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Feature #4821

closed

PPPoE WANs do not take full advantage of NIC driver queues for receiving traffic

Added by Jim Pingle over 8 years ago. Updated about 3 years ago.

Status:
Closed
Priority:
Low
Assignee:
Category:
Interfaces
Target version:
-
Start date:
07/08/2015
Due date:
% Done:

0%

Estimated time:
Plus Target Version:
Release Notes:

Description

On PPPoE WANs packets are only received on one NIC driver queue (queue0) while packets are transmitted from all queues (queue0 and queue1). This has been observed on multiple systems with PPPoE-based WANs and igb(4) NICs, though it may also affect L2TP and PPTP type WANs since they all use mpd.

On my WAN (igb1 with PPPoE on top):

dev.igb.1.queue0.tx_packets: 2535085
dev.igb.1.queue0.rx_packets: 5365670
dev.igb.1.queue1.tx_packets: 2711996
dev.igb.1.queue1.rx_packets: 0

Other non-PPPoE interfaces on the same unit, including additional WANs, show activity in all driver queues.

On another, different, firewall with igb(4) NICs and PPPoE, the same condition is present:

dev.igb.0.queue0.tx_packets: 8504662
dev.igb.0.queue0.rx_packets: 29342831
dev.igb.0.queue1.tx_packets: 3543617
dev.igb.0.queue1.rx_packets: 0

On lower speed WANs there are no negative effects, but on higher-speed PPPoE WANs such as gigabit links it can cause some disparity where traffic is transmitted at the expected rate but not received at the expected rate.

How to check (on systems with igb NICs):

sysctl -a | grep '\.igb\..*x_pack'

Look for the PPPoE WAN physical interface and check if has activity in the tx queue1 and rx queue1, or only the tx queue1 (or higher queues)

Currently only tested on pfSense 2.2.3-RELEASE amd64 images, needs more feedback/testing to confirm if it happens on additional versions/architectures.

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