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diff --git a/docs/configuration/protocols/md-bgp.md b/docs/configuration/protocols/md-bgp.md deleted file mode 100644 index 0af79f6e..00000000 --- a/docs/configuration/protocols/md-bgp.md +++ /dev/null @@ -1,1414 +0,0 @@ -(routing-bgp)= - -# BGP - -{abbr}`BGP (Border Gateway Protocol)` is one of the Exterior Gateway Protocols -and the de facto standard interdomain routing protocol. The latest BGP version -is 4. BGP-4 is described in {rfc}`1771` and updated by {rfc}`4271`. {rfc}`2858` -adds multiprotocol support to BGP. - -VyOS makes use of {abbr}`FRR (Free Range Routing)` and we would like to thank -them for their effort! - -## Basic Concepts - -(bgp-autonomous-systems)= - -### Autonomous Systems - -From {rfc}`1930`: - -> An AS is a connected group of one or more IP prefixes run by one or more -> network operators which has a SINGLE and CLEARLY DEFINED routing policy. - -Each {abbr}`AS (Autonomous System)` 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. 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 -provides distance vector metric and loop detection to BGP. - -```{cfgcmd} set protocols bgp system-as \<asn\> - -Set local {abbr}`ASN (Autonomous System Number)` that this router represents. -This is a a mandatory option! -``` - -(bgp-address-families)= - - -### Address Families - - -Multiprotocol extensions enable BGP to carry routing information for multiple -network layer protocols. BGP supports an Address Family Identifier (AFI) for -IPv4 and IPv6. - - -(bgp-route-selection)= - - -### Route Selection - - -The route selection process used by FRR's BGP implementation uses the following -decision criterion, starting at the top of the list and going towards the -bottom until one of the factors can be used. - - -01. **Weight check** - - - Prefer higher local weight routes to lower routes. - - -02. **Local preference check** - - - Prefer higher local preference routes to lower. - - -03. **Local route check** - - - Prefer local routes (statics, aggregates, redistributed) to received routes. - - -04. **AS path length check** - - - Prefer shortest hop-count AS_PATHs. - - -05. **Origin check** - - - Prefer the lowest origin type route. That is, prefer IGP origin routes to - EGP, to Incomplete routes. - - -06. **MED check** - - - Where routes with a MED were received from the same AS, prefer the route - with the lowest MED. - - -07. **External check** - - - Prefer the route received from an external, eBGP peer over routes received - from other types of peers. - - -08. **IGP cost check** - - - Prefer the route with the lower IGP cost. - - -09. **Multi-path check** - - - If multi-pathing is enabled, then check whether the routes not yet - distinguished in preference may be considered equal. If - {cfgcmd}`bgp bestpath as-path multipath-relax` is set, all such routes are - considered equal, otherwise routes received via iBGP with identical AS_PATHs - or routes received from eBGP neighbours in the same AS are considered equal. - - -10. **Already-selected external check** - - - Where both routes were received from eBGP peers, then prefer the route - which is already selected. Note that this check is not applied if - {cfgcmd}`bgp bestpath compare-routerid` is configured. This check can - prevent some cases of oscillation. - - -11. **Router-ID check** - - - Prefer the route with the lowest router-ID. If the route has an - ORIGINATOR_ID attribute, through iBGP reflection, then that router ID is - used, otherwise the router-ID of the peer the route was received from is - used. - - -12. **Cluster-List length check** - - - The route with the shortest cluster-list length is used. The cluster-list - reflects the iBGP reflection path the route has taken. - - -13. **Peer address** - - - Prefer the route received from the peer with the higher transport layer - address, as a last-resort tie-breaker. - - -(bgp-capability-negotiation)= - - -### Capability Negotiation - - -When adding IPv6 routing information exchange feature to BGP. There were some -proposals. {abbr}`IETF (Internet Engineering Task Force)` -{abbr}`IDR (Inter Domain Routing)` adopted a proposal called Multiprotocol -Extension for BGP. The specification is described in {rfc}`2283`. The protocol -does not define new protocols. It defines new attributes to existing BGP. When -it is used exchanging IPv6 routing information it is called BGP-4+. When it is -used for exchanging multicast routing information it is called MBGP. - - -*bgpd* supports Multiprotocol Extension for BGP. So if a remote peer supports -the protocol, *bgpd* can exchange IPv6 and/or multicast routing information. - - -Traditional BGP did not have the feature to detect a remote peer's -capabilities, e.g. whether it can handle prefix types other than IPv4 unicast -routes. This was a big problem using Multiprotocol Extension for BGP in an -operational network. {rfc}`2842` adopted a feature called Capability -Negotiation. *bgpd* use this Capability Negotiation to detect the remote peer's -capabilities. If a peer is only configured as an IPv4 unicast neighbor, *bgpd* -does not send these Capability Negotiation packets (at least not unless other -optional BGP features require capability negotiation). - - -By default, FRR will bring up peering with minimal common capability for the -both sides. For example, if the local router has unicast and multicast -capabilities and the remote router only has unicast capability the local router -will establish the connection with unicast only capability. When there are no -common capabilities, FRR sends Unsupported Capability error and then resets the -connection. - - -## Configuration - - -(bgp-router-configuration)= - - -### BGP Router Configuration - - -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. - -```{cfgcmd} set protocols bgp system-as \<asn\> - -Set local autonomous system number that this router represents. This is a -mandatory option! -``` - -#### Peers Configuration - - -##### Defining Peers - -```{cfgcmd} set protocols bgp neighbor \<address|interface\> remote-as \<asn\> - -This command creates a new neighbor whose remote-as is \<asn\>. The neighbor -address can be an IPv4 address or an IPv6 address or an interface to use -for the connection. The command is applicable for peer and peer group. -``` - - -```{cfgcmd} set protocols bgp neighbor \<address|interface\> remote-as 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 -bgp <asn>` command the connection will be denied. -``` - - -```{cfgcmd} set protocols bgp neighbor \<address|interface\> remote-as external - -Create a peer as you would when you specify an ASN, except that if the -peers ASN is the same as mine as specified under the {cfgcmd}`protocols -bgp <asn>` command the connection will be denied. -``` - - -```{cfgcmd} set protocols bgp neighbor \<address|interface\> remote-as auto - -Create a peer as you would when you specify an ASN, except that the peers -remote ASN is detected automatically from the OPEN message. -``` - - -```{cfgcmd} set protocols bgp neighbor \<address|interface\> local-role \<role\> [strict] - -BGP roles are defined in RFC {rfc}`9234` and provide an easy way to -add route leak prevention, detection and mitigation. The local Role -value is negotiated with the new BGP Role capability which has a -built-in check of the corresponding value. In case of a mismatch the -new OPEN Roles Mismatch Notification <2, 11> would be sent. -The correct Role pairs are: - -Provider - Customer - -Peer - Peer - -RS-Server - RS-Client - -If {cfgcmd}`strict` is set the BGP session won’t become established -until the BGP neighbor sets local Role on its side. This -configuration parameter is defined in RFC {rfc}`9234` and is used to -enforce the corresponding configuration at your counter-parts side. - -Routes that are sent from provider, rs-server, or the peer local-role -(or if received by customer, rs-client, or the peer local-role) will -be marked with a new Only to Customer (OTC) attribute. - -Routes with this attribute can only be sent to your neighbor if your -local-role is provider or rs-server. Routes with this attribute can -be received only if your local-role is customer or rs-client. - -In case of peer-peer relationship routes can be received only if OTC -value is equal to your neighbor AS number. - -All these rules with OTC will help to detect and mitigate route leaks -and happen automatically if local-role is set. -``` - - -```{cfgcmd} set protocols bgp neighbor \<address|interface\> shutdown - -This command disable the peer or peer group. To reenable the peer use -the delete form of this command. -``` - - -```{cfgcmd} set protocols bgp neighbor \<address|interface\> description \<text\> - -Set description of the peer or peer group. -``` - - -```{cfgcmd} set protocols bgp neighbor \<address|interface\> update-source \<address|interface\> - -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. -``` - -(bgp-capability-negotiation-1)= - - -##### Capability Negotiation - -```{cfgcmd} set protocols bgp neighbor \<address|interface\> capability dynamic - -This command would allow the dynamic update of capabilities over an -established BGP session. -``` - - -```{cfgcmd} set protocols bgp neighbor \<address|interface\> capability extended-nexthop - -Allow bgp to negotiate the extended-nexthop capability with it’s peer. -If you are peering over a IPv6 Link-Local address then this capability -is turned on automatically. If you are peering over a IPv6 Global Address -then turning on this command will allow BGP to install IPv4 routes with -IPv6 nexthops if you do not have IPv4 configured on interfaces. -``` - - -```{cfgcmd} set protocols bgp neighbor \<address|interface\> disable-capability-negotiation - -Suppress sending Capability Negotiation as OPEN message optional -parameter to the peer. This command only affects the peer is -configured other than IPv4 unicast configuration. - -When remote peer does not have capability negotiation feature, -remote peer will not send any capabilities at all. In that case, -bgp configures the peer with configured capabilities. - -You may prefer locally configured capabilities more than the negotiated -capabilities even though remote peer sends capabilities. If the peer is -configured by {cfgcmd}`override-capability`, VyOS ignores received -capabilities then override negotiated capabilities with configured values. - -Additionally you should keep in mind that this feature fundamentally -disables the ability to use widely deployed BGP features. BGP unnumbered, -hostname support, AS4, Addpath, Route Refresh, ORF, Dynamic Capabilities, -and graceful restart. -``` - - -```{cfgcmd} set protocols bgp neighbor \<address|interface\> override-capability - -This command allow override the result of Capability Negotiation with -local configuration. Ignore remote peer’s capability value. -``` - - -```{cfgcmd} set protocols bgp neighbor \<address|interface\> strict-capability-match - -This command forces strictly compare remote capabilities and local -capabilities. If capabilities are different, send Unsupported Capability -error then reset connection. - -You may want to disable sending Capability Negotiation OPEN message -optional parameter to the peer when remote peer does not implement -Capability Negotiation. Please use {cfgcmd}`disable-capability-negotiation` -command to disable the feature. -``` - -##### Peer Parameters - -```{cfgcmd} set protocols bgp neighbor \<address|interface\> address-family \<ipv4-unicast|ipv6-unicast\> allowas-in number \<number\> - -This command accept incoming routes with AS path containing AS -number with the same value as the current system AS. This is -used when you want to use the same AS number in your sites, -but you can’t connect them directly. - - The number parameter (1-10) configures the amount of accepted - occurences of the system AS number in AS path. - - This command is only allowed for eBGP peers. It is not applicable - for peer groups. -``` - - -```{cfgcmd} set protocols bgp neighbor \<address|interface\> address-family \<ipv4-unicast|ipv6-unicast\> as-override - -This command override AS number of the originating router with -the local AS number. - -Usually this configuration is used in PEs (Provider Edge) to -replace the incoming customer AS number so the connected CE ( -Customer Edge) can use the same AS number as the other customer -sites. This allows customers of the provider network to use the -same AS number across their sites. - -This command is only allowed for eBGP peers. -``` - - -```{cfgcmd} set protocols bgp neighbor \<address|interface\> address-family \<ipv4-unicast|ipv6-unicast\> attribute-unchanged \<as-path|med|next-hop\> - -This command specifies attributes to be left unchanged for -advertisements sent to a peer or peer group. -``` - - -```{cfgcmd} set protocols bgp neighbor \<address|interface\> address-family \<ipv4-unicast|ipv6-unicast\> maximum-prefix \<number\> - -This command specifies a maximum number of prefixes we can receive -from a given peer. If this number is exceeded, the BGP session -will be destroyed. The number range is 1 to 4294967295. -``` - - -```{cfgcmd} set protocols bgp neighbor \<address|interface\> address-family \<ipv4-unicast|ipv6-unicast\> nexthop-self - -This command forces the BGP speaker to report itself as the -next hop for an advertised route it advertised to a neighbor. -``` - - -```{cfgcmd} set protocols bgp neighbor \<address|interface\> address-family \<ipv4-unicast|ipv6-unicast\> remove-private-as - -This command removes the private ASN of routes that are advertised -to the configured peer. It removes only private ASNs on routes -advertised to EBGP peers. - -If the AS-Path for the route has only private ASNs, the private -ASNs are removed. - -If the AS-Path for the route has a private ASN between public -ASNs, it is assumed that this is a design choice, and the -private ASN is not removed. -``` - - -```{cfgcmd} set protocols bgp neighbor \<address|interface\> address-family \<ipv4-unicast|ipv6-unicast\> soft-reconfiguration inbound - -Changes in BGP policies require the BGP session to be cleared. Clearing has a -large negative impact on network operations. Soft reconfiguration enables you -to generate inbound updates from a neighbor, change and activate BGP policies -without clearing the BGP session. - -This command specifies that route updates received from this neighbor will be -stored unmodified, regardless of the inbound policy. When inbound soft -reconfiguration is enabled, the stored updates are processed by the new -policy configuration to create new inbound updates. - -:::{note} -Storage of route updates uses memory. If you enable soft -reconfiguration inbound for multiple neighbors, the amount of memory used -can become significant. -::: -``` - - -```{cfgcmd} set protocols bgp neighbor \<address|interface\> address-family \<ipv4-unicast|ipv6-unicast\> weight \<number\> - -This command specifies a default weight value for the neighbor’s -routes. The number range is 1 to 65535. -``` - - -```{cfgcmd} set protocols bgp neighbor \<address|interface\> advertisement-interval \<seconds\> - -This command specifies the minimum route advertisement interval for -the peer. The interval value is 0 to 600 seconds, with the default -advertisement interval being 0. -``` - - -```{cfgcmd} set protocols bgp neighbor \<address|interface\> disable-connected-check - -This command allows peerings between directly connected eBGP peers -using loopback addresses without adjusting the default TTL of 1. -``` - - -```{cfgcmd} set protocols bgp 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 neighbor \<address|interface\> ebgp-multihop \<number\> - -This command allows sessions to be established with eBGP neighbors -when they are multiple hops away. When the neighbor is not directly -connected and this knob is not enabled, the session will not establish. -The number of hops range is 1 to 255. This command is mutually -exclusive with {cfgcmd}`ttl-security hops`. -``` - - -```{cfgcmd} set protocols bgp neighbor \<address|interface\> local-as \<asn\> [no-prepend] [replace-as] - -Specify an alternate AS for this BGP process when interacting with -the specified peer or peer group. With no modifiers, the specified -local-as is prepended to the received AS_PATH when receiving routing -updates from the peer, and prepended to the outgoing AS_PATH (after -the process local AS) when transmitting local routes to the peer. - -If the {cfgcmd}`no-prepend` attribute is specified, then the supplied -local-as is not prepended to the received AS_PATH. - -If the {cfgcmd}`replace-as` attribute is specified, then only the supplied -local-as is prepended to the AS_PATH when transmitting local-route -updates to this peer. - -:::{note} -This command is only allowed for eBGP peers. -::: -``` - - -```{cfgcmd} set protocols bgp neighbor \<address|interface\> passive - -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 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 neighbor \<address|interface\> ttl-security hops \<number\> - -This command enforces Generalized TTL Security Mechanism (GTSM), -as specified in {rfc}`5082`. With this command, only neighbors -that are specified number of hops away will be allowed to -become neighbors. The number of hops range is 1 to 254. This -command is mutually exclusive with {cfgcmd}`ebgp-multihop`. -``` - -##### Peer Groups - -Peer groups are used to help improve scaling by generating the same update -information to all members of a peer group. Note that this means that the -routes generated by a member of a peer group will be sent back to that -originating peer with the originator identifier attribute set to indicated -the originating peer. All peers not associated with a specific peer group -are treated as belonging to a default peer group, and will share updates. - -```{cfgcmd} set protocols bgp peer-group \<name\> - - This command defines a new peer group. You can specify to the group the same - parameters that you can specify for specific neighbors. - - :::{note} - If you apply a parameter to an individual neighbor IP address, you - override the action defined for a peer group that includes that IP - address. - ::: -``` - - -```{cfgcmd} set protocols bgp neighbor \<address|interface\> peer-group \<name\> - -This command bind specific peer to peer group with a given name. -``` - -#### Network Advertisement Configuration - -```{cfgcmd} set protocols bgp 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 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 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 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 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 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 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 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: -connected, kernel, ospf, rip, static, table. -``` - - -```{cfgcmd} set protocols bgp 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: connected, kernel, ospf, rip, static, table. -``` - - -```{cfgcmd} set protocols bgp 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: connected, kernel, -ospf, rip, static, table. -``` - -#### General Configuration -##### Common parameters - -```{cfgcmd} set protocols bgp parameters allow-martian-nexthop - - When a peer receives a martian nexthop as part of the NLRI for a route - permit the nexthop to be used as such, instead of rejecting and resetting - the connection. -``` - - -```{cfgcmd} set protocols bgp 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 address-family \<ipv4-unicast|ipv6-unicast\> maximum-paths \<ebgp|ibgp\> \<number\> - -This command defines the maximum number of parallel routes that -the BGP can support. In order for BGP to use the second path, the -following attributes have to match: Weight, Local Preference, AS -Path (both AS number and AS path length), Origin code, MED, IGP -metric. Also, the next hop address for each path must be different. -``` - - -```{cfgcmd} set protocols bgp parameters no-hard-administrative-reset - -Do not send Hard Reset CEASE Notification for "Administrative Reset" -events. When set and Graceful Restart Notification capability is exchanged -between the peers, Graceful Restart procedures apply, and routes will be retained. -``` - - -```{cfgcmd} set protocols bgp parameters log-neighbor-changes - -This command enable logging neighbor up/down changes and reset reason. -``` - - -```{cfgcmd} set protocols bgp parameters no-client-to-client-reflection - -This 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 -to disable client-to-client reflection. -``` - - -```{cfgcmd} set protocols bgp parameters no-fast-external-failover - -Disable immediate session reset if peer's connected link goes down. -``` - - -```{cfgcmd} set protocols bgp parameters no-ipv6-auto-ra - -By default, FRR sends router advertisement packets when Extended Next Hop is -on or when a connection is established directly using the device name (Unnumbered BGP). -Setting this option prevents FRR from sending router advertisement packets, but could break Unnumbered BGP. -``` - - -```{cfgcmd} set protocols bgp listen range \<prefix\> peer-group \<name\> - -This command is useful if one desires to loosen the requirement for BGP -to have strictly defined neighbors. Specifically what is allowed is for -the local router to listen to a range of IPv4 or IPv6 addresses defined -by a prefix and to accept BGP open messages. When a TCP connection -(and subsequently a BGP open message) from within this range tries to -connect the local router then the local router will respond and connect -with the parameters that are defined within the peer group. One must define -a peer-group for each range that is listed. If no peer-group is defined -then an error will keep you from committing the configuration. -``` - - -```{cfgcmd} set protocols bgp listen limit \<number\> - -This command goes hand in hand with the listen range command to limit the -amount of BGP neighbors that are allowed to connect to the local router. -The limit range is 1 to 5000. -``` - - -```{cfgcmd} set protocols bgp parameters ebgp-requires-policy - -This command changes the eBGP behavior of FRR. By default FRR enables -{rfc}`8212` functionality which affects how eBGP routes are advertised, -namely no routes are advertised across eBGP sessions without some -sort of egress route-map/policy in place. In VyOS however we have this -RFC functionality disabled by default so that we can preserve backwards -compatibility with older versions of VyOS. With this option one can -enable {rfc}`8212` functionality to operate. -``` - - -```{cfgcmd} set protocols bgp parameters labeled-unicast \<explicit-null | ipv4-explicit-null | ipv6-explicit-null\> - -By default, locally advertised prefixes use the implicit-null label to -encode in the outgoing NLRI. - -The following command uses the explicit-null label value for all the -BGP instances. -``` - -##### Administrative Distance - -```{cfgcmd} set protocols bgp 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 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 timers holdtime \<seconds\> - - 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 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. -``` - -##### 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 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 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 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 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 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 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 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 parameters bestpath as-path ignore - -Ignore AS_PATH length when selecting a route -``` - - -```{cfgcmd} set protocols bgp 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 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 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 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 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 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 neighbor \<address|interface\> address-family \<ipv4-unicast|ipv6-unicast\> distribute-list \<export|import\> \<number\> - -This command applies 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 neighbor \<address|interface\> address-family \<ipv4-unicast|ipv6-unicast\> prefix-list \<export|import\> \<name\> - -This command applies 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 neighbor \<address|interface\> address-family \<ipv4-unicast|ipv6-unicast\> route-map \<export|import\> \<name\> - -This command applies 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 neighbor \<address|interface\> address-family \<ipv4-unicast|ipv6-unicast\> filter-list \<export|import\> \<name\> - -This command applies 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 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. -``` - - -```{cfgcmd} set protocols bgp neighbor \<address|interface\> solo - -This command prevents from sending back prefixes learned from the neighbor. -``` - -#### 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. - - -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 neighbor \<address\> address-family \<ipv4-unicast|ipv6-unicast\> route-reflector-client - -This command specifies the given neighbor as route reflector client. -``` - - -```{cfgcmd} set protocols bgp parameters cluster-id \<id\> - -This command specifies cluster ID which identifies a collection of route -reflectors and their clients, and is used by route reflectors to avoid -looping. By default cluster ID is set to the BGP router id value, but can be -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 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). -``` - - -```{cfgcmd} set protocols bgp parameters confederation peers \<nsubasn\> - -This command sets other confederations \<nsubasn\> as members of autonomous -system specified by {cfgcmd}`confederation identifier <asn>`. -``` - -## Operational Mode Commands -### Show - -```{opcmd} show bgp \<ipv4|ipv6\> - - This command displays all entries in BGP routing table. -``` - - -```none -BGP table version is 10, local router ID is 10.0.35.3, vrf id 0 -Default local pref 100, local AS 65000 -Status codes: s suppressed, d damped, h history, * valid, > best, = multipath, - i internal, r RIB-failure, S Stale, R Removed -Nexthop codes: @NNN nexthop's vrf id, < announce-nh-self -Origin codes: i - IGP, e - EGP, ? - incomplete -RPKI validation codes: V valid, I invalid, N Not found - - Network Next Hop Metric LocPrf Weight Path -*> 198.51.100.0/24 10.0.34.4 0 0 65004 i -*> 203.0.113.0/24 10.0.35.5 0 0 65005 i - -Displayed 2 routes and 2 total paths -``` - - -```{opcmd} show bgp \<ipv4|ipv6\> \<address|prefix\> - -This command displays information about the particular entry in the BGP -routing table. -``` - - -```none -BGP routing table entry for 198.51.100.0/24 -Paths: (1 available, best #1, table default) - Advertised to non peer-group peers: - 10.0.13.1 10.0.23.2 10.0.34.4 10.0.35.5 - 65004 - 10.0.34.4 from 10.0.34.4 (10.0.34.4) - Origin IGP, metric 0, valid, external, best (First path received) - Last update: Wed Jan 6 12:18:53 2021 -``` - - -```{opcmd} show bgp cidr-only - -This command displays routes with classless interdomain routing (CIDR). -``` - - -```{opcmd} show bgp \<ipv4|ipv6\> community \<value\> - -This command displays routes that belong to specified BGP communities. -Valid value is a community number in the range from 1 to 4294967200, -or AA:NN (autonomous system-community number/2-byte number), no-export, -local-as, or no-advertise. -``` - - -```{opcmd} show bgp \<ipv4|ipv6\> community-list \<name\> - -This command displays routes that are permitted by the BGP -community list. -``` - - -```{opcmd} show bgp \<ipv4|ipv6\> dampening dampened-paths - -This command displays BGP dampened routes. -``` - - -```{opcmd} show bgp \<ipv4|ipv6\> dampening flap-statistics - -This command displays information about flapping BGP routes. -``` - - -```{opcmd} show bgp \<ipv4|ipv6\> filter-list \<name\> - -This command displays BGP routes allowed by the specified AS Path -access list. -``` - - -```{opcmd} show bgp \<ipv4|ipv6\> neighbors \<address\> advertised-routes - -This command displays BGP routes advertised to a neighbor. -``` - - -```{opcmd} show bgp \<ipv4|ipv6\> neighbors \<address\> received-routes - -This command displays BGP routes originating from the specified BGP -neighbor before inbound policy is applied. To use this command inbound -soft reconfiguration must be enabled. -``` - - -```{opcmd} show bgp \<ipv4|ipv6\> neighbors \<address\> routes - -This command displays BGP received-routes that are accepted after filtering. -``` - - -```{opcmd} show bgp \<ipv4|ipv6\> neighbors \<address\> dampened-routes - -This command displays dampened routes received from BGP neighbor. -``` - - -```{opcmd} show bgp \<ipv4|ipv6\> regexp \<text\> - -This command displays information about BGP routes whose AS path -matches the specified regular expression. -``` - - -```{opcmd} show bgp \<ipv4|ipv6\> summary - -This command displays the status of all BGP connections. -``` - - -```none -IPv4 Unicast Summary: -BGP router identifier 10.0.35.3, local AS number 65000 vrf-id 0 -BGP table version 11 -RIB entries 5, using 920 bytes of memory -Peers 4, using 82 KiB of memory - -Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd -10.0.13.1 4 65000 148 159 0 0 0 02:16:01 0 -10.0.23.2 4 65000 136 143 0 0 0 02:13:21 0 -10.0.34.4 4 65004 161 163 0 0 0 02:16:01 1 -10.0.35.5 4 65005 162 166 0 0 0 02:16:01 1 - -Total number of neighbors 4 -``` - -### Reset - -```{opcmd} reset bgp \<ipv4|ipv6\> \<address\> [soft [in|out]] - -This command resets BGP connections to the specified neighbor IP address. -With argument {cfgcmd}`soft` this command initiates a soft reset. If -you do not specify the {cfgcmd}`in` or {cfgcmd}`out` options, both -inbound and outbound soft reconfiguration are triggered. -``` - - -```{opcmd} reset bgp all - -This command resets all BGP connections of given router. -``` - - -```{opcmd} reset bgp \<ipv4|ipv6\> external - -This command resets all external BGP peers of given router. -``` - - -```{opcmd} reset bgp \<ipv4|ipv6\> peer-group \<name\> [soft [in|out]] - -This command resets BGP connections to the specified peer group. -With argument {cfgcmd}`soft` this command initiates a soft reset. If -you do not specify the {cfgcmd}`in` or {cfgcmd}`out` options, both -inbound and outbound soft reconfiguration are triggered. -``` - -## Examples -### IPv4 peering - -A simple eBGP configuration: - -**Node 1:** - -```none -set protocols bgp system-as 65534 -set protocols bgp neighbor 192.168.0.2 ebgp-multihop '2' -set protocols bgp neighbor 192.168.0.2 remote-as '65535' -set protocols bgp neighbor 192.168.0.2 update-source '192.168.0.1' -set protocols bgp neighbor 192.168.0.2 address-family ipv4-unicast -set protocols bgp address-family ipv4-unicast network '172.16.0.0/16' -set protocols bgp parameters router-id '192.168.0.1' -``` - -**Node 2:** - -```none -set protocols bgp system-as 65535 -set protocols bgp neighbor 192.168.0.1 ebgp-multihop '2' -set protocols bgp neighbor 192.168.0.1 remote-as '65534' -set protocols bgp neighbor 192.168.0.1 update-source '192.168.0.2' -set protocols bgp neighbor 192.168.0.1 address-family ipv4-unicast -set protocols bgp address-family ipv4-unicast network '172.17.0.0/16' -set protocols bgp parameters router-id '192.168.0.2' -``` - -Don't forget, the CIDR declared in the network statement MUST **exist in your -routing table (dynamic or static), the best way to make sure that is true is -creating a static route:** - -**Node 1:** - -```none -set protocols static route 172.16.0.0/16 blackhole distance '254' -``` - -**Node 2:** - -```none -set protocols static route 172.17.0.0/16 blackhole distance '254' -``` - -### IPv6 peering - -A simple BGP configuration via IPv6. - -**Node 1:** - -```none -set protocols bgp system-as 65534 -set protocols bgp neighbor 2001:db8::2 ebgp-multihop '2' -set protocols bgp neighbor 2001:db8::2 remote-as '65535' -set protocols bgp neighbor 2001:db8::2 update-source '2001:db8::1' -set protocols bgp neighbor 2001:db8::2 address-family ipv6-unicast -set protocols bgp address-family ipv6-unicast network '2001:db8:1::/48' -set protocols bgp parameters router-id '10.1.1.1' -``` - -**Node 2:** - -```none -set protocols bgp system-as 65535 -set protocols bgp neighbor 2001:db8::1 ebgp-multihop '2' -set protocols bgp neighbor 2001:db8::1 remote-as '65534' -set protocols bgp neighbor 2001:db8::1 update-source '2001:db8::2' -set protocols bgp neighbor 2001:db8::1 address-family ipv6-unicast -set protocols bgp address-family ipv6-unicast network '2001:db8:2::/48' -set protocols bgp parameters router-id '10.1.1.2' -``` - -Don't forget, the CIDR declared in the network statement **MUST exist in your -routing table (dynamic or static), the best way to make sure that is true is -creating a static route:** - -**Node 1:** - -```none -set protocols static route6 2001:db8:1::/48 blackhole distance '254' -``` - -**Node 2:** - -```none -set protocols static route6 2001:db8:2::/48 blackhole distance '254' -``` - -### Route Filtering - -Route filter can be applied using a route-map: - -**Node1:** - -```none -set policy prefix-list AS65535-IN rule 10 action 'permit' -set policy prefix-list AS65535-IN rule 10 prefix '172.16.0.0/16' -set policy prefix-list AS65535-OUT rule 10 action 'deny' -set policy prefix-list AS65535-OUT rule 10 prefix '172.16.0.0/16' -set policy prefix-list6 AS65535-IN rule 10 action 'permit' -set policy prefix-list6 AS65535-IN rule 10 prefix '2001:db8:2::/48' -set policy prefix-list6 AS65535-OUT rule 10 action 'deny' -set policy prefix-list6 AS65535-OUT rule 10 prefix '2001:db8:2::/48' - -set policy route-map AS65535-IN rule 10 action 'permit' -set policy route-map AS65535-IN rule 10 match ip address prefix-list 'AS65535-IN' -set policy route-map AS65535-IN rule 10 match ipv6 address prefix-list 'AS65535-IN' -set policy route-map AS65535-IN rule 20 action 'deny' -set policy route-map AS65535-OUT rule 10 action 'deny' -set policy route-map AS65535-OUT rule 10 match ip address prefix-list 'AS65535-OUT' -set policy route-map AS65535-OUT rule 10 match ipv6 address prefix-list 'AS65535-OUT' -set policy route-map AS65535-OUT rule 20 action 'permit' - -set protocols bgp system-as 65534 -set protocols bgp neighbor 2001:db8::2 address-family ipv4-unicast route-map export 'AS65535-OUT' -set protocols bgp neighbor 2001:db8::2 address-family ipv4-unicast route-map import 'AS65535-IN' -set protocols bgp neighbor 2001:db8::2 address-family ipv6-unicast route-map export 'AS65535-OUT' -set protocols bgp neighbor 2001:db8::2 address-family ipv6-unicast route-map import 'AS65535-IN' -``` - -**Node2:** - -```none -set policy prefix-list AS65534-IN rule 10 action 'permit' -set policy prefix-list AS65534-IN rule 10 prefix '172.17.0.0/16' -set policy prefix-list AS65534-OUT rule 10 action 'deny' -set policy prefix-list AS65534-OUT rule 10 prefix '172.17.0.0/16' -set policy prefix-list6 AS65534-IN rule 10 action 'permit' -set policy prefix-list6 AS65534-IN rule 10 prefix '2001:db8:1::/48' -set policy prefix-list6 AS65534-OUT rule 10 action 'deny' -set policy prefix-list6 AS65534-OUT rule 10 prefix '2001:db8:1::/48' - -set policy route-map AS65534-IN rule 10 action 'permit' -set policy route-map AS65534-IN rule 10 match ip address prefix-list 'AS65534-IN' -set policy route-map AS65534-IN rule 10 match ipv6 address prefix-list 'AS65534-IN' -set policy route-map AS65534-IN rule 20 action 'deny' -set policy route-map AS65534-OUT rule 10 action 'deny' -set policy route-map AS65534-OUT rule 10 match ip address prefix-list 'AS65534-OUT' -set policy route-map AS65534-OUT rule 10 match ipv6 address prefix-list 'AS65534-OUT' -set policy route-map AS65534-OUT rule 20 action 'permit' - -set protocols bgp system-as 65535 -set protocols bgp neighbor 2001:db8::1 address-family ipv4-unicast route-map export 'AS65534-OUT' -set protocols bgp neighbor 2001:db8::1 address-family ipv4-unicast route-map import 'AS65534-IN' -set protocols bgp neighbor 2001:db8::1 address-family ipv6-unicast route-map export 'AS65534-OUT' -set protocols bgp neighbor 2001:db8::1 address-family ipv6-unicast route-map import 'AS65534-IN' -``` - -We could expand on this and also deny link local and multicast in the rule 20 -action deny. |