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Manual Chapter: Using Forward Error Correction with Network Access
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Using Forward Error Correction with Network Access

Overview: Using FEC on network access tunnels

Forward error correction (FEC) is a technique for controlling data transmission errors over unreliable or noisy communication channels. With FEC, the sender encodes messages with a little extra error-correcting code. FEC enables recovery of lost packets to avoid retransmission and increase throughput on lossy links. FEC is frequently used when retransmission is not possible or is costly.

In Access Policy Manager®, you can use FEC on network access tunnels. You can do this provided that you configure a network access resource for Datagram Transport Level Security (DTLS) and configure two virtual servers with the same IP address. Users connect on a TCP/HTTPS virtual server. Another virtual server handles DTLS for the network access resource.

Note: FEC is not included on every BIG-IP® system.

Task summary

Creating a network access resource for DTLS

You configure a network access resource to allow users access to your local network through a secure VPN tunnel. You configure the resource to use Datagram Transport Level Security (DTLS) as a prerequisite for using forward error correcting (FEC) on the connection.
  1. On the Main tab, click Access Policy > Network Access .
    The Network Access List screen opens.
  2. Click the Create button.
    The New Resource screen opens.
  3. In the Name field, type a name for the resource.
  4. Click Finished to save the network access resource.
  5. On the menu bar, click Network Settings.
  6. In the Enable Network Tunnel area, for Network Tunnel, retain the default setting Enable.
  7. In the General Settings area from the Supported IP Version list, retain the default setting IPV4, or select IPV4 & IPV6.
    If you select IPV4 & IPV6, the IPV4 Lease Pool and IPV6 Lease Pool lists are displayed. They include existing pools of IPv4 addresses and IPv6 addresses, respectively.
  8. Select the appropriate lease pools from the lists.
    APM® assigns IP addresses to a client computer's virtual network from the lease pools that you specify.
  9. From the Client Settings list, select Advanced.
    Additional settings are displayed.
  10. Select the DTLS check box.
    A DTLS Port field displays with the default port, 4433.
  11. Click Update.

Adding a FEC profile to a connectivity profile

You add a forward error correction (FEC) profile to a connectivity profile to apply on a network access tunnel.
Note: A connectivity profile contains default settings for network access compression. However, compression is not active when a network access connection is configured for DTLS.
  1. On the Main tab, click Access Policy > Secure Connectivity .
    A list of connectivity profiles displays.
  2. Select the connectivity profile that you want to update and click Edit Profile.
    The Edit Connectivity Profile popup screen opens and displays General Settings.
  3. From the FEC Profile list, select the default profile, /Common/fec.
    A FEC profile is a network tunnel profile. You can configure a custom FEC profile in the Network area on the BIG-IP system.
  4. Click OK.
    The popup screen closes, and the Connectivity Profile List displays.
To provide functionality with a connectivity profile, you must add the connectivity profile and an access profile to a virtual server.

Configuring a webtop for network access

A webtop allows your users to connect and disconnect from the network access connection.
  1. On the Main tab, click Access Policy > Webtops .
    The Webtops screen displays.
  2. Click Create.
    The New Webtop screen opens.
  3. In the Name field, type a name for the webtop.
  4. Select the type of webtop to create.
    Option Description
    Network Access Select Network Access for a webtop to which you will assign only a single network access resource.
    Portal Access Select Portal Access for a webtop to which you assign only portal access resources.
    Full Select Full for a webtop to which you assign one or more network access resources, multiple portal access resources, and multiple application access app tunnel resources, or any combination of the three types.
  5. Click Finished.
The webtop is now configured, and appears in the list. You can edit the webtop further, or assign it to an access policy.
To use this webtop, it must be assigned to an access policy with an advanced resource assign action or with a webtop, links and sections assign action.

Creating an access profile

You create an access profile to provide the access policy configuration for a virtual server that establishes a secured session.
  1. On the Main tab, click Access Policy > Access Profiles .
    The Access Profiles List screen opens.
  2. Click Create.
    The New Profile screen opens.
  3. In the Name field, type a name for the access profile.
    Note: An access profile name must be unique among all access profile and any per-request policy names.
  4. From the Profile Type list, select one these options:
    • LTM-APM: Select for a web access management configuration.
    • SSL-VPN: Select to configure network access, portal access, or application access. (Most access policy items are available for this type.)
    • ALL: Select to support LTM-APM and SSL-VPN access types.
    • SSO: Select to configure matching virtual servers for Single Sign-On (SSO).
      Note: No access policy is associated with this type of access profile
    • RDG-RAP: Select to validate connections to hosts behind APM when APM acts as a gateway for RDP clients.
    • SWG - Explicit: Select to configure access using Secure Web Gateway explicit forward proxy.
    • SWG - Transparent: Select to configure access using Secure Web Gateway transparent forward proxy.
    • System Authentication: Select to configure administrator access to the BIG-IP® system (when using APM as a pluggable authentication module).
    • Identity Service: Used internally to provide identity service for a supported integration. Only APM creates this type of profile.
      Note: You can edit Identity Service profile properties.
    Note: Depending on licensing, you might not see all of these profile types.
    Additional settings display.
  5. In the Language Settings area, add and remove accepted languages, and set the default language.
    A browser uses the highest priority accepted language. If no browser language matches the accepted languages list, the browser uses the default language.
  6. Click Finished.
The access profile displays in the Access Profiles List. Default-log-setting is assigned to the access profile.

Verifying log settings for the access profile

Confirm that the correct log settings are selected for the access profile to ensure that events are logged as you intend.
Note: Log settings are configured in the Access Policy Event Logs area of the product. They enable and disable logging for access system and URL request filtering events. Log settings also specify log publishers that send log messages to specified destinations.
  1. On the Main tab, click Access Policy > Access Profiles .
    The Access Profiles List screen opens.
  2. Click the name of the access profile that you want to edit.
    The properties screen opens.
  3. On the menu bar, click Logs.
    The access profile log settings display.
  4. Move log settings between the Available and Selected lists.
    You can assign up to three log settings that enable access system logging to an access profile. You can assign additional log settings to an access profile provided that they enable logging for URl request logging only.
    Note: Logging is disabled when the Selected list is empty.
  5. Click Update.
An access profile is in effect when it is assigned to a virtual server.

Adding network access to an access policy

Before you assign a network access resource to an access policy, you must:
  • Create a network access resource.
  • Create an access profile.
  • Define a network access webtop or a full webtop.
When you assign a network access resource to an access policy branch, a user who successfully completed the branch rule (which includes that access policy item) starts a network access tunnel.
  1. On the Main tab, click Access Policy > Access Profiles .
    The Access Profiles List screen opens.
  2. Click the name of the access profile for which you want to edit the access policy.
    The properties screen opens for the profile you want to edit.
  3. On the menu bar, click Access Policy.
    The Access Policy screen opens.
  4. In the General Properties area, click the Edit Access Policy for Profile profile_name link.
    The visual policy editor opens the access policy in a separate screen.
  5. Click the (+) icon anywhere in the access policy to add a new action item.
    Note: Only an applicable subset of access policy items is available for selection in the visual policy editor for any access profile type.
    A popup screen opens, listing predefined actions on tabs such as General Purpose, Authentication, and so on.
  6. Select one of the following resource assignment actions and click Add.
    Option Description
    Resource Assign Select the Resource Assign action to add a network access resource only. Resource Assign does not allow you to add a webtop or ACLs. If you want to add ACLs, a webtop, or webtop links after you add a Resource Assign action, you can add them with the individual actions ACL Assign and Webtop, Links and Sections Assign.
    Note: Webtop sections are for use with a full webtop only.
    Advanced Resource Assign Select the Advanced Resource Assign action to add network access resources, and optionally add a webtop, webtop links, webtop sections, and one or more ACLs.
  7. Select the resource or resources to add.
    • If you added an Advanced Resource Assign action, on the Resource Assignment screen, click Add New Entry, then click Add/Delete, and select and add resources from the tabs, then click Update.
    • If you added a Resource Assign action, next to Network Access Resources, click Add/Delete.
    If you add a full webtop and multiple network access resources, Auto launch can be enabled for only one network access resource. (With Auto launch enabled, a network access resource starts automatically when the user reaches the webtop.)
  8. Click Save.
  9. Click Apply Access Policy to save your configuration.
A network access tunnel is assigned to the access policy. You may also assign a network access or full webtop. On the full webtop, users can click the link for a network access resource to start the network access tunnel, or a network access tunnel (that is configured with Auto launch enabled) can start automatically.
After you complete the access policy, you must define a connectivity profile. In the virtual server definition, you must select the access policy and connectivity profile.

Creating an HTTPS virtual server for network access

Create a virtual server for HTTPS traffic.
  1. On the Main tab, click Local Traffic > Virtual Servers .
    The Virtual Server List screen opens.
  2. Click the Create button.
    The New Virtual Server screen opens.
  3. In the Name field, type a unique name for the virtual server.
  4. In the Destination Address/Mask field, type the IP address for a host virtual server.
    This field accepts an address in CIDR format (IP address/prefix). However, when you type the complete IP address for a host, you do not need to type a prefix after the address.
  5. In the Service Port field, type 443 or select HTTPS from the list.
  6. From the HTTP Profile list, select http.
  7. If you use client SSL, for the SSL Profile (Client) setting, select a client SSL profile.
  8. If you use server SSL, for the SSL Profile (Server) setting, select a server SSL profile.
  9. In the Access Policy area, from the Access Profile list, select the access profile that you configured earlier.
  10. In the Access Policy area, from the Connectivity Profile list, select the connectivity profile.
  11. Click Finished.
The HTTPS virtual server displays on the list.

Configuring a virtual server for DTLS

To configure DTLS mode for a network access connection, you must configure a virtual server specifically for use with DTLS.
  1. On the Main tab, click Local Traffic > Virtual Servers .
    The Virtual Server List screen opens.
  2. Click the Create button.
    The New Virtual Server screen opens.
  3. In the Name field, type a unique name for the virtual server.
  4. In the Destination Address field, type the IP address in CIDR format.
    The supported format is address/prefix, where the prefix length is in bits. For example, an IPv4 address/prefix is 10.0.0.1/32 or 10.0.0.0/24, and an IPv6 address/prefix is ffe1::0020/64 or 2001:ed8:77b5:2:10:10:100:42/64.
    Note: This is the same IP address as the TCP (HTTPS) virtual server to which your users connect.
  5. In the Service Port field, type the port number that you specified in the DTLS Port field in the network access resource configuration.
    By default, the DTLS port is 4433.
  6. From the Protocol list, select UDP.
  7. For the SSL Profile (Client) setting, in the Available box, select a profile name, and using the Move button, move the name to the Selected box.
  8. In the Access Policy area, from the Connectivity Profile list, select the connectivity profile.
    Use the same connectivity profile that you specified for the TCP (HTTPS) virtual server to which your users connect.
  9. Click Finished.

Network settings for a network access resource

Network settings specify tunnel settings, session settings, and client settings.

Setting Value Description
Network Tunnel Enable When you enable a network tunnel, you configure the network access tunnel to provide network access. Clear the Enable option to hide all network settings and to disable the tunnel.
Supported IP Version IPV4 or IPV4&IPV6 Sets the Network Access tunnel to support either an IPv4 lease pool, or both IPv4 and IPv6 lease pools.
Important: Network access with IPv6 alone is not supported. An IPv6 tunnel requires a simultaneous IPv4 tunnel, which is automatically established when you assign IPv4 and IPv6 lease pools, and set the version to IPv4&IPv6.
General Settings Basic/Advanced Select Advanced to show settings for Proxy ARP, SNAT Pool, and Session Update.
IPv4 Lease Pool List selection of existing IPv4 lease pools Assigns internal IP addresses to remote network access clients, using configured lease pools. Select a lease pool from the drop-down list. To create a lease pool within this screen, click the + sign next to Lease Pool.
IPv6 Lease Pool List selection of existing IPv6 lease pools Assigns internal IP addresses to remote network access clients, using configured lease pools. Select a lease pool from the drop-down list. To create a lease pool within this screen, click the + sign next to Lease Pool.
Compression No Compression/GZIP Compression Select GZIP Compression to compress all traffic between the Network Access client and the Access Policy Manager®, using the GZIP deflate method.
Proxy ARP Enable Proxy ARP allows remote clients to use IP addresses from the LAN IP subnet, and no configuration changes are required on other devices such as routers, hosts, or firewalls. IP address ranges on the LAN subnet are configured in a lease pool and assigned to network access tunnel clients. When this setting is enabled, a host on the LAN that sends an ARP query for a client address gets a response from Access Policy Manager with its own MAC address. Traffic is sent to the Access Policy Manager and forwarded to clients over network access tunnels.
SNAT Pool List selection of None, Auto Map, or SNAT pool name Specifies the name of a SNAT pool used for implementing selective and intelligent SNATs. The default is Auto Map. If you have defined a SNAT on the system, that SNAT is available as an option on this list. The following two options are always available.
  • None specifies that the system uses no SNAT pool for this network resource.
  • Auto Map specifies that the system uses all of the self IP addresses as the translation addresses for the pool.
Note: To support CIFS/SMB and VoIP protocols, select None and configure routable IP addresses in the lease pool
Session Update Threshold Integer (bytes per second) Defines the average byte rate that either ingress or egress tunnel traffic must exceed, in order for the tunnel to update a session. If the average byte rate falls below the specified threshold, the system applies the inactivity timeout, which is defined in the Access Profile, to the session.
Session Update Window Integer (seconds) Defines the time value in seconds that the system uses to calculate the EMA (Exponential Moving Average) byte rate of ingress and egress tunnel traffic.
Client Settings Basic/Advanced Select Advanced to configure client proxy, DTLS, domain reconnect settings, and client certificate options.
Force all traffic through tunnel Enable/disable Specifies that all traffic (including traffic to or from the local subnet) is forced over the VPN tunnel.
Use split tunneling for traffic Enable/disable Specifies that only the traffic targeted to a specified address space is sent over the network access tunnel. With split tunneling, all other traffic bypasses the tunnel. By default, split tunneling is not enabled. When split tunneling is enabled, all traffic passing over the network access connection uses this setting.
IPV4 LAN Address Space IPv4 IP address, IP address and network mask Provides a list of addresses or address/mask pairs describing the target LAN. When using split tunneling, only the traffic to these addresses and network segments goes through the tunnel configured for Network Access. You can add multiple address spaces to the list, one at a time. For each address space, type the IP address and the network mask and click Add.
IPV6 LAN Address Space IPv6 IP address, IP address and network mask Provides a list of IPv6 addresses or address/mask pairs describing the target LAN. When using split tunneling, only the traffic to these addresses and network segments goes through the tunnel configured for Network Access. You can add multiple address spaces to the list, one at a time. For each address space, type the IP address and the network mask and click Add. This list appears only when you select IPV4&IPV6 in the Supported IP Version setting.
DNS Address Space domain names, with or without wildcards Provides a list of domain names describing the target LAN DNS addresses. This field only appears if you use split tunneling. You can add multiple address spaces to the list, one at a time. For each address space, type the domain name, in the form site.siterequest.com or *.siterequest.com, and click Add.
Exclude Address Space IP address/network mask pairs Specifies address spaces whose traffic is not forced through the tunnel. For each address space that you want to exclude, type the IP address and the network mask and click Add.
Allow Local Subnet Enable/disable Select this option to enable local subnet access and local access to any host or subnet in routes that you have specified in the client routing table. When you enable this setting, the system does not support integrated IP filtering.
Client Side Security > Prohibit routing table changes during Network Access connection Enable/disable This option closes the network access session if the client's IP routing table is modified during the session.
Client Side Security > Integrated IP filtering engine Enable/disable Select this option to protect the resource from outside traffic (traffic generated by network devices on the client's LAN), and to ensure that the resource is not leaking traffic to the client's LAN.
Client Side Security > Allow access to local DHCP server Enable/disable This option appears when the Integrated IP filtering engine option is enabled. This option allows the client access to connect through the IP filtering engine, to use a DHCP server local to the client to renew the client DHCP lease locally. This option is not required or available when IP filtering is not enabled, because clients can renew their leases locally.
Important: This option does not renew the DHCP lease for the IP address assigned from the network access lease pool; this applies only to the local client IP address.
Client Traffic Classifier List selection Specifies a client traffic classifier to use with this network access tunnel, for Windows clients.
Client Options > Client for Microsoft Networks Enable/disable Select this option to allow the client PC to access remote resources over a VPN connection. This option is enabled by default. This allows the VPN to work like a traditional VPN, so a user can access files and printers from the remote Microsoft network.
Client Options > File and printer sharing for Microsoft networks Enable/disable Select this option to allow remote hosts to access shared resources on the client computer over the network access connection. This allows the VPN to work in reverse, and a VPN user to share file shares and printers with remote LAN users and other VPN users.
Provide client certificate on Network Access connection when requested Enable/disable If client certificates are required to establish an SSL connection, this option must always be enabled. However, you can disable this option if the client certificates are only requested in an SSL connection. In this case, the client is configured not to send client certificates.
Reconnect to Domain > Synchronize with Active Directory policies on connection establishment Enable/disable When enabled, this option emulates the Windows logon process for a client on an Active Directory domain. Network policies are synchronized when the connection is established, or at logoff. The following items are synchronized:
  • Logon scripts are started as specified in the user profile.
  • Drives are mapped as specified in the user profile.
  • Group policies are synchronized as specified in the user profile. Group Policy logon scripts are started when the connection is established, and Group Policy logoff scripts are run when the network access connection is stopped.
Reconnect to Domain > Run logoff scripts on connection termination Enable/disable This option appears when Synchronize with Active Directory policies on connection establishment is enabled. Enable this option if you want the system to run logoff scripts, as configured on the Active Directory domain, when the connection is stopped.
Client Interface Speed Integer, bits per second Specifies the maximum speed of the client interface connection, in bits per second.
Display connection tray icon Enable/disable When enabled, balloon notifications for the network access tray icon (for example, when a connection is made) are displayed. Disable this option to prevent balloon notifications.
Client Power Management Ignore, Prevent, or Terminate Specifies how network access handles client power management settings, for example, when the user puts the system in standby, or closes the lid on a laptop.
  • Ignore - ignores the client settings for power management.
  • Prevent - prevents power management events from occurring when the client is enabled.
  • Terminate - terminates the client when a power management event occurs.
DTLS Enable/disable Specifies, when enabled, that the network access connection uses Datagram Transport Level Security (DTLS). DTLS uses UDP instead of TCP, to provides better throughput for high-demand applications like VoIP or streaming video, especially with lossy connections.
DTLS Port Port number Specifies the port number that the network access resource uses for secure UDP traffic with DTLS. The default is 4433.
Client Proxy Settings Enable/disable Enables several additional settings that specify client proxy connections for this network resource. Client proxy settings apply to the proxy behind the Access Policy Manager and do not affect the VPN tunnel transport, or interact with the TLS or DTLS configuration. Use client proxy settings when intranet web servers are not directly accessible from the Access Policy Manager internal subnet. Client proxy settings apply only to HTTP, HTTPS, and FTP connections. SOCKS connections can also be proxied, with a custom PAC file.
Client Proxy Uses HTTP for Proxy Autoconfig Script Enable/disable Some applications, like Citrix® MetaFrame, can not use the client proxy autoconfig script when the browser attempts to use the file:// prefix to locate it. Select this option to specify that the browser uses http:// to locate the proxy autoconfig file, instead of file://.
Client Proxy Autoconfig Script URL The URL for a proxy auto-configuration script, if one is used with this connection.
Client Proxy Address IP address The IP address for the client proxy server that network access clients use to connect to the Internet.
Client Proxy Port Port number The port number of the proxy server that network access clients use to connect to the Internet.
Bypass Proxy For Local Addresses Enable/disable Select this option if you want to allow local intranet addresses to bypass the proxy server.
Client Proxy Exclusion List IP addresses, domain names, with wildcards Specifies the web addresses that do not need to be accessed through your proxy server. You can use wildcards to match domain and host names, or addresses. For example, www.*.com, 128.*, 240.8, 8., mygroup.*, *.*.
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