Smart Tips. Enabling WAN Load Balancing. Key Features. Network Diagram. Overview. Featured Products. WAN Failover. Enabling WAN Load Balancing Page 1

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1 Smart Tips Enabling WAN Load Balancing Overview Many small businesses today use broadband links such as DSL or Cable, favoring them over the traditional link such as T1/E1 or leased lines because of the higher bandwidth and lower cost. However, service providers do not guarantee the same service level agreements (SLAs) or reliability for broadband links as for traditional T1 and leased lines. Voice over IP and other mission-critical traffic can be extremely sensitive to any interruption in service. Therefore, small businesses, experiencing a surge of applications that require more WAN bandwidth and faster Internet connections, are looking for a solution that is both cost-effective and reliable. Load balancing technology, which improves the throughput and reliability of Internet or WAN connections, has led many small businesses to deploy multiple broadband WAN links. WAN load balancing improves throughput and reliability by allowing two or more Internet connections to be used concurrently, and also by providing a redundant link for backup if one connection fails. Cisco Small Business routers deliver robust and intelligently managed load balancing and failover features for small businesses seeking reliable, cost-effective WAN connectivity. This Smart Tip describes how to create a reliable WAN Internet connection by setting up load balancing and failover with dual WAN interfaces. Featured Products Cisco Small Business RV Series routers: RV042, RV042G, RV082, and RV016 Network Diagram Figure 1 illustrates a sample WAN load balancing implementation using a Cisco small business router. Figure 1 Internet Dual WAN Topology In this implementation, a WAN router at the main office is connected to two different Internet service providers (ISPs). Each WAN interface receives its IP addresses dynamically and has firewall and NAT enabled, by default. Load balancing is enabled for dual WAN access. With this configuration, hosts on the main office LAN, with IP addresses on the /24 network, can access the Internet using both Internet connections concurrently. Key Features The key features provided by WAN load balancing are WAN failover and load balancing. WAN Failover WAN1 IP: Dynamic from ISP (e.g ) WAN2 IP: Dynamic from ISP2 (e.g ) WAN Router Main Office LAN: /24 WAN When implementing WAN failover, a redundant broadband WAN link is deployed as backup. The primary WAN interface is used for all the traffic flow while another WAN link provides a backup link. The backup WAN link becomes active when the primary WAN link goes down, and becomes idle after the primary WAN link is restored. On Cisco Small Business RV Series routers, WAN failover is called Smart Link Backup Enabling WAN Load Balancing Page 1

2 WAN Load Balancing Load balancing uses the WAN links concurrently to maximize total traffic throughput by balancing the load over the links. If one link fails, the surviving link carries all the traffic until the link is restored. When a failed link becomes operational, traffic is once again load balanced across both links. This document describes outgoing load balancing, which applies to traffic originating on the local network and going to the Internet. Incoming load balancing, which is not described here, applies to traffic coming from the Internet. Design Tips Select Load Balancing or Failover To maximize network utilization, WAN load balancing is preferable because it uses both links concurrently. However, failover mode may be preferable under some circumstance, such as when one of the WAN links has low capacity compared to the primary link, and the primary link is not fully utilized. Select Links and Service Providers Avoid deploying load balancing or failover with a single point of failure, such as a single telephone wire, or a single ISP. For example, use one xdsl link over a telephone line and a second link over a broadband cable from two different ISPs. Using an additional T1/E1 or other leased line will provide superior quality of service (QoS). Detecting Loss of Connectivity to Internet Detecting the loss of connectivity to the Internet is vital for successful failover. Cisco small business routers provide configurable options for detecting the loss of connectivity. The primary mechanism is to periodically ping the default gateway, ISP host, remote host, or DNS lookup host. In most situations, pinging the default gateway is sufficient. However, when a second DSL or cable modem router is deployed in front of the Cisco small business router and the broadband router functions as the gateway and DNS server, the best practice is to ping a specific host, such as a DNS server, on the ISP network or public Internet. VPN with WAN Load Balancing When using Cisco Small Business RV Series routers, VPN connections cannot utilize load balancing over multiple WAN connections. The VPN connection has to be configured with a single WAN interface, and in the event of a link failure, the client or other endpoint must manually switch to the surviving WAN link. Cisco ISR routers can be used to provide VPN redundancy and load balancing. Protocol Binding In load balancing mode, either WAN port will carry any outbound protocol unless protocol binding is configured. When a protocol is bound to a particular WAN port, all outgoing traffic of that protocol will be directed to the specified WAN port. For example, if the HTTPS protocol is bound to WAN1 and the FTP protocol is bound to WAN2, then the WAN router will automatically route all outbound HTTPS traffic to WAN1 interface and all outbound FTP traffic to WAN2. If Design Tips a link fails, traffic bound to that interface will still failover to the other link. Protocol binding is useful when links are of unequal quality and certain traffic, such as voice over IP, should be directed to the better connection. Load Balancing Mechanism Cisco Small Business RV Series routers use per session-based load balancing. A session can be a TCP connection, a UDP session, or an ICMP packet. A UDP session is defined as the UDP packets having the same source and destination address and port that arrive at the router within one UDP session timeout interval, which is typically 30 seconds. This section describes the configuration required to implement WAN load balancing on a Cisco Small Business RV Series router. It includes the following topics: Preconfiguration Checklist, page 2 Configuring WAN Interface Settings, page 2 Configuring Failover, page 3 Configuring Load Balancing, page 3 Verifying Load Balancing Status, page 5 Preconfiguration Checklist Check the cabling between the WAN port on the RV router and the Ethernet ports on the DSL or cable modem. Verify connectivity between the RV router and any LAN switches used in the deployment. Verify LAN connectivity. The default LAN network is /24. Local PCs and servers should be able to communicate with each other and with the RV router. Configuring WAN Interface Settings Each WAN interface must be configured separately before configuring WAN load balancing. The default WAN setting of the RV router is set to get its IP address dynamically from the ISP. Firewalling and NAT are also enabled by default. Step 1 Go to Setup > Network -> WAN settings and click the config icon for the WAN1 and WAN2 interfaces to make any changes required to the interface settings. The default connection type is obtain an IP automatically. If using a static IP address provided by the ISP, configure the IP address, default gateway, and DNS server accordingly. Enabling WAN Load Balancing Page 2

3 Figure 2 WAN Settings Figure 3 Port Statistics Configuring Failover The RV042 and RV082 router provide a single physical port for either a second WAN interface or for a DMZ network. Therefore a DMZ cannot be implemented when using dual WAN connections on these routers. Step 2 Go to System Summary and in the port statistics section verify that each WAN interface shows Connect status and has received a valid IP address, default gateway, and DNS server address from each ISP. Skip this step if configuring WAN load balancing. Step 1 To configure WAN failover mode, go to System Management > DualWAN, and select Smart Link Backup. Step 2 Figure 4 Set the primary WAN interface to WAN1 or WAN2. Enabling Smart Link Backup (Failover) For DDNS settings, Go to Setup > DDNS to configure DDNS entries for each WAN Interface. Refer to the Enabling WAN Public Access with DDNS and Port Forwarding Smart Tip for details. Configuring Load Balancing Step 1 Go to System Management > DualWAN, and select Load Balance (Auto Mode). Enabling WAN Load Balancing Page 3

4 Figure 5 Enabling Load Balance (Auto Mode) Step 4 (Optional) To bind specific protocol traffic to the WAN1 interface, scroll down to the Protocol Binding section, select the protocol from the Service pull-down selection list. Enter the source and destination and IP addresses to bind for the protocol, check Enable, and click Add to list. To create additional services that are not on the selection list, click Service Management and add the required TCP or UDP port numbers. To bind all traffic for a specific protocol (any IP address), enter to for Source IP and Destination IP. Step 2 Click the Config icon for WAN1, and on the Interface Setting page, enter the upstream and downstream bandwidth. Step 3 Enable Network Service Detection, and select Default Gateway. Figure 6 Load Balancing Interface Setting Figure 7 shows an example of binding the Session Initiation Protocol (SIP) to the WAN1 interface. SIP_UDP & SIP_TCP services are created under Service Management. Figure 7 Protocol Binding Step 5 Click the Config icon for WAN2 and repeat Step 3 and Step 4 for the second WAN interface. To set an additional failover detection method, select the appropriate checkbox and enter the public IP address associated with each host. Enabling WAN Load Balancing Page 4

5 Verifying Load Balancing Status Step 1 Go to Log > System Statistics and verify that the WAN1 and WAN2 interfaces both show Connect status (Figure 8). Step 2 From different hosts on the LAN, open a number of Internet connections. The counters for the Received Packets, Received Bytes, Sent Packets, and Sent Bytes should increment for both interfaces. Figure 8 System Statistics Step 4 Manually disconnect each WAN connection and verify that failover has occurred by going to Log > System Log and search for log entries describing the event (Figure 9). Figure 9 System Log Step 3 From different clients on the LAN, enter the tracert (Windows) or traceroute (Linux, Unix, or MacOS) commands for a public web site or host and verify that the route path utilizes both WAN connections. Cisco and the Cisco Logo are trademarks of Cisco Systems, Inc. and/or its affiliates in the U.S. and other countries. A listing of Cisco's trademarks can be found at Third-party trademarks mentioned are the property of their respective owners. The use of the word partner does not imply a partnership relationship between Cisco and any other company. (1005R) 2012 Cisco Systems, Inc. All rights reserved. Enabling WAN Load Balancing Page 5