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Auto FailoverSo... My router has three Interfaces.
Gig 0/0 WAN1 Gig 0/1 WAN2 Gig 0/3 LAN
WAN1 and WAN2 are two different upstream providers on two different subnets.
I understand I can do:
!WAN1 ip route 0.0.0.0 0.0.0.0 184.x.x.1 !WAN2 ip route 0.0.0.0 0.0.0.0 12.x.x.1
This configuration should load balance
-or-
!WAN1 ip route 0.0.0.0 184.x.x.1 !WAN2 ip route 0.0.0.0 12.x.x.1 254
This configuration should do auto failover
Now here is my question. If 184.x.x.1 is a router sitting right next to my router connected by a patch cable, it is very probable that 184.x.x.1 is still pingable even if the next hop is down.
How can the router determine that WAN1 is down and go to WAN2 or does it try to route the destination through WAN1 and if the destination is unreachable go through WAN2?
I am assuming that the rest is as simple as having the correct IP addresses on each Interface, IP NAT inside on gig 0/3 and IP NAT outside on both gig 0/1 and gig 0/2?
Thanks! |
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tubbynetreminds me of the danse russe MVM join:2008-01-16 Gilbert, AZ |
this is done through state of the phy on your router. if you lose the interface with the next hop, it drops out of the table.
ip-sla is your friend to check reachability beyond your next hop to your upstreams.
q. |
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How does this look?
! track 10 rtr 1 reachability delay down 1 up 1 ! interface Gig 0/0 description ISP1 ip address 184.x.x.x 255.255.255.0 ip nat outside ip virtual-reassembly ! interface Gig 0/1 description ISP2 ip address 10.105.86.1 255.255.255.0 ip nat outside ip virtual-reassembly ! interface Gig 0/3 description LAN ip nat inside ip virtual-reassembly ! ip route 0.0.0.0 0.0.0.0 FastEthernet0/0 184.x.x.1 track 10 ip route 0.0.0.0 0.0.0.0 FastEthernet0/1 10.105.86.2 10 ! ip nat inside source route-map ISP1 interface FastEthernet0/0 overload ip nat inside source route-map ISP2 interface FastEthernet0/1 overload ! ip sla 1 icmp-echo 8.8.8.8 source-interface Gig 0/0 timeout 1000 threshold 2 frequency 3 ip sla schedule 1 life forever start-time now ! route-map ISP2 permit 10 match ip address 1 match interface Gig 0/1 ! route-map ISP1 permit 10 match ip address 1 match interface Gig 0/0 ! |
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