Single Domain Using Layer 2 and Layer 3 Redundancy

The example shown in Single ESRP Domain Using Layer 2 and Layer 3 Redundancy uses four Extreme Networks devices as edge switches that perform Layer 2 switching for VLAN Sales.

The edge switches are dual-homed two switches that are configured to support ESRP domain esrp1. The ESRP switches perform Layer 2 switching and Layer 3 routing between the edge switches and the outside world. Each ESRP switch has the VLAN Sales configured using the identical IP address. The ESRP switches then connect to the routed enterprise normally, using the desired routing protocol (for example, RIP or OSPF).
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Single ESRP Domain Using Layer 2 and Layer 3 Redundancy

In this example, the ESRP master performs both Layer 2 switching and Layer 3 routing services for VLAN Sales. To prevent bridging loops in the VLAN, the ESRP slave performs no switching or routing for VLAN Sales while the ESRP master is operating.

There are four paths between each ESRP switch and the edge switches for VLAN Sales. All the paths are used to send ESRP packets, allowing for four redundant paths for communication. The edge switches, being ESRP-aware, allow traffic within the VLAN to failover quickly because these edge switches sense when a master/slave transition occurs and flush FDB entries associated with the uplinks to the ESRP-enabled switches.

This example assumes the following:
  • ESRP election algorithm used is the default for standard mode (ports > track > priority > mac).
  • The inter-router backbone is running OSPF, with other routed VLANs already properly configured. Similar commands would be used to configure a switch on a network running RIP.
  • Ports added to the VLAN have already been removed from VLAN default.
  • The same IP address is specified for all VLANs participating in ESRP.
  • The master is determined by the programmed MAC address of the switch because the number of active links for the VLAN and the priority are identical for both switches.

The following commands are used to configure both ESRP switches:

create vlan sales
configure vlan sales add ports 1:1-1:4
configure vlan sales ipaddress
enable ipforwarding
create esrp esrp1
configure esrp esrp1 domain-id 4096
configure esrp esrp1 add master sales
enable esrp esrp1
configure ospf add vlan sales area passive
configure ospf routerid
enable ospf