Configuring the MNLB Forwarding
Agent

This chapter describes how to configure a Cisco router as an MNLB Forwarding Agent to operate in conjunction with a Cisco LocalDirector serving as Services Manager.

The components of the MNLD Feature Set for LocalDirector are described in Chapter 1, "Overview: Load Balancing with the MNLB Feature Set for LocalDirector".

Configuration Tasks

The following sections describe forwarding agent configuration tasks.

Enabling Cisco Express Forwarding

Cisco Express Forwarding (CEF) is advanced Layer 3 IP switching technology. CEF optimizes network performance and scalability for networks with large and dynamic traffic patterns, such as the Internet, on networks characterized by intensive Web-based applications, or interactive sessions.

To enable CEF, use the following command in global configuration mode:

Command Purpose

Router(config) ip cef distributed
Enables CEF.

Command	Purpose
Router(config) ip cef distributed	Enables CEF.

Note When you enable CEF globally, all interfaces that support CEF are enabled by default. If you want to turn off CEF on a particular interface, you can do so.

Enabling NetFlow Switching

We recommend that you enable NetFlow switching on all interfaces that will carry MNLB traffic, although it is not required. To enable NetFlow switching, use the following commands, beginning in global configuration mode:

Step Command Purpose

1 .

Router(config)# ip flow-cache feature-accelerate
Specify IP flow cache.

2 .

For VIP interfaces on Cisco 7500 series routers:
Router(config)# interface type slot/port-adapter/port

For all other routers:
Router(config)# interface type slot/port
Specifies the interface, and enters interface configuration mode.

3 .

Router(config-if)# ip route-cache flow
Enables flow switching on the interface.

Normally the size of the NetFlow cache will meet your needs. However, you can increase or decrease the number of entries maintained in the cache by using the following command in global configuration mode

Command Purpose

Router(config)# ip flow-cache entries number
Changes the number of entries maintained in the NetFlow cache. The number of entries can be 1024 to 524288. The default is 64536.

Command	Purpose
Router(config)# ip flow-cache entries number	Changes the number of entries maintained in the NetFlow cache. The number of entries can be 1024 to 524288. The default is 64536.

Enabling Multicast Routing

You must enable multicast routing on all interfaces to the services manager.

To enable multicast routing on all interfaces, use the following command in global configuration mode:

Command Purpose

Router(config)# ip multicast-routing
Enables multicast routing.

Command	Purpose
Router(config)# ip multicast-routing	Enables multicast routing.

To have the router join a multicast group and enable IGMP, use the following command in interface configuration mode:

Command Purpose

Router(config-if)# ip igmp join-group ¹ group-address²
Joins a multicast group.

¹This command must be configured on all interfaces that will listen for the services manager multicasts.
²The group address must match that configured within the services manager configuration.

Command	Purpose
Router(config-if)# ip igmp join-group ¹ group-address²	Joins a multicast group.

Configuring the Router as a Forwarding Agent

To configure the router as a forwarding agent, use the following commands, beginning in global configuration mode:

Step Command Purpose

1 .

Router(config)# ip casa control-address igmp-address
Specify the control address and IGMP address of the forwarding agent. The control address is a unique ip address used by forwarding-agent to send and receive control message between the service manager and the forwarding-agent. The recommended IGMP address is 224.0.1.2.

2 .

Router(config) forwarding-agent pool [initial-affinity] [max-affinity]
Adjusts the memory allocated for the forwarding agent's affinity pools. The default pool size is 5000 and there is no maximum pool size.

3 .

Router(config) forwarding-agent num [passwd [timeout]]
Specify the port number.

Note The forwarding agent IGMP address and port must match the IGMP address and port configured on the services manager and the ip igmp join-group command.

Monitoring the Forwarding Agent

To monitor the status of the forwarding agent, use the following commands in EXEC mode:

Command Purpose

Router# show ip casa affinities
Display the status of affinities.

Router# show ip casa oper
Display the operational status of the forwarding agent.

Router# show ip casa stats
Display statistical information about the forwarding agent.

Router# show ip casa wildcard
Display information about wildcard blocks.

Command	Purpose
Router# show ip casa affinities	Display the status of affinities.
Router# show ip casa oper	Display the operational status of the forwarding agent.
Router# show ip casa stats	Display statistical information about the forwarding agent.
Router# show ip casa wildcard	Display information about wildcard blocks.

Configuration Examples

This section provides the following configuration examples:

The network configured is shown in Figure 2.

Figure 2: MultiNode Load Balancing Network Configuration

Forwarding Agent Configuration for FA2

In the following example all disabled interfaces have been omitted to simplify the display.

FA2#wr t                 
Building configuration...
 
Current configuration:
!
version 12.0
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
service udp-small-servers
service tcp-small-servers
!
hostname FA2
!
!
microcode CIP flash slot0:cip26-5
microcode reload
ip subnet-zero
ip flow-cache feature-accelerate
no ip domain-lookup
!         
ip cef distributed
ip casa 206.10.20.34 224.0.1.2
 forwarding-agent 1637 
!
interface Ethernet0/0
 ip address 172.26.56.18 255.255.255.224
 no ip directed-broadcast
 ip route-cache flow
 ip igmp join-group 224.0.1.2
 no ip mroute-cache
!
interface Ethernet0/1
 ip address 172.26.56.37 255.255.255.224
 no ip directed-broadcast
!
!
!
router eigrp 777
 network 172.26.0.0
!
 
no ip classless
!
line con 0
 exec-timeout 0 0
 transport input none
line aux 0
line vty 0 4
 exec-timeout 0 0
login
!         
end

Services Manager Configuration for SM

SM# wr t
Building configuration...
: Saved
: LocalDirector 420 Version 3.0.0.127
syslog output 20.3
no syslog console
enable password 000000000000000000000000000000 encrypted
hostname SM
no shutdown ethernet 0
no shutdown ethernet 1
no shutdown ethernet 2
no shutdown ethernet 3
interface ethernet 0 auto
interface ethernet 1 auto
interface ethernet 2 auto
interface ethernet 3 auto
mtu 0 1500
mtu 1 1500
mtu 2 1500
mtu 3 1500
multiring all
no secure 0
no secure 1
no secure 2 
no secure 3
ping-allow 0
ping-allow 1
ping-allow 2
ping-allow 3
ip address 172.26.56.19 255.255.255.248
route 172.26.10.249 255.255.255.255 172.26.56.20 1
route 206.10.20.33 255.255.255.255 172.26.56.17 1
route 206.10.20.34 255.255.255.255 172.26.56.18 1
no rip passive
failover ip address 0.0.0.0
failover
password cisco
telnet 161.0.0.0 255.0.0.0
no snmp-server contact
no snmp-server location
casa service-manager port 1638
casa service-manager multicast-ttl 60
tftp-server 172.26.10.249 /tftpboot/LD 
virtual 172.26.56.13:0:0:tcp is
virtual 172.26.56.2:0:0:tcp is
redirection 172.26.56.13:0:0:tcp dispatched casa wildcard-ttl 60 fixed-ttl 60 igmp 224.0.1.2 port 1637
redirection 172.26.56.2:0:0:tcp dispatched casa wildcard-ttl 60 fixed-ttl 60 igmp 224.0.1.2 port 1637
real 172.26.56.34:0:0:tcp is
real 172.26.56.33:0:0:tcp is
real 172.26.56.6:0:0:tcp is
real 172.26.56.10:0:0:tcp is
bind 172.26.56.13:0:0:tcp 172.26.56.33:0:0:tcp
bind 172.26.56.13:0:0:tcp 172.26.56.34:0:0:tcp
bind 172.26.56.2:0:0:tcp 172.26.56.10:0:0:tcp
bind 172.26.56.2:0:0:tcp 172.26.56.6:0:0:tcp
: end

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