This document describes how to configure WAN (or ISP) redundancies, wherein multiple WAN links terminate on the same end router. This document also explains how to configure Network Address Translation (NAT) when there are multiple ISP's for internet connectivity and you want seamless failover i.e. when Primary ISP goes down then Secondary takes over with correct NAT with the use of the secondary ISP's public IP address.
Prerequisites
Requirements
There are no specific requirements for this document. Basic understanding of creating IP SLA and Static Routing.Configuration of IP SLA must be supported on the device and platform.
Components Used
This document is not restricted to specific software and hardware versions. It applies to all Cisco routers that run Cisco IOS and where IP SLA and Track can be configured.
Best Dual Wan Routers (Best Business Firewall Routers in 2019) Mark B. You get the dual WAN port used for FailOver and Load-Balancing (if you connect 3G/4G/LTE modems to the two USB ports, it will be added to the load balancing pool). And I have two ISPs that I want to use together in a dual wan router so that if one isp goes down, the.
The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If the network is live, make sure that you understand the potential impact of any command.
Configure
Network Diagram
Configurations
ISP 1 and ISP 2 directly connect to the Internet. For test purposes, use the IP address 10.10.10.10 as a reference to Internet.
Customer Edge Router Configurations
Interface Configurations
Track, IP SLA and Default Route Configurations.
When Track 8 is UP, Traffic to the Internet flows through ISP 1.
When Track 8 is DOWN, Traffic to the Internet flows through ISP 2.
Cisco Recomendations
Note: Cisco recommends these default values when you configure the IP SLA: 1. Threshold(millisecs): 5000 2. Timeout(millisecs): 5000 3. Frequency(secs): 60
Additional configurations for NAT Failover:
The route maps are created to match IP address defined by access list 101 and also match`the exit interface.
These commands enable Port Address Translation (PAT), where the IP addresses to be translated are defined by the route map. The IP address to be translated into are defined after the interface keyword.
Verify
Use this section in order to confirm that your configuration works properly.
Track status can be verified with the use of the show track command.
When the primary ISP link is UP, the Traffic flows through it.
When the primary ISP link is DOWN, secondary link fails over.
Once the link to the primary ISP link comes back up, traffic automatically starts to flow through it.
Similarly for NAT Failover:
When primary ISP link is UP, NAT translation occurs via Primary ISP link.
When primary ISP link is DOWN, NAT translation occurs via Secondary ISP link.
When primary ISP link comes back UP, NAT translation occurs via Primary ISP link
Troubleshoot
This section provides information you can use in order to troubleshoot your configuration.
Troubleshooting must be done mainly from static routing, IP SLA and Track configuration perspective.
Primarily, in such scenarios, troubleshoot starts when you analyse the cause of failure of primary link.
Posted byCCNA4 years ago
Archived
How can I effectually set up fail over between a primary fibre circuit, and a backup DSL. (Cisco)
My original thoughts were two NAT overload both interfaces, tracking the interfaces and have a default route out both interfaces with the backup with a higher cost.
Something like the below:
track 100 ip sla 100 reachability delay down 10 up 20
track 101 ip sla 101 reachability delay down 10 up 20
ip local policy route-map LocalPolicy
ip nat inside source route-map DYN_NAT interface <WAN1 Interface> overload
ip nat inside source route-map FAILOVER_NAT interface <WAN2 Interface> overload
ip route 0.0.0.0 0.0.0.0 <ISP1 Gateway> track 100
ip route 0.0.0.0 0.0.0.0 <ISP2 Gateway> 10 track 101