• Hot Standby topology — VIP RHI is only supported on the ServerIron Router (R) platform. A Hot Standby topology is not supported for the R code base. Therefore, VIP RHI is not applicable to Hot Standby topologies. • Symmetric and sym-active topologies — In both symmetric and sym-active topologies, only the owner of
the VIP (the VIP in the ACTIVE state) will inject the route. In this topology, the ServerIron will withdraw the VIP route when a VIP transitions from Active to Standby state. Similarly, the ServerIron will inject the VIP route when a VIP transitions from Standby to Active, if the VIP is healthy at the time of the transition.
Configuration Considerations
Before you enable RHI, consider the following three issues:
• Static route redistribution — It is required to redistribute the host route for the VIP into OSPF. To enable redistribution of static routes, enter commands such as the following:
ServerIronA(config)# router ospf
ServerIronA(config-ospf-router)# area 0
ServerIronA(config-ospf-router)# redistribution static
Syntax: [no] redistribution static
• Virtual server constraints — Only a single virtual server with VIP RHI enabled should be associated with the subnet for an interface. For example, if you enable VIP RHI for a virtual server 1.1.1.101 and the
associated interface has an IP address 1.1.1.106/24, do not enable VIP RHI on any other virtual server in the subnet prefix 1.1.1.0/24. User should not configure two VIPs in the same subnet prefix with VIP RHI enabled for these two virtual servers.
• Disabling network route advertisement for an interface associated with VIP RHI — The ip dont- advertise command configures the ServerIron to block advertisement of the network on the interface. If you do not block advertisement of the network, the ServerIron will advertise a route to the network containing the VIP even if the VIP itself is unavailable. After you enter the ip dont-advertise command, the ServerIron advertises only a host route to the VIP address. Thus, if the VIP is not healthy, the ServerIron will remove the static host route for the VIP address and also not advertise a network route for the network containing the VIP address.
ServerIronA(config)# interface ethernet 4/15
ServerIronA(config-if-4/15)# ip address 10.1.1.99 255.255.255.0 ServerIronA(config-if-4/15)# ip dont-advertise 10.1.1.99 255.255.255.0
ServerIronA(config-if-4/15)# exit
Syntax: ip dont-advertise <ip-addr> <mask> I <ip-addr>/<mask-bits>
Enabling or Disabling VIP RHI
The ServerIron can enable VIP RHI globally or at the VIP sublevel.
To enable VIP RHI feature globally for all VIPs, enter commands such as the following:
SLB-ServerIron#con t
SLB-ServerIron(config)#server global-advertise-vip-route
Syntax: [no] server global-advertise-vip-route
To enable VIP RHI for an individual virtual server, enter commands such as the following:
SLB-ServerIron#con t
SLB-ServerIron(config)#server virtual vs1
SLB-ServerIron(config-vs-vs1#advertise-vip-route
Syntax: [no] advertise-vip-route
To disable VIP RHI for an individual virtual server, enter commands such as the following:
SLB-ServerIron#con t
SLB-ServerIron(config)#server virtual vs1
SLB-ServerIron(config-vs-vs1# disable-advertise-vip-route SLB-ServerIron(config-vs-vs1)#end
Syntax: [no] disable-advertise-vip-route
This command is useful if you need to enable VIP RHI globally and disable it for a few virtual servers.
Defining the Health of a VIP Port
There are two options for defining VIP port health:
• By default, a VIP port will be considered healthy as long as there is at least one healthy real server port bound to it.
• You can define the percentage of bound real server ports that should be healthy in order to consider the VIP port healthy.
To define the percentage of bound real server ports that must be healthy to consider a VIP port healthy, enter commands such as the following:
ServerIronA#con t
ServerIronA(config)# server rhi-active-bindings-threshold 20
Syntax: [no] server rhi-active-bindings-threshold <percent> A valid range for <percent> is 1-100.
If the <percent> parameter is not set, the percentage is 0. In this case, the default method will be used to determine the health of the VIP port. For example, a VIP port will be considered healthy as long as there is at least one healthy real server port bound to it.
As another example, consider a virtual server 1.1.1.101 with port http configured. This port http of the virtual server is bound to port http of real server 1.1.1.15 and port http of real server 1.1.1.44. If you have not configured any active bindings threshold percentage, then port http of VIP 1.1.1.101 will be considered healthy as long as at least one of the two bound real server ports is healthy.
If you configure an active bindings threshold percentage of 100, then this setting requires all bound real server ports for the VIP port to be healthy, in order to consider the VIP port as healthy. If real server port http for real
server 1.1.1.15 goes down, then VIP port http is no longer considered healthy because only 50% of the bound real server ports are healthy. The configuration in this example requires 100% of the bound real server ports to be up in order to consider the VIP port as healthy.