我有一个 mythbuntu 14.04 服务器。
# uname -a
Linux KISE-055 3.16.0-55-generic #74~14.04.1-Ubuntu SMP Tue Nov 17 10:15:59 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux
我已将 MTU 设置为 4000 而不是 1500 以获取巨型数据包...
# ip link
...
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 4000 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000
link/ether 90:fb:a6:eb:d7:f3 brd ff:ff:ff:ff:ff:ff
我设置了 MTU/etc/network/interfaces
# cat /etc/network/interfaces
auto lo
iface lo inet loopback
#primary wired interface
auto eth0
iface eth0 inet dhcp
post-up /sbin/ifconfig eth0 mtu 4000
在‘ifconfig’的输出中可以看到……
~$ ifconfig
eth0 Link encap:Ethernet HWaddr 90:fb:a6:eb:d7:f3
inet addr:192.168.0.55 Bcast:192.168.0.255 Mask:255.255.255.0
inet6 addr: fe80::92fb:a6ff:feeb:d7f3/64 Scope:Link
⇛ ⇛ UP BROADCAST RUNNING MULTICAST MTU:4000 Metric:1 ⇚ ⇚
RX packets:43654 errors:0 dropped:0 overruns:0 frame:0
TX packets:41807 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:29877609 (29.8 MB) TX bytes:21276131 (21.2 MB)
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:65536 Metric:1
RX packets:2010 errors:0 dropped:0 overruns:0 frame:0
TX packets:2010 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:279223 (279.2 KB) TX bytes:279223 (279.2 KB)
但系统不响应来自 LAN 上其他计算机的巨型数据包。因此，所有客户端都必须使用 1500 的 MTU 才能与服务器通信。
这是尼克……
02:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 03)
Subsystem: Foxconn International, Inc. Device 0e22
Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR+ FastB2B- DisINTx+
Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
Latency: 0, Cache Line Size: 64 bytes
Interrupt: pin A routed to IRQ 47
Region 0: I/O ports at e800 [size=256]
Region 2: Memory at fafff000 (64-bit, prefetchable) [size=4K]
Region 4: Memory at faff8000 (64-bit, prefetchable) [size=16K]
Expansion ROM at fdfe0000 [disabled] [size=128K]
Capabilities: [40] Power Management version 3
Flags: PMEClk- DSI- D1+ D2+ AuxCurrent=375mA PME(D0+,D1+,D2+,D3hot+,D3cold+)
Status: D0 NoSoftRst+ PME-Enable- DSel=0 DScale=0 PME-
Capabilities: [50] MSI: Enable+ Count=1/1 Maskable- 64bit+
Address: 00000000fee0200c Data: 4142
Capabilities: [70] Express (v2) Endpoint, MSI 01
DevCap: MaxPayload 256 bytes, PhantFunc 0, Latency L0s <512ns, L1 <64us
ExtTag- AttnBtn- AttnInd- PwrInd- RBE+ FLReset-
DevCtl: Report errors: Correctable- Non-Fatal- Fatal- Unsupported-
RlxdOrd- ExtTag- PhantFunc- AuxPwr- NoSnoop-
MaxPayload 128 bytes, MaxReadReq 512 bytes
DevSta: CorrErr+ UncorrErr- FatalErr- UnsuppReq+ AuxPwr+ TransPend-
LnkCap: Port #0, Speed 2.5GT/s, Width x1, ASPM L0s L1, Exit Latency L0s <512ns, L1 <64us
ClockPM+ Surprise- LLActRep- BwNot-
LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk+
ExtSynch- ClockPM- AutWidDis- BWInt- AutBWInt-
LnkSta: Speed 2.5GT/s, Width x1, TrErr- Train- SlotClk+ DLActive- BWMgmt- ABWMgmt-
DevCap2: Completion Timeout: Not Supported, TimeoutDis+, LTR-, OBFF Not Supported
DevCtl2: Completion Timeout: 50us to 50ms, TimeoutDis-, LTR-, OBFF Disabled
LnkCtl2: Target Link Speed: 2.5GT/s, EnterCompliance- SpeedDis-
Transmit Margin: Normal Operating Range, EnterModifiedCompliance- ComplianceSOS-
Compliance De-emphasis: -6dB
LnkSta2: Current De-emphasis Level: -6dB, EqualizationComplete-, EqualizationPhase1-
EqualizationPhase2-, EqualizationPhase3-, LinkEqualizationRequest-
Capabilities: [ac] MSI-X: Enable- Count=4 Masked-
Vector table: BAR=4 offset=00000000
PBA: BAR=4 offset=00000800
Capabilities: [cc] Vital Product Data
Unknown small resource type 00, will not decode more.
Capabilities: [100 v1] Advanced Error Reporting
UESta: DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt- UnxCmplt- RxOF- MalfTLP- ECRC- UnsupReq- ACSViol-
UEMsk: DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt- UnxCmplt- RxOF- MalfTLP- ECRC- UnsupReq- ACSViol-
UESvrt: DLP+ SDES+ TLP- FCP+ CmpltTO- CmpltAbrt- UnxCmplt- RxOF+ MalfTLP+ ECRC- UnsupReq- ACSViol-
CESta: RxErr- BadTLP- BadDLLP- Rollover- Timeout- NonFatalErr+
CEMsk: RxErr- BadTLP- BadDLLP- Rollover- Timeout- NonFatalErr+
AERCap: First Error Pointer: 00, GenCap+ CGenEn- ChkCap+ ChkEn-
Capabilities: [140 v1] Virtual Channel
Caps: LPEVC=0 RefClk=100ns PATEntryBits=1
Arb: Fixed- WRR32- WRR64- WRR128-
Ctrl: ArbSelect=Fixed
Status: InProgress-
VC0: Caps: PATOffset=00 MaxTimeSlots=1 RejSnoopTrans-
Arb: Fixed- WRR32- WRR64- WRR128- TWRR128- WRR256-
Ctrl: Enable+ ID=0 ArbSelect=Fixed TC/VC=ff
Status: NegoPending- InProgress-
Capabilities: [160 v1] Device Serial Number 16-00-00-00-68-4c-e0-00
Kernel driver in use: r8169