Query regarding local-preference and prepend

[donnie]

Hi all,

I have 2 mpls circuits each connected to a router meant for my local area network's outgoing traffic.

I like to configure my pair of routers in a active-standby kind of HA, where all incoming/outgoing traffic will go through my primary router CE1. In the event my primary router or the 1st MPLS circuit fails , i expect all incoming/outgoing traffic to go through my secondary router CE2. Pls refer to my attached diagram for more details. Is my configuration below able to achieve what i want? In the event sw1 is down, how will the traffic route? Pls advise. TIA!

 

1)Primary router(CE1)

Interface GigabitEthernet0/0
description WAN cirucit
ip address 2.2.2.6 255.255.255.252
no ip reditects
no ip unreachables
duplex full
speed 1000
no cdp enable
no mop enabled

Interface GigabitEthernet0/1
description LAN
ip address 192.168.1.2 255.255.255.0
standby 1 ip 192.168.1.1
standby 1 priority 150
standby 1 preempt
duplex auto
speed auto
no cdp enable
no mop enabled

router bgp 12345
bgp log-neighbor-changes
network 192.168.1.0 mask 255.255.255.0
neighbor 2.2.2.5 remote-as 4321
neighbor 2.2.2.5 soft-reconfiguration inbound
neighbor 2.2.2.5 route-map preference in

route-map preference permit 10
set local-preference 200

2)Secondary router(CE2)

Interface GigabitEthernet0/0
description WAN cirucit
ip address 2.2.2.2 255.255.255.252
no ip reditects
no ip unreachables
duplex full
speed 1000
no cdp enable
no mop enabled

Interface GigabitEthernet0/1
description LAN
ip address 192.168.1.3 255.255.255.0
standby 1 ip 192.168.1.1
standby 1 preempt
duplex auto
speed auto
no cdp enable
no mop enabled

router bgp 12345
bgp log-neighbor-changes
network 192.168.1.0 mask 255.255.255.0
neighbor 2.2.2.5 remote-as 4321
neighbor 2.2.2.5 soft-reconfiguration inbound
neighbor 2.2.2.5 route-map prepend out

route-map prepend permit 10
set as-path prepend 12345 12345 12345 12345

[ahmedshoaib]

Hi;

The configuration is looking fine for BGP primary & secondary link selection. You need to add a l3 link between CE1 & CE2 and run iBGP with next-hop self feature. 

Now below are failover scenarios:

1. Primary MPLS link is down.

Outgoing traffic: Local LAN à CE1 (192.168.1.2) à CE2 (via iBGP link) à MPLS cloud.

Return traffic: MPLS cloud à CE2 à Local LAN (Now here is asymmetric traffic).

Solution: You need to IP SLA and call in HSRP track feature to track the Primary BGP link, once link down traffic automatically shift to CE2 RTR.

2. Switch-1 down.

Outgoing traffic: Local LAN à CE2 (192.168.1.3) à CE1 (via iBGP link) à MPLS cloud.

Return traffic: reach MPLS cloud à CE1 à CE2 (via iBGP link) à Local LAN

3. Switch-1 down & Primary MPLS down.

Outgoing traffic: Local LAN à CE2 (192.168.1.3) à MPLS cloud.

Return traffic: reach MPLS cloud à CE2 à Local LAN

 Thanks & Best regards;