vLLM-Ascend now supports prefill-decode (PD) disaggregation with EP (Expert Parallel) options. This guide take one-by-one steps to verify these features with constrained resources.
Take the Qwen3-30B-A3B model as an example, use vllm-ascend v0.10.1rc1 (with vLLM v0.10.1.1) on 3 Atlas 800T A2 servers to deploy the "1P2D" architecture. Assume the ip of the prefiller server is 192.0.0.1, and the decoder servers are 192.0.0.2 (decoder 1) and 192.0.0.3 (decoder 2). On each server, use 2 NPUs to deploy one service instance.
## Verify Multi-Node Communication Environment
### Physical Layer Requirements
- The physical machines must be located on the same WLAN, with network connectivity.
- All NPUs must be interconnected. Intra-node connectivity is via HCCS, and inter-node connectivity is via RDMA.
### Verification Process
1. Single Node Verification:
Execute the following commands on each node in sequence. The results must all be `success` and the status must be `UP`:
```bash
# Check the remote switch ports
for i in {0..7}; do hccn_tool -i $i -lldp -g | grep Ifname; done
# Get the link status of the Ethernet ports (UP or DOWN)
for i in {0..7}; do hccn_tool -i $i -link -g ; done
# Check the network health status
for i in {0..7}; do hccn_tool -i $i -net_health -g ; done
# View the network detected IP configuration
for i in {0..7}; do hccn_tool -i $i -netdetect -g ; done
# View gateway configuration
for i in {0..7}; do hccn_tool -i $i -gateway -g ; done
# View NPU network configuration
cat /etc/hccn.conf
```
2. Get NPU IP Addresses
```bash
for i in {0..7}; do hccn_tool -i $i -ip -g;done
```
3. Cross-Node PING Test
```bash
# Execute on the target node (replace 'x.x.x.x' with actual npu ip address)
for i in {0..7}; do hccn_tool -i $i -ping -g address x.x.x.x;done
```
## Generate Ranktable
The rank table is a JSON file that specifies the mapping of Ascend NPU ranks to nodes. For more details please refer to the [vllm-ascend examples](https://github.com/vllm-project/vllm-ascend/blob/main/examples/disaggregated_prefill_v1/README.md). Execute the following commands for reference.
Assume that we use device 0,1 on the prefiller server node and device 6,7 on both of the decoder server nodes. Take the following commands as an example. (`--local-device-ids` is necessary if you specify certain NPU devices on the local server.)
Run a proxy server on the same node with prefiller service instance. You can get the proxy program in the repository's examples: [load\_balance\_proxy\_server\_example.py](https://github.com/vllm-project/vllm-ascend/blob/main/examples/disaggregated_prefill_v1/load_balance_proxy_server_example.py)
```shell
python load_balance_proxy_server_example.py \
--host 192.0.0.1 \
--port 8080 \
--prefiller-hosts 192.0.0.1 \
--prefiller-port 13700 \
--decoder-hosts 192.0.0.2 192.0.0.3 \
--decoder-ports 13700 13700
```
## Verification
Check service health using the proxy server endpoint.
