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Issues with router throughput while using multihomed BGP network

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  • Issues with router throughput while using multihomed BGP network

    We have a multihomed WAN connectivity, the primary link is give the priority as it has 100 Mbps and we wish to failover to secondary (30 Mbps) only when primary is down. Attached the diagram for reference.

    Previous to the BGP link we had a static connectivity to single ISP(ISP1) and this used to be the default routing path. Now for redundancy purpose we have changed the default path to go via the bgp network.

    After changing the default route to BGP we have noticed that the download speed dropped down to 20 kb/s, also the outside interface usage not crossing 3 Mb/s. Later for testing purpose we have shutdown the secondary ISP interface (int g0/2) and suddenly the outside interface bandwidth gone up to 50 % of its capacity and also the download speed increased to the normal values.

    We are continuiing with the secondary interface shutdown and planning to manually bring this interface if primary goes down. Any idea why the bandwidth is dropping when both ISP interfaces are active. Below are the BGP configurations in the WAN router, please help me to fix this issue because i am clueless about the problem.

    !
    !
    interface Loopback0
    ip address 2.2.2.2 255.255.255.255
    !
    interface GigabitEthernet0/1
    description ISP-1 OUTSIDE
    ip address 141.41.176.26 255.255.255.252
    load-interval 30
    duplex full
    speed 100
    !
    interface GigabitEthernet0/2
    description ISP-2 OUTSIDE
    ip address 180.51.19.10 255.255.255.252
    load-interval 30
    shutdown
    duplex full
    speed 1000
    !
    interface GigabitEthernet0/1/0
    description Static INT to FIREWALL
    switchport access vlan 141
    no ip address
    duplex full
    speed 100
    !
    interface GigabitEthernet0/1/1
    description BGP INT to FIREWALL
    switchport access vlan 102
    no ip address
    duplex full
    speed 100
    !
    interface GigabitEthernet0/1/2
    description DNS
    switchport access vlan 102
    no ip address
    !
    interface Vlan102
    description ###BGP WAN Pool - VLAN ###
    ip address 102.15.150.1 255.255.255.224
    !
    interface Vlan141
    description ISP-1 WAN Pool VLAN
    ip address 141.41.176.125 255.255.255.224
    !
    router bgp 123456
    bgp log-neighbor-changes
    network 102.15.150.0 mask 255.255.255.0
    neighbor 180.51.19.10 remote-as 12121
    neighbor 180.51.19.10 description isp2
    neighbor 180.51.19.10 soft-reconfiguration inbound
    neighbor 180.51.19.10 route-map isp2 out
    neighbor 141.41.176.26 remote-as 45450
    neighbor 141.41.176.26 description isp1
    neighbor 141.41.176.26 soft-reconfiguration inbound
    neighbor 141.41.176.26 route-map isp1 out
    maximum-paths 2
    !
    ip route 102.15.150.0 255.255.255.0 Null0 220
    !
    ip prefix-list isp1 seq 5 permit 102.15.150.0/24
    !
    ip prefix-list isp2 seq 5 permit 102.15.150.0/24
    access-list 10 permit 102.15.150.0 0.0.0.255
    !
    route-map isp1 permit 10
    match ip address prefix-list isp1
    !
    route-map isp2 permit 20
    match ip address 10
    set as-path prepend 123456 123456
    !
    Attached Files

  • #2
    Re: Issues with router throughput while using multihomed BGP network

    BGP is a huge topic with many options. I suggest getting with your ISP to troubleshoot. I can't really help out with just looking at a config.
    CCNA, CCNA-Security, CCNP
    CCIE Security (In Progress)

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