Supported Platforms
Related Documentation
- ACX, M, MX, PTX, T Series
- Example: Associating the MED Path Attribute with the IGP Metric and Delaying MED Updates
- ACX, M, MX, PTX, SRX, T Series, QFabric System, QFX Series standalone switches
- Understanding Route Filters for Use in Routing Policy Match Conditions
- ACX, J, M, MX, PTX, SRX, T Series, QFabric System, QFX Series standalone switches
- Understanding BGP Path Selection
- ACX, J, M, MX, SRX Series
- Understanding External BGP Peering Sessions
- BGP Configuration Overview
Example: Configuring the MED Using Route Filters
This example shows how to configure a policy that uses route filters to modify the multiple exit discriminator (MED) metric to advertise in BGP update messages.
Requirements
No special configuration beyond device initialization is required before you configure this example.
Overview
To configure a route-filter policy that modifies the advertised MED metric in BGP update messages, include the metric statement in the policy action.
Figure 1 shows a typical network with internal peer sessions and multiple exit points to a neighboring autonomous system (AS).
Figure 1: Typical Network with IBGP Sessions and Multiple Exit Points

Device R4 has multiple loopback interfaces configured to simulate advertised prefixes. The extra loopback interface addresses are 44.44.44.44/32 and 144.144.144.144/32. This example shows how to configure Device R4 to advertise a MED value of 30 to Device R3 for all routes except 144.144.144.144. For 144.144.144.144, a MED value of 10 is advertised to Device 3. A MED value of 20 is advertised to Device R2, regardless of the route prefix.
Configuration
CLI Quick Configuration
To quickly configure this example, copy the following commands, paste them into a text file, remove any line breaks, change any details necessary to match your network configuration, and then copy and paste the commands into the CLI at the [edit] hierarchy level.
Device R1
Device R2
Device R3
Device R4
Configuring Device R1
Step-by-Step Procedure
The following example requires you to navigate various levels in the configuration hierarchy. For information about navigating the CLI, see Using the CLI Editor in Configuration Mode in the CLI User Guide.
To configure Device R1:
- Configure the device interfaces.[edit interfaces fe-1/2/0 unit 1]user@R1# set family inet address 12.12.12.1/24
[edit interfaces fe-1/2/1 unit 2]user@R1# set family inet address 13.13.13.1/24
[edit interfaces lo0 unit 1]user@R1# set family inet address 192.168.1.1/32 - Configure BGP.[edit protocols bgp group internal]user@R1# set type internaluser@R1# set local-address 192.168.1.1user@R1# set export send-directuser@R1# set neighbor 192.168.2.1user@R1# set neighbor 192.168.3.1
- Configure OSPF.[edit protocols ospf area 0.0.0.0]user@R1# set interface lo0.1 passiveuser@R1# set interface fe-1/2/0.1user@R1# set interface fe-1/2/1.2
- Configure a policy that accepts direct routes.
Other useful options for this scenario might be to accept routes learned through OSPF or local routes.
[edit policy-options policy-statement send-direct term 1]user@R1# set from protocol directuser@R1# set then accept - Configure the router ID and autonomous system (AS) number.[edit routing-options]user@R1# set autonomous-system 123user@R1# set router-id 192.168.1.1
Results
From configuration mode, confirm your configuration by entering the show interfaces, show protocols, show policy-options, and show routing-options commands. If the output does not display the intended configuration, repeat the instructions in this example to correct the configuration.
If you are done configuring the device, enter commit from configuration mode.
Configuring Device R2
Step-by-Step Procedure
The following example requires you to navigate various levels in the configuration hierarchy. For information about navigating the CLI, see Using the CLI Editor in Configuration Mode in the CLI User Guide.
To configure Device R2:
- Configure the device interfaces.[edit interfaces fe-1/2/0 unit 3]user@R2# set family inet address 12.12.12.21/24
[edit interfaces fe-1/2/1 unit 4]user@R2# set family inet address 24.24.24.2/24
[edit interfaces lo0 unit 2]user@R2# set family inet address 192.168.2.1/32 - Configure BGP.[edit protocols bgp group internal]user@R2# set type internaluser@R2# set local-address 192.168.2.1user@R2# set export send-directuser@R2# set neighbor 192.168.1.1user@R2# set neighbor 192.168.3.1
[edit protocols bgp group external]user@R2# set type externaluser@R2# set export send-directuser@R2# set peer-as 4user@R2# set neighbor 24.24.24.4 - Configure OSPF.[edit protocols ospf area 0.0.0.0]user@R2# set interface lo0.2 passiveuser@R2# set interface fe-1/2/0.3user@R2# set interface fe-1/2/1.4
- Configure a policy that accepts direct routes.
Other useful options for this scenario might be to accept routes learned through OSPF or local routes.
[edit policy-options policy-statement send-direct term 1]user@R2# set from protocol directuser@R2# set then accept - Configure the router ID and autonomous system (AS) number.[edit routing-options]user@R2# set autonomous-system 123user@R2# set router-id 192.168.2.1
Results
From configuration mode, confirm your configuration by entering the show interfaces, show protocols, show policy-options, and show routing-options commands. If the output does not display the intended configuration, repeat the instructions in this example to correct the configuration.
If you are done configuring the device, enter commit from configuration mode.
Configuring Device R3
Step-by-Step Procedure
The following example requires you to navigate various levels in the configuration hierarchy. For information about navigating the CLI, see Using the CLI Editor in Configuration Mode in the CLI User Guide.
To configure Device R3:
- Configure the device interfaces.[edit interfaces fe-1/2/0 unit 5]user@R3# set family inet address 13.13.13.3/24
[edit interfaces fe-1/2/1 unit 6]user@R3# set family inet address 34.34.34.3/24
[edit interfaces lo0 unit 3]user@R3# set family inet address 192.168.3.1/32 - Configure BGP.[edit protocols bgp group internal]user@R3# set type internaluser@R3# set local-address 192.168.3.1user@R3# set export send-directuser@R3# set neighbor 192.168.1.1user@R3# set neighbor 192.168.2.1
[edit protocols bgp group external]user@R3# set type externaluser@R3# set export send-directuser@R3# set peer-as 4user@R3# set neighbor 34.34.34.4 - Configure OSPF.[edit protocols ospf area 0.0.0.0]user@R3# set interface lo0.3 passiveuser@R3# set interface fe-1/2/0.5user@R3# set interface fe-1/2/1.6
- Configure a policy that accepts direct routes.
Other useful options for this scenario might be to accept routes learned through OSPF or local routes.
[edit policy-options policy-statement send-direct term 1]user@R3# set from protocol directuser@R3# set then accept - Configure the router ID and autonomous system (AS) number.[edit routing-options]user@R3# set autonomous-system 123user@R3# set router-id 192.168.3.1
Results
From configuration mode, confirm your configuration by entering the show interfaces, show protocols, show policy-options, and show routing-options commands. If the output does not display the intended configuration, repeat the instructions in this example to correct the configuration.
If you are done configuring the device, enter commit from configuration mode.
Configuring Device R4
Step-by-Step Procedure
The following example requires you to navigate various levels in the configuration hierarchy. For information about navigating the CLI, see Using the CLI Editor in Configuration Mode in the CLI User Guide.
To configure Device R4:
- Configure the device interfaces.[edit interfaces fe-1/2/0 unit 7]user@R4# set family inet address 24.24.24.4/24
[edit interfaces fe-1/2/1 unit 8]user@R4# set family inet address 34.34.34.4/24
[edit interfaces lo0 unit 4]user@R4# set family inet address 192.168.4.1/32user@R4# set family inet address 44.44.44.44/32user@R4# set family inet address 144.144.144.144/32Device R4 has multiple loopback interface addresses to simulate advertised prefixes.
- Configure a policy that accepts direct routes.
Other useful options for this scenario might be to accept routes learned through OSPF or local routes.
[edit policy-options policy-statement send-direct term 1]user@R4# set from protocol directuser@R4# set then accept - Configure BGP.[edit protocols bgp group external]user@R4# set type externaluser@R4# set export send-directuser@R4# set peer-as 123
- Configure the two MED policies.[edit policy-options]set policy-statement med-10 from route-filter 144.144.144.144/32 exact set policy-statement med-10 then metric 10 set policy-statement med-10 then accept
set policy-statement med-30 from route-filter 0.0.0.0/0 longer set policy-statement med-30 then metric 30 set policy-statement med-30 then accept - Configure the two EBGP neighbors, applying the two MED
policies to Device R3, and a MED value of 20 to Device R2.[edit protocols bgp group external]user@R4# set neighbor 34.34.34.3 export med-10user@R4# set neighbor 34.34.34.3 export med-30user@R4# set neighbor 24.24.24.2 metric-out 20
- Configure the router ID and autonomous system (AS) number.[edit routing-options]user@R4# set autonomous-system 4user@R4# set router-id 192.168.4.1
Results
From configuration mode, confirm your configuration by entering the show interfaces, show protocols, show policy-options, and show routing-options commands. If the output does not display the intended configuration, repeat the instructions in this example to correct the configuration.
If you are done configuring the device, enter commit from configuration mode.
Verification
Confirm that the configuration is working properly.
- Checking the Active Path from Device R1 to Device R4
- Verifying That Device R4 Is Sending Its Routes Correctly
Checking the Active Path from Device R1 to Device R4
Purpose
Verify that the active path goes through Device R2.
Action
From operational mode, enter the show route protocol bgp command.
user@R1> show route protocol bgp
inet.0: 13 destinations, 19 routes (13 active, 0 holddown, 0 hidden) + = Active Route, - = Last Active, * = Both 12.12.12.0/24 [BGP/170] 4d 01:13:32, localpref 100, from 192.168.2.1 AS path: I > to 12.12.12.2 via fe-1/2/0.1 13.13.13.0/24 [BGP/170] 3d 05:36:10, localpref 100, from 192.168.3.1 AS path: I > to 13.13.13.3 via fe-1/2/1.2 24.24.24.0/24 [BGP/170] 4d 01:13:32, localpref 100, from 192.168.2.1 AS path: I > to 12.12.12.2 via fe-1/2/0.1 34.34.34.0/24 [BGP/170] 3d 05:36:10, localpref 100, from 192.168.3.1 AS path: I > to 13.13.13.3 via fe-1/2/1.2 44.44.44.44/32 *[BGP/170] 00:06:03, MED 20, localpref 100, from 192.168.2.1 AS path: 4 I > to 12.12.12.2 via fe-1/2/0.1 144.144.144.144/32 *[BGP/170] 00:06:03, MED 10, localpref 100, from 192.168.3.1 AS path: 4 I > to 13.13.13.3 via fe-1/2/1.2 192.168.2.1/32 [BGP/170] 4d 01:13:32, localpref 100, from 192.168.2.1 AS path: I > to 12.12.12.2 via fe-1/2/0.1 192.168.3.1/32 [BGP/170] 3d 05:36:10, localpref 100, from 192.168.3.1 AS path: I > to 13.13.13.3 via fe-1/2/1.2 192.168.4.1/32 *[BGP/170] 00:06:03, MED 20, localpref 100, from 192.168.2.1 AS path: 4 I > to 12.12.12.2 via fe-1/2/0.1
Meaning
The output shows that the preferred path to the routes advertised by Device R4 is through Device R2 for all routes except 144.144.144.144/32. For 144.144.144.144/32, the preferred path is through Device R3.
Verifying That Device R4 Is Sending Its Routes Correctly
Purpose
Make sure that Device R4 is sending update messages with a value of 20 to Device R2 and a value of 30 to Device R3.
Action
From operational mode, enter the show route advertising-protocol bgp command.
user@R4> show route advertising-protocol bgp
24.24.24.2
inet.0: 11 destinations, 13 routes (11 active, 0 holddown, 0 hidden) Prefix Nexthop MED Lclpref AS path * 24.24.24.0/24 Self 20 I * 34.34.34.0/24 Self 20 I * 44.44.44.44/32 Self 20 I * 144.144.144.144/32 Self 20 I * 192.168.4.1/32 Self 20 I
user@R4> show route advertising-protocol bgp
34.34.34.3
inet.0: 11 destinations, 13 routes (11 active, 0 holddown, 0 hidden) Prefix Nexthop MED Lclpref AS path * 24.24.24.0/24 Self 30 I * 34.34.34.0/24 Self 30 I * 44.44.44.44/32 Self 30 I * 144.144.144.144/32 Self 10 I * 192.168.4.1/32 Self 30 I
Meaning
The MED column shows that Device R4 is sending the correct MED values to its two EBGP neighbors.
Related Documentation
- ACX, M, MX, PTX, T Series
- Example: Associating the MED Path Attribute with the IGP Metric and Delaying MED Updates
- ACX, M, MX, PTX, SRX, T Series, QFabric System, QFX Series standalone switches
- Understanding Route Filters for Use in Routing Policy Match Conditions
- ACX, J, M, MX, PTX, SRX, T Series, QFabric System, QFX Series standalone switches
- Understanding BGP Path Selection
- ACX, J, M, MX, SRX Series
- Understanding External BGP Peering Sessions
- BGP Configuration Overview
Published: 2014-07-23
Supported Platforms
Related Documentation
- ACX, M, MX, PTX, T Series
- Example: Associating the MED Path Attribute with the IGP Metric and Delaying MED Updates
- ACX, M, MX, PTX, SRX, T Series, QFabric System, QFX Series standalone switches
- Understanding Route Filters for Use in Routing Policy Match Conditions
- ACX, J, M, MX, PTX, SRX, T Series, QFabric System, QFX Series standalone switches
- Understanding BGP Path Selection
- ACX, J, M, MX, SRX Series
- Understanding External BGP Peering Sessions
- BGP Configuration Overview