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ADC
14.1 - Current Release 13.1 13.0 12.1
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Sandwich Environment

September 14, 2021
Contributed by: 
S C

A Citrix ADC deployment in a sandwich mode can load balance network traffic through firewalls in both directions: ingress (traffic entering the network from the outside, such as the internet) and egress (traffic leaving the network to the internet).

In this setup, a Citrix ADC is located on each side of a set of firewalls. The Citrix ADC placed between the firewalls and the Internet, called the external Citrix ADC that handles ingress traffic selects the best firewall, based on the configured method. The Citrix ADC between the firewalls and the private network, called the internal Citrix ADC tracks the firewall from which the initial packet for a session is received. It then makes sure that all subsequent packets for that session are sent to the same firewall.

The internal Citrix ADC can be configured as a regular traffic manager to load balance traffic across the private network servers. This configuration also allows traffic originating from the private network (egress) to be load balanced across the firewalls.

The following diagram shows the sandwich firewall load balancing environment.

Figure 1. Firewall Load Balancing (Sandwich)

Firewalls-sandwich

The service type ANY configures the Citrix ADC to accept all traffic.

To avail benefits related to HTTP and TCP, configure the service and virtual server with type HTTP or TCP. For FTP to work, configure the service with type FTP.

Configuring the External Citrix ADC in a Sandwich Environment

Perform the following tasks to configure the external Citrix ADC in a sandwich environment

  • Enable the load balancing feature.
  • Configure a wildcard service for each firewall.
  • Configure a monitor for each wildcard service.
  • Configure a wildcard virtual server for traffic coming from the Internet.
  • Configure the virtual server in MAC rewrite mode.
  • Bind services to the wildcard virtual server.
  • Save and Verify the Configuration.

Enable the load balancing feature

To enable load balancing by using the command line interface

At the command prompt, type the following command to enable load balancing and verify the configuration:

enable ns feature LB
show ns feature
<!--NeedCopy-->

Example:

> enable ns feature LoadBalancing
 Done
> show ns feature

        Feature                        Acronym              Status
        -------                        -------              ------
 1)     Web Logging                    WL                   OFF
 2)     Surge Protection               SP                   ON
 3)     Load Balancing                 LB                   ON
 .
 .
 .
 24)    NetScaler Push                 push                 OFF
 Done
<!--NeedCopy-->

To enable load balancing by using the configuration utility

Navigate to System > Settings and, in Configure Basic Features, select Load Balancing.

Configure a wildcard service for each firewall

To configure a wildcard service for each firewall by using the command line interface

At the command prompt, type:

add service <name> <serverName> ANY *
<!--NeedCopy-->

Example:

add service Service-HTTP-1 10.102.29.5 ANY *
<!--NeedCopy-->

To configure a wildcard service for each firewall by using the configuration utility

Navigate to Traffic Management > Load Balancing > Services and add a service. Specify ANY in the Protocol field and * in the Port field.

Configure a monitor for each wildcard service

A PING monitor is bound by default to the service. You need to configure a transparent monitor to monitor hosts on the trusted side through individual firewalls. You can then bind the transparent monitor to services. The default PING monitor monitors the connectivity only between the Citrix ADC appliance and the upstream device. The transparent monitor monitors all the devices existing in the path from the appliance to the device that owns the destination IP address specified in the monitor. If a transparent monitor is not configured and the status of the firewall is UP but one of the next hop devices from that firewall is down, the appliance includes the firewall while performing load balancing and forwards the packet to the firewall. However, the packet is not delivered to the final destination because one of the next hop devices is down. By binding a transparent monitor, if any of the devices (including the firewall) are down, the service is marked as DOWN and the firewall is not included when the appliance performs firewall load balancing.

Binding a transparent monitor overrides the PING monitor. To configure a PING monitor in addition to a transparent monitor, after you create and bind a transparent monitor, you need to bind a PING monitor to the service.

To configure a transparent monitor by using the command line interface

At the command prompt, type the following commands to configure a transparent monitor and verify the configuration:

add lb monitor <monitorName> <type> [-destIP <ip_addr|ipv6_addr|*>] [-transparent (YES | NO )]
bind lb monitor <monitorName> <serviceName>
<!--NeedCopy-->

Example:

add monitor monitor-HTTP-1 HTTP -destip 10.10.10.11 -transparent YES
bind monitor monitor-HTTP-1 fw-svc1
To bind a PING monitor, type the following command:
bind monitor PING fw-svc1
<!--NeedCopy-->

To create and bind a transparent monitor by using the configuration utility

Navigate to Traffic Management > Load Balancing > Monitors, and then create and bind a transparent monitor.

Configure a wildcard virtual server for traffic coming from the Internet

To configure a wildcard virtual server for traffic coming from the Internet by using the command line interface

At the command prompt, type:

add lb vserver <name> ANY * *
<!--NeedCopy-->

Example:

add lb vserver Vserver-LB-1 ANY * *
<!--NeedCopy-->

To configure a wildcard virtual server for traffic coming from the Internet by using the configuration utility

Navigate to Traffic Management > Load Balancing > Virtual Servers and create a wildcard virtual server. Specify ANY in the Protocol field and * in the Port field.

Configure the virtual server in MAC rewrite mode

To configure the virtual server in MAC rewrite mode by using the command line interface

At the command prompt, type:

set lb vserver <name>@ -m <RedirectionMode>
<!--NeedCopy-->

Example:

set lb vserver Vserver-LB-1 -m MAC
<!--NeedCopy-->

To configure the virtual server in MAC rewrite mode by using the configuration utility

  1. Navigate to Traffic Management > Load Balancing > Virtual Servers, and select the virtual server for which you want to configure the redirection mode (for example, Vserver-LB-1).
  2. Edit the Basic Settings section, and click more.
  3. From the Redirection Mode drop-down list, select MAC Based.

Bind services to the wildcard virtual server

To bind a service to the wildcard virtual server by using the command line interface

At the command prompt, type:

bind lb vserver <name> <serviceName>
<!--NeedCopy-->

Example:

bind lb vserver Vserver-LB-1 Service-HTTP-1
<!--NeedCopy-->

To bind a service to the wildcard virtual server by using the configuration utility

  1. Navigate to Traffic Management > Load Balancing > Virtual Servers and select the virtual server for which you want to bind the service.
  2. Click in the Services section and select a service to bind.

Save and Verify the Configuration

When you’ve finished the configuration tasks, be sure to save the configuration. Ensure that the settings are correct.

To save and verify the configuration by using the command line interface

At the command prompt, type the following commands to configure a transparent monitor and verify the configuration:

save ns config
show vserver
<!--NeedCopy-->

Example:

save config
sh lb vserver FWLBVIP1
FWLBVIP1 (*:*) - ANY    Type: ADDRESS
        State: UP
        Last state change was at Mon Jun 14 06:40:14 2010
        Time since last state change: 0 days, 00:00:11.240
        Effective State: UP  ARP:DISABLED
        Client Idle Timeout: 120 sec
        Down state flush: ENABLED
        Disable Primary Vserver On Down : DISABLED
        No. of Bound Services :  2 (Total)       2 (Active)
        Configured Method: SRCIPDESTIPHASH
        Mode: MAC
        Persistence: NONE
        Connection Failover: DISABLED

1) fw_svc_1 (10.102.29.251: *) - ANY State: UP  Weight: 1
2) fw_svc_2 (10.102.29.18: *) - ANY State: UP   Weight: 1
 Done
show service fw-svc1
        fw-svc1 (10.102.29.251:*) - ANY
        State: DOWN
        Last state change was at Thu Jul  8 10:04:50 2010
        Time since last state change: 0 days, 00:00:38.120
        Server Name: 10.102.29.251
        Server ID : 0   Monitor Threshold : 0
        Max Conn: 0     Max Req: 0      Max Bandwidth: 0 kbits
        Use Source IP: NO
        Client Keepalive(CKA): NO
        Access Down Service: NO
        TCP Buffering(TCPB): YES
        HTTP Compression(CMP): NO
        Idle timeout: Client: 120 sec   Server: 120 sec
        Client IP: DISABLED
        Cacheable: NO
        SC: OFF
        SP: OFF
        Down state flush: ENABLED

1)      Monitor Name: monitor-HTTP-1
                State: DOWN     Weight: 1
                Probes: 5       Failed [Total: 5 Current: 5]
                Last response: Failure - Time out during TCP connection establishment stage
                Response Time: 2000.0 millisec
2)      Monitor Name: ping
                State: UP       Weight: 1
                Probes: 3       Failed [Total: 0 Current: 0]
                Last response: Success - ICMP echo reply received.
                Response Time: 1.415 millisec
 Done
<!--NeedCopy-->

Configuring the Internal Citrix ADC in a Sandwich Environment

Perform the following tasks to configure the internal Citrix ADC in a sandwich environment

For traffic from the server (egress)

  • Enable the load balancing feature.
  • Configure a wildcard service for each firewall.
  • Configure a monitor for each wildcard service.
  • Configure a wildcard virtual server to load balance the traffic sent to the firewalls.
  • Configure the virtual server in MAC rewrite mode.
  • Bind firewall services to the wildcard virtual server.

For traffic across private network servers

  • Configure a service for each virtual server.
  • Configure a monitor for each service.
  • Configure an HTTP virtual server to balance traffic sent to the servers.
  • Bind HTTP services to the HTTP virtual server.
  • Save and Verify the Configuration.

Enable the load balancing feature

You can configure load balancing entities such as services and virtual servers when the load balancing feature is disabled. But they will not function until you enable the feature.

To enable load balancing by using the command line interface

At the command prompt, type the following command to enable load balancing and verify the configuration:

enable ns feature LB
show ns feature
<!--NeedCopy-->

Example:

> enable ns feature LoadBalancing
 Done
> show ns feature

        Feature                        Acronym              Status
        -------                        -------              ------
 1)     Web Logging                    WL                   OFF
 2)     Surge Protection               SP                   ON
 3)     Load Balancing                 LB                   ON
 .
 .
 .
 24)    NetScaler Push                 push                 OFF
 Done
<!--NeedCopy-->

To enable load balancing by using the configuration utility

Navigate to System > Settings and, in Configure Basic Features, select Load Balancing.

Configure a wildcard service for each firewall

To configure a wildcard service for each firewall by using the command line interface

At the command prompt, type:

add service <name> <serverName> ANY *
<!--NeedCopy-->

Example:

add service Service-HTTP-1 10.102.29.5 ANY *
<!--NeedCopy-->

To configure a wildcard service for each firewall by using the configuration utility

Navigate to Traffic Management > Load Balancing > Services and add a service. Specify ANY in the Protocol field and * in the Port field.

Configure a monitor for each wildcard service

A PING monitor is bound by default to the service. You need to configure a transparent monitor to monitor hosts on the trusted side through individual firewalls. You can then bind the transparent monitor to services. The default PING monitor monitors the connectivity only between the Citrix ADC appliance and the upstream device. The transparent monitor monitors all the devices existing in the path from the appliance to the device that owns the destination IP address specified in the monitor. If a transparent monitor is not configured and the status of the firewall is UP but one of the next hop devices from that firewall is down, the appliance includes the firewall while performing load balancing and forwards the packet to the firewall. However, the packet is not delivered to the final destination because one of the next hop devices is down. By binding a transparent monitor, if any of the devices (including the firewall) are down, the service is marked as DOWN and the firewall is not included when the appliance performs firewall load balancing.

Binding a transparent monitor overrides the PING monitor. To configure a PING monitor in addition to a transparent monitor, after you create and bind a transparent monitor, you need to bind a PING monitor to the service.

To configure a transparent monitor by using the command line interface

At the command prompt, type the following commands to configure a transparent monitor and verify the configuration:

add lb monitor <monitorName> <type> [-destIP <ip_addr|ipv6_addr|*>] [-transparent (YES | NO )]
bind lb monitor <monitorName> <serviceName>
<!--NeedCopy-->

Example:

add monitor monitor-HTTP-1 HTTP -destip 10.10.10.11 -transparent YES
bind monitor monitor-HTTP-1 fw-svc1
<!--NeedCopy-->

To create and bind a transparent monitor by using the configuration utility

  1. Navigate to Traffic Management > Load Balancing > Monitors and create a monitor.
  2. In the Create Monitor dialog box, enter the required parameters, and select Transparent.

Configure a wildcard virtual server to load balance the traffic sent to the firewalls

To configure a wildcard virtual server to load balance the traffic sent to the firewalls by using the command line interface

At the command prompt, type:

add lb vserver <name> ANY * *
<!--NeedCopy-->

Example:

add lb vserver Vserver-LB-1 ANY * *
<!--NeedCopy-->

To configure a wildcard virtual server for traffic coming from the Internet by using the configuration utility

  1. Navigate to Traffic Management > Load Balancing > Virtual Servers and create a wildcard virtual server.

  2. Specify ANY in the Protocol field and * in the Port field.

To configure a wildcard virtual server to load balance the traffic sent to the firewalls by using the configuration utility

  1. Navigate to Traffic Management > Load Balancing > Virtual Servers.
  2. In the details pane, click Add.
  3. In the Create Virtual Server (Load Balancing) dialog box, specify values for the following parameters as shown:
    • Name—name
  4. In Protocol, select ANY, and in IP Address and Port, select *.
  5. Click Create, and then click Close. The virtual server you created appears in the Load Balancing Virtual Servers pane.

Configure the virtual server in MAC rewrite mode

To configure the virtual server in MAC rewrite mode by using the command line interface

At the command prompt, type:

set lb vserver <name>@ -m <RedirectionMode>
<!--NeedCopy-->

Example:

set lb vserver Vserver-LB-1 -m MAC
<!--NeedCopy-->

To configure the virtual server in MAC rewrite mode by using the configuration utility

  1. Navigate to Traffic Management > Load Balancing > Virtual Servers, and select the virtual server for which you want to configure the redirection mode (for example, Vserver-LB-1).
  2. Edit the Basic Settings section, and click more.
  3. From the Redirection Mode drop-down list, select MAC Based.

Bind firewall services to the wildcard virtual server

To bind firewall services to the wildcard virtual server by using the command line interface

At the command prompt, type:

bind lb vserver <name> <serviceName>
<!--NeedCopy-->

Example:

bind lb vserver Vserver-LB-1 Service-HTTP-1
<!--NeedCopy-->

To bind firewall services to the wildcard virtual server by using the configuration utility

  1. Navigate to Traffic Management > Load Balancing > Virtual Servers, and select a virtual server.
  2. Click in the Service section, and select a service to bind.

Note: You can bind a service to multiple virtual servers.

Configure a service for each virtual server

To configure a service for each virtual server by using the command line interface

At the command prompt, type:

add service <name> <serverName> HTTP <port>
<!--NeedCopy-->

Example:

add service Service-HTTP-1 10.102.29.5 HTTP 80
<!--NeedCopy-->

To configure a service for each virtual server by using the configuration utility

  1. Navigate to Traffic Management > Load Balancing > Services, and configure a service for each virtual server.
  2. Specify HTTP in the Protocol field, and select HTTP under Available Monitors.

To configure a service for each virtual server by using the configuration utility

  1. Navigate to Traffic Management > Load Balancing > Services.
  2. In the details pane, click Add.
  3. In the Create Service dialog box, specify values for the following parameters as shown:
    • Service Name—name
    • Server—serverName
    • Port—port
  4. In Protocol, specify HTTP. Under Available Monitors, select HTTP.
  5. Click Create, and then click Close. The service you created appears in the Services pane.

Configure a monitor for each service

To bind a monitor to a service by using the command line interface

At the command prompt, type:

bind lb monitor <monitorName> <ServiceName>
<!--NeedCopy-->

Example:

bind mon monitor-HTTP-1 Service-HTTP-1
<!--NeedCopy-->

To bind a monitor to a service by using the configuration utility

Navigate to Traffic Management > Load Balancing > Services, double-click a service, and add a monitor.

Configure an HTTP virtual server to balance traffic sent to the servers

To configure an HTTP virtual server to balance traffic sent to the servers by using the command line interface

At the command prompt, type:

add lb vserver <name> HTTP <ip> <port>
<!--NeedCopy-->

Example:

add lb vserver Vserver-LB-1 HTTP 10.102.29.60 80
<!--NeedCopy-->

To configure an HTTP virtual server to balance traffic sent to the servers by using the configuration utility

  1. Navigate to Traffic Management > Load Balancing > Virtual Services, and configure an HTTP virtual server.
  2. Specify HTTP in the Protocol field.

To configure an HTTP virtual server to balance traffic sent to the servers by using the configuration utility

  1. Navigate to Traffic Management > Load Balancing > Virtual Servers.
  2. In the details pane, click Add.
  3. In the Create Virtual Server (Load Balancing) dialog box, specify values for the following parameters as shown:
    • Name—name
    • IP Address—IP Address Note: If the virtual server uses IPv6, select the IPv6 check box and enter the address in IPv6 format (for example, 1000:0000:0000:0000:0005:0600:700a:888b).
    • Port—port
  4. Under Protocol, select HTTP.
  5. Click Create, and then click Close. The virtual server you created appears in the Load Balancing Virtual Servers pane.

Save and Verify the Configuration

When you’ve finished the configuration tasks, be sure to save the configuration. You should also check to make sure that the settings are correct.

To save and verify the configuration by using the command line interface

At the command prompt, type the following commands to configure a transparent monitor and verify the configuration:

  • save ns config
  • show vserver

Example:

save config
show lb vserver FWLBVIP2
        FWLBVIP2 (*:*) - ANY    Type: ADDRESS
        State: UP
        Last state change was at Mon Jun 14 07:22:54 2010
        Time since last state change: 0 days, 00:00:32.760
        Effective State: UP
        Client Idle Timeout: 120 sec
        Down state flush: ENABLED
        Disable Primary Vserver On Down : DISABLED
        No. of Bound Services :  2 (Total)       2 (Active)
        Configured Method: LEASTCONNECTION
        Current Method: Round Robin, Reason: A new service is bound
        Mode: MAC
        Persistence: NONE
        Connection Failover: DISABLED

1) fw-int-svc1 (10.102.29.5: *) - ANY State: UP Weight: 1
2) fw-int-svc2 (10.102.29.9: *) - ANY State: UP Weight: 1
 Done
show service fw-int-svc1
        fw-int-svc1 (10.102.29.5:*) - ANY
        State: DOWN
        Last state change was at Thu Jul  8 14:44:51 2010
        Time since last state change: 0 days, 00:01:50.240
        Server Name: 10.102.29.5
        Server ID : 0   Monitor Threshold : 0
        Max Conn: 0     Max Req: 0      Max Bandwidth: 0 kbits
        Use Source IP: NO
        Client Keepalive(CKA): NO
        Access Down Service: NO
        TCP Buffering(TCPB): NO
        HTTP Compression(CMP): NO
        Idle timeout: Client: 120 sec   Server: 120 sec
        Client IP: DISABLED
        Cacheable: NO
        SC: OFF
        SP: OFF
        Down state flush: ENABLED

1)      Monitor Name: monitor-HTTP-1
                State: DOWN     Weight: 1
                Probes: 9       Failed [Total: 9 Current: 9]
                Last response: Failure - Time out during TCP connection establishment stage
                Response Time: 2000.0 millisec
2)      Monitor Name: ping
                State: UP       Weight: 1
                Probes: 3       Failed [Total: 0 Current: 0]
                Last response: Success - ICMP echo reply received.
                Response Time: 1.275 millisec
 Done
<!--NeedCopy-->

To save and verify the configuration by using the configuration utility

  1. In the Details pane, click Save.
  2. In the Save Config dialog box, click Yes.
  3. Navigate to Traffic Management > Load Balancing > Virtual Servers.
  4. In the Details pane, select the virtual server that you created in step 5.
  5. Verify that the settings displayed in the Details pane are correct.
  6. Navigate to Traffic Management > Load Balancing > Services.
  7. In the Details pane, select the services that you created in step 5.
  8. Verify that the settings displayed in the Details pane are correct.

Monitoring a Firewall Load Balancing Set up in a Sandwich Environment

After the configuration is up and running, you should view the statistics for each service and virtual server to check for possible problems.

Viewing the Statistics of a Virtual Server

To evaluate the performance of virtual servers or to troubleshoot problems, you can display details of the virtual servers configured on the Citrix ADC appliance. You can display a summary of statistics for all the virtual servers, or you can specify the name of a virtual server to display the statistics only for that virtual server. You can display the following details:

  • Name
  • IP address
  • Port
  • Protocol
  • State of the virtual server
  • Rate of requests received
  • Rate of hits

To display virtual server statistics by using the command line interface

To display a summary of the statistics for all the virtual servers currently configured on the Citrix ADC, or for a single virtual server, at the command prompt, type:

stat lb vserver [-detail] [<name>]
<!--NeedCopy-->

Example:

>stat lb vserver -detail
Virtual Server(s) Summary
                      vsvrIP  port     Protocol        State    Req/s   Hits/s
One                        *    80         HTTP           UP      5/s      0/s
Two                        *     0          TCP         DOWN      0/s      0/s
Three                      *  2598          TCP         DOWN      0/s      0/s
dnsVirtualNS    10.102.29.90    53          DNS         DOWN      0/s      0/s
BRVSERV            10.10.1.1    80         HTTP         DOWN      0/s      0/s
LBVIP           10.102.29.66    80         HTTP           UP      0/s      0/s
 Done

<!--NeedCopy-->

To display virtual server statistics by using the configuration utility

  1. Navigate to Traffic Management > Load Balancing > Virtual Servers > Statistics.
  2. If you want to display the statistics for only one virtual server, in the details pane, select the virtual server, and click Statistics.

Viewing the Statistics of a Service

You can view the rate of requests, responses, request bytes, response bytes, current client connections, requests in surge queue, current server connections, and so forth using the service statistics.

To view the statistics of a service by using the command line interface

At the command prompt, type:

stat service <name>
<!--NeedCopy-->

Example:

stat service Service-HTTP-1
<!--NeedCopy-->

To view the statistics of a service by using the configuration utility

  1. Navigate to Traffic Management > Load Balancing > Services > Statistics.
  2. If you want to display the statistics for only one service, select the service, and click Statistics.
Sandwich Environment
September 14, 2021
Contributed by: 
S C
September 14, 2021
Contributed by: 
S C

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