nconnect trunking works even when v4.1-trunking is disabled on ONTAP
// "nconnect=N on the client causes multi-TCP-stream trunking to the same server IP even when v4.1-trunking is disabled on the ONTAP SVM."
Overview
When nfs.v4.1-trunking is disabled on an ONTAP SVM, the NFS client can still open multiple TCP connections to the same server using the nconnect mount option (e.g. nconnect=4) and bind these connections to the same NFSv4.1 session.
ONTAP permits these extra connections — it does not reject or reset them. The client establishes N TCP streams, all to the same server IP address.
Key distinction vs. true session trunking
| Feature | v4.1-trunking enabled | nconnect only (trunking disabled) |
|---|---|---|
| Multiple TCP streams | Yes | Yes |
| Multiple server IPs (multi-path) | Yes | No — same IP only |
| Requires multiple LIFs / IPs | Yes | No |
| Client parallelism benefit | Yes | Yes (same NIC/path) |
Practical implication
nconnect is useful for increasing per-mount concurrency even without the multi-path session-trunking feature. The performance benefit comes from parallelizing NFS RPC dispatch across N TCP streams rather than from distributing load across multiple network paths.
True session trunking (with v4.1-trunking enabled and multiple LIF IPs) adds the further benefit of aggregating bandwidth across multiple physical paths into a single mount — something nconnect alone cannot achieve.