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EIGRP vs BGP route path selection scenario

Joshua Engels
Level 1
Level 1

I am looking for a routing solution to the following scenario.  It is a fairly simple design. 

 

I have two WAN connections between sites A and B.  One is a 20 Meg Metro Ethernet Circuit running EIGRP.  The other is a 10 Meg MPLS running BGP.  What do I need to do in my configuration to make sure that the 20 Meg connection is the chosen path based off the fact that it has better speed and bandwidth?  It appears to me that the MPLS is the preferred path even though it is slower.

 

See attached Diagram:

 

Site A Config

interface GigabitEthernet1/0/12
 description PADC COX P2P 20 Meg
 no switchport
 bandwidth 20480
 ip address 172.20.1.1 255.255.255.252

 

interface GigabitEthernet2/0/2
 description LEVEL 3 MPLS
 no switchport
 bandwidth 10240
 ip address 172.22.0.2 255.255.255.252

 

router eigrp 1
 network 10.0.1.0 0.0.0.255
 network 172.20.1.0 0.0.0.3
 network 192.168.76.8 0.0.0.3
  redistribute bgp 65003 metric 100 1 255 1 1500 route-map MPLS_NETWORKS
 redistribute static route-map DEFAULT_ROUTE

!
router bgp 65003
 bgp log-neighbor-changes
 redistribute static
 redistribute eigrp 1
 neighbor 172.22.0.1 remote-as 1
 default-information originate
!

 

Site B Config

interface GigabitEthernet0/1
 description COX Communications 10 Meg to Venyu
 bandwidth 20480
 ip address 172.20.1.2 255.255.255.252
 duplex auto
 speed auto
 service-policy output VOIP
!
interface GigabitEthernet0/2
 description Level 3 MPLS
 bandwidth 10240
 ip address 172.22.1.2 255.255.255.252
 duplex full
 speed 100

 

router eigrp 1
 network 10.3.1.0 0.0.0.31
 network 10.52.1.0 0.0.0.255
 network 10.76.6.0 0.0.0.255
 network 172.20.1.0 0.0.0.3
 network 192.168.63.64 0.0.0.63
 network 192.168.76.249 0.0.0.0
 passive-interface default
 no passive-interface GigabitEthernet0/0
 no passive-interface GigabitEthernet0/1
!
router bgp 65003
 bgp log-neighbor-changes
 network 10.3.1.0 mask 255.255.255.224
 network 10.52.1.0 mask 255.255.255.0
 network 10.76.6.0 mask 255.255.255.0
 network 192.168.76.249 mask 255.255.255.255
 neighbor 172.22.1.1 remote-as 1

 

 

3 Replies 3

Jon Marshall
Hall of Fame
Hall of Fame

If each router is receiving advertisements for the same networks/subnet masks from both BGP and EIGRP it will always choose the BGP routes because they have a lower AD ie. 20 vs EIGRP 90.

Doesn't matter what the bandwidth is.

If you want to prefer the 20Mbps links then there are a number of options -

1) if you can summarise each sites subnets then advertise the summary via BGP and the more specific via EIGRP.  More specific will be chosen even before AD is taken into account.

2) change the AD of either BGP or EIGRP so EIGRP ends up with the lower AD

3) run BGP on both links although you would still need to manipulate the attributes to make sure the link you want is used.

Jon

To your knowledge, are there any potential issues that I should be aware of when manipulating the AD?  I have done this in a GNS3 lab with success however I want to make sure I do not adversely affect something in my network.

Difficult to say without knowing the rest of your network as it depends on what else is there i terms of L3 devices.

Are you running BGP or EIGRP with any other L3 devices at each site ?

Jon

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