Precautions, Components | Cisco Systems 3745, 831, 3725, 1751

∙This configuration guide uses private addresses only. When using private addresses and connecting to the Internet, an appropriate Network Address Translation (NAT) or Port Address Translation (PAT) configuration is required to provide connectivity over the Internet.

∙The ODR provides a default route only to the spoke, the configuration support hub and spoke topology; no split tunneling

PRECAUTIONS

Before configurations are made to any router, confirm the following:

∙The spoke router can reach the DMVPN hub directly over the Internet.

∙The DMVPN hub is configured and operational.

COMPONENTS

∙Cisco IOS Software Release 12.3(11)T3(fc2)

∙Cisco 831, 1751, 3725 and 3745 Routers

Figure 1 illustrates the network for the sample configuration.

The information presented in this document was created from devices in a specific lab environment. All devices started with a cleared (default) configuration. It is imperative to understand the potential impact of any command before implementing it in a live network.

This configuration uses two DMVPN hub routers. Each hub router is configured with a separate DMVPN tunnel network (192.168.1.0/24 and 192.168.2.0/24). The first tunnel on the spokes is used for direct connectivity through the first DMVPN hub and the second tunnel on the spokes is used for the second DMVPN hub. During normal operations with dual hubs, the spoke router load-balances the traffic between both hubs. Connectivity between the spoke routers is provided through the hub routers in hub and spoke topology. During a failure, the ODR protocol will time out the failed path, and it will use one active path to the active hub router.

Using ODR, the hub router learns about the remote networks using the CDP protocol. By default, CDP is disabled on the tunnel interface. To allow the hub and spoke routers to exchange routes, CDP must be enabled on the tunnel interface. ODR allows for push of the default route from the hub router to the spoke router. The hub router configuration only accepts spoke routers network ranges defined with the “ distribute-list 101 in” in order to prevent the risk of learning the DHCP public network of spoke router from the tunnel interface with ODR. All routing protocols should be disabled on the spoke routers to activate ODR on the spoke routers.

By default, CDP sends updates every sixty seconds. This update interval may not be frequent enough to provide faster re-convergence of IP routes on the hub router side of the network. A quicker re-convergence rate may be necessary if the spoke connects to one of several hub routers via asynchronous interfaces such as modem lines.

ODR expects to receive periodic CDP updates, which contain IP prefix information. When ODR fails to receive updates for routes that it has installed in the routing table, these ODR routes are first marked invalid and eventually removed from the routing table (by default, ODR routes are marked invalid after 180 seconds and are removed from the routing table after 240 seconds). These defaults are based on the default CDP update interval. Configuration changes made to either the CDP or ODR timers should be reflected through changes made to both.

For additional information about configuring ODR timers, refer to: http://www.cisco.com/en/US/products/sw/iosswrel/ps1835/products_configuration_guide_chapter09186a00800ca75f.html#1000989

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1751, 3745, 3725, 831 specifications

Cisco Systems has established itself as a leader in networking and communications technologies, providing an extensive range of products that cater to various needs in the digital landscape. Among its noteworthy offerings are the Cisco 1751, 831, 3745, and 3725 routers, each designed to address specific requirements within business environments, from small offices to larger enterprises.

The Cisco 1751 is a modular router that delivers high-performance routing capabilities for small to medium-sized businesses. It features two slots for WAN interface cards, which provide flexibility in connectivity options. With support for both digital and analog connections, the 1751 is ideal for organizations looking to integrate voice and data services over a single network. Furthermore, it comes equipped with Cisco's IOS software, offering robust security features and advanced routing protocols, ensuring reliable performance.

The Cisco 831 router is designed to provide small branch offices with a reliable and secure Internet connection. This device incorporates an integrated firewall, VPN support, and advanced security features, making it an excellent choice for businesses that prioritize data protection. The 831 supports various WAN technologies, including DSL and cable, empowering organizations to select the most suitable connectivity type for their operations.

On a larger scale, the Cisco 3745 router is tailored for medium to large enterprises seeking high-capacity routing solutions. With its high performance and support for numerous interfaces, the 3745 can manage substantial data traffic efficiently. Key features include integrated voice support, which allows for convergence of voice and data applications, and advanced QoS capabilities, ensuring that critical applications receive the necessary bandwidth and priority.

Lastly, the Cisco 3725 serves as another powerful option for organizations needing flexibility and performance. Similar to the 3745, it supports modular WAN interfaces and offers compatibility with various data and voice technologies. The 3725's enhanced memory and processing capabilities allow it to handle demanding applications, making it suitable for larger networks requiring reliable connectivity and security features.

In conclusion, Cisco Systems' 1751, 831, 3745, and 3725 routers are exceptional networking solutions tailored for different business sizes and demands. Each model boasts specific features designed to enhance performance, security, and scalability, thereby empowering organizations to optimize their digital infrastructures in an increasingly interconnected world.