Implement flat-mode network model with BGP support

This document describes how to implement a flat-mode network model with Border Gateway Protocol (BGP) support. When you implement a network model with BGP support, BGP dynamically ensures that pods in different L2 domains can communicate with each other.

For more information about flat-mode network models, see Flat vs island mode network models .

How to implement a flat-mode network that uses BGP

To implement a cluster on a flat-mode network model with BGP support, make the following changes to the cluster's cluster.yaml file:

• Set the spec.clusterNetwork.advancedNetworking field to true in the cluster resource.
• Set the spec.clusterNetwork.flatIPv4 field to true in the cluster resource.
• When spec.clusterNetwork.flatIPv4 is set to true , the field spec.clusterNetwork.pods.cidrBlocks is ignored and can be omitted. However, you will need to define a ClusterCIDRConfigs section in the yaml file (per-node, per-nodepool and/or per-cluster). See the example cluster.yaml file below for details.
• Append a NetworkGatewayGroup resource to the cluster.yaml file and specify the floating IPs to use for BGP peering. Ensure that the name is default and the namespace is the cluster namespace.
• Append FlatIPMode and BGPPeer resources to the cluster.yaml file. The name of the FlatIPMode resource must be default , and all resources must be in the cluster namespace.

For Preview, only IPv4 BGP Peers and sessions are supported. However, if your environment supports Multiprotocol BGP (MP-BGP), IPv4 and IPv6 routes can be advertised over these IPv4 sessions. IPv6 BGP Peer configuration isn't supported.

The following excerpt of a cluster.yaml file shows how to implement flat-mode networking with BGP support. Note that the IP addresses that appear in this excerpt are only examples and you will need to replace them with your own IP addresses:

  apiVersion 
 : 
  
 baremetal.cluster.gke.io/v1 
 kind 
 : 
  
 Cluster 
 metadata 
 : 
  
 name 
 : 
  
 bm 
  
 namespace 
 : 
  
 cluster-bm 
 spec 
 : 
 ... 
  
 clusterNetwork 
 : 
  
 advancedNetworking 
 : 
  
 true 
  
 flatIPv4 
 : 
  
 true 
  
 ... (other cluster config omitted) 
 apiVersion 
 : 
  
 networking.gke.io/v1 
 kind 
 : 
  
 NetworkGatewayGroup 
 metadata 
 : 
  
 name 
 : 
  
 default 
  
 namespace 
 : 
  
 cluster-bm 
 spec 
 : 
  
 floatingIPs 
 : 
  
 - 
  
 10.0.1.100 
  
 - 
  
 10.0.2.100 
 .... 
 apiVersion 
 : 
  
 baremetal.cluster.gke.io/v1alpha1 
 kind 
 : 
  
 FlatIPMode 
 metadata 
 : 
  
 name 
 : 
  
 default 
  
 namespace 
 : 
  
 cluster-bm 
 spec 
 : 
  
 enableBGPIPv4 
 : 
  
 true 
  
 enableBGPIPv6 
 : 
  
 false 
  
 peerSelector 
 : 
  
 flatip-peer 
 : 
  
 "true" 
 .... 
 apiVersion 
 : 
  
 networking.gke.io/v1 
 kind 
 : 
  
 BGPPeer 
 metadata 
 : 
  
 name 
 : 
  
 bgppeer1 
  
 namespace 
 : 
  
 cluster-bm 
  
 labels 
 : 
  
 flatip-peer 
 : 
  
 "true" 
 spec 
 : 
  
 localASN 
 : 
  
 65001 
  
 peerASN 
 : 
  
 65000 
  
 peerIP 
 : 
  
 10.0.1.254 
  
 sessions 
 : 
  
 2 
 .... 
 apiVersion 
 : 
  
 networking.gke.io/v1 
 kind 
 : 
  
 BGPPeer 
 metadata 
 : 
  
 name 
 : 
  
 bgppeer2 
  
 namespace 
 : 
  
 cluster-bm 
  
 labels 
 : 
  
 flatip-peer 
 : 
  
 "true" 
 spec 
 : 
  
 localASN 
 : 
  
 65001 
  
 peerASN 
 : 
  
 65000 
  
 peerIP 
 : 
  
 10.0.2.254 
  
 sessions 
 : 
  
 2 
 .... 
 apiVersion 
 : 
  
 baremetal.cluster.gke.io/v1alpha1 
 kind 
 : 
  
 ClusterCIDRConfig 
 metadata 
 : 
  
 name 
 : 
  
 cluster-wide-1 
  
 namespace 
 : 
  
 cluster-bm 
 spec 
 : 
  
 ipv4 
 : 
  
 cidr 
 : 
  
 "192.168.0.0/16" 
  
 perNodeMaskSize 
 : 
  
 24