CISCO SD-WAN vEdge Routers User Guide
- June 14, 2024
- Cisco
Table of Contents
CISCO SD-WAN vEdge Routers
First Published: 2020-05-15
Last Modified: 2020-08-17
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Read Me First
Related References
- Release Notes
- Cisco SD-WAN Controller Compatibility Matrix and Server Recommendations
User Documentation
- Cisco SD-WAN (Cisco vEdge Devices)
- User Documentation for Cisco vEdge Devices
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What’s New in Cisco SD-WAN
Cisco is constantly enhancing the SD-WAN solution with every release and we
try and keep the content in line with the latest enhancements. The following
table lists new and modified features we documented in the Configuration,
Command Reference, and Hardware Installation guides. For information on
additional features and fixes that were committed to the Cisco SD-WAN
solution, see the Resolved and Open Bugs section in the Release Notes.
What’s New in Cisco SD-WAN (vEdge) Release 20. x
TCP Optimization: Cisco vEdge Devices TCP optimization fine-tunes the
processing of TCP data traffic to decrease round-trip latency and improve
throughput. Optimizing TCP traffic is especially useful for improving TCP
traffic performance on long-latency links, such as transcontinental links and
the high-latency transport links used by VSAT satellite communications
systems. TCP optimization can also improve the performance of SaaS
applications.
- Configure TCP Optimization, on page 5
- Monitor TCP Optimization, on page 8
Table 1: Feature History
Supported Platforms
TCP Optimization is supported on the following platforms:
- Cisco vEdge 1000
- Cisco vEdge 2000
- Cisco ISR1100 6G
TCP Optimization is not supported on the following platforms
- Cisco vEdge 100
- Cisco vEdge 100b
- Cisco vEdge 100m
- Cisco vEdge 100mw
- Cisco vEdge 5000
- Cisco ISR1100 4G
- Cisco ISR1100 4GLTEGB
- Cisco ISR1100 4GLTENA
- Cisco ISR 1100X Series Integrated Services Routers
For more information on supported software features and protocols, see Platform Architecture and Capabilities. Note TCP optimization is not supported on DNS traffic. TCP optimization fine-tunes the processing of TCP data traffic to decrease round-trip latency and improve throughput. You can optimize TCP traffic in service-side VPNs on vEdge routers. Optimizing TCP traffic is especially useful for improving TCP traffic performance on long-latency links, such as transcontinental links and the high-latency transport links used by VSAT satellite communications systems. TCP optimization can also improve the performance of SaaS applications. With TCP optimization, a vEdge router acts as a TCP proxy between a client that is initiating a TCP flow and a server that is listening for a TCP flow, as illustrated in the following figure:
This figure shows two vEdge routers acting as proxies. vEdge-1 is the proxy for the client and is called the client proxy. vEdge-2 is the proxy for the server, called the server proxy. Without TCP optimization, the client establishes a TCP connection directly to the server. When you enable TCP optimization on the two routers, vEdge-1 terminates the TCP connection from the client and establishes a TCP connection with vEdge 2. The vEdge-2 router then establishes a TCP connection to the server. The two vEdge routers cache the TCP traffic in their buffers to ensure that the traffic from the client reaches the server without the TCP connection timing out.
It is recommended that you configure TCP optimization on both the vEdge
routers, the router closer to the client, and the router closer to the server.
This configuration is sometimes referred to as a dual-ended proxy. While it is
possible to configure TCP optimization only on the vEdge router closer to the
client, called single-ended proxy, this configuration is not recommended
because the TCP optimization process is
compromised. TCP is a bidirectional protocol and operates only when
connection-initiation messages (SYNs) are acknowledged by ACK messages in a
timely fashion. If both the client and the server are connected to the same
vEdge router, no TCP optimization is performed.
To use TCP optimization, you first enable the feature on the vEdge router. Then you define which TCP traffic to optimize.
- To use TCP optimization on a vEdge router, you must enable it: vEdge(config-system)# tcp-optimization enabled On vEdge 1000 and vEdge 2000 routers, enabling TCP optimization carves out a separate CPU core to use for performing TCP optimization, which is a CPU-intensive process.
- To enable TCP optimization for all TCP traffic in a VPN, include the following command when configuring service-side VPNs on a vEdge router:
For example, to enable TCP optimization in VPN 1
To display information about the TCP flows that the vEdge router is
optimizing, use the show app tcp-opt active-flows command to view flows that
are currently active and the show app tcp-opt expired-flows
command to view flows that were active but have expired.
Reboot the vEdge router
To enable TCP optimization for a specific flow of TCP traffic in a VPN, create
a centralized data policy that includes the optimization action. Use the match
conditions in the data policy to define the VPN
in which to optimize the TCP traffic and the traffic properties to match. The
following example enables TCP optimization on all TCP traffic destined to port
22, which is used for SSH sessions: The TCP optimization feature is enabled
based on the data policy. The data policy match needs to be created for the
TCP flows in both directions. For example, if the TCP flow is from
10.20.24.17:30000 -> 10.20.25.18:5001, the data policy to enable TCP
optimization must be created to match the reverse direction. That is from
10.20.25.18:5001 -> 10.20.24.17:30000.
Monitor TCP Optimization
If TCP optimization is enabled on a router, you can view information about how the optimization is affecting the processing and throughput of TCP data traffic on the router:
- From the Cisco vManage menu, choose Monitor > Devices.
- Cisco vManage Release 20.6.x and earlier: From the Cisco vManage menu, choose Monitor > Network.
- Choose a vEdge router.
- Click TCP Optimization–WAN Throughput. The right pane displays the WAN throughput, in megabits per second.
The right pane contains the following elements
- Chart Options—This includes the Filter Options drop-down and time periods.
- Click Filter to limit the data to display based on VPN, local TLOC color, destination IP address, remote TLOC color, and remote system IP address.
- Click a predefined or custom time period for which to display data.
- Average optimized throughput information in graphical format.
- WAN graph legend—Identifies non-optimized and TCP-optimized packet throughput.
- The right pane shows the hourly average throughput and the total optimized throughput, both in megabits per second.
- Click TCP Optimization–Flows in the left pane to display information about TCP-optimized traffic flows.
- The right pane contains the following elements:
- Chart Options—This includes the Filter drop-down and time periods. Click Filter to limit the data to display based on VPN, local TLOC color, destination IP address, remote TLOC color, and remote system
- IP address. Click a predefined or custom time period for which to display data.
- Average optimized throughput information in graphical format.
- Flows graph legend—Identifies traffic flows. The right pane contains the following elements:
- Set perspective—Select the flow direction.
- Search box—Includes the Search Options drop-down, for a Contains or Match string.
- Flow table that lists the flow destination, usage, and percentage of total traffic for all TCP-optimized flows. By default, the first six flows are selected.
- Check the checkbox for the flows to select and deselect flows to display. The graphical display in the right pane plots information for the selected flows.
- Click TCP Optimization–Connections in the left pane to display status information about all the tunnels over
- which the most TCP-optimized traffic is flowing. The right pane contains the following elements:
TCP Optimization Connections in Graphical Format
- Connection State boxes—Select the connection state or states to display TCP optimization information about.
- The right pane contains the following elements Filter criteria.
- Flow table that lists information about each of the tunnels, including the tunnel’s connection state.