols bgp <asn> address-family <ipv4-unicast|ipv6-unicast>
+ redistribute <route source> route-map <name>
+
+ This command allows to use route map to filter redistributed routes.
+ There are six modes available for route source: bgp, connected, kernel,
+ ospf, rip, static.
+
+
+General Configuration
---------------------
+Common parametrs
+^^^^^^^^^^^^^^^^
+
+.. cfgcmd:: set protocols bgp <asn> parameters router-id <id>
+
+ This command specifies the router-ID. If router ID is not specified it will
+ use the highest interface IP address.
+
.. cfgcmd:: set protocols bgp <asn> maximum-paths <ebgp|ibgp> <number>
This command defines the maximum number of parallel routes that
@@ -657,38 +560,278 @@ General configuration
Tis command disables route reflection between route reflector clients.
By default, the clients of a route reflector are not required to be
fully meshed and the routes from a client are reflected to other clients.
- However, if the clients are fully meshed, route reflection is not required.
- In this case, use the :cfgcmd:`no-client-to-client-reflection` command
+ However, if the clients are fully meshed, route reflection is not required.
+ In this case, use the :cfgcmd:`no-client-to-client-reflection` command
to disable client-to-client reflection.
.. cfgcmd:: set protocols bgp <asn> parameters no-fast-external-failover
Disable immediate sesison reset if peer's connected link goes down.
+
+Administrative Distance
+^^^^^^^^^^^^^^^^^^^^^^^
+
+.. cfgcmd:: set protocols bgp <asn> parameters distance global
+ <external|internal|local> <distance>
+
+ This command change distance value of BGP. The arguments are the distance
+ values for external routes, internal routes and local routes respectively.
+ The distance range is 1 to 255.
+
+.. cfgcmd:: set protocols bgp <asn> parameters distance prefix <subnet>
+ distance <distance>
+
+ This command sets the administrative distance for a particular route. The
+ distance range is 1 to 255.
+
+ .. note:: Routes with a distance of 255 are effectively disabled and not
+ installed into the kernel.
+
+
Timers
^^^^^^
.. cfgcmd:: set protocols bgp <asn> timers holdtime <seconds>
- This command specifies hold-time in seconds. The timer can
- range from 4 to 65535.The default value is 180 second. If
- you set value to 0 VyOS will not hold routes.
+ This command specifies hold-time in seconds. The timer range is
+ 4 to 65535. The default value is 180 second. If you set value to 0
+ VyOS will not hold routes.
.. cfgcmd:: set protocols bgp <asn> timers keepalive <seconds>
This command specifies keep-alive time in seconds. The timer
- can range from 4 to 65535.The default value is 60 second.
+ can range from 4 to 65535. The default value is 60 second.
-Route Reflector Configuration
+
+Route Dampening
+^^^^^^^^^^^^^^^
+
+When a route fails, a routing update is sent to withdraw the route from the
+network's routing tables. When the route is re-enabled, the change in
+availability is also advertised. A route that continually fails and returns
+requires a great deal of network traffic to update the network about the
+route's status.
+
+Route dampening wich described in :rfc:`2439` enables you to identify routes
+that repeatedly fail and return. If route dampening is enabled, an unstable
+route accumulates penalties each time the route fails and returns. If the
+accumulated penalties exceed a threshold, the route is no longer advertised.
+This is route suppression. Routes that have been suppressed are re-entered
+into the routing table only when the amount of their penalty falls below a
+threshold.
+
+A penalty of 1000 is assessed each time the route fails. When the penalties
+reach a predefined threshold (suppress-value), the router stops advertising
+the route.
+
+Once a route is assessed a penalty, the penalty is decreased by half each time
+a predefined amount of time elapses (half-life-time). When the accumulated
+penalties fall below a predefined threshold (reuse-value), the route is
+unsuppressed and added back into the BGP routing table.
+
+No route is suppressed indefinitely. Maximum-suppress-time defines the maximum
+time a route can be suppressed before it is re-advertised.
+
+.. cfgcmd:: set protocols bgp <asn> parameters dampening
+ half-life <minutes>
+
+ This command defines the amount of time in minutes after
+ which a penalty is reduced by half. The timer range is
+ 10 to 45 minutes.
+
+.. cfgcmd:: set protocols bgp <asn> parameters dampening
+ re-use <seconds>
+
+ This command defines the accumulated penalty amount at which the
+ route is re-advertised. The penalty range is 1 to 20000.
+
+.. cfgcmd:: set protocols bgp <asn> parameters dampening
+ start-suppress-time <seconds>
+
+ This command defines the accumulated penalty amount at which the
+ route is suppressed. The penalty range is 1 to 20000.
+
+.. cfgcmd:: set protocols bgp <asn> parameters dampening
+ max-suppress-time <seconds>
+
+ This command defines the maximum time in minutes that a route is
+ suppressed. The timer range is 1 to 255 minutes.
+
+
+Route Selection Configuration
+-----------------------------
+
+.. cfgcmd:: set protocols bgp <asn> parameters always-compare-med
+
+ This command provides to compare the MED on routes, even when they were
+ received from different neighbouring ASes. Setting this option makes the
+ order of preference of routes more defined, and should eliminate MED
+ induced oscillations.
+
+.. cfgcmd:: set protocols bgp <asn> parameters bestpath as-path confed
+
+ This command specifies that the length of confederation path sets and
+ sequences should be taken into account during the BGP best path
+ decision process.
+
+.. cfgcmd:: set protocols bgp <asn> parameters bestpath as-path multipath-relax
+
+ This command specifies that BGP decision process should consider paths
+ of equal AS_PATH length candidates for multipath computation. Without
+ the knob, the entire AS_PATH must match for multipath computation.
+
+.. cfgcmd:: set protocols bgp <asn> parameters bestpath as-path ignore
+
+ Ignore AS_PATH length when selecting a route
+
+.. cfgcmd:: set protocols bgp <asn> parameters bestpath compare-routerid
+
+ Ensure that when comparing routes where both are equal on most metrics,
+ including local-pref, AS_PATH length, IGP cost, MED, that the tie is
+ broken based on router-ID.
+
+ If this option is enabled, then the already-selected check, where
+ already selected eBGP routes are preferred, is skipped.
+
+ If a route has an ORIGINATOR_ID attribute because it has been reflected,
+ that ORIGINATOR_ID will be used. Otherwise, the router-ID of the peer
+ the route was received from will be used.
+
+ The advantage of this is that the route-selection (at this point) will
+ be more deterministic. The disadvantage is that a few or even one lowest-ID
+ router may attract all traffic to otherwise-equal paths because of this
+ check. It may increase the possibility of MED or IGP oscillation, unless
+ other measures were taken to avoid these. The exact behaviour will be
+ sensitive to the iBGP and reflection topology.
+
+.. cfgcmd:: set protocols bgp <asn> parameters bestpath med confed
+
+ This command specifies that BGP considers the MED when comparing routes
+ originated from different sub-ASs within the confederation to which this
+ BGP speaker belongs. The default state, where the MED attribute is not
+ considered.
+
+.. cfgcmd:: set protocols bgp <asn> parameters bestpath med missing-as-worst
+
+ This command specifies that a route with a MED is always considered to be
+ better than a route without a MED by causing the missing MED attribute to
+ have a value of infinity. The default state, where the missing MED
+ attribute is considered to have a value of zero.
+
+.. cfgcmd:: set protocols bgp <asn> parameters default local-pref
+ <local-pref value>
+
+ This command specifies the default local preference value. The local
+ preference range is 0 to 4294967295.
+
+.. cfgcmd:: set protocols bgp <asn> parameters deterministic-med
+
+ This command provides to compare different MED values that advertised by
+ neighbours in the same AS for routes selection. When this command is
+ enabled, routes from the same autonomous system are grouped together, and
+ the best entries of each group are compared.
+
+.. cfgcmd:: set protocols bgp <asn> address-family ipv4-unicast network
+ <prefix> backdoor
+
+ This command allows the router to prefer route to specified prefix learned
+ via IGP through backdoor link instead of a route to the same prefix learned
+ via EBGP.
+
+
+Route Filtering Configuration
-----------------------------
+In order to control and modify routing information that is exchanged between
+peers you can use route-map, filter-list, prefix-list, distribute-list.
+
+For inbound updates the order of preference is:
+
+ - route-map
+ - filter-list
+ - prefix-list, distribute-list
+
+For outbound updates the order of preference is:
+
+ - prefix-list, distribute-list
+ - filter-list
+ - route-map
+
+ .. note:: The attributes :cfgcmd:`prefix-list` and :cfgcmd:`distribute-list`
+ are mutually exclusive, and only one command (distribute-list or
+ prefix-list) can be applied to each inbound or outbound direction for a
+ particular neighbor.
+
+.. cfgcmd:: set protocols bgp <asn> neighbor <address|interface> address-family
+ <ipv4-unicast|ipv6-unicast> distribute-list <export|import> <number>
+
+ This command applys the access list filters named in <number> to the
+ specified BGP neighbor to restrict the routing information that BGP learns
+ and/or advertises. The arguments :cfgcmd:`export` and :cfgcmd:`import`
+ specify the direction in which the access list are applied.
+
+.. cfgcmd:: set protocols bgp <asn> neighbor <address|interface> address-family
+ <ipv4-unicast|ipv6-unicast> prefix-list <export|import> <name>
+
+ This command applys the prfefix list filters named in <name> to the
+ specified BGP neighbor to restrict the routing information that BGP learns
+ and/or advertises. The arguments :cfgcmd:`export` and :cfgcmd:`import`
+ specify the direction in which the prefix list are applied.
+
+.. cfgcmd:: set protocols bgp <asn> neighbor <address|interface> address-family
+ <ipv4-unicast|ipv6-unicast> route-map <export|import> <name>
+
+ This command applys the route map named in <name> to the specified BGP
+ neighbor to control and modify routing information that is exchanged
+ between peers. The arguments :cfgcmd:`export` and :cfgcmd:`import`
+ specify the direction in which the route map are applied.
+
+.. cfgcmd:: set protocols bgp <asn> neighbor <address|interface> address-family
+ <ipv4-unicast|ipv6-unicast> filter-list <export|import> <name>
+
+ This command applys the AS path access list filters named in <name> to the
+ specified BGP neighbor to restrict the routing information that BGP learns
+ and/or advertises. The arguments :cfgcmd:`export` and :cfgcmd:`import`
+ specify the direction in which the AS path access list are applied.
+
+.. cfgcmd:: set protocols bgp <asn> neighbor <address|interface> address-family
+ <ipv4-unicast|ipv6-unicast> capability orf <receive|send>
+
+ This command enables the ORF capability (described in :rfc:`5291`) on the
+ local router, and enables ORF capability advertisement to the specified BGP
+ peer. The :cfgcmd:`receive` keyword configures a router to advertise ORF
+ receive capabilities. The :cfgcmd:`send` keyword configures a router to
+ advertise ORF send capabilities. To advertise a filter from a sender, you
+ must create an IP prefix list for the specified BGP peer applied in inbound
+ derection.
+
+
+BGP Scaling Configuration
+-------------------------
+
BGP routers connected inside the same AS through BGP belong to an internal BGP
-session, or IBGP. In order to prevent routing table loops, IBGP speaker does not
-advertise IBGP-learned routes to other IBGP speaker (Split Horizon mechanism).
-As such, IBGP requires a full mesh of all peers. For large networks, this
-quickly becomes unscalable. Introducing route reflectors removes the need for
-the full-mesh. Route reflectors mechanism is described in :rfc:`4456` and
-updated by :rfc:`7606`.
+session, or IBGP. In order to prevent routing table loops, IBGP speaker does
+not advertise IBGP-learned routes to other IBGP speaker (Split Horizon
+mechanism). As such, IBGP requires a full mesh of all peers. For large
+networks, this quickly becomes unscalable.
+
+There are two ways that help us to mitigate the BGPs full-mesh requirement in
+a network:
+
+ - Using BGP route-reflectors
+ - Using BGP confederation
+
+
+Route Reflector Configuration
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Introducing route reflectors removes the need for the full-mesh. When you
+configure a route reflector you have to tell the router whether the other IBGP
+router is a client or non-client. A client is an IBGP router that the route
+reflector will “reflect” routes to, the non-client is just a regular IBGP
+neighbor. Route reflectors mechanism is described in :rfc:`4456` and updated
+by :rfc:`7606`.
.. cfgcmd:: set protocols bgp <asn> neighbor <address> address-family
<ipv4-unicast|ipv6-unicast> route-reflector-client
@@ -703,6 +846,30 @@ updated by :rfc:`7606`.
set to an arbitrary 32-bit value.
+Confederation Configuration
+^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+A BGP confederation divides our AS into sub-ASes to reduce the number of
+required IBGP peerings. Within a sub-AS we still require full-mesh IBGP but
+between these sub-ASes we use something that looks like EBGP but behaves like
+IBGP (called confederation BGP). Confederation mechanism is described in
+:rfc:`5065`
+
+.. cfgcmd:: set protocols bgp <subasn> parameters confederation identifier
+ <asn>
+
+ This command specifies a BGP confederation identifier. <asn> is the number
+ of the autonomous system that internally includes multiple sub-autonomous
+ systems (a confederation). <subasn> is the number sub-autonomous system
+ inside <asn>.
+
+.. cfgcmd:: set protocols bgp <subasn> parameters confederation confederation
+ peers <nsubasn>
+
+ This command sets other confederations <nsubasn> as members of autonomous
+ system specified by :cfgcmd:`confederation identifier <asn>`.
+
+
Operational Mode Commands
=========================
@@ -764,6 +931,15 @@ Show
This command displays BGP dampened routes.
+.. opcmd:: show ip bgp flap-statistics
+
+ This command displays information about flapping BGP routes.
+
+.. opcmd:: show ip bgp filter-list <name>
+
+ This command displays BGP routes allowed by by the specified AS Path
+ access list.
+
.. opcmd:: show <ip|ipv6> bgp neighbors <address> advertised-routes
This command displays BGP routes advertised to a neighbor.
@@ -837,6 +1013,7 @@ Reset
you do not specify the :cfgcmd:`in` or :cfgcmd:`out` options, both
inbound and outbound soft reconfiguration are triggered.
+
Configuration Examples
----------------------