3

On the right side you can see 2 multilayer switches. With those two switches I want to enable HSRP for each WAN router.

What has to be done in order to accomplish this? and why?

[enter image description here

  • Nothing, because HSRP is for host-facing interfaces. Between routers you use a dynamic routing protocol (OSPF, EIGRP...), not HSRP. – JFL Feb 19 '18 at 14:32
  • @JFL and if I want to use HSRP I have to those interfaces on the L3-Switch to an access-link in order to create own VLANs vor each WAN router. Because then I am able to create one SVI for each router and can use HSRP. right? – watchme Feb 19 '18 at 22:01
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The picture clearly shows a routing protocol between the routers and the 3560 switches, but for clarification, HSRP is configured as follows:

The standby ip interface configuration command activates HSRP on the configured interface. If an IP address is specified, that address is used as the designated address for the Hot Standby group. If no IP address is specified, the address is learned through the standby function. You must configure at least one Layer 3 port on the LAN with the designated address. Configuring an IP address always overrides another designated address currently in use.

When the standby ip command is enabled on an interface and proxy ARP is enabled, if the interface’s Hot Standby state is active, proxy ARP requests are answered using the Hot Standby group MAC address. If the interface is in a different state, proxy ARP responses are suppressed.

Example:

enter image description here

The above shows a segment of a network configured for HSRP. Each router is configured with the MAC address and IP network address of the virtual router. Instead of configuring hosts on the network with the IP address of Router A, you configure them with the IP address of the virtual router as their default router. When Host C sends packets to Host B, it sends them to the MAC address of the virtual router.

If for any reason, Router A stops transferring packets, Router B responds to the virtual IP address and virtual MAC address and becomes the active router, assuming the active router duties. Host C continues to use the IP address of the virtual router to address packets destined for Host B, which Router B now receives and sends to Host B.

Until Router A resumes operation, HSRP allows Router B to provide uninterrupted service to users on Host C’s segment that need to communicate with users on Host B’s segment and also continues to perform its normal function of handling packets between the Host A segment and Host B.

Configuration for example:

RouterA# configure terminal
RouterA(config)# interface Vlan2
RouterA(config-if)# ip address 172.20.128.1 255.255.255.0
RouterA(config-if)# standby 1 ip 172.20.128.3
RouterA(config-if)# standby 1 priority 105
RouterA(config-if)# standby 1 preempt
RouterA(config-if)# end


RouterB# configure terminal
RouterB(config)# interface Vlan2
RouterB(config-if)# ip address 172.20.128.2 255.255.255.0
RouterB(config-if)# standby 1 ip 172.20.128.3
RouterB(config-if)# standby 1 preempt
RouterB(config-if)# end


HostC:
IP: 172.20.128.32
Subnet: 255.255.255.0
Gateway: 172.20.128.3
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  • Thank you, this an the other answer gave me exactly the information I needed! – watchme Feb 19 '18 at 14:52
  • No problem! Glad i could help you. – user36472 Feb 19 '18 at 14:53

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