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Citrix ADC
Current Release 13.0 12.1 11.1
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TCP配置

October 4, 2021
Contributed by:
C

TCP Citrix ADC设备可以配置be specified in an entity called a TCP profile, which is a collection of TCP settings. The TCP profile can then be associated with services or virtual servers that want to use these TCP configurations.

A default TCP profile can be configured to set the TCP configurations that will be applied by default, globally to all services and virtual servers.

Note:

当一个服务的TCP参数有不同的值ice, virtual server, and globally, the value of the most-specific entity (the service) is given the highest precedence. The Citrix ADC appliance also provides other approaches for configuring TCP. Read on for more information.

Supported TCP configuration

的Citrix ADC appliance supports the following TCP capabilities:

Defending TCP against spoofing attacks

的Citrix ADC implementation ofwindow attenuation is RFC 4953 compliant.

Explicit Congestion Notification (ECN)

的appliance sends notification of the network congestion status to the sender of the data and takes corrective measures for data congestion or data corruption. The Citrix ADC implementation of ECN is RFC 3168 compliant.

Round trip time measurement (RTTM) using the timestamp option

For the TimeStamp option to work, at least one side of the connection (client or server) must support it. The Citrix ADC implementation of theTimeStampoption is RFC 1323 compliant.

Detection of spurious retransmissions

This can be done using TCP duplicate selective acknowledgment (D-SACK) and forward RTO-Recovery (F-RTO). If there are spurious retransmissions, the congestion control configurations are reverted to their original state. The Citrix ADC implementation of D-SACK is RFC 2883 compliant, and F-RTO is RFC 5682 compliant.

Congestion control

此功能使用新no, BIC, CUBIC, Nile, and TCP Westwood algorithms.

Window scaling

This increases theTCP receivewindow size beyond its maximum value of 65,535 bytes.

Points to consider before you configure window scaling

  • You do not set a high value for the scale factor, because this might have adverse effects on the appliance and the network.
  • You do not configure window scaling unless you clearly know why you want to change the window size.
  • Both hosts in the TCP connection send a window scale option during connection establishment. If only one side of a connection sets this option, window scaling is not used for the connection.
  • Each connection for the same session is an independent window scaling session. For example, when a client’s request and the server’s response flow through the appliance, it is possible to have window scaling between the client and the appliance without window scaling between the appliance and the server.

TCP maximum congestion window

的window size is a user configurable one. The default value is 8190 bytes.

Selective acknowledgment (SACK)

This uses the data receiver (either a Citrix ADC appliance or a client) notifies the sender about all the segments that have been received successfully.

Forward acknowledgment (FACK)

This functionality avoids TCP congestion by explicitly measuring the total number of data bytes outstanding in the network, and helping the sender (either a Citrix ADC or a client) control the amount of data injected into the network during retransmission timeouts.

TCP connection multiplexing

This functionality enables reuse of existing TCP connections. The Citrix ADC appliance stores established TCP connections to the reuse pool. Whenever a client request is received, the appliance checks for an available connection in the reuse pool and serves the new client if the connection is available. If it is unavailable, the appliance creates a connection for the client request and stores the connection to the reuse pool. The Citrix ADC supports connection multiplexing for HTTP, SSL, and DataStream connection types.

Dynamic receive buffering

This allows the receive buffer to be adjusted dynamically based on memory and network conditions.

Multipath TCP Connection

Multipath TCP (MPTCP) connections between the client and the Citrix ADC appliance. MPTCP connections are not supported between the Citrix ADC appliace and the back-end server. The Citrix ADC implementation of MPTCP is RFC 6824 and RFC 8684 compliant supporting both MPTCP version 0 and 1.

You can view MPTCP statistics such as active MPTCP connections and active subflow connections by using the command line interface.

At the command prompt, type one of the following commands to display a summary or detailed summary of MPTCP statistics, or to clear the statistics display:

  1. Stat MPTCP
  2. Stat mptcp –detail
  3. Clearstats basic

Note:

To establish an MPTCP connection, both the client and the Citrix ADC appliance must support the same MPTCP version. If you use the Citrix ADC appliance as an MPTCP gateway for your servers, the servers do not have to support MPTCP. When the client starts a new MPTCP connection, the appliance identifies the client’s MPTPC version from the MP_CAPABALE option in the SYN packet. If the client’s version is higher than the one supported on the appliance, the appliance indicates its highest version in the MP_CAPABALE option of the SYN-ACK packet. The client then falls back to a lower version and sends the version number in the MP_CAPABALE option of the ACK packet. If that version is supportable, the appliance continues the MPTCP connection. Otherwise, the appliance falls back to a regular TCP. The Citrix ADC appliance does not initiate subflows (MP_JOIN’s). The appliance expects the client to initiate subflows.

Support for additional address advertisement (ADD_ADDR) in MPTCP

In an MPTCP deployment, if you have a virtual server bound with an IP set that has additional virtual server IP addresses, then the additional address advertisement (ADD_ADDR) functionality advertises the IP address of the virtual servers bound to the IP set. Clients can initiate moreMP-JOINsub flows to the advertised IP addresses.

Points to remember about MPTCP ADD_ADDR functionality

  • You can send a maximum of 10 IP addresses as part of theADD_ADDRoption. If there are more than 10 IP addresses with themptcpAdvertiseparameter enabled, after advertising the 10 IP address, the appliance ignore the rest of the IP addresses.
  • If the MP-CAPABLE subflow is made to one of the IP addresses in the IP set instead of the primary virtual server IP address, then the virtual server IP address is advertised if themptcpAdvertiseparameter is enabled for the virtual server IP address

Configure more address advertisement (ADD_ADDR) feature to advertise more VIP address by using the CLI

You can configure theMPTCP ADD_ADDRfunctionality for both IPv4 and IPv6 address types. In general, multiple IPv4 and IPv6 IPs can be attached to a single IP set and the parameter can be enabled on any subset of IP addresses. In the ADD_ADDR feature, only the IP addresses that have the “mptcpAdvertise” option enabled is advertised and the remaining IP addresses from the IP set is ignored. Complete the following steps to configure theADD_ADDRfeature:

  1. Add an IP set.
  2. Add an IP address of type virtual server IP (VIP) with MPTCP advertise enabled.
  3. Bind the IP address with the IP set.
  4. Configure IP set with the load balancing virtual server.

Add an IP set

At the command prompt, type:

add ipset  [-td ]

Example:

add ipset ipset_1

Add an IP address of type virtual server IP (VIP) with MPTCP advertise enabled

At the command type:

add ns ip @  [-mptcpAdvertise ( YES | NO )] -type

Example:

add ns ip 10.10.10.10 255.255.255.255 -mptcpAdvertise YES -type VIP

Bind IP addresses to the IP set

At the command prompt, type:

bind ipset

Example:

bind ipset ipset_1 10.10.10.10

Configure IP set to load balancing virtual server

At the command prompt, type:

set lb vserver  [-ipset ]

Example:

set lb vserver lb1 -ipset ipset_1

Sample Configuration:

Add ipset ipset_1 add ns ip 10.10.10.10 255.255.255.255 -mptcpAdvertise YES -type VIP bind ipset ipset_1 10.10.10.10 set lb vserver lb1 -ipset ipset_1

Configure advertising external IP address using ADD_ADDR functionality

If the advertised IP address is owned by the external entity and the Citrix ADC appliance needs to advertise the IP address, the “MPTCPAdvertise” parameter must be enabled with state and ARP parameters disabled.

Complete the following steps to configureADD_ADDRfor advertising the external IP address.

  1. Add an IP address of type virtual server IP (VIP) with MPTCP advertise enabled.
  2. Bind the IP address with the IP set.
  3. Bind IP set with the load balancing virtual server

Add external IP address of type virtual server IP (VIP) with MPTCP advertise enabled

At the command prompt, type:

add ns ip @  [-mptcpAdvertise ( YES | NO )] -type  -state DISABLED -arp DISABLED

Example:

add ns ip 10.10.10.10 255.255.255.255 -mptcpAdvertise YES -type VIP -state DISABLED -arp DISABLED

Bind IP addresses to the IP set

At the command prompt, type:

bind ipset

Example:

bind ipset ipset_1 10.10.10.10

Configure IP set to load balancing virtual server

At the command prompt, type:

set lb vserver  [-ipset ]

Example:

set lb vserver lb1 -ipset ipset_1

Sample Configuration:

add ns ip 10.10.10.10 255.255.255.255 -mptcpAdvertise YES -type VIP state DISABLED -arp DISABLED bind ipset ipset_1 10.10.10.10 set lb vserver lb1 -ipset ipset_1

Complete the following step to advertise the IP address to the MPTCP enabled clients:

  1. Navigate toSystem > Network > IPs.
  2. In the details pane, clickAdd.
  3. In theCreate IP Addresspage, select theMPTCP Advertisecheck box to set the parameter. By default, it is disabled.

GUI procedure to advertise IP address to MPTCP clients

Extracting the TCP/IP path overlay option and inserting the client-IP HTTP header

Extracting TCP/IP path overlay and inserting client-IP HTTP header. Data transport through overlay networks often uses connection termination or Network Address Translation (NAT), in which the IP address of the source client is lost. To avoid this, the Citrix ADC appliance extracts the TCP/IP path overlay option and inserts the source client’s IP address into the HTTP header. With the IP address in the header, the web server can identify the source client that made the connection. The extracted data is valid for a lifetime of the TCP connection and therefore, this prevents the next hop host from having to interpret the option again. This option is applicable only for web services that have the client-IP insertion option enabled.

TCP segmentation offload

Offloads TCP segmentation to the NIC. If you set the option as “AUTOMATIC”, TCP segmentation is offloaded to the NIC, if NIC is supported.

This is used for resisting SYN flood attacks. You can enable or disable theSYNCOOKIEmechanism for TCP handshake with clients. DisablingSYNCOOKIEpreventsSYNattack protection on the Citrix ADC appliance.

learning MSS to enable MSS learning for all the virtual servers configured on the appliance

Supportable TCP Parameters

的following table provides a list of TCP parameters and its default value configured on a Citrix ADC appliance.

Parameter Default Value Description
Window Management
TCP Delayed-ACK Timer 100 millisec Timeout for TCP delayed ACK, in milliseconds.
TCP minimum Retransmission Timeout(RTO) in milli sec 1000 milli sec Minimum retransmission timeout, in milliseconds, specified in 10-millisecond increments (value must yield a whole number if divided by 10)
Connection idle time before starting keep-alive probes 900 seconds Silently drop TCP established connections on idle timeouts established connections on idle timeout
TCP Timestamp Option DISABLED 的timestamp option allows for accurate RTT measurement. Enable or Disable TCP Timestamp option.
Multipath TCP session timeout 0 seconds MPTCP session timeout in seconds. If this value is not set, idle. MPTCP sessions are flushed after the virtual server’s client idle timeout.
Silently Drop HalfClosed connections on idle timeout 0 seconds Silently drop TCP half closed connections on idle timeout.
Silently Drop Established connections on idle timeout DISABLED Silently drop TCP established connections on idle timeout
Memory Management
TCP Buffer Size 131072 bytes TCP buffer size is the receive buffer size on the Citrix ADC. This buffer size is advertised to clients and servers from Citrix ADC and it controls their ability to send data to Citrix ADC. The default buffer size is 8K and usually it is safe to increment this when talking to internal server farms. The buffer size is also impact by the actual application layer in Citrix ADC like for SSL endpoint cases it is set to 40 K and for Compression it is set to 96 K.Note:的buffer size argument must be set for dynamic adjustments to take place.
TCP Send Buffer Size 8190 bytes TCP Send Buffer Size
TCP Dynamic Receive Buffering DISABLED Enable or disable dynamic receive buffering. When enabled, it allows the receive buffer to be adjusted dynamically based on memory and network conditions.Note:的buffer size argument must be set for dynamic adjustments to take place
TCP Max congestion window(CWND) 524288 bytes TCP Maximum Congestion Window
Window Scaling status ENALBED Enable or disable window scaling.
Window Scaling factor 8 Factor used to calculate the new window size. This argument is needed only when window scaling is enabled.
Connection Setup
Keep-alive probes DISABLED 发送periodic TCP keep-alive (KA) probes to check if peer is still up.
Connection idle time before starting keep-alive probes 900 seconds Duration, in seconds, for the connection to be idle, before sending a keep-alive (KA) probe.
Keep-alive probe interval 75 seconds Time interval, in seconds, before the next keep-alive (KA) probe, if the peer does not respond.
Maximum keep-alive probes to be missed before dropping connection. 3 Number of keep-alive (KA) probes to be sent when not acknowledged, before assuming the peer to be down.
RST window attenuation (spoof protection). DISABLED Enable or disable RST window attenuation to protect against spoofing. When enabled, the reply is with corrective ACK when a sequence number is invalid.
Accept RST with last acknowledged sequence number. ENABLED
Data transfer
Immediate ACK on PUSH packet ENABLED 发送immediate positive acknowledgment (ACK) on receipt of TCP packets with PUSH flag.
Maximum packets per MSS 0 Maximum number of octets to allow in a TCP data segment
Nagle’s Algorithm DISABLED Nagle’s Algorithm fights with the problem of small packets in TCP transmission. Applications like Telnet and other real time engines which require every key stroke to be passed to the other side often create small packets. With Nagle’s algorithm Citrix ADC can buffer such small packets and sends them together to increase on the connection efficiency. This algorithm needs to work along with other TCP optimization techniques in the Citrix ADC.
Maximum TCP segments allowed in a burst 10 MSS Maximum number of TCP segments allowed in a burst
Maximum out-of-order packets to queue 300 Maximum size of out-of-order packets queue. A value of 0 means no limit
Congestion Control
TCP Flavor CUBIC
Initial congestion window(cwnd) setting 4 MSS Initial maximum upper limit on the number of TCP packets that can be outstanding on the TCP link to the server
TCP Explicit Congestion Notification(ECN) DISABLED Explicit Congestion Notification (ECN) provides end to end notification of network congestion without dropping packets.
TCP Max congestion window(CWND) 524288 bytes TCP maintains a congestion window (CWND), limiting the total number of unacknowledged packets that may be in transit end-to-end. In TCP, the congestion window is one of the factors that determines the number of bytes that can be outstanding at any time. The congestion window is a means of stopping a link between the sender and the receiver from becoming overloaded with too much traffic. It is calculated by estimating how much congestion there is on the link.
TCP Hybrid Start (HyStart) 8 bytes
TCP minimum Retransmission Timeout(RTO) in milli sec 1000 Minimum retransmission timeout, in milliseconds, specified in 10-millisecond increments (value must yield a whole number if divided by 10).
TCP dupack threshold DISABLED
Burst Rate Control 3 TCP Burst Rate Control DISABLED/FIXED/DYNAMIC. FIXED requires a TCP rate to be set
TCP Rate DISABLED TCP connection payload send rate in Kb/s
TCP速率最大队列 0 Maximum connection queue size in bytes, when BurstRateControl is used.
MPTCP
Multipath TCP DISABLED Multipath TCP (MPTCP) is a set of extensions to regular TCP to provide a Multipath TCP service, which enables a transport connection to operate across multiple paths simultaneously.
Multipath TCP drop data on pre-established subflow DISABLED Enable or disable silently dropping the data on Pre-Established subflow. When enabled, DSS data packets are dropped silently instead of dropping the connection when data is received on pre established subflow.
Multipath TCP fastopen DISABLED 启用或禁用TCP fastopen多路径。当enabled, DSS data packets are accepted before receiving the third ack of SYN handshake.
Multipath TCP session timeout 0 seconds MPTCP session timeout in seconds. If this value is not set, idle MPTCP sessions are flushed after the virtual server’s client idle timeout.
Security
SYN spoof protection DISABLED Enable or disable drop of invalid SYN packets to protect against spoofing. When disabled, established connections are reset when a SYN packet is received.
TCP Syncookie DISABLED This is used for resisting SYN flood attacks. Enable or disable the SYNCOOKIE mechanism for TCP handshake with clients. Disabling SYNCOOKIE prevents SYN attack protection on the Citrix ADC appliance.
loss Detection and Recovery
Duplicate Selective Acknowledgment (DSACK) ENABLED A Citrix ADC appliance uses Duplicate Selective Acknowledgment (DSACK) to determine if a retransmission was sent in error.
Forward RTO recovery (FRTO) ENABLED Detects spurious TCP retransmission timeouts. After retransmitting the first unacknowledged segment triggered by a timeout, the algorithm of the TCP sender monitors the incoming acknowledgments to determine whether the timeout was spurious. It then decides whether to send new segments or retransmit unacknowledged segments. The algorithm effectively helps to avoid another unnecessary retransmissions and thereby improves TCP performance in the case of a spurious timeout.
TCP Forward Acknowledgment (FACK) ENABLED Enable or disable FACK (Forward ACK).
Selective Acknowledgement(SACK) status ENABLED TCP SACK addresses the problem of multiple packet losses which reduces the overall throughput capacity. With selective acknowledgment the receiver can inform the sender about all the segments which are received successfully, enabling the sender to only retransmit the segments which were lost. This technique helps Citrix ADC improve overall throughput and reduce the connection latency.
Maximum packets per retransmission 1 Allows Citrix ADC to control how many packets to be retransmitted in one attempt. When Citrix ADC receives a partial ACK and it has to do retransmission then this setting is considered. This does not impact the RTO based retransmissions.
TCP Delayed-ACK Timer 100 millisec Timeout for TCP delayed ACK, in milliseconds
TCO Optimization
TCP Optimization mode TRANSPARENT TCP Optimization modes TRANSPARENT/ENDPOINT
Apply adaptive TCP optimizations DISABLED Apply Adaptive TCP optimizations
TCP Segmentation Offload AUTOMATIC Offload TCP segmentation to the NIC. If set to AUTOMATIC, TCP segmentation is offloaded to the NIC, if the NIC supports it.
ACK Aggregation DISABLED Enable or disable ACK Aggregation
TCP时候(或Time_wait) 40 secs Time to elapse before releasing a closed TCP connection
Delink client and server on RST DISABLED Delink client and server connection, when there is outstanding data to be sent to the other side.

Setting Global TCP Parameters

的Citrix ADC appliance allows you to specify values for TCP parameters that are applicable to all Citrix ADC services and virtual servers. This can be done using:

  • Default TCP profile
  • Global TCP command
  • TCP buffering feature

Note:

的recvBuffSizeparameter of the set ns tcpParam command is deprecated from release 9.2 onwards. In later releases, set the buffer size by using thebufferSizeparameter of the set ns tcpProfile command. If you upgrade to a release where therecvBuffSizeparameter is deprecated, thebufferSizeparameter is set to its default value.

Default TCP profile

A TCP profile, named asnstcp_default_profile, is used to specify TCP configurations that is used if no TCP configurations are provided at the service or virtual server level.

Notes:

  • Not all TCP parameters can be configured through the default TCP profile. Some settings have to be performed by using the global TCP command (see section below).

  • 的default profile does not have to be explicitly bound to a service or virtual server.

To configure the default TCP profile

  • Using the command line interface, at the command prompt enter:

    set ns tcpProfile nstcp_default_profile...

  • On the GUI, navigate toSystem>Profiles, clickTCP Profilesand update nstcp_default_profile.

Global TCP command

另一种方法可以使用配置全球TCP parameters is the global TCP command. In addition to some unique parameters, this command duplicates some parameters that can be set by using a TCP profile. Any update made to these duplicate parameters is reflected in the corresponding parameter in the default TCP profile.

For example, if the SACK parameter is updated using this approach, the value is reflected in the SACK parameter of the default TCP profile (nstcp_default_profile).

Note:

Citrix recommends that you use this approach only for TCP parameters that are not available in the default TCP profile.

To configure the global TCP command

  • Using the command line interface, at the command prompt enter:

    set ns tcpParam …

  • On the GUI, navigate toSystem > Settings. ClickChange TCP parametersand, update the required TCP parameters.

TCP buffering feature

Citrix ADC provides a feature called TCP buffering that you can use to specify the TCP buffer size. The feature can be enabled globally or at service level.

Note:

的buffer size can also be configured in the default TCP profile. If the buffer size has different values in the TCP buffering feature and the default TCP profile, the greater value is applied.

To configure the TCP buffering feature globally

  • At the command prompt enter:

    enable ns mode TCPB

    set ns tcpbufParam -size -memLimit

  • On the GUI, navigate toSystem>Settings, clickConfigure Modesand, selectTCP Buffering.

    And, navigate toSystem>Settings, clickChange TCP parameters, specify values forBuffer sizeandMemory usage limit.

Setting Service or Virtual Server Specific TCP Parameters

Using TCP profiles, you can specify TCP parameters for services and virtual servers. You must define a TCP profile (or use a built-in TCP profile) and associate the profile with the appropriate service and virtual server.

Note:

You can also modify the TCP parameters of default profiles as per your requirements.

You can specify the TCP buffer size at service level using the parameters specified by the TCP buffering feature.

To specify service or virtual server level TCP configurations by using the command line interface

At the command prompt, perform the following:

  1. Configure the TCP profile.

    set ns tcpProfile ...

  2. Bind the TCP profile to the service or virtual server.

set service  ....

Example:

> set service service1 -tcpProfileName profile1

To bind the TCP profile to the virtual server:

set lb vserver  ....

Example:

>设置磅vserver lbvserver1 -tcpProfileName资料e1

To specify service or virtual server level TCP configurations by using the GUI

At the GUI, perform the following:

  1. Configure the TCP profile.

    Navigate toSystem>Profiles>TCP Profiles, and create the TCP profile.

  2. Bind the TCP profile to the service or virtual server.

    Navigate toTraffic Management>load Balancing>Services/Virtual Servers, and create the TCP profile, which should be bound to the service or virtual server.

Built-in TCP Profiles

For convenience of configuration, the Citrix ADC provides some built-in TCP profiles. Review the built-in profiles listed for the following and select a profile and use it as it is or modify it to meet your requirements. You can bind these profiles to your required services or virtual servers.

Built-in profile Description
nstcp_default_profile Represents the default global TCP settings on the appliance.
nstcp_default_tcp_lan Useful for back-end server connections, where these servers reside on the same LAN as the appliance.
nstcp_default_WAN useful for WAN deployments.
nstcp_default_tcp_lan_thin_stream Similar to the nstcp_default_tcp_lan profile. However, the settings are tuned for small size packet flows.
nstcp_default_tcp_interactive_stream Similar to the nstcp_default_tcp_lan profile. However, it has a reduced delayed ACK timer and ACK onPUSH packetsettings.
nstcp_default_tcp_lfp Useful for long fat pipe networks (WAN) on the client side. Long fat pipe networks have long delay, high bandwidth lines with minimal packet drops.
nstcp_default_tcp_lfp_thin_stream Similar to the nstcp_default_tcp_lfp profile. However, the settings are tuned for small size packet flows.
nstcp_default_tcp_lnp Useful for long narrow pipe networks (WAN) on the client side. Long narrow pipe networks have considerable packet loss occasionally.
nstcp_default_tcp_lnp_thin_stream Similar to the nstcp_default_tcp_lnp profile. However, the settings are tuned for small size packet flows.
nstcp_internal_apps Useful for internal applications on the appliance (for example, GSLB site syncing). This contains tuned window scaling and SACK options for the desired applications. This profile should not be bound to applications other than internal applications.
nstcp_default_Mobile_profile Useful for mobile devices.
nstcp_default_XA_XD_profile Useful for a XenApp or XenDesktop deployment.

Sample TCP Configurations

Sample command line interface examples for configuring the following:

Defending TCP against spoofing attacks

Enable the Citrix ADC to defend TCP against spoof attacks. By default the “rstWindowAttenuation” parameter is disabled. This parameter is enabled to protect the appliance against spoofing. If you enable, it replies with corrective acknowledgment (ACK) for an invalid sequence number. Possible values are Enabled, Disabled.

Where, theRSTwindow attenuate parameter protects the appliance against spoofing. When enabled, reply with corrective ACK when a sequence number is invalid.

> set ns tcpProfile profile1 -rstWindowAttenuate ENABLED -spoofSynDrop ENABLED Done > set lb vserver lbvserver1 -tcpProfileName profile1 Done

Explicit Congestion Notification (ECN)

Enable ECN on the required TCP profile

> set ns tcpProfile profile1 -ECN ENABLED Done > set lb vserver lbvserver1 -tcpProfileName profile1 Done

Selective Acknowledgment (SACK)

Enable SACK on the required TCP profile.

> set ns tcpProfile profile1 -SACK ENABLED Done > set lb vserver lbvserver1 -tcpProfileName profile1 Done

Forward Acknowledgment (FACK)

Enable FACK on the required TCP profile.

> set ns tcpProfile profile1 -FACK ENABLED > set lb vserver lbvserver1 -tcpProfileName profile1

Window Scaling (WS)

Enable window scaling and set the window scaling factor on the required TCP profile.

set ns tcpProfile profile1 –WS ENABLED –WSVal 9 Done set lb vserver lbvserver1 -tcpProfileName profile1 Done

Maximum Segment Size (MSS)

Update the MSS related configurations.

> set ns tcpProfile profile1 –mss 1460 - maxPktPerMss 512 Done > set lb vserver lbvserver1 -tcpProfileName profile1 Done

Citrix ADC to learn the MSS of a virtual server

Enable the Citrix ADC to learn the VSS and update other related configurations.

> set ns tcpParam -learnVsvrMSS ENABLED –mssLearnInterval 180 -mssLearnDelay 3600 Done

TCP keep-alive

Enable TCP keep-alive and update other related configurations.

> set ns tcpProfile profile1 –KA ENABLED –KaprobeUpdateLastactivity ENABLED -KAconnIdleTime 900 -KAmaxProbes 3 -KaprobeInterval 75Done>设置磅vserver lbvserver1 -tcpProfileName资料e1Done

Buffer size - using TCP profile

Specify the buffer size.

> set ns tcpProfile profile1 –bufferSize 8190Done>设置磅vserver lbvserver1 -tcpProfileName资料e1Done

Buffer size - using TCP buffering feature

Enable the TCP buffering feature (globally or for a service) and then specify the buffer size and the memory limit.

> enable ns feature TCPBDone> set ns tcpbufParam -size 64 -memLimit 64Done

MPTCP

Enable MPTCP and then set the optional MPTCP configurations.

> set ns tcpProfile profile1 -mptcp ENABLEDDone> set ns tcpProfile profile1 -mptcpDropDataOnPreEstSF ENABLED -mptcpFastOpen ENABLED -mptcpSessionTimeout 7200Done> set ns tcpparam -mptcpConCloseOnPassiveSF ENABLED -mptcpChecksum ENABLED -mptcpSFtimeout 0 -mptcpSFReplaceTimeout 10-mptcpMaxSF 4 -mptcpMaxPendingSF 4 -mptcpPendingJoinThreshold 0 -mptcpRTOsToSwitchSF 2 -mptcpUseBackupOnDSS ENABLEDDone

Congestion control

Set the required TCP congestion control algorithm.

set ns tcpProfile profile1 -flavor WestwoodDone>设置磅vserver lbvserver1 -tcpProfileName资料e1Done

Dynamic receive buffering

Enable dynamic receive buffering on the required TCP profile.

> set ns tcpProfile profile1 -dynamicReceiveBuffering ENABLEDDone>设置磅vserver lbvserver1 -tcpProfileName资料e1Done

Support for TCP Fast Open (TFO) in Multipath TCP (MPTCP)

A Citrix ADC appliance now supports the TCP Fast Open (TFO) mechanism for establishing Multipath TCP (MPTCP) connections and speed up data transfers. The mechanism allows subflow data to be carried during the initial MPTCP connection handshake in SYN and SYN-ACK packets and also enables data to be consumed by the receiving node during the MPTCP connection establishment.

For more information, seeTCP Fast Opentopic.

A Citrix ADC appliance now enables you to configure a variable length TCP Fast Open (TFO) cookie of a minimum size of 4 bytes and a maximum size of 16 bytes in a TCP profile. By doing this, the appliance can respond with the configured TFO cookie size in the SYN-ACK packet to the client.

To configure the TCP Fast Open (TFO) cookie in a TCP profile by using the command line interface

At the command prompt, type:

设置tcpProfile nstcp_default_profile -tcpFastOpenCookieSize

Example

设置tcpProfile nstcp_default_profile -tcpFastOpenCookieSize 8

To configure the TCP Fast Open (TFO) cookie in a TCP profile by using the GUI

  1. Navigate toConfiguration>System> Profiles.
  2. In the details pane, go toTCP Profilestab and select a TCP profile.
  3. In theConfigure TCP Profilepage, set theTCP Fast Opencookie size.
  4. ClickOKandDone.

的TCPSyncookieparameter is enabled by default in TCP profiles to provide robust (RFC 4987) based protection against SYN Attacks. If you need to accommodate custom TCP clients that are not compatible with this protection but still want to ensure a fallback in case of attack, thesynAttackDetectionhandles this for you by automatically activating theSYNCookiebehavior internally for time determined by theautosyncookietimeoutparameter..

To configure the maximum SYN ACK retransmission threshold by using the command line interface:

At the command prompt, type:

set ns tcpparam [-maxSynAckRetx ] Set ns tcpparam [-maxSynAckRetx 150]

To configure auto SYN cookie timeout interval by using the command line interface

At the command prompt, type:

set ns tcpparam [-autosyncookietimeout ]

Set ns tcpparam [-autosyncookietimeout 90]

当enabled, the parameter delinks client and server connection when there is outstanding data to be sent to the other side. By default, the parameter is disabled.

set ns tcpparam -delinkClientServerOnRST ENABLED Done
TCP配置
October 4, 2021
Contributed by:
C
October 4, 2021
Contributed by:
C

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