Gossip Protocol

Gossip is a peer-to-peer communication protocol in which nodes periodically exchange state information about themselves and about other nodes they know about. The gossip process runs every second and exchanges state messages with up to three other nodes in the cluster. The nodes exchange information about themselves and about the other nodes that they have gossiped about, so all nodes quickly learn about all other nodes in the cluster. A gossip message has a version associated with it, so that during a gossip exchange, older information is overwritten with the most current state for a particular node. 

Here is how the gossiper works: 

1. Once per second, the gossiper will choose a random node in the cluster and initi‐ alize a gossip session with it. Each round of gossip requires three messages.

2. The gossip initiator sends its chosen friend a GossipDigestSyn message. 

3. When the friend receives this message, it returns a GossipDigestAck message.

4. When the initiator receives the ack message from the friend, it sends the friend a GossipDigestAck2 message to complete the round of gossip.

more -> https://docs.datastax.com/en/cassandra-oss/3.x/cassandra/architecture/archGossipAbout.html

ubuntu@ds201-node1:~$ /home/ubuntu/node1/resources/cassandra/bin/nodetool describecluster

Cluster Information:

Name: Test Cluster

Snitch: com.datastax.bdp.snitch.DseDelegateSnitch

DynamicEndPointSnitch: enabled

Partitioner: org.apache.cassandra.dht.Murmur3Partitioner

Schema versions:

00abff53-2837-363a-abd8-b75594c5631e: [127.0.0.1, 127.0.0.2, 127.0.0.3, 127.0.0.4]

ubuntu@ds201-node1:~$ /home/ubuntu/node1/resources/cassandra/bin/nodetool status aug_space;

Datacenter: Cassandra

=====================

Status=Up/Down

|/ State=Normal/Leaving/Joining/Moving

--  Address    Load       Tokens       Owns (effective)  Host ID                               Rack

UN  127.0.0.1  380.53 KiB  1            77.1%             39e7bbfa-2250-41a2-975b-f6a32e8677d0  rack1

UN  127.0.0.2  365.82 KiB  1            89.2%             606d2798-fa58-4656-bcba-5ef8a9c5012f  rack1

UN  127.0.0.3  335.28 KiB  1            89.2%             ab14e681-7a13-4027-8b4c-0f40a2428a85  rack1

UN  127.0.0.4  323.7 KiB  1            44.6%             a411cdb0-f8a1-4f4b-ac44-c1b4ff703124  rack1

ubuntu@ds201-node1:~$ /home/ubuntu/node1/resources/cassandra/bin/nodetool gossipinfo;

/127.0.0.1

  generation:1694106957

  heartbeat:120749

  STATUS:25:NORMAL,0

  LOAD:120733:389660.0

  SCHEMA:117734:00abff53-2837-363a-abd8-b75594c5631e

  DC:41:Cassandra

  RACK:18:rack1

  RELEASE_VERSION:4:4.0.0.2284

  NATIVE_TRANSPORT_ADDRESS:3:127.0.0.1

  X_11_PADDING:92056:{"dse_version":"6.0.0","workloads":"Cassandra","workload":"Cassandra","active":"true","server_id":"08-00-27-32-1E-DD","graph":false,"health":0.9}

  NET_VERSION:1:256

  HOST_ID:2:39e7bbfa-2250-41a2-975b-f6a32e8677d0

  NATIVE_TRANSPORT_READY:54:true

  NATIVE_TRANSPORT_PORT:6:9041

  NATIVE_TRANSPORT_PORT_SSL:7:9041

  STORAGE_PORT:8:7000

  STORAGE_PORT_SSL:9:7001

  JMX_PORT:10:7199

  TOKENS:24:<hidden>

/127.0.0.2

  generation:1694107334

  heartbeat:120358

  STATUS:51:NORMAL,4223372036854775807

  LOAD:120300:374600.0

  SCHEMA:117343:00abff53-2837-363a-abd8-b75594c5631e

  DC:65:Cassandra

  RACK:18:rack1

  RELEASE_VERSION:4:4.0.0.2284

  NATIVE_TRANSPORT_ADDRESS:3:127.0