Overview of Accelerated Networking
What is Accelerated Networking
Accelerated networking enables single root I/O virtualization (SR-IOV) on VMs such as a Cisco CSR 1000V VM. The accelerated networking path bypasses the virtual switch, increases the speed of network traffic, improves the networking performance, and reduces the network latency and jitter.
Usually, all the networking traffic in and out of the VM traverses the host and the virtual switch. However, with accelerated networking, the network traffic arrives at the virtual machine's network interface (NIC), and is then forwarded to the VM. Thus, all the network policies that the virtual switch applies are now offloaded and applied in the hardware.
For more information about the accelerated networking functionality that is available in Microsoft Azure, see Create a Linux VM With Accelerated Networking Using Azure CLI.
Accelerated networking is available in CSR 1000V public cloud deployments and in government cloud deployments for a Cisco CSR 1000V version Cisco IOS XE Gibraltar 16.10.1 or later.
If you are upgrading to Cisco IOS XE Gibraltar 16.10.x and 16.11.x, use a Microsoft Azure Accelerated Networking (AN) .bin image from www.cisco.com. For example, csr1000v-universalk9azn.16.10.x.SSA.bin.
Support for Azure-PMD
The Azure-PMD (Poll Mode Driver) functionality on Azure offers a faster, user-space packet processing framework for performance-intensive applications. This framework bypasses the virtual machine's kernel network stack. In a typical packet processing that uses the kernel network stack, the process is interrupt-driven. When the network interface receives the incoming packets, there is an interruption to the kernel to process the packet and a context switch from the kernel space to the user space. Azure-PMD eliminates the context switching and the interrupt-driven method in favor of a user-space implementation that uses poll mode drivers for fast packet processing.
Starting the Cisco IOS XE 17.3 release, you can enable the Azure-PMD functionality for CSR 1000V running on Microsoft Azure. This functionality increases the performance of the CSR 1000V when compared to the previous versions that use accelerated networking.
Supported VM Instance Types
The following VM instance types support the Accelerated Networking functionality:
IOS XE Version | Supported VM Instance Types |
---|---|
16.12.x |
DS2_v2 / D2_v2 DS3_v2 / D3_v2 DS4_v2 / D4_v2 |
17.1.x |
DS2_v2 / D2_v2 DS3_v2 / D3_v2 DS4_v2 / D4_v2 |
17.2.x |
DS2_v2 / D2_v2 DS3_v2 / D3_v2 DS4_v2 / D4_v2 |
17.3.x |
DS2_v2 / D2_v2 DS3_v2 / D3_v2 DS4_v2 / D4_v2 F16s_v2 F32s_v2 |
Support for Mellanox Hardware
Microsoft Azure cloud has two types of hardware that support the accelerated networking functionality. The following table specifies the Mellanox versions supported for the accelerated networking functionality.
IOS XE Version |
Support for Accelerated Networking |
Support for MLX4 |
Support for MLX5 |
Support for Azure-PMD |
---|---|---|---|---|
16.10.x |
Yes |
Yes |
No |
No |
16.11.x |
Yes |
Yes |
No |
No |
16.12.x |
Yes |
Yes |
Yes |
No |
17.1 |
Yes |
Yes |
Yes |
No |
17.2 |
Yes |
Yes |
Yes |
No |
17.3 |
Yes |
Yes |
Yes |
Yes |
![]() Note |
MLX4 (Mellanox 4) is also referred to as ~ connectx3 = cx3, and MLX5 (Mellanox 5) is also referred as connectx4 = cx4. You can't specify which NIC Azure uses MLX4 or MLX5 for your VM deployment. Cisco recommends that you upgrade to CSR 1000V 16.12 version or later to use the accelerated networking functionality. |