ARISTA - BGP Commands - Revision history

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	== Configuring BGP on Arista EOS ==		== Configuring BGP on Arista EOS ==

Admin at 06:40, 16 December 2025

2025-12-16T06:40:36Z

← Older revision		Revision as of 06:40, 16 December 2025
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	You can define BGP neighbors, which are other BGP routers with which your device will exchange routing information.		You can define BGP neighbors, which are other BGP routers with which your device will exchange routing information.

	~~###~~ Add a Neighbor		Add a Neighbor

	<nowiki>		<nowiki>
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	neighbor 192.168.1.1 remote-as 65002</nowiki>		neighbor 192.168.1.1 remote-as 65002</nowiki>

	~~###~~ Specify the Neighbor’s Address Family		Specify the Neighbor’s Address Family

	<nowiki>		<nowiki>
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	address-family ipv4 unicast</nowiki>		address-family ipv4 unicast</nowiki>

	~~###~~ Configure the Neighbor's Update Source		Configure the Neighbor's Update Source

	<nowiki>		<nowiki>
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	neighbor 192.168.1.1 update-source Ethernet1</nowiki>		neighbor 192.168.1.1 update-source Ethernet1</nowiki>

	~~###~~ Configure BGP Peer Group		Configure BGP Peer Group

	You can also configure peer groups to simplify neighbor configurations.		You can also configure peer groups to simplify neighbor configurations.
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	You can configure BGP for different address families (IPv4, IPv6) using the address-family command.		You can configure BGP for different address families (IPv4, IPv6) using the address-family command.

	~~###~~ IPv4 Unicast Address Family		IPv4 Unicast Address Family

	<nowiki>		<nowiki>
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	address-family ipv4 unicast</nowiki>		address-family ipv4 unicast</nowiki>

	~~###~~ IPv6 Unicast Address Family		IPv6 Unicast Address Family

	<nowiki>		<nowiki>
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	BGP supports multiple path attributes to control route selection and advertisement. Below are some common attributes that can be configured.		BGP supports multiple path attributes to control route selection and advertisement. Below are some common attributes that can be configured.

	~~###~~ Configure Local Preference		Configure Local Preference

	Local preference is used to prefer a particular route within an AS.		Local preference is used to prefer a particular route within an AS.
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	bgp bestpath local-preference 200</nowiki>		bgp bestpath local-preference 200</nowiki>

	~~###~~ Configure MED (Multi-Exit Discriminator)		Configure MED (Multi-Exit Discriminator)

	MED is used to influence the route selection across different ASes.		MED is used to influence the route selection across different ASes.
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	bgp bestpath med 50</nowiki>		bgp bestpath med 50</nowiki>

	~~###~~ Configure Weight		Configure Weight

	Weight is a Cisco-specific attribute that influences route preference. It is local to the router and does not propagate to other routers.		Weight is a Cisco-specific attribute that influences route preference. It is local to the router and does not propagate to other routers.
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	BGP allows filtering of incoming and outgoing routes to control the routing table and BGP advertisements.		BGP allows filtering of incoming and outgoing routes to control the routing table and BGP advertisements.

	~~###~~ Prefix List		Prefix List

	You can use prefix lists to filter specific IP prefixes.		You can use prefix lists to filter specific IP prefixes.
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	ip prefix-list myFilter permit 192.168.0.0/16</nowiki>		ip prefix-list myFilter permit 192.168.0.0/16</nowiki>

	~~###~~ Route Map		Route Map

	Route maps can be used for more advanced filtering and route manipulation.		Route maps can be used for more advanced filtering and route manipulation.
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	route-map MyRouteMap permit 10</nowiki>		route-map MyRouteMap permit 10</nowiki>

	~~###~~ Apply a Route Map to a BGP Neighbor		Apply a Route Map to a BGP Neighbor

	<nowiki>		<nowiki>
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	neighbor 192.168.1.1 route-map MyRouteMap in</nowiki>		neighbor 192.168.1.1 route-map MyRouteMap in</nowiki>

	~~###~~ Distribute List		Distribute List

	A distribute list can be used to filter routes based on access lists.		A distribute list can be used to filter routes based on access lists.
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	== BGP Route Advertisement ==		== BGP Route Advertisement ==

	~~###~~ Advertise Networks		Advertise Networks

	You can advertise networks into BGP using the `network` command.		You can advertise networks into BGP using the `network` command.
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	network 10.0.0.0/24</nowiki>		network 10.0.0.0/24</nowiki>

	~~###~~ Advertise Aggregate Address		Advertise Aggregate Address

	You can advertise a summarized or aggregate address.		You can advertise a summarized or aggregate address.
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	BGP allows configuration of timers for various BGP operations, including keepalive and hold timers.		BGP allows configuration of timers for various BGP operations, including keepalive and hold timers.

	~~###~~ Configure Keepalive and Hold Timers		Configure Keepalive and Hold Timers

	<nowiki>		<nowiki>
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	neighbor 192.168.1.1 timers 30 90</nowiki>		neighbor 192.168.1.1 timers 30 90</nowiki>

	~~###~~ Configure BGP Maximum Prefix Limit		Configure BGP Maximum Prefix Limit

	<nowiki>		<nowiki>
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	Once BGP is configured, there are several show commands to verify and troubleshoot BGP.		Once BGP is configured, there are several show commands to verify and troubleshoot BGP.

	~~###~~ Show BGP Summary		Show BGP Summary

	<nowiki>		<nowiki>
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	This will display the BGP neighbors, state, and prefix counts.		This will display the BGP neighbors, state, and prefix counts.

	~~###~~ Show BGP Route		Show BGP Route

	<nowiki>		<nowiki>
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	This will display the BGP routing table.		This will display the BGP routing table.

	~~###~~ Show BGP Neighbor Information		Show BGP Neighbor Information

	<nowiki>		<nowiki>
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	This will display detailed information about a specific BGP neighbor.		This will display detailed information about a specific BGP neighbor.

	~~###~~ Show BGP Advertised Routes		Show BGP Advertised Routes

	<nowiki>		<nowiki>
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	== Troubleshooting BGP ==		== Troubleshooting BGP ==

	~~###~~ BGP Debugging Commands		BGP Debugging Commands

	You can enable debugging to capture BGP activity.		You can enable debugging to capture BGP activity.
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	This command will show live BGP updates, state changes, and route advertisements.		This command will show live BGP updates, state changes, and route advertisements.

	~~###~~ Display BGP Events		Display BGP Events

	<nowiki>		<nowiki>

Admin: Created page with "Category:Wiki == Configuring BGP on Arista EOS == To start configuring BGP, you need to enter global configuration mode and enable BGP for a specific Autonomous System (AS). router bgp [AS_NUMBER] Example: router bgp 65001 == BGP Neighbors Configuration == You can define BGP neighbors, which are other BGP routers with which your device will exchange routing information. ### Add a Neighbor neighbor [IP_ADDRESS] r..."

2025-12-16T06:39:56Z

Created page with "Category:Wiki == Configuring BGP on Arista EOS == To start configuring BGP, you need to enter global configuration mode and enable BGP for a specific Autonomous System (AS). <nowiki> router bgp [AS_NUMBER]</nowiki> Example: <nowiki> router bgp 65001</nowiki> == BGP Neighbors Configuration == You can define BGP neighbors, which are other BGP routers with which your device will exchange routing information. ### Add a Neighbor <nowiki> neighbor [IP_ADDRESS] r..."

New page

[[Category:Wiki]]

== Configuring BGP on Arista EOS ==

To start configuring BGP, you need to enter global configuration mode and enable BGP for a specific Autonomous System (AS).

<nowiki>
router bgp [AS_NUMBER]</nowiki>

Example:
<nowiki>
router bgp 65001</nowiki>

== BGP Neighbors Configuration ==

You can define BGP neighbors, which are other BGP routers with which your device will exchange routing information.

### Add a Neighbor

<nowiki>
neighbor [IP_ADDRESS] remote-as [AS_NUMBER]</nowiki>

Example:
<nowiki>
neighbor 192.168.1.1 remote-as 65002</nowiki>

### Specify the Neighbor’s Address Family

<nowiki>
address-family [ipv4 | ipv6] unicast</nowiki>

Example:
<nowiki>
address-family ipv4 unicast</nowiki>

### Configure the Neighbor's Update Source

<nowiki>
neighbor [IP_ADDRESS] update-source [INTERFACE_NAME]</nowiki>

Example:
<nowiki>
neighbor 192.168.1.1 update-source Ethernet1</nowiki>

### Configure BGP Peer Group

You can also configure peer groups to simplify neighbor configurations.

<nowiki>
neighbor [PEER_GROUP_NAME] peer-group
neighbor [PEER_GROUP_NAME] remote-as [AS_NUMBER]</nowiki>

Example:
<nowiki>
neighbor PeerGroup1 peer-group
neighbor PeerGroup1 remote-as 65002</nowiki>

== BGP Address Family Configuration ==

You can configure BGP for different address families (IPv4, IPv6) using the address-family command.

### IPv4 Unicast Address Family

<nowiki>
address-family ipv4 unicast</nowiki>

Example:
<nowiki>
router bgp 65001
address-family ipv4 unicast</nowiki>

### IPv6 Unicast Address Family

<nowiki>
address-family ipv6 unicast</nowiki>

Example:
<nowiki>
router bgp 65001
address-family ipv6 unicast</nowiki>

== BGP Path Attributes Configuration ==

BGP supports multiple path attributes to control route selection and advertisement. Below are some common attributes that can be configured.

### Configure Local Preference

Local preference is used to prefer a particular route within an AS.

<nowiki>
bgp bestpath local-preference [VALUE]</nowiki>

Example:
<nowiki>
bgp bestpath local-preference 200</nowiki>

### Configure MED (Multi-Exit Discriminator)

MED is used to influence the route selection across different ASes.

<nowiki>
bgp bestpath med [VALUE]</nowiki>

Example:
<nowiki>
bgp bestpath med 50</nowiki>

### Configure Weight

Weight is a Cisco-specific attribute that influences route preference. It is local to the router and does not propagate to other routers.

<nowiki>
neighbor [IP_ADDRESS] weight [VALUE]</nowiki>

Example:
<nowiki>
neighbor 192.168.1.1 weight 100</nowiki>

== BGP Route Filtering ==

BGP allows filtering of incoming and outgoing routes to control the routing table and BGP advertisements.

### Prefix List

You can use prefix lists to filter specific IP prefixes.

<nowiki>
ip prefix-list [PREFIX_LIST_NAME] permit|deny [NETWORK/MASK]</nowiki>

Example:
<nowiki>
ip prefix-list myFilter permit 192.168.0.0/16</nowiki>

### Route Map

Route maps can be used for more advanced filtering and route manipulation.

<nowiki>
route-map [MAP_NAME] permit|deny [SEQUENCE_NUMBER]</nowiki>

Example:
<nowiki>
route-map MyRouteMap permit 10</nowiki>

### Apply a Route Map to a BGP Neighbor

<nowiki>
neighbor [IP_ADDRESS] route-map [MAP_NAME] in|out</nowiki>

Example:
<nowiki>
neighbor 192.168.1.1 route-map MyRouteMap in</nowiki>

### Distribute List

A distribute list can be used to filter routes based on access lists.

<nowiki>
neighbor [IP_ADDRESS] distribute-list [ACCESS_LIST_NAME] in|out</nowiki>

Example:
<nowiki>
neighbor 192.168.1.1 distribute-list MyAccessList out</nowiki>

== BGP Route Advertisement ==

### Advertise Networks

You can advertise networks into BGP using the `network` command.

<nowiki>
network [NETWORK/MASK]</nowiki>

Example:
<nowiki>
network 10.0.0.0/24</nowiki>

### Advertise Aggregate Address

You can advertise a summarized or aggregate address.

<nowiki>
aggregate-address [NETWORK/MASK]
</nowiki>

Example:
<nowiki>
aggregate-address 10.0.0.0/16</nowiki>

== BGP Timers and Parameters ==

BGP allows configuration of timers for various BGP operations, including keepalive and hold timers.

### Configure Keepalive and Hold Timers

<nowiki>
neighbor [IP_ADDRESS] timers [KEEPALIVE_INTERVAL] [HOLD_TIME]</nowiki>

Example:
<nowiki>
neighbor 192.168.1.1 timers 30 90</nowiki>

### Configure BGP Maximum Prefix Limit

<nowiki>
neighbor [IP_ADDRESS] maximum-prefix [MAX_PREFIXES]
</nowiki>

Example:
<nowiki>
neighbor 192.168.1.1 maximum-prefix 5000</nowiki>

== BGP Show Commands ==

Once BGP is configured, there are several show commands to verify and troubleshoot BGP.

### Show BGP Summary

<nowiki>
show ip bgp summary</nowiki>

This will display the BGP neighbors, state, and prefix counts.

### Show BGP Route

<nowiki>
show ip bgp</nowiki>

This will display the BGP routing table.

### Show BGP Neighbor Information

<nowiki>
show ip bgp neighbors [IP_ADDRESS]</nowiki>

This will display detailed information about a specific BGP neighbor.

### Show BGP Advertised Routes

<nowiki>
show ip bgp neighbors [IP_ADDRESS] advertised-routes</nowiki>

This will display the routes advertised to a specific BGP neighbor.

== Troubleshooting BGP ==

### BGP Debugging Commands

You can enable debugging to capture BGP activity.

<nowiki>
debug ip bgp</nowiki>

This command will show live BGP updates, state changes, and route advertisements.

### Display BGP Events

<nowiki>
show logging | include BGP</nowiki>

This will filter the log for BGP-specific events and errors.

== Useful Links ==

* [Arista EOS Documentation](https://www.arista.com/en/support/eos)
* [RFC 4271 - BGPv4 Specification](https://tools.ietf.org/html/rfc4271)
* [Arista BGP Configuration Guide](https://www.arista.com/en/support/bgp)
* [Cisco BGP Command Reference](https://www.cisco.com/c/en/us/td/docs/iosxr/ncs5500/bgp/bgp-command-reference-650/b-bgp-cg/b-bgp-cg_chapter_010.html)