CISCO 8000V Catalyst Edge Software User Guide

CISCO 8000V Catalyst Edge Software

Red Hat Enterprise Linux (RHEL) is an enterprise virtualization product produced by Red Hat. RHEL is based on Kernel-based Virtual Machine (KVM) – an open-source, full virtualization solution for Linux on x86 hardware that contains virtualization extensions. From the Cisco IOS XE 17.12.1 release, the Cisco Catalyst 8000V is also supported on Intel Atom® C3000 processor (Denverton) CPU-based servers with Intel x550 NIC on RHEL 8.4 KVM hyperv. You can run Cisco Catalyst 8000V on other x86 CPUs with different versions of hypervisor operating systems, but support is only available on these listed versions. You can install the Cisco Catalyst 8000V virtual router as a virtual machine on Red Hat KVM virtualization. The installation procedure first involves the manual creation of a VM. This is followed by installing a .iso file or a qcow2 file. You can install Cisco Catalyst 8000V in a KVM environment by using the following:

• GUI Tool: Download and install the virt manager RPM package on the KVM server. Virt-manager is a desktop user interface for managing virtual machines. Installation by using the GUI is the recommended installation method.
• Command Line Interface: In this installation method, use the command line interface to install the Cisco Catalyst 8000V VM.

Note

• Deploying the OVA template in a KVM environment is not supported.
• KUGCisco Catalyst 8000V supports the Virtio vNIC type on the KVM implementation. KVM supports a maximum of 26 vNICs.• Installation Requirements for KVM, on page 1
• Creating a KVM Instance, on page 3
• Cloning the VM, on page 6
• Increasing the KVM Configuration Performance, on page 6
• Configure the halt_poll_ns Parameter, on page 10

Installation Requirements for KVM

The KVM requirements for Cisco Catalyst 8000V using Cisco IOS XE 17.4.x releases and later are as follows:

KVM Versions

Cisco IOS XE 17.4.x releases Cisco IOS XE 17.5.x releases

Cisco IOS XE 17.6.x releases

| Linux KVM based on Red Hat Enterprise Linux 7.5 and 7.7 are recommended for release 17.4.1 – tested and meets performance benchmarks.
Cisco IOS XE 17.6.3 release| Supports SUSE Linux Enterprise Server version 15 SP3.
Cisco IOS XE 17.7.x releases Cisco IOS XE 17.8.x releases Cisco IOS XE 17.9.x releases Cisco IOS XE 17.10.x releases Cisco IOS XE 17.11.x releases

Cisco IOS XE 17.12 releases

| Linux KVM based on Red Hat Enterprise Linux 7.7 and 8.4 are recommended.

Table 1: Supported VNICs

Note
If a vNIC with an i40evf driver is used, the maximum number of physical VLANs is limited to 512, shared across all (Virtual Functions) VFs, and the number of VLANs for a VF can be further limited by the host (PF) driver for untrusted VFs. The latest Intel i40e PF driver limits untrusted VFs to a maximum of 8 VLANs/sub-interfaces.

Maximum number of vNICs supported per VM instance – 26

•  vCPUs. The following vCPU configurations are supported:
• 1 vCPU: requires minimum 4 GB RAM allocation
• 2 vCPUs: requires minimum 4 GB RAM allocation
• 4 vCPUs: requires minimum 4 GB RAM allocation
• 8 vCPUs: requires minimum 8 GB RAM allocation
• 16 vCPUs: requires minimum 8 GB RAM allocation (supported from Cisco IOS XE 17.11.1a)
• Virtual CPU cores – 1 vCPU is required
• Virtual hard disk size – 8 GB minimum
• Virtual CD/DVD drive installed (applicable only when installing using a .iso file or when providing Day0 configuration via an ISO) – required

Creating a KVM Instance

Creating the VM Using the GUI Tool

Before you begin
Download and install the virt manager RPM package on the KVM server. Download either the .qcow2 image or the .iso image from the Cisco Software Download page, and copy the file onto a local device or a network device.

Step 1
Launch the virt-manager GUI.

Step 2
Click Create a New Virtual Machine.

Step 3
Do one of the following:

• If you have downloaded the .qcow2 file, select Import Existing Disk Image.
• If you have downloaded the .iso file, select Local Install Media (ISO Image or CDROM).

Step 4
Select the Cisco Catalyst 8000V qcow2 or iso file location.

Step 5
Configure the memory and the CPU parameters.

Step 6
Configure the virtual machine storage.

Step 7
(Optional) To add additional hardware before creating the VM, select Customize Configuration before installation. The system displays the Add Hardware button. Click this button to add various hardware options, such as additional disks
or a serial port interface.

Step 8
(Optional) To add a serial console, follow the procedure as mentioned in Adding a Serial Console, on page 3.

Step 9
(Optional) If you want to customize your configuration before you create the VM, see Customizing Configuration Before Creating the VM, on page 4.

Step 10
Click Finish.

Step 11
Access the Cisco Catalyst 8000V console by performing one of the following actions:

• If you are using a virtual console, double-click the VM instance to access the VM console.
• If you are using a serial console, see Booting the Cisco Catalyst 8000V and Accessing the Console.

Adding a Serial Console

Perform this task to enable access to the Cisco Catalyst 8000V instance by adding a serial console.

Step 1
Click Add Hardware.

Step 2
Select the Serial option from the menu.

Step 3
From the Device Type drop-down menu, select TCP net console (tcp).

Step 4
Specify the port number, and select the Use Telnet checkbox.

Step 5
Click Finish.

Step 6
After adding all necessary hardware, click Begin Installation. Customizing Configuration Before Creating the VM

Before you begin

Perform the Creating the VM Using the GUI Tool, on page 3 task by using a .qcow2 or an .iso image. Before you click Finish, select the Customize configuration before installing option. The Add Hardware button appears. Proceed to this procedure which describes the optional steps after selecting the Customize Configuration Before Install option.

Step 1
Click Add Hardware.

Step 2
Select the Storage option.

Step 3
Select the Select Managed Or Other Existing Storage checkbox.

Step 4

Click Browse and navigate to the c8000v_config.iso location. This step is applicable only when you add a Day0 or bootstrap configuration.

Step 5
From the Device-type drop-down menu, select IDE CDROM.

Step 6
Click Finish.

Step 7
After adding all the necessary hardware, click Begin Installation. To perform the bootstrap configuration, see Day 0 Configuration.

Creating the VM Using CLI

• Download and install the first-install RPM package on the KVM server.
• Download the .qcow2 image from the Cisco Catalyst 8000V software installation image package and copy it onto a local or network device.

Step 1
To create the VM for a .qcow2 image, use the first-install command to create the instance and boot. Use the following syntax:

Example

• first-install \
• connect=qemu:///system \
• name=my_c8kv_vm \-os-type=linux \
• os-variant=rhel4 \ –arch=x86_64 \
• cpu host \
• vcpus=1,sockets=1,cores=1,threads=1 \
• hvm \
• ram=4096 \
• import \
• disk path=,bus=ide,format=qcow2 \
• network bridge=virbr0,model=virtio \
• no reboot

Step 2
To create the VM, for a .iso image, perform the following steps: Create an 8G disk image in the .qcow2 format using the qemu-img command.

Example
qemu-img create -f qcow2 c8000v_disk.qcow2 8G Use the first install command to install the Cisco Catalyst 8000V instance. This requires the correct permissions to create a new VM. The following example creates a 1 vCPU Cisco Catalyst 8000V with 4G of RAM, one network interface, and one serial port.

Example
virt-install \

• connect=qemu:///system \
• name=my_c8000v_vm \
• description “Test VM” \
• os-type=linux \
• os-variant=rhel4 \
• arch=x86_64 \
• cpu host \
• vcpus=1,sockets=1,cores=1,threads=1 \
• hvm \
• ram=4096 \
• cdrom= \
• disk path=c8000v_disk.qcow2,bus=virtio,size=8,sparse=false,cache=none,format=qcow2 \
• network bridge=virbr0,model=virtio \
• noreboot

The first-install command creates a new VM instance and Cisco Catalyst 8000V installs the image onto the specified disk file. After the installation is complete, the Cisco Catalyst 8000V VM is shut down. You can start the VM by executing the virsh start command. If you want to provide the day0 configuration through the c8000v_config.iso disk image, add a parameter to the virt-install command. For example, –disk path=/my/path/c8000v_config.iso,device=cdrom,bus=ide. For more information, see Day 0 Configuration.

Note
Red Hat Enterprise Linux – Setting Host Mode  Due to an issue specific to Red Hat Enterprise Linux, when you launch Cisco Catalyst 8000V in a Red Hat Enterprise Linux environment using virt-install, set the host mode as follows:

• In Red Hat Enterprise Linux 6, use:cpu host
• In Red Hat Enterprise Linux 7, use:

Cloning the VM

Issue
In a KVM environment, when you clone a Cisco Catalyst 8000V virtual machine using the virt-manager virtual machine manager, it results in a Cisco Catalyst 8000V virtual machine that you might not be able to boot. The issue is caused by an increase in the size of the cloned image size created by virtue-manager compared to the original Cisco Catalyst 8000V VM image. The extra bytes (in the KB range) cause the boot failure.

There are three workarounds

• Use the first-clone command to clone the Cisco Catalyst 8000V VM image.
• For a cloned Cisco Catalyst 8000V VM image created by virtue-manager during the bootup, select the GOLDEN image to boot instead of packages. conf.
• In the Create a new virtual machine window, deselect Allocate Entire Disk Now before the new Cisco Catalyst 8000V VM is created.
• This ensures that the cloned Cisco Catalyst 8000V VM image can boot up. However, this workaround does not support nested cloning. Use this method only on the first cloned Cisco Catalyst 8000V VM image.

Increasing the KVM Configuration Performance

• You can increase the performance for a Cisco Catalyst 8000V running in a KVM environment by modifying some settings on the KVM host.
• These settings are independent of the IOS XE configuration settings on the Cisco Catalyst 8000V instance.
• To improve the KVM configuration performance, Cisco recommends that you:
• Enable vCPU pinning
• Enable emulator pinning
• Enable numa tuning. Ensure that all the vCPUs are pinned to the physical cores on the same socket.
• Set hugepage memory backing
• Use virtio instead of IDE
• Use graphics VNC instead of SPICE
• Remove unused devices USB, tablet etc.
• Disable me balloon

Note
In addition to the above-mentioned, do the following:

Enable CPU Pinning
Increase the performance for the KVM environments by using the KVM CPU Affinity option to assign a
virtual machine to a specific processor. To use this option, configure CPU pinning on the KVM host.

• In the KVM host environment, use the following commands:
• virsh nodeinfo: To verify the host topology to find out how many vCPUs are available for pinning by using the following command.
• virsh capabilities: To verify the available vCPU numbers.
• virsh vcpupin <vcpu#> <host core#>: To pin the virtual CPUs to sets of processor cores.
• This KVM command must be executed for each vCPU on your Cisco Catalyst 8000V instance. The following example pins virtual CPU 1 to host core 3: virsh vcpupin c8000v 1 3
• The following example shows the KVM commands needed if you have aCisco Catalyst 8000V configuration with four vCPUs and the host has eight cores:
• virsh vcpupin c8000v 0 2
• virsh vcpupin c8000v 1 3
• virsh vcpupin c8000v 2 4
• virsh vcpupin c8000v 3 5

The host core number can be any number from 0 to 7. For more information, see the KVM documentation. When you configure CPU pinning, consider the CPU topology of the host server. If you are using a Cisco Catalyst 8000V instance with multiple cores, do not configure CPU pinning across multiple sockets.

Note
BIOS Settings
Optimize the performance of the KVM configuration by applying the recommended BIOS settings as mentioned in the following table: For information about Red Hat Enterprise Linux requirements, see the subsequent sections.

Host OS Settings
In the host side, Cisco recommends that you use hugepages and enable emulator pinning. The following are some of the recommended settings in the host side:

• Enable IOMMU=pt
• Enable intel_iommu=on
• Enable hugepages
• Use SR-IOV if your system supports it for higher networking performance. Please check SR-IOV limitations your system might have.

In addition to enabling hugepages and emulator pinning, the following settings are also recommended: nmi_watchdog=0 elevator=cfq transparent_hugepage=never

IO Settings
You can use SR-IOV for better performance. However, note that this might bring in some limitations such as number of virtual functions (VF), OpenStack limitations for SR-IOV like QoS support, live migration and security group support.
If you use a modern vSwitch like fd.io VPP or OVS-DPDK, reserve at least 2 cores for the VPP worker threads  or the OVS-DPDK PMD threads.  Configure the following parameters to run the VPP through command line:

• cpu host: This parameter causes the VM to inherit the host OS flags. You require libvirt 0.9.11 or greater for this to be included in the xml configuration.
• m 8192: You require 8GB RAM for optimal zero packet drop rates.
• rombar=0: To disable PXE boot delays, set rombar=0 to the end of each device option list or add “” to the device xml configuration.

Sample XMLs for KVM Performance Improvement

• Sample XML for numa tuning
• Sample XML for vCPU and emulator pinning
• Sample XML for hugepages
• 4194304
• Sample XML for virtio instead of IDE
• /usr/libexec/qemu-kvmIO Settings

You can use SR-IOV for better performance. However, note that this might bring in some limitations such as number of virtual functions (VF), OpenStack limitations for SR-IOV like QoS support, live migration and  security group support.
If you use a modern vSwitch like fd.io VPP or OVS-DPDK, reserve at least 2 cores for the VPP worker threads or the OVS-DPDK PMD threads. Configure the following parameters to run the VPP through command line: cpu host: This parameter causes the VM to inherit the host OS flags. You require libvirt 0.9.11 or greater for this to be included in the xml configuration. -m 8192: You require 8GB RAM for optimal zero packet drop rates.  rombar=0: To disable PXE boot delays, set rombar=0 to the end of each device option list or add “” to the device xml configuration.

• Sample XMLs for KVM Performance Improvement
• Sample XML for numa tuning
• Sample XML for vCPU and emulator pinning
• Sample XML for hugepages
• 4194304
• Sample XML for virtio instead of IDE
• /usr/libexec/qemu-kvm2\. When you load the module, perform the following configuration:
• rmmod kvm_intel
• rmmod kvm
• modprobe kvm halt_poll_ns=0
• mpdprobe kvm_intel

When you boot the device, add kvm.halt_poll_ns= in the parameters section of grub2.

References

• 1133155 – virt-install --cpu host should use host-model if libvirt supports it
• Cisco Catalyst 8000V Edge Software Installation And Configuration Guide - Configuring Console Access [Cisco Catalyst 8000V Edge Software] - Cisco

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