BGP DMZ link bandwidth for unequal cost recursive load balancing

Updated: September 11, 2026

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Describes support for unequal cost load balancing for recursive prefixes using BGP DMZ link bandwidth to distribute traffic based on link capacity.

BGP DMZ link bandwidth for unequal cost recursive load balancing is a feature that provides support for unequal cost load balancing for recursive prefixes on a local node using BGP DMZ link bandwidth. The system achieves unequal load balancing by using the dmz-link-bandwidth command in BGP neighbor configuration mode and the bandwidth command in interface configuration mode.

Enable BGP unequal cost recursive load balancing

Enable BGP unequal cost recursive load balancing.

Before you begin

Ensure the network configuration supports BGP and interface bandwidth settings.

Procedure

Enter global configuration mode to begin making configuration changes.
Example:
```
Router# config
```
Enter BGP router configuration mode and specify the local Autonomous System Number (ASN) for your router.
Example:
```
Router(config)# router bgp 120
```
Specify the BGP address family, IPv4 or IPv6 unicast, to configure routing for the desired protocol.
Example:
```
Router(config-bgp)# address-family ipv4 unicast
```
Set the maximum number of parallel BGP paths, for eBGP, iBGP, or both, that can be used for load balancing, and optionally enable unequal-cost multipath.
Example:
```
Router(config-bgp-af)# maximum-paths ebgp 3
```
Exit the address-family configuration mode and return to BGP router configuration mode.
Example:
```
Router(config-bgp-af)# exit
```
Select the BGP neighbor you want to configure by specifying its IP address.
Example:
```
Router(config-bgp)# neighbor 10.0.0.0
```
Enable the DMZ link-bandwidth feature for the specified BGP neighbor, allowing the router to use per-link bandwidth information for load balancing.
Example:
```
Router(config-bgp-nbr)# dmz-link-bandwidth
Router(config-bgp-nbr)# commit
```

Configure BGP unequal cost recursive load balancing: example

Provide a sample configuration for unequal cost recursive load balancing.

This example shows the configuration for various interfaces and BGP settings to achieve unequal cost recursive load balancing.

Procedure

Execute these commands in configuration mode to set up BGP with multiple neighbors, enable DMZ link-bandwidth, and apply route policies:

Example:


Router(config)#interface Loopback0  
Router(config-if)#ipv4 address 20.20.20.20 255.255.255.255  
Router(config-if)#exit  

Router(config)#interface MgmtEth0/RSP0/CPU0/0  
Router(config-if)#ipv4 address 8.43.0.10 255.255.255.0  
Router(config-if)#exit  

Router(config)#interface TenGigE0/3/0/0  
Router(config-if)#bandwidth 8000000  
Router(config-if)#ipv4 address 11.11.11.11 255.255.255.0  
Router(config-if)#ipv6 address 11:11:0:1::11/64  
Router(config-if)#exit  

Router(config)#interface TenGigE0/3/0/1  
Router(config-if)#bandwidth 7000000  
Router(config-if)#ipv4 address 11.11.12.11 255.255.255.0  
Router(config-if)#ipv6 address 11:11:0:2::11/64  
Router(config-if)#exit  

Router(config)#interface TenGigE0/3/0/2  
Router(config-if)#bandwidth 6000000  
Router(config-if)#ipv4 address 11.11.13.11 255.255.255.0  
Router(config-if)#ipv6 address 11:11:0:3::11/64  
Router(config-if)#exit  

Router(config)#interface TenGigE0/3/0/3  
Router(config-if)#bandwidth 5000000  
Router(config-if)#ipv4 address 11.11.14.11 255.255.255.0  
Router(config-if)#ipv6 address 11:11:0:4::11/64  
Router(config-if)#exit  

Router(config)#interface TenGigE0/3/0/4  
Router(config-if)#bandwidth 4000000  
Router(config-if)#ipv4 address 11.11.15.11 255.255.255.0  
Router(config-if)#ipv6 address 11:11:0:5::11/64  
Router(config-if)#exit  

Router(config)#interface TenGigE0/3/0/5  
Router(config-if)#bandwidth 3000000  
Router(config-if)#ipv4 address 11.11.16.11 255.255.255.0  
Router(config-if)#ipv6 address 11:11:0:6::11/64  
Router(config-if)#exit  

Router(config)#interface TenGigE0/3/0/6  
Router(config-if)#bandwidth 2000000  
Router(config-if)#ipv4 address 11.11.17.11 255.255.255.0  
Router(config-if)#ipv6 address 11:11:0:7::11/64  
Router(config-if)#exit  

Router(config)#interface TenGigE0/3/0/7  
Router(config-if)#bandwidth 1000000  
Router(config-if)#ipv4 address 11.11.18.11 255.255.255.0  
Router(config-if)#ipv6 address 11:11:0:8::11/64  
Router(config-if)#exit  

Router(config)#interface TenGigE0/4/0/0  
Router(config-if)#description CONNECTED TO IXIA 1/3 transceiver permit pid all  
Router(config-if)#exit  

Router(config)#interface TenGigE0/4/0/2  
Router(config-if)#ipv4 address 9.9.9.9 255.255.0.0  
Router(config-if)#ipv6 address 9:9::9/64  
Router(config-if)#ipv6 enable  
Router(config-if)#exit  

Router(config)#route-policy pass-all  
Router(config-rpl)#pass  
Router(config-rpl)#end-policy  

Router(config)#router static  
Router(config-static)#address-family ipv4 unicast  
Router(config-static-afi)#202.153.144.0/24 8.43.0.1  
Router(config-static-afi)#exit  
Router(config-static)#exit  

Router(config)#router bgp 100  
Router(config-bgp)#bgp router-id 20.20.20.20  
Router(config-bgp)#address-family ipv4 unicast  
Router(config-bgp-af)#maximum-paths eibgp 8  
Router(config-bgp-af)#redistribute connected  
Router(config-bgp-af)#exit  

Router(config-bgp)#neighbor 11.11.11.12  
Router(config-bgp-nbr)#remote-as 200  
Router(config-bgp-nbr)#dmz-link-bandwidth  
Router(config-bgp-nbr)#address-family ipv4 unicast  
Router(config-bgp-nbr-af)#route-policy pass-all in  
Router(config-bgp-nbr-af)#route-policy pass-all out  
Router(config-bgp-nbr-af)#exit  
Router(config-bgp-nbr)#exit  

Router(config-bgp)#neighbor 11.11.12.12  
Router(config-bgp-nbr)#remote-as 200  
Router(config-bgp-nbr)#dmz-link-bandwidth  
Router(config-bgp-nbr)#address-family ipv4 unicast  
Router(config-bgp-nbr-af)#route-policy pass-all in  
Router(config-bgp-nbr-af)#route-policy pass-all out  
Router(config-bgp-nbr-af)#exit  
Router(config-bgp-nbr)#exit  

Router(config-bgp)#neighbor 11.11.13.12  
Router(config-bgp-nbr)#remote-as 200  
Router(config-bgp-nbr)#dmz-link-bandwidth  
Router(config-bgp-nbr)#address-family ipv4 unicast  
Router(config-bgp-nbr-af)#route-policy pass-all in  
Router(config-bgp-nbr-af)#route-policy pass-all out  
Router(config-bgp-nbr-af)#exit  
Router(config-bgp-nbr)#exit  

Router(config-bgp)#neighbor 11.11.14.12  
Router(config-bgp-nbr)#remote-as 200  
Router(config-bgp-nbr)#dmz-link-bandwidth  
Router(config-bgp-nbr)#address-family ipv4 unicast  
Router(config-bgp-nbr-af)#route-policy pass-all in  
Router(config-bgp-nbr-af)#route-policy pass-all out  
Router(config-bgp-nbr-af)#exit  
Router(config-bgp-nbr)#exit  

Router(config-bgp)#neighbor 11.11.15.12  
Router(config-bgp-nbr)#remote-as 200  
Router(config-bgp-nbr)#dmz-link-bandwidth  
Router(config-bgp-nbr)#address-family ipv4 unicast  
Router(config-bgp-nbr-af)#route-policy pass-all in  
Router(config-bgp-nbr-af)#route-policy pass-all out  
Router(config-bgp-nbr-af)#exit  
Router(config-bgp-nbr)#exit  

Router(config-bgp)#neighbor 11.11.16.12  
Router(config-bgp-nbr)#remote-as 200  
Router(config-bgp-nbr)#dmz-link-bandwidth  
Router(config-bgp-nbr)#address-family ipv4 unicast  
Router(config-bgp-nbr-af)#route-policy pass-all in  
Router(config-bgp-nbr-af)#route-policy pass-all out  
Router(config-bgp-nbr-af)#exit  
Router(config-bgp-nbr)#exit  

Router(config-bgp)#neighbor 11.11.17.12  
Router(config-bgp-nbr)#remote-as 200  
Router(config-bgp-nbr)#dmz-link-bandwidth  
Router(config-bgp-nbr)#address-family ipv4 unicast  
Router(config-bgp-nbr-af)#route-policy pass-all in  
Router(config-bgp-nbr-af)#route-policy pass-all out  
Router(config-bgp-nbr-af)#exit  
Router(config-bgp-nbr)#exit  

Router(config-bgp)#neighbor 11.11.18.12  
Router(config-bgp-nbr)#remote-as 200  
Router(config-bgp-nbr)#dmz-link-bandwidth  
Router(config-bgp-nbr)#address-family ipv4 unicast  
Router(config-bgp-nbr-af)#route-policy pass-all in  
Router(config-bgp-nbr-af)#route-policy pass-all out  
Router(config-bgp-nbr-af)#exit  
Router(config-bgp-nbr)#exit  

Router(config-bgp)#exit  
Router(config)#commit

Verify the running configuration.

Example:

Router# show running-config
interface Loopback0
 ipv4 address 20.20.20.20 255.255.255.255
!
!
interface FourHundredGige0/1/0/0
 bandwidth 8000000 
 ipv4 address 11.11.11.11 255.255.255.0
 ipv6 address 11:11:0:1::11/64
!
interface FourHundredGige0/0/0/0
 bandwidth 7000000
 ipv4 address 11.11.12.11 255.255.255.0
 ipv6 address 11:11:0:2::11/64
!
interface FourHundredGige0/3/0/0
 bandwidth 6000000
 ipv4 address 11.11.13.11 255.255.255.0
 ipv6 address 11:11:0:3::11/64
!
interface FourHundredGige0/4/0/0
 bandwidth 5000000
 ipv4 address 11.11.14.11 255.255.255.0
 ipv6 address 11:11:0:4::11/64
!
interface FourHundredGige0/0/0/0
 bandwidth 4000000
 ipv4 address 11.11.15.11 255.255.255.0
 ipv6 address 11:11:0:5::11/64
!
interface FourHundredGige0/2/0/0
 bandwidth 3000000
 ipv4 address 11.11.16.11 255.255.255.0
 ipv6 address 11:11:0:6::11/64
!
interface FourHundredGige0/3/0/0
 bandwidth 2000000
 ipv4 address 11.11.17.11 255.255.255.0
 ipv6 address 11:11:0:7::11/64
!
interface FourHundredGige0/3/0/0
 bandwidth 1000000
 ipv4 address 11.11.18.11 255.255.255.0
 ipv6 address 11:11:0:8::11/64
!
interface FourHundredGige0/4/0/0
 description CONNECTED TO IXIA 1/3
 transceiver permit pid all
!
interface FourHundredGige0/4/0/0
 ipv4 address 9.9.9.9 255.255.0.0
 ipv6 address 9:9::9/64
 ipv6 enable
!
route-policy pass-all
  pass
end-policy
!
router static
 address-family ipv4 unicast
  202.153.144.0/24 8.43.0.1
 !
!
router bgp 100
 bgp router-id 10.20.20.20
 address-family ipv4 unicast
  maximum-paths eibgp 8
  redistribute connected
 !
 neighbor 11.11.11.12
  remote-as 200
  dmz-link-bandwidth    
  address-family ipv4 unicast
   route-policy pass-all in
   route-policy pass-all out
  !
 !
 neighbor 11.11.12.12
  remote-as 200
  dmz-link-bandwidth
  address-family ipv4 unicast
   route-policy pass-all in
   route-policy pass-all out
  !
 !
 neighbor 10.11.13.12
  remote-as 200
  dmz-link-bandwidth
  address-family ipv4 unicast
   route-policy pass-all in
   route-policy pass-all out
  !
 !
 neighbor 11.11.14.12
  remote-as 200
  dmz-link-bandwidth
  address-family ipv4 unicast
   route-policy pass-all in
   route-policy pass-all out
  !
 !
 neighbor 11.11.15.12
  remote-as 200
  dmz-link-bandwidth
  address-family ipv4 unicast
   route-policy pass-all in
   route-policy pass-all out
  !
 !
 neighbor 11.11.16.12
  remote-as 200
  dmz-link-bandwidth
  address-family ipv4 unicast
   route-policy pass-all in
   route-policy pass-all out
  !
 !
 neighbor 11.11.17.12
  remote-as 200
  dmz-link-bandwidth
  address-family ipv4 unicast
   route-policy pass-all in
   route-policy pass-all out
  !
 !
 neighbor 11.11.18.12
  remote-as 200
  dmz-link-bandwidth
  address-family ipv4 unicast
   route-policy pass-all in
   route-policy pass-all out
  !
 !
!

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