error 111- Connection refused for cassandra

I am learning to use Datastax AstraDB to vector storage. I am trying to follow a tutorial. I am using cassio to connect with astraDB using the following code:

ASTRA_DB_APPLICATION_TOKEN = os.environ.get("ASTRA_DB_APPLICATION_TOKEN")
ASTRA_DB_ID = os.environ.get("ASTRA_DB_ID")
cassio.init(token=ASTRA_DB_APPLICATION_TOKEN,database_id=ASTRA_DB_ID)

There seems to be no warning or error for the above code. But when I try to store the vectors, I get the error

from langchain.vectorstores.cassandra import Cassandra
embeddings = OllamaEmbeddings(model="llama3")
session = None
astra_vector_store = Cassandra(
    embedding=embeddings,
    table_name="groq_project",
    session=session
)

Here is the full error:

---------------------------------------------------------------------------
ConnectError                              Traceback (most recent call last)
File /home/time/miniconda3/envs/bias-vision/lib/python3.9/site-packages/httpx/_transports/default.py:72, in map_httpcore_exceptions()
     71 try:
---> 72     yield
     73 except Exception as exc:

File /home/time/miniconda3/envs/bias-vision/lib/python3.9/site-packages/httpx/_transports/default.py:236, in HTTPTransport.handle_request(self, request)
    235 with map_httpcore_exceptions():
--> 236     resp = self._pool.handle_request(req)
    238 assert isinstance(resp.stream, typing.Iterable)

File /home/time/miniconda3/envs/bias-vision/lib/python3.9/site-packages/httpcore/_sync/connection_pool.py:256, in ConnectionPool.handle_request(self, request)
    255     self._close_connections(closing)
--> 256     raise exc from None
    258 # Return the response. Note that in this case we still have to manage
    259 # the point at which the response is closed.

File /home/time/miniconda3/envs/bias-vision/lib/python3.9/site-packages/httpcore/_sync/connection_pool.py:236, in ConnectionPool.handle_request(self, request)
    234 try:
    235     # Send the request on the assigned connection.
--> 236     response = connection.handle_request(
    237         pool_request.request
    238     )
    239 except ConnectionNotAvailable:
...
     86     raise
     88 message = str(exc)
---> 89 raise mapped_exc(message) from exc

ConnectError: [Errno 111] Connection refused