Cisco Systems 78-11741-02 Configuring IOS SLB Dynamic Feedback Protocol, Configuring NAT, IPC-145

Configuring Server Load Balancing

IOS SLB Configuration Task List

Configuring IOS SLB Dynamic Feedback Protocol

To configure IOS SLB DFP, use the following commands beginning in global configuration mode:

	Command	Purpose
Step 1
	Router(config)# ip slb dfp [password password	Configures DFP and, optionally, sets a password
	[timeout]]	and initiates SLB DFP configuration mode.
Step 2
	Router(config-slb-dfp)# agent ip-address port [timeout	Configures a DFP agent.
	[retry-count [retry-interval]]]

Configuring NAT

To configure IOS SLB NAT mode for a specific server farm, use the following commands beginning in global configuration mode:

	Command	Purpose
Step 1
	Router(config)# ip slb serverfarm serverfarm-name	Adds a server farm definition to the IOS SLB
		configuration and initiates server farm
		configuration mode.
Step 2
	Router(config-slb-sfarm)# nat server	Configures server NAT.
Step 3
	Router(config-slb-sfarm)# real ip-address	Identifies a real server to the IOS SLB function
		and initiates real server configuration mode.

Implementing IOS SLB Stateless Backup

Stateless backup, based on the Hot Standby Router Protocol (HSRP), provides high network availability by routing IP flows from hosts on Ethernet networks without relying on the availability of any single Layer 3 switch. Stateless backup is particularly useful for hosts that do not support a router discovery protocol (such as the Intermediate System-to-Intermediate System [IS-IS] Interdomain Routing Protocol [IDRP]) and do not have the functionality to shift to a new Layer 3 switch when their selected Layer 3 switch reloads or loses power.

How IOS SLB Stateless Backup Works

A Layer 3 switch running HSRP detects a failure by sending and receiving multicast UDP hello packets. When the IOS SLB switch running HSRP detects that the designated active Layer 3 switch has failed, the selected backup Layer 3 switch assumes control of the HSRP group MAC and IP addresses. (You can also select a new standby Layer 3 switch at that time.) Both the primary and the backup Layer 3 switch must be on the same subnetwork.

The chosen MAC and IP addresses must be unique and must not conflict with any others on the same network segment. The MAC address is selected from a pool of Cisco MAC addresses. Configure the last byte of the MAC address by using the HSRP group number. When HSRP is running, it selects an active Layer 3 switch and instructs its device layer to listen on an additional (dummy) MAC address.

IOS SLB switching software supports HSRP over 10/100 Ethernet, Gigabit Ethernet, FEC, GEC, and Bridge Group Virtual Interface (BVI) connections.

Cisco IOS IP Configuration Guide

IPC-145