Bug 183602 - Bonding Interface keeps alle Links in status updelay
Bonding Interface keeps alle Links in status updelay
Product: Red Hat Enterprise Linux 4
Classification: Red Hat
Component: kernel (Show other bugs)
All Linux
medium Severity high
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Assigned To: Andy Gospodarek
Brian Brock
Depends On:
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Reported: 2006-03-02 03:25 EST by Hansjoerg Maurer
Modified: 2014-06-29 18:57 EDT (History)
3 users (show)

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Fixed In Version:
Doc Type: Bug Fix
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Last Closed: 2008-04-07 10:58:21 EDT
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Description Hansjoerg Maurer 2006-03-02 03:25:40 EST
Description of problem:

we are running  2.6.9-22.0.2.ELsmp
with two active-backup bonding interfaces in an HA environment with two switches.

Because the switch takes some time from bbeing operational even if a link up is
shown, we had to add an updelay bonding module parameter.

According to README.bonding the updelay parameter
shoul not be used, if there are no active links.

"Note that when a bonding interface has no active links, the
driver will immediately reuse the first link that goes up, even if
updelay parameter was specified.  If there are slave interfaces
waiting for the updelay timeout to expire, the interface that first
went into that state will be immediately reused.  This reduces down
time of the network if the value of updelay has been overestimated."

If I do an 
ifdown bond0
ifup bond0

both interfaces stay in the updelay status even if the link is up.
and no network traffic is possible at all.

see attachedc the logs and two modprobe.conf configurations which both lead to
the same result.

Mar  2 08:57:04 cph2 kernel: Ethernet Channel Bonding Driver: v2.6.1 (October
29, 2004)
Mar  2 08:57:04 cph2 kernel: bonding: MII link monitoring set to 100 ms
Mar  2 08:57:04 cph2 kernel: ip_tables: (C) 2000-2002 Netfilter core team
Mar  2 08:57:06 cph2 kernel: bonding: bond0: enslaving eth0 as a backup
interface with a down link.
Mar  2 08:57:06 cph2 kernel: bonding: bond0: enslaving eth2 as a backup
interface with a down link.
Mar  2 08:57:08 cph2 kernel: tg3: eth0: Link is up at 1000 Mbps, full duplex.
Mar  2 08:57:08 cph2 kernel: tg3: eth0: Flow control is off for TX and off for RX.
Mar  2 08:57:08 cph2 kernel: bonding: bond0: link status up for interface eth0,
enabling it in 300000 ms.
Mar  2 08:57:08 cph2 kernel: e1000: eth2: e1000_watchdog: NIC Link is Up 1000
Mbps Full Duplex
Mar  2 08:57:08 cph2 kernel: bonding: bond0: link status up for interface eth2,
enabling it in 300000 ms.
Mar  2 09:02:09 cph2 kernel: bonding: bond0: link status definitely up for
interface eth0.
Mar  2 09:02:09 cph2 kernel: bonding: bond0: making interface eth0 the new
active one.
Mar  2 09:02:09 cph2 kernel: bonding: bond0: link status definitely up for
interface eth2.

install bond0 /sbin/modprobe --ignore-install -o bonding0 bonding miimon=1000
downdelay=1000 updelay=30000 mode=active-backup primary=eth2
remove bond0 /sbin/modprobe -r --ignore-remove bonding0
install bond1 /sbin/modprobe --ignore-install -o bonding1 bonding miimon=100
downdelay=1000 updelay=300000 mode=active-backup primary=eth1
remove bond1 /sbin/modprobe -r --ignore-remove bonding1

options bonding  mode=active-backup miimon=100 max_bonds=2 downdelay=1000
alias bond0 bonding
alias bond1 bonding

Actual results:
network not available

Expected results:
not all interfaces of a bond shoul stay in updelay state

Additional info:
Comment 1 Andy Gospodarek 2006-03-13 11:21:37 EST
I want to make sure I understand your problem correctly, so I would like to ask
a question to clarify.

Does your network connectivity come back 5 minutes after performing 

# ifdown bond0
# ifup bond0

or does it never come back at all?  

Your logs indicate that the bonds come back up, so after 5 minutes I would
expect the traffic to continue to flow.  I need to know if your complaint is
that the traffic never comes back or if the complaint is that it takes 5 minutes
for the traffic to come back.

Comment 2 Need Real Name 2006-03-13 12:44:22 EST

the traffic comes back after 5 minutes.
After ifup bond0 both interfaces (eth0 and eth2) of the trunk 
show an active link but stay in updelay for 300s.
According to the docs, updelay should be ignored
if there is no active link in the bond.

The problems is not only related to the ifup / ifdown command.
It occurs, if we plug in and out both interfaces, too.

In our configuration we have two bonding interfaces
bond0 with eth0 and eth2
bond1 with eth2 and eth3
both located on two dualport NICS and connected to two

If you need additional infos, testing, let me now.

I looked at the code and the function 
bond_change_active_slave (L1895)
(I put in some write statements)

is not called in this case
 if (((!bond->curr_active_slave) ||
                     (bond->curr_active_slave->dev->flags & IFF_NOARP)) &&
                    (new_slave->link != BOND_LINK_DOWN)) {

but unfortunatly I am not really good in C and I don't understand the networking
concepts behind the code, which make me unable to work on it


Comment 3 Andy Gospodarek 2006-03-13 16:49:28 EST
For an ifup/ifdown command sequence the updelay function is working as designed.
 It should take 5 minutes for the links to become active again when testing this

When both links go down it seems the value for 'updelay' will only be ignored if
both slave links go down (shown as down by the file /proc/net/bonding/bond0).  I
will need to find some tg3 cards before I can test this, so I will let you know
my findings later this week.

Comment 4 Andy Gospodarek 2006-03-20 14:33:26 EST
Both the latest RHEL and upstream kernels seem to have code that behaves in the
manner you are describing.  I have test RHEL kernels and see updelay being
honored and I have examined the upsteam code to determine the behaviour will be
the same there.  

I'm not sure the information in the documentation is the desired behaviour.  I
do not think it is wise for the kernel to decide in some cases that updelay
should be ignored completely and bring the interface up anyway.  I will
investigate this upstream, but I don't think this is something we will put into
our kernel without it being upstream.

Please let me know why this feature would be important to you and I can them
decide how continue -- either a code change to ignore the updelay as the
documentation states or a documentation update to remove the section that says
updelay will be ignored.
Comment 5 Hansjoerg Maurer 2006-03-21 02:44:09 EST
Thank you for your replies

The reason we use the updelay parameter is, that when we boot up
an ethernet switch it takes some time (about 3 minutes) from showing a link to
actually forwarding pakets.
The updelay parameter is problematic when
- pluging in and out both network interfaces of a running failover trunk within
  the updelay phase (e.G. to change cabeling)
- doing a ifdown bond0; ifup bond0 brings the interface not until the updelay is
over (e.g. after changing theetwork konfiguration)

The behavior the docs describe (see below) would solve both issues.
The updelay parameter should in my opinion prevent
the bond to use a a link which recently comes up and is not ready,
while there is another link in up state available and working.

If bond comes to a situation, where no active links are available
(after an ifdown bond0; ifup bond0 or after a plugging of both ports,)
I do not see any benefit of the updelay parameter.
- if all links stay in updelay => no traffic is possible
- if, when no actice link is available any more and updelay is ommited, in this
case, the bond would start working again immediatly after the switch works
 => network downtime is reduced to a minimum or even no downtime would occur
if a plug out and in again  the firts slave port and then the second slave port
within the updelay phase.

Or do you see a case, where it would make sense, that
updelay keeps BOTH slaves of a bond in state down for 5 minutes.
Its the worts case for a bond and e.g. a HA system and in this case
network should return as fast as possible, which means when the first switch
starts forwarding packets (and I think this is the point the docs diescribe) and
not when updelay is over for all slaves.

I hope it was possible for me to explain the issue.

If it is not possible to solve this issue, the following part of the doc
should be replaced by a warning, that using updelay can keep a bond interface
down (alle Slaves in state down)  even if both ports are working properly

"Note that when a bonding interface has no active links, the
driver will immediately reuse the first link that goes up, even if
updelay parameter was specified.  "

Comment 6 John W. Linville 2006-03-21 08:22:07 EST
Without taking a position on the design of the bonding driver, I would suggest 
that you disable spanning tree (or enable portfast or the equivalent) on the 
ports in question on the switch.  That should eliminate your need for the 
updelay parameter. 
Comment 7 Hansjoerg Maurer 2006-03-21 08:35:14 EST
we have already done this.
The problem is, when booting one switch (both ports are connected to two
differnet foundry switches), the switch show a link up very early (e.g. when
testing the ports) without forwarding. If we don't use updelay, bonding will try
to activate this port and resuse it (with resulting heartbeat und drbd errors ...)

Comment 8 Andy Gospodarek 2008-04-07 10:58:21 EDT
This bug has seen no activity in the last year, so I can only presume it is no
longer a problem.  If there is still an issue that needs to be resolved, please
re-open this bug and I will be happy to help resolve it.  Thank you.

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