Document ID: 5217
Updated: Feb 10, 2006
Contents
Introduction
The Content Switching Module (CSM) provides high-performance Server Load Balancing (SLB) between network devices and server farms based on Layer 4 through 7 information packets. Server farms that are represented as virtual servers can improve scalability and availability of services for your network. You can add new servers and remove failed or existing servers at any time without affecting the virtual server's availability.
Clients connect to the CSM by supplying the virtual IP (VIP) address of the virtual server. When a client initiates a connection to the virtual server, the CSM chooses a real server (a physical device that is assigned to a server farm) for the connection based on configured load-balancing algorithms and policies (access rules). Policies manage traffic by defining where to send client requests for information.
Before You Begin
Conventions
For more information on document conventions, see the Cisco Technical Tips Conventions.
Prerequisites
There are no specific prerequisites for this document.
Components Used
This configuration can be used with any software and hardware versions that support the CSM.
Background Theory
Clients and servers communicate through the CSM using either Layer 2 or Layer 3 technology in a specific VLAN configuration. Clients connect to the client side VLAN and servers connect to the server side VLAN. Servers and clients can exist on different subnets. Servers can also be located more than one hop away and connect to the server-side VLAN through routers. A client sends a request to one of the module's VIP addresses. The CSM forwards this request to a server that can respond to the request. The server then forwards the response to the CSM, and the CSM forwards the response to the client.
When the client-side and server-side VLANs are on the same subnets, you can configure the CSM in single subnet (bridge) mode. This document describes single subnet (bridge) mode.
When the client-side and server-side VLANs are on different subnets, you can configure the CSM to operate in a secure (router) mode. For more information, refer to Configuring Secure (Router) Mode on the CSM.
Configure
Network Diagram
The following diagram illustrates different VLANs and different subnets.
Configurations
Complete these steps:
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Create the client and server VLAN on the MSFC.
cat#conf t cat(config)#vlan 100 cat(config-vlan)#exit cat(config)#vlan 200 cat(config-vlan)#
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Configure physical interfaces that connects the client (uplink) to the corresponding VLAN.
cat(config)#inter fastEthernet 2/1 cat(config-if)#switchport cat(config-if)#switchport access vlan 100 cat(config-if)#no shut
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Configure physical interfaces that connects the servers to the corresponding VLAN.
cat(config)#inter fastEthernet 2/3 cat(config-if)#switchport cat(config-if)#switchport access vlan 200 cat(config-if)#no shutdown cat(config)#inter fastEthernet 2/4 cat(config-if)#switchport cat(config-if)#switchport access vlan 200 cat(config-if)#no shutdown
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Configure the CSM.
cat(config)#module csm 3 cat(config-module-csm)#
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Create the client-side VLAN and gateway.
cat(config-module-csm)#vlan 100 client cat(config-slb-vlan-client)#ip address 172.17.63.217 255.255.255.192 cat(config-slb-vlan-client)#gateway 172.17.63.214 cat(config-slb-vlan-client)#
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Create the server-side VLAN.
cat(config-module-csm)#vlan 200 server cat(config-slb-vlan-server)#ip address 172.17.63.217 255.255.255.192
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Create the server farm.
cat(config-module-csm)#serverfarm wwwfarm cat(config-slb-sfarm)#real 172.17.63.215 cat(config-slb-real)#inservice cat(config-slb-real)#real 172.17.63.216 cat(config-slb-real)#inservice
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Create Vserver and associate server farm.
cat(config-module-csm)#vserver server cat(config-slb-vserver)#virtual 172.17.63.241 tcp www cat(config-slb-vserver)#serverfarm wwwfarm cat(config-slb-vserver)#inservice
This is a sample configuration of SLB using the Cisco Catalyst 6500 and the CSM.
| CSM (WS-X6066-SLB-APC) Running Config |
|---|
Building configuration... Current configuration : 3863 bytes ! version 12.1 service timestamps debug uptime service timestamps log uptime no service password-encryption ! hostname cat ! boot system flash sup-bootflash:c6sup11-jsv-mz.121-11b.E ! redundancy main-cpu auto-sync standard ip subnet-zero ! mls qos statistics-export interval 300 mls qos statistics-export delimiter | ! !--- CSM located in slot 3. Module running as Active. ! module ContentSwitchingModule 3 ! !--- Client side CSM VLAN 100 !--- Gateway pointing to the MSFC. ! vlan 100 client ip address 172.17.63.217 255.255.255.192 gateway 172.17.63.214 ! !--- Server side CSM VLAN 200. ! vlan 200 server ip address 172.17.63.217 255.255.255.192 ! !--- Server farm configuration. ! serverfarm WWWFARM nat server no nat client real 172.17.63.215 inservice real 172.17.63.216 inservice ! !--- VServer configuration. ! vserver SERVER virtual 172.17.63.241 tcp www serverfarm WWWFARM persistent rebalance inservice ! interface GigabitEthernet1/1 no ip address shutdown ! interface GigabitEthernet1/2 no ip address shutdown ! !--- Connection to upstream device. ! interface FastEthernet2/1 switchport switchport access vlan 100 switchport mode access no ip address ! interface FastEthernet2/2 no ip address shutdown ! !--- Connection to Web servers. ! interface FastEthernet2/3 switchport switchport access vlan 200 switchport mode access no ip address ! interface FastEthernet2/4 switchport switchport access vlan 200 switchport mode access no ip address ! interface FastEthernet2/5 no ip address shutdown ! !--- MSFC VLAN 100. ! interface Vlan100 ip address 172.17.63.214 255.255.255.192 ! ip classless ip route 0.0.0.0 0.0.0.0 172.17.63.193 no ip http server ! ! line con 0 line vty 0 4 login ! end |
Verify (show Commands)
show module csm # status Command
The show module csm # status command displays the status of the SLB module. The module has to be online.
cat#show module csm 3 status SLB Module is online in slot 3. Configuration Download state: COMPLETE, SUCCESS
show module csm # vserver name word detail Command
The show module csm # vservers name word detail command displays detailed virtual server information. You also see the state of the virtual server and how many connections there are. This is the best command to use for getting virtual server information.
cat#show module csm 3 vservers name server detail SERVER, state = OPERATIONAL, v_index = 10 virtual = 172.17.63.241/32:80, TCP, service = NONE, advertise = FALSE idle = 3600, replicate csrp = none, vlan = ALL, pending = 30 max parse len = 600, persist rebalance = TRUE conns = 0, total conns = 4 Default policy: server farm = WWWFARM sticky: timer = 0, subnet = 0.0.0.0, group id = 0 Policy Tot Conn Client pkts Server pkts ------------------------------------------------------ (default) 4 56 56
show module csm # real detail Command
The show module csm # real detail command displays information for each real server, such as the server farm where each server resides, the servers' states, thresholds, and connections.
cat#show module csm 3 real detail 172.17.63.215, WWWFARM, state = OPERATIONAL conns = 0, maxconns = 4294967295, minconns = 0 weight = 8, weight(admin) = 8, metric = 0, remainder = 0 total conns established = 2, total conn failures = 2 172.17.63.216, WWWFARM, state = OPERATIONAL conns = 0, maxconns = 4294967295, minconns = 0 weight = 8, weight(admin) = 8, metric = 0, remainder = 0 total conns established = 2, total conn failures = 2 cat#show module csm 3 real detail
show module csm # serverfarm name word detail Command
The show module csm # serverfarms name word detail command displays the server farm information. This command shows the predictor used for load balancing. In this example, round robin, which is default, is being used.
cat#show module csm 3 serverfarms name wwwfarm detail WWWFARM, predictor = RoundRobin, nat = SERVER virtuals inservice: 1, reals = 2, bind id = 0, fail action = none inband health config: <none> retcode map = <none> Real servers: 172.17.63.215, weight = 8, OPERATIONAL, conns = 0 172.17.63.216, weight = 8, OPERATIONAL, conns = 0 Total connections = 0
show module csm # vlan detail Command
The show module csm # vlan detail command displays the VLAN information for the client and the server.
cat#show module csm 3 vlan detail vlan IP address IP mask type --------------------------------------------------- 100 172.17.63.217 255.255.255.192 CLIENT GATEWAYS 172.17.63.214 200 172.17.63.217 255.255.255.192 SERVER cat#
Troubleshoot
You should be able to ping the real server and CSM gateway from the Catalyst 6500 by issuing the ping or ping module csm # reals commands.
cat#ping module csm 3 reals IP address Reachable -------------------------- 172.17.63.215 Yes 172.17.63.216 Yes cat#ping module csm 3 gateway IP address Reachable -------------------------- 172.17.63.214 Yes
Another good troubleshooting command is show module csm # arp. The CSM will learn the addresses. Make sure the gateway and reals are showing up.
cat#show module csm 3 arp Internet Address Physical Interface VLAN Type Status -------------------------------------------------------------------- 172.17.63.210 00-E0-B6-01-FA-49 100 LEARNED up(0 misses) 172.17.63.214 00-04-C0-C0-68-00 100 GATEWAY up(0 misses) 172.17.63.215 00-60-B0-87-DC-1A 200 REAL up(0 misses) 172.17.63.216 00-50-DA-BF-A1-7F 200 REAL up(0 misses) 172.17.63.217 00-30-F2-71-5D-2E 100/200 --SLB-- local 172.17.63.222 00-02-B9-45-A2-91 100 LEARNED up(0 misses) 172.17.63.241 00-30-F2-71-5D-2D 0 VSERVER local
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Refer to Cisco Technical Tips Conventions for information on conventions used in this document.