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New Member

Dual ISP Connections with Load Balancing and Redundancy using NAT

Is it possible to configure a router that connects to two different ISP's using NAT on both links for load balancing and redundancy. Some internal users must use one ISP connection and the other the second one. If one of the links fail everybody must access the internet via the available link. BGP connections to the ISP's.

  • Other Network Infrastructure Subjects
Cisco Employee

Re: Dual ISP Connections with Load Balancing and Redundancy usin

This can work if configured properly. You will need to use HSRP on the local LAN and BGP peering to the ISP. All you need to get from the ISP is a default route. To load-balance using HSRP on the LAN, you will need to have more than 1 VLAN or use multiple HSRP groups in the same subnets.

Keep in mind, since you are using NAT, the flow cannot be asymmetric. In other words, the path of communication to the ISP must go through the same router for both source to destination and destination to source.

New Member

Re: Dual ISP Connections with Load Balancing and Redundancy usin

i have faced similar type of problem ...but i am able to do load balancing with route-maps but i am not able to keep other link as backup i.e. i am not getting fall back.can u explain me what is the use of command "set ip next-hop DG1 DG2 DG3..DG6" ????? As i can set multiple next hop so if first one fails it should go automatically to next default gateway..

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