Brocade Virtual ADX Server Load Balancing Guide (Supporting ADX v03.1.00) - Manual (Page 140)

124 Brocade Virtual ADX Server Load Balancing Guide
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Miscellaneous options
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VIP route health injection
VIP route health injection (RHI) allows the Brocade Virtual ADX to advertise the availability of an
IPv4 or IPv6 VIP address (instead of a real host) throughout the network. Multiple Brocade Virtual
ADX devices with identical VIP addresses and services can exist throughout the network. This
feature allows the Brocade Virtual ADX VIP to be used in lieu of the same VIP on other Brocade
Virtual ADX devices if the VIP is no longer healthy on those devices. A VIP can also provide the
services because it is logically closer to the client systems than the other Brocade Virtual ADX
devices.
Specifically, you can configure a Brocade Virtual ADX to check the health of a VIP configured on it
and inject a VIP route into the network to force a preferred route to the VIP. VIP RHI checks the VIP
health and reports one of the following:
• VIP is healthy. If the VIP is healthy, the Brocade Virtual ADX injects a VIP route into its route
table for the VIP. The Brocade Virtual ADX then advertises the route to other routers using an
IGP routing protocol, such as OSPF or OSFPv3.
• VIP is not healthy. The Brocade Virtual ADX removes the IP route to the VIP from its route table.
As a result, the route is withdrawn by the routing protocols and is no longer used by upstream
routers. The upstream routers instead use another route to the same VIP.
NOTE
IPv4 uses the OSPF routing protocol. For IPV6, the OSPFv3 routing protocol is used.
Routers receiving client traffic for the VIP select the best route to the VIP. As a result, clients enjoy
fast response time regardless of their location, because their gateway routers use the best path to
the VIP. RHI also prevents client traffic from being routed to a VIP that is unavailable.
VIP route health injection advertises the host route to the VIP instead of a network route to the VIP's
subnet. This approach ensures that the clients' gateway routers receive a route to the IP address
only if that VIP is available.
Configuration of VIP RHI is the same in most cases for IPv4 and IPv6 addresses. It is clearly shown
in the following sections where there are differences in configuration commands or procedures.
NOTE
Disabling the real ports of all real servers using the server disable-all-real command causes the
respective virtual port's RHI state to become "Not Healthy", and the VIP host route will not be
advertised. In contrast, when you disable the virtual port of virtual server, the RHI state of a virtual
port will not become "Not Healthy", and the Brocade Virtual ADX will keep advertising the VIP host
route.
Injecting and deleting VIP route based on VIP health
The route for a VIP is injected when the VIP was previously unhealthy and is now deemed to be
healthy. Similarly, the route for the VIP is withdrawn if it was previously healthy and is now down.
The health of a VIP is based on the health of its VIP ports. The health of a VIP port is based on the
health of the real server ports bound to that VIP port.
You can configure any of the traditional health checks supported for the real servers. When a real
server port fails the health check, the Brocade Virtual ADX will check if the real server port is bound
to a VIP port whose VIP has the RHI feature enabled. If so, the Brocade Virtual ADX will determine
how many real server ports bound to the VIP port are healthy. If the amount is below the threshold
(if percentage threshold is configured) or if none of the other real server ports are healthy (if