visionshaa.blogg.se - Router alley router on a stick

The packets will be sent continuously from the router to the destination IP in order to check reachability of the destination. The following commands will configure a Service Level Agreement (SLA) operation which will send ICMP ECHO packets to destination IP 1.1.1.100 from source interface Ethernet0/0 (which is the WAN interface of ROUTER1).

Configurationįirst configure the tracking mechanism on the active router. This means that if a destination IP stops responding to ICMP requests, then HSRP will trigger a failover condition and the standby router will take over and start passing traffic. In our example we will configure reachability tracking using SLA. HSRP supports different types of tracking, such as interface tracking, routing table tracking, reachability tracking etc. The limitation of the above though is that you can have only one ISP which must provide an Ethernet connectivity for the WAN links.Īnother important aspect of the configuration that we’ll implement is “reachability tracking”.

The network will provide a single IP address on the WAN side so that we can configure inbound traffic to reach internal servers (by configuring static NAT for example).

Provide redundancy on the two ISP links.

The network above can be implemented in a single building/data center, but can also be implemented in two separate buildings/data centers.īy extending the two LAN and WAN switches and connecting them with a network cable (usually fiber optic cable) you can easily extend the network in two different buildings or data centers.Īlso, by configuring HSRP on the WAN side, we can have two advantages: The two switches on the LAN side and the two switches on the WAN side will provide the required L2 connectivity for HSRP to run on both the LAN and WAN connections. Remember that for HSRP to work, we need to provide Layer2 connectivity between the routers. In our network above we will configure HSRP on both the LAN and the WAN interfaces of the two Routers. Here we have a network setup which is very useful in enterprises for providing ISP redundancy. Now configure a default gateway address of 10.10.10.3 for your LAN hosts. ! set priority to 100 to make it the standby router (this is the default value) ! increase its priority to 110 to make it active (default priority is 100) ! preempt allows the router to become the active router when its priority is higher ! enable HSRP group 1 and set the virtual address to 10.10.10.3 Let’s see an actual configuration below: Configuration This means that if the tracked interface of the active router fails, then HSRP will trigger a failover to the standby router. With HSRP, we can also track a specific interface. RTR-A will be configured as the Active HSRP router by setting a higher hsrp priority.

This address will serve as the default gateway address for all hosts on the LAN. Interface FE0/1 on RTR-A will have a physical IP address 10.10.10.1 and interface FE0/1 on RTR-B will have a physical IP address 10.10.10.2.Īn HSRP address 10.10.10.3 will be also configured on both routers. From the diagram above, HSRP will be running between interfaces FE0/1 on the two LAN routers. Let’s see a diagram below to explain the first network example case:įirst of all, HSRP must be configured between interfaces that have Layer2 connectivity between them. In this article we will discuss two different network scenarios where HSRP can be used to provide redundancy between two paths from an internal LAN network towards the outside world (WAN or Internet). No matter which router gateway is up and running (either the primary or the secondary), the virtual HSRP address will stay the same. Using HSRP, the two routers will have a physical IP address configured on their LAN-facing interface, but they will have also a Virtual (HSRP address) which will be used as the default gateway address for hosts on the LAN. With HSRP we can have two gateway routers, one active and one standby, which will provide resiliency regarding the default gateway address. If that single default gateway fails, then communication outside the LAN is not possible. In a Local Area Network (LAN), all hosts (PC, Servers etc) have a single default gateway address configured which is used to route packets outside the LAN. The standard router redundancy protocol which is used by other vendors is VRRP (Virtual Router Redundancy Protocol), however Cisco has created its own proprietary protocol (HSRP) which works very well on Cisco routers. HSRP (Hot Standby Router Protocol) is the Cisco proprietary protocol for providing redundancy in router networks.