kern/72022: packet loss on loopback interface

George Potapov nephrite at
Wed Sep 22 23:20:18 PDT 2004

>Number:         72022
>Category:       kern
>Synopsis:       packet loss on loopback interface
>Confidential:   no
>Severity:       serious
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Thu Sep 23 06:20:17 GMT 2004
>Originator:     George Potapov
>Release:        5.3-BETA5
FreeBSD 5.3-BETA5 FreeBSD 5.3-BETA5 #16: Wed Sep 22 19:18:47 MSD 2004     root at  i386
when trying to send packets via loopback interface there occurs strange packet loss:

nephrite at nephrite:/usr/home/nephrite$ ping
--- ping statistics ---
134 packets transmitted, 65 packets received, 51% packet loss
round-trip min/avg/max/stddev = 0.053/0.067/0.124/0.009 ms

the same for any local network services like sendmail or oops http proxy. "Real" network interfaces like my 3Com card work fine.

Here is ifconfig output:
        inet netmask 0xffffff00 broadcast
        ether 00:10:5a:b3:7f:d2
        media: Ethernet 10baseT/UTP (10baseT/UTP <half-duplex>)
        status: active
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 16384
        inet netmask 0xff000000 

Here is my kernel config:
machine         i386
cpu             I486_CPU
cpu             I586_CPU
cpu             I686_CPU
ident           NEPHRITE

options         SCHED_4BSD              # 4BSD scheduler
options         INET                    # InterNETworking
options         FFS                     # Berkeley Fast Filesystem
options         SOFTUPDATES             # Enable FFS soft updates support
options         UFS_ACL                 # Support for access control lists
options         UFS_DIRHASH             # Improve performance on big directories
options         MD_ROOT                 # MD is a potential root device
options         NFSCLIENT               # Network Filesystem Client
options         MSDOSFS                 # MSDOS Filesystem
options         CD9660                  # ISO 9660 Filesystem
options         PROCFS                  # Process filesystem (requires PSEUDOFS)
options         PSEUDOFS                # Pseudo-filesystem framework
options         GEOM_GPT                # GUID Partition Tables.
options         COMPAT_43               # Compatible with BSD 4.3 [KEEP THIS!]
options         COMPAT_FREEBSD4         # Compatible with FreeBSD4
options         KTRACE                  # ktrace(1) support
options         SYSVSHM                 # SYSV-style shared memory
options         SYSVMSG                 # SYSV-style message queues
options         SYSVSEM                 # SYSV-style semaphores
options         _KPOSIX_PRIORITY_SCHEDULING # POSIX P1003_1B real-time extension
options         KBD_INSTALL_CDEV        # install a CDEV entry in /dev
options         AHC_REG_PRETTY_PRINT    # Print register bitfields in debug
                                        # output.  Adds ~128k to driver.
options         AHD_REG_PRETTY_PRINT    # Print register bitfields in debug
                                        # output.  Adds ~215k to driver.
options         ADAPTIVE_GIANT          # Giant mutex is adaptive.

options         ZERO_COPY_SOCKETS
options         DEVICE_POLLING
options         HZ=1000

# Bus support.  Do not remove isa, even if you have no isa slots
device          isa
device          pci

# Floppy drives
device          fdc

# ATA and ATAPI devices
device          ata
device          atadisk         # ATA disk drives
device          atapicd         # ATAPI CDROM drives
device          atapifd         # ATAPI floppy drives
options         ATA_STATIC_ID   # Static device numbering

# atkbdc0 controls both the keyboard and the PS/2 mouse
device          atkbdc          # AT keyboard controller
device          atkbd           # AT keyboard

device          vga             # VGA video card driver

device          splash          # Splash screen and screen saver support

# syscons is the default console driver, resembling an SCO console
device          sc

# Enable this for the pcvt (VT220 compatible) console driver
#device         vt
#options        XSERVER         # support for X server on a vt console
#options        FAT_CURSOR      # start with block cursor

#device         agp             # support several AGP chipsets

# Floating point support - do not disable.
device          npx

# Serial (COM) ports
device          sio             # 8250, 16[45]50 based serial ports

# If you've got a "dumb" serial or parallel PCI card that is
# supported by the puc(4) glue driver, uncomment the following
# line to enable it (connects to the sio and/or ppc drivers):
#device         puc

# PCI Ethernet NICs that use the common MII bus controller code.
# NOTE: Be sure to keep the 'device miibus' line in order to use these NICs!
device          miibus          # MII bus support
device          ether
device          xl

# Pseudo devices.
device          loop            # Network loopback
device          mem             # Memory and kernel memory devices
device          random          # Entropy device
device          pty             # Pseudo-ttys (telnet etc)
device          md              # Memory "disks"
device          gif             # IPv6 and IPv4 tunneling

device bpf

# USB support
device          uhci            # UHCI PCI->USB interface
device          ohci            # OHCI PCI->USB interface
device          usb             # USB Bus (required)
#device         udbp            # USB Double Bulk Pipe devices
device          ugen            # Generic
device          uhid            # "Human Interface Devices"
device          ukbd            # Keyboard
device          ulpt            # Printer
device          ums             # Mouse

device          io

and here is dmesg output
Copyright (c) 1992-2004 The FreeBSD Project.
Copyright (c) 1979, 1980, 1983, 1986, 1988, 1989, 1991, 1992, 1993, 1994
        The Regents of the University of California. All rights reserved.
FreeBSD 5.3-BETA5 #16: Wed Sep 22 19:18:47 MSD 2004
    root at
Timecounter "i8254" frequency 1193182 Hz quality 0
CPU: Intel(R) Celeron(R) CPU 2.40GHz (2400.04-MHz 686-class CPU)
  Origin = "GenuineIntel"  Id = 0xf29  Stepping = 9
real memory  = 528416768 (503 MB)
avail memory = 511619072 (487 MB)
npx0: [FAST]
npx0: <math processor> on motherboard
npx0: INT 16 interface
pcib0: <Host to PCI bridge> pcibus 0 on motherboard
pir0: <PCI Interrupt Routing Table: 7 Entries> on motherboard
pci0: <PCI bus> on pcib0
$PIR: No matching entry for 0.29.INTA
$PIR: No matching entry for 0.29.INTB
$PIR: No matching entry for 0.29.INTC
$PIR: No matching entry for 0.29.INTD
pci0: <display, VGA> at device 2.0 (no driver attached)
uhci0: <Intel 82801DB (ICH4) USB controller USB-A> port 0xd800-0xd81f irq 12 at 
device 29.0 on pci0
usb0: <Intel 82801DB (ICH4) USB controller USB-A> on uhci0
usb0: USB revision 1.0
uhub0: Intel UHCI root hub, class 9/0, rev 1.00/1.00, addr 1
uhub0: 2 ports with 2 removable, self powered
ums0: A4Tech USB Optical Mouse, rev 1.10/0.01, addr 2, iclass 3/1
ums0: 7 buttons and Z dir.
uhci1: <Intel 82801DB (ICH4) USB controller USB-B> port 0xd000-0xd01f irq 9 at d
evice 29.1 on pci0
usb1: <Intel 82801DB (ICH4) USB controller USB-B> on uhci1
usb1: USB revision 1.0
uhub1: Intel UHCI root hub, class 9/0, rev 1.00/1.00, addr 1
uhub1: 2 ports with 2 removable, self powered
uhci2: <Intel 82801DB (ICH4) USB controller USB-C> port 0xd400-0xd41f irq 7 at d
evice 29.2 on pci0
usb2: <Intel 82801DB (ICH4) USB controller USB-C> on uhci2
usb2: USB revision 1.0
uhub2: Intel UHCI root hub, class 9/0, rev 1.00/1.00, addr 1
uhub2: 2 ports with 2 removable, self powered
pci0: <serial bus, USB> at device 29.7 (no driver attached)
pcib1: <PCIBIOS PCI-PCI bridge> at device 30.0 on pci0
pci1: <PCI bus> on pcib1
xl0: <3Com 3c900B-TPO Etherlink XL> port 0xc000-0xc07f mem 0xdd000000-0xdd00007f
 irq 11 at device 1.0 on pci1
xl0: selecting 10baseT transceiver, half duplex
xl0: Ethernet address: 00:10:5a:b3:7f:d2
isab0: <PCI-ISA bridge> at device 31.0 on pci0
isa0: <ISA bus> on isab0
atapci0: <Intel ICH4 UDMA100 controller> port 0xf000-0xf00f,0x376,0x170-0x177,0x
3f6,0x1f0-0x1f7 at device 31.1 on pci0
ata0: channel #0 on atapci0
ata1: channel #1 on atapci0
pci0: <serial bus, SMBus> at device 31.3 (no driver attached)
pci0: <multimedia, audio> at device 31.5 (no driver attached)
cpu0 on motherboard
atkbdc0: <Keyboard controller (i8042)> at port 0x64,0x60 on isa0
atkbd0: <AT Keyboard> irq 1 on atkbdc0
kbd0 at atkbd0
atkbd0: [GIANT-LOCKED]
fdc0: <Enhanced floppy controller> at port 0x3f0-0x3f5 irq 6 drq 2 on isa0
fdc0: [FAST]
fd0: <1440-KB 3.5" drive> on fdc0 drive 0
sc0: <System console> at flags 0x100 on isa0
sc0: VGA <16 virtual consoles, flags=0x300>
sio0 at port 0x3f8-0x3ff irq 4 flags 0x10 on isa0
sio0: type 16550A
sio1 at port 0x2f8-0x2ff irq 3 on isa0
sio1: type 16550A
vga0: <Generic ISA VGA> at port 0x3c0-0x3df iomem 0xa0000-0xbffff on isa0
unknown: <PNP0303> can't assign resources (port)
unknown: <PNP0c02> can't assign resources (port)
unknown: <PNP0501> can't assign resources (port)
unknown: <PNP0700> can't assign resources (port)
unknown: <PNP0501> can't assign resources (port)
Timecounter "TSC" frequency 2400042440 Hz quality 800
Timecounters tick every 1.000 msec
ad0: 76319MB <ST380011A/3.06> [155061/16/63] at ata0-master UDMA100
ATAPI_RESET time = 40us
acd0: CDROM <_NEC CD-ROM CD-3002A/C000> at ata1-master UDMA33
Mounting root from ufs:/dev/ad0s1a
pid 739: corrected slot count (2->1)
occurs from time to time.
Just boot, enter "ping localhost" and wait, it will happen very soon.
not known :-(

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