Calico Packet drops observed in the network.

What is Calico Packet drops observed in the network.

Understanding Calico

Calico is a powerful open-source networking and network security solution for containers, virtual machines, and native host-based workloads. It is widely used in Kubernetes environments to provide scalable and efficient networking with support for network policy enforcement.

Identifying the Symptom

When using Calico, you might encounter network issues such as packet drops. This can manifest as intermittent connectivity problems, increased latency, or complete loss of communication between pods or nodes.

Common Error Encountered

One common error related to packet drops is the CALICO-1008 issue, which is often caused by an MTU mismatch in the network configuration.

Explaining the Issue: CALICO-1008

The error code CALICO-1008 indicates that there is a mismatch in the Maximum Transmission Unit (MTU) settings across the network. MTU defines the largest size of a packet that can be transmitted over the network. A mismatch can lead to packet fragmentation or drops, causing network instability.

Why MTU Mismatch Occurs

MTU mismatch can occur due to different network interfaces having different MTU settings, or when the MTU settings on the nodes do not align with the network infrastructure requirements.

Steps to Fix the MTU Mismatch Issue

To resolve the CALICO-1008 issue, you need to ensure that the MTU settings are consistent across your network. Follow these steps:

Step 1: Check Current MTU Settings

First, verify the current MTU settings on your nodes. You can do this by running the following command on each node:

ip link show

Look for the mtu value in the output for each network interface.

Step 2: Determine the Correct MTU Value

Consult your network infrastructure documentation or network administrator to determine the correct MTU value that should be used across your network. This value is often 1500 for Ethernet networks but may vary based on your specific setup.

Step 3: Update MTU Settings

Once you have the correct MTU value, update the MTU settings on each node. Use the following command to set the MTU:

sudo ip link set dev <interface-name> mtu <desired-mtu-value>

Replace <interface-name> with the name of your network interface and <desired-mtu-value> with the correct MTU value.

Step 4: Verify Changes

After updating the MTU settings, verify that the changes have been applied correctly by running:

ip link show

Ensure that the mtu value matches the desired MTU value across all nodes.

Additional Resources

For more information on configuring MTU settings in Calico, refer to the official Calico MTU documentation. You can also explore the Calico Kubernetes Getting Started Guide for further insights into setting up and managing Calico in Kubernetes environments.