使用定向无线中继时吞吐量骤降至接近零的技术问询

Alright, let's tackle this throughput drop issue with your Lightpointe AireLink 60 SX point-to-point wireless links. I’ve worked with similar millimeter-wave setups before, so here’s a structured, hands-on troubleshooting plan to get your 1Gbit/s connection back on track:

Wireless links live or die by their physical layer, especially 60GHz millimeter-wave gear which is hyper-sensitive to disruptions:

• Verify Unobstructed Line-of-Sight (LoS): Even 177m is short, but check if any new obstacles (construction scaffolding, overgrown tree branches, temporary structures) popped up between the two antennas. A single leaf cluster can tank 60GHz signal strength. Use binoculars to visually inspect the path, or log into the AireLink web UI to check RSSI (Received Signal Strength Indicator) and SNR (Signal-to-Noise Ratio). Aim for an SNR above 25dB for stable 1Gbps throughput.
• Re-align Antennas: A tiny shift (even 1-2 degrees) can cause catastrophic signal loss. Access the RF diagnostics tab in the web UI, then slowly adjust the azimuth/elevation of one antenna while monitoring RSSI. Lock it in when you get the highest, most stable reading—repeat for the other end.
• Hardware Health Check:
  • Feel the radio units: If they’re too hot to hold, overheating is throttling performance. Ensure proper ventilation around both devices.
  • Swap Ethernet cables with known-good Cat6a cables (1Gbps needs shielded, high-quality cabling to avoid interference).
  • Power-cycle both radios first—transient firmware glitches often clear up with a simple reboot.

Sharing a single /24 subnet across the link can introduce broadcast-related problems:

• Check for Broadcast/Multicast Storms: DHCP requests, ARP floods, or misconfigured IoT devices can flood the wireless link with unneeded traffic. Use the AireLink’s traffic monitoring tool to see if broadcast/multicast traffic makes up more than 10% of total throughput.
  • Fix: Enable broadcast/multicast filtering on both radios (most point-to-point gear lets you limit or prioritize this traffic). For a longer-term fix, split the subnet into two smaller ranges (e.g., 192.168.0.0/25 for Site A, 192.168.0.128/25 for Site B) and use a router between them to contain broadcast domains.
• Duplicate IP Addresses: A conflicting IP can cause ARP flapping and traffic chaos. Run arp -a on a server at each site to check for matching IP/MAC pairs, or review DHCP server logs for duplicate lease complaints.
• VLAN Mismatches: If you’re using VLANs, confirm both radios have identical tagging settings. Mismatched VLANs will silently drop traffic without triggering obvious errors.

Your mix of SMB, VOIP, and Exchange traffic can strain the link if not prioritized properly:

• QoS Configuration: If VOIP calls spiked around the time of the drop, misconfigured QoS might be throttling all traffic to prioritize voice. Log into the AireLink UI and set up QoS rules: mark VOIP traffic with DSCP EF (46) and assign it the highest priority, while limiting non-critical SMB transfers during peak hours.
• MTU Mismatch: If you enabled jumbo frames on some devices but not others, packet fragmentation will kill throughput. Ensure all devices (radios, servers, clients) use the same MTU size—stick to 1500 if you haven’t fully tested jumbo frames end-to-end.

Outdated software often causes intermittent performance issues:

• Update Radio Firmware: Check Lightpointe’s official resources for the latest firmware for the AireLink 60 SX. Update one radio at a time (to avoid losing connectivity entirely) and follow the vendor’s step-by-step instructions—this fixes known bugs related to throughput and signal stability.
• Check Core Server Health: If the DHCP/DNS server at Site A is lagging, clients will send repeated requests that flood the link. Verify the server is responding quickly to DHCP leases and DNS queries.

• Packet Capture: Use Wireshark on a client at each site to capture traffic across the link. Look for excessive TCP retransmissions, CRC errors, or dropped packets—these indicate underlying packet loss on the wireless link.
• Vendor Diagnostics: Use the AireLink’s built-in error rate monitoring to check for RF interference from nearby 60GHz devices (like other wireless bridges or industrial radar systems).

Start with the physical layer checks—they’re the fastest to rule out and are almost always the root cause with millimeter-wave links. Let me know which step leads you to the issue!

内容的提问来源于stack exchange，提问作者Stephan