我有一台 Mellanox 100gb/s 交换机（运行 Cumulus Linux 4.1），用于连接多台服务器，每台服务器都配有 Mellanox ConnectX 5 100gb/s 卡。这些服务器通过 DAC 电缆连接到交换机。在交换机工作时，我只能获得 25Gb/s 的端口速度。
我检查了交换机，发现每个 QSFP 交换机端口似乎都在运行 4 个单独的 25Gb/s 端口，如下表所示。服务器连接到端口 swp1 至 8。
cumulus@cumulus:mgmt:~$ net show interface all
State Name Spd MTU Mode LLDP Summary
----- ------- ---- ----- --------- --------------------------- ------------------
UP lo N/A 65536 Loopback IP: 127.0.0.1/8
lo IP: ::1/128
UP eth0 100M 1500 Mgmt SomeOtherSwitch (24) Master: mgmt(UP)
eth0 IP: 172.20.72.5/24
UP swp1s0 25G 9216 Trunk/L2 Master: bridge(UP)
DN swp1s1 N/A 9216 Default
DN swp1s2 N/A 9216 Default
DN swp1s3 N/A 9216 Default
UP swp2s0 25G 9216 Trunk/L2 Master: bridge(UP)
DN swp2s1 N/A 9216 Default
DN swp2s2 N/A 9216 Default
DN swp2s3 N/A 9216 Default
UP swp3s0 25G 9216 Trunk/L2 Master: bridge(UP)
DN swp3s1 N/A 9216 Default
DN swp3s2 N/A 9216 Default
DN swp3s3 N/A 9216 Default
UP swp4s0 25G 9216 Trunk/L2 Master: bridge(UP)
DN swp4s1 N/A 9216 Default
DN swp4s2 N/A 9216 Default
DN swp4s3 N/A 9216 Default
UP swp5s0 25G 9216 Trunk/L2 Master: bridge(UP)
DN swp5s1 N/A 9216 Default
DN swp5s2 N/A 9216 Default
DN swp5s3 N/A 9216 Default
UP swp6s0 25G 9216 Trunk/L2 Master: bridge(UP)
DN swp6s1 N/A 9216 Default
DN swp6s2 N/A 9216 Default
DN swp6s3 N/A 9216 Default
UP swp7s0 25G 9216 Trunk/L2 Master: bridge(UP)
DN swp7s1 N/A 9216 Default
DN swp7s2 N/A 9216 Default
DN swp7s3 N/A 9216 Default
UP swp8s0 25G 9216 Trunk/L2 Master: bridge(UP)
DN swp8s1 N/A 9216 Default
DN swp8s2 N/A 9216 Default
根据 ethtool，服务器通过其 ConnectX 卡支持所需的 100gbps 链接模式：
Settings for enp175s0f0:
Supported ports: [ Backplane ]
Supported link modes: 1000baseKX/Full
10000baseKR/Full
40000baseKR4/Full
40000baseCR4/Full
40000baseSR4/Full
40000baseLR4/Full
25000baseCR/Full
25000baseKR/Full
25000baseSR/Full
50000baseCR2/Full
50000baseKR2/Full
100000baseKR4/Full
100000baseSR4/Full
100000baseCR4/Full
100000baseLR4_ER4/Full
Supported pause frame use: Symmetric
Supports auto-negotiation: Yes
Supported FEC modes: Not reported
Advertised link modes: 1000baseKX/Full
10000baseKR/Full
40000baseKR4/Full
40000baseCR4/Full
40000baseSR4/Full
40000baseLR4/Full
25000baseCR/Full
25000baseKR/Full
25000baseSR/Full
50000baseCR2/Full
50000baseKR2/Full
100000baseKR4/Full
100000baseSR4/Full
100000baseCR4/Full
100000baseLR4_ER4/Full
Advertised pause frame use: Symmetric
Advertised auto-negotiation: Yes
Advertised FEC modes: Not reported
Link partner advertised link modes: Not reported
Link partner advertised pause frame use: No
Link partner advertised auto-negotiation: Yes
Link partner advertised FEC modes: Not reported
Speed: 25000Mb/s
Duplex: Full
Port: Direct Attach Copper
PHYAD: 0
Transceiver: internal
Auto-negotiation: on
Supports Wake-on: d
Wake-on: d
Current message level: 0x00000004 (4)
link
Link detected: yes
我在设置时是否遗漏了什么？我尝试手动将链接速度设置为 100000，但网络没有任何变化。
答案1
我找到了对 /etc/cumulus/ports.conf 的引用，看起来有问题的端口实际上被设置为 4x 25G 端口运行。
我已将此配置文件编辑为更符合我喜好的内容，下面是适合我的配置：
cumulus@cumulus:mgmt:~$ cat /etc/cumulus/ports.conf
# ports.conf --
#
# This file controls port speed, aggregation and subdivision.
#
# For example, the QSFP28 ports can be split into multiple interfaces. This
# file sets the number of interfaces per port and the speed of those interfaces.
#
# You must reload switchd for changes to take effect.
#
# mlnx,x86_MSN2100 has:
# 16 QSFP28 ports numbered 1-16
# These ports are configurable as 40G, 50G, 2x50G, or 100G; or a subset
# of them can be split into 4x25G or 4x10G.
#
# QSFP28 ports
#
# <port label> = [40G|50G|100G]
# or when split = [2x50G|4x10G|4x25G]
1=100G
2=100G
3=100G
4=100G
5=100G
6=100G
7=100G
8=100G
9=100G
10=100G
11=100G
12=100G
13=100G
14=100G
15=100G
16=4x10G