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Message-ID: <20070903175928.2a001d51@oldman>
Date: Mon, 3 Sep 2007 17:59:28 +0100
From: Stephen Hemminger <shemminger@...ux-foundation.org>
To: netdev@...r.kernel.org
Subject: Fw: [Bug 8975] New: Broadcasting fails when default gateway can't
be reached.
This looks like another manifestation of the Linux arp differences
from end user expectation.
Begin forwarded message:
Date: Mon, 3 Sep 2007 08:19:26 -0700 (PDT)
From: bugme-daemon@...zilla.kernel.org
To: shemminger@...ux-foundation.org
Subject: [Bug 8975] New: Broadcasting fails when default gateway can't be reached.
http://bugzilla.kernel.org/show_bug.cgi?id=8975
Summary: Broadcasting fails when default gateway can't be
reached.
Product: Networking
Version: 2.5
KernelVersion: 2.6.22
Platform: All
OS/Version: Linux
Tree: Mainline
Status: NEW
Severity: normal
Priority: P1
Component: IPV4
AssignedTo: shemminger@...l.org
ReportedBy: enrique.arizonbenito@...il.com
Most recent kernel where this bug did not occur: N/A (I tried with 2.6.18-4 and
2.6.22
Distribution: - Debian 4.0 2.6.18-4 kernel & custom-kernel 2.6.22 from Mainline
-
Hardware Environment:
serv#lspci
00:00.0 Host bridge: VIA Technologies, Inc. VT82C693A/694x [Apollo PRO133x]
(rev 44)
00:01.0 PCI bridge: VIA Technologies, Inc. VT82C598/694x [Apollo MVP3/Pro133x
AGP]
00:07.0 ISA bridge: VIA Technologies, Inc. VT82C596 ISA [Mobile South] (rev 23)
00:07.1 IDE interface: VIA Technologies, Inc.
VT82C586A/B/VT82C686/A/B/VT823x/A/C PIPC Bus Master IDE (rev 10)
00:07.3 Host bridge: VIA Technologies, Inc. VT82C596 Power Management (rev 30)
00:09.0 Ethernet controller: Realtek Semiconductor Co., Ltd.
RTL-8139/8139C/8139C+ (rev 10)
01:00.0 VGA compatible controller: ATI Technologies Inc Rage 128 RL/VR AGP
serv:~# lsmod
Module Size Used by
ipv6 213856 14
ipt_MASQUERADE 3584 1
iptable_nat 7044 1
ip_nat 16428 2 ipt_MASQUERADE,iptable_nat
ip_conntrack 47156 3 ipt_MASQUERADE,iptable_nat,ip_nat
nfnetlink 6680 2 ip_nat,ip_conntrack
ip_tables 12104 1 iptable_nat
x_tables 12932 3 ipt_MASQUERADE,iptable_nat,ip_tables
dm_snapshot 15644 0
dm_mirror 18000 0
dm_mod 48952 2 dm_snapshot,dm_mirror
loop 14216 0
serio_raw 6532 0
floppy 52004 0
i2c_viapro 8340 0
i2c_core 19472 1 i2c_viapro
psmouse 34568 0
rtc 11572 0
via_agp 9728 1
agpgart 29360 1 via_agp
shpchp 32796 0
pci_hotplug 28088 1 shpchp
pcspkr 2816 0
evdev 9088 0
ext3 116488 2
jbd 47272 1 ext3
ide_disk 14848 4
via82cxxx 8452 0 [permanent]
generic 5508 0 [permanent]
ide_core 107760 3 ide_disk,via82cxxx,generic
8139cp 20736 0
8139too 24192 0
mii 5376 2 8139cp,8139too
processor 23724 0
serv:~# cat /proc/interrupts
CPU0
0: 798632 XT-PIC timer
1: 38 XT-PIC i8042
2: 0 XT-PIC cascade
6: 2 XT-PIC floppy
8: 1 XT-PIC rtc
10: 228692 XT-PIC eth0
14: 11482 XT-PIC ide0
NMI: 0
LOC: 0
ERR: 0
MIS: 0
Software Environment:
serv:~# ifconfig
eth0 Link encap:Ethernet HWaddr 00:C0:26:A0:C6:99
inet addr:192.168.0.10 Bcast:192.168.0.255 Mask:255.255.255.0
inet6 addr: fe80::2c0:26ff:fea0:c699/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:62020 errors:0 dropped:0 overruns:0 frame:0
TX packets:174169 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:10881985 (10.3 MiB) TX bytes:204869648 (195.3 MiB)
Interrupt:10 Base address:0xe800
eth0:1 Link encap:Ethernet HWaddr 00:C0:26:A0:C6:99
inet addr:192.168.10.1 Bcast:192.168.10.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
Interrupt:10 Base address:0xe800
serv:~# route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
192.168.0.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
192.168.10.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
0.0.0.0 192.168.0.1 0.0.0.0 UG 0 0 0 eth0
Problem Description:
Broadcasting fail in next "unusual" cases:
- default route points to any gateway (192.168.0.1).
- The physical ethernet connection to the gateway is broke so ARP doesn't
work.
Steps to reproduce:
Case 1: Router is connected:
Client ------- switch -------- router
|
|
Server
Case 2: Router is diconnected:
Client ------- switch router
|
|
Server
- I setup a DHCP server and a client machine tries to get an IP setup from it.
- The client and the server always have a correct physical connection.
- With the physical connection working fine (wire connected) everything works
fine.
- When the router get disconnected next happen:
The Client never receives the broadcast data with the IP setup.
Still, using tcpdump I can see the server trying to broadcast the data
through physical interface eth0 -but such data never goes out the wire since
the client hangs for ever).
tcpdump also shows the server is trying to solve the ARP entry for the
router IP.
When I delete the default gateway (route del -net 0.0.0.0) everything works
fine again.
(Without the eth0:1 alias the behaviour is similar)
Regards,
Enrique
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