Repo sync failing with PLP0000: Importer indicated a failed response

Environment

• Red Hat Satellite

Issue

• When attempting to sync Redhat repositories from the Satellite GUI, below Error message is displayed.

Yum Metadata: HTTPSConnectionPool(host='cdn.redhat.com', port=443): Read timed out.
Errors:
PLP0000: Importer indicated a failed response

Exception:
Katello::Errors::PulpError: PLP0000: Importer indicated a failed response
Backtrace:
/opt/theforeman/tfm/root/usr/share/gems/gems/katello-3.0.0.105/app/lib/actions/pulp/abstract_async_task.rb:121:in `block in external_task='
/opt/theforeman/tfm/root/usr/share/gems/gems/katello-3.0.0.105/app/lib/actions/pulp/abstract_async_task.rb:119:in `each'
/opt/theforeman/tfm/root/usr/share/gems/gems/katello-3.0.0.105/app/lib/actions/pulp/abstract_async_task.rb:119:in `external_task='
/opt/theforeman/tfm/root/usr/share/gems/gems/katello-3.0.0.105/app/lib/actions/pulp/repository/sync.rb:48:in `external_task='
/opt/theforeman/tfm/root/usr/share/gems/gems/dynflow-0.8.13.3/lib/dynflow/action/polling.rb:98:in `poll_external_task_with_rescue'
/opt/theforeman/tfm/root/usr/share/gems/gems/dynflow-0.8.13.3/lib/dynflow/action/polling.rb:21:in `run'
/opt/theforeman/tfm/root/usr/share/gems/gems/dynflow-0.8.13.3/lib/dynflow/action/cancellable.rb:9:in `run'
/opt/theforeman/tfm/root/usr/share/gems/gems/katello-3.0.0.105/app/lib/actions/pulp/abstract_async_task.rb:45:in `run'
/opt/theforeman/tfm/root/usr/share/gems/gems/dynflow-0.8.13.3/lib/dynflow/action.rb:506:in `block (3 levels) in execute_run'
/opt/theforeman/tfm/root/usr/share/gems/gems/dynflow-0.8.13.3/lib/dynflow/middleware/stack.rb:26:in `call'
/opt/theforeman/tfm/root/usr/share/gems/gems/dynflow-0.8.13.3/lib/dynflow/middleware/stack.rb:26:in `pass'
/opt/theforeman/tfm/root/usr/share/gems/gems/dynflow-0.8.13.3/lib/dynflow/middleware.rb:17:in `pass'

Resolution

• Since SACK was not set on Satellite server when performing TCP Handshake to CDN thus enabling SACK flag on Satellite Server resolves the issue.

Note: To enable SACK on satellite server,
Edit /etc/sysctl.conf file and set 'net.ipv4.tcp_sack = 1'

For more KB articles/solutions related to Red Hat Satellite 6.x Repository Issues, please refer to the Red Hat Satellite Consolidated Troubleshooting Article for Red Hat Satellite 6.x Repository Issues.

Root Cause

• Packets were getting dropped during client <<<----->>> Red Hat CDN sync.
• No ACK packets sent to cdn from Satellite Server.
• More TCP retransmission's sent to satellite from Red Hat cdn.

Diagnostic Steps

• SACK is not set during TCP handshake.
• SSL ports were proper and SSL handshake between Satellite and CDN was proper.

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