Xen users - Jul 2010 - Problem pinging the xen guest after live migration

Hi ,


  I am getting the delay in pinging (from different network) , the guest
after live migration .

  Here is the scenario:

0.   OS : RHEL5.4  86_64

1.   Host-A.

      Port eth1 , it is trunked with  three subnets

             xxx.xx.15.xxx
             xxx.xx.16.xxx
             xxx.xx.17.xxx

     Guest created on  15, 16 ,17 subnets.

     Gust15-A  created on subnet 15
     Gust16-A  created on subnet 16
     Gust17-A  created on subnet 17

2.   Host-B.

      Port eth0 and eth1  are bonded to bond0

      Bond0 is trunked, with three subnets.

             xxx.xx.15.xxx
             xxx.xx.16.xxx
             xxx.xx.17.xxx


     Guest created on  15, 16 ,17 subnets.

     Gust15-B  created on subnet 15
     Gust16-B  created on subnet 16
     Gust17-B  created on subnet 17

     I have used  the mode option   in /etc/modprobe.conf as
     options bond0 mode=1 miimon=100  ,  As because  mode=4 did not work, It
seems  the
     link aggregation is not properly set or something else. As the switch
configuration is
     the part of different team, I can''t explain it clearly here.

     But with mode=1 , it is working at this stage.

3.  I am trying to live migrate Guest15-A and other guests to Host-b.
Migration is ok.
    But,there is 5 munites  delay.  The guests are pingable only after 4/5
munites
    from different network  after migration.



Can anyone please advice , where to check?  Do you think it is the switch
configuration issues?

If server side configuration issue then I can do it.  If it is switch side
issues , please
give me the pointers or advice , so that I can discuss with the network
team.

If more explanation is needed , please let me know.

Thanks in advance.


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On Sat, 2010-07-03 at 17:57 -0400, Srija G wrote:
Hi ,


  I am getting the delay in pinging (from different network) , the guest  after
live migration .

  Here is the scenario:

0.   OS : RHEL5.4  86_64

1.   Host-A.

      Port eth1 , it is trunked with  three subnets

             xxx.xx.15.xxx
             xxx.xx.16.xxx
             xxx.xx.17.xxx

     Guest created on  15, 16 ,17 subnets.

     Gust15-A  created on subnet 15
     Gust16-A  created on subnet 16
     Gust17-A  created on subnet 17

2.   Host-B.

      Port eth0 and eth1  are bonded to bond0

      Bond0 is trunked, with three subnets.

             xxx.xx.15.xxx
             xxx.xx.16.xxx
             xxx.xx.17.xxx


     Guest created on  15, 16 ,17 subnets.

     Gust15-B  created on subnet 15
     Gust16-B  created on subnet 16
     Gust17-B  created on subnet 17

     I have used  the mode option   in /etc/modprobe.conf as
     options bond0 mode=1 miimon=100  ,  As because  mode=4 did not work, It
seems  the
     link aggregation is not properly set or something else. As the switch
configuration is
     the part of different team, I can't explain it clearly here.

     But with mode=1 , it is working at this stage.

3.  I am trying to live migrate Guest15-A and other guests to Host-b. Migration
is ok.
    But,there is 5 munites  delay.  The guests are pingable only after 4/5
munites
    from different network  after migration.



Can anyone please advice , where to check?  Do you think it is the switch
configuration issues?

If server side configuration issue then I can do it.  If it is switch side
issues , please
give me the pointers or advice , so that I can discuss with the network team.

If more explanation is needed , please let me know.

Thanks in advance.

1. Ping after

2. What happens if you issue the ping command from the _migrated_ domU and then
tries pinging it from the another network? (the switch might "remember


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> On Sat, 2010-07-03 at 17:57 -0400, Srija G wrote:
> Hi ,
> [snip]
> Can anyone please advice , where to check?  Do you think it is the switch
configuration issues?
>
>    
It''s almost certainly a switch issue: the switch doesn''t know
that the
MAC address for the recently migrated machine is on a different port.

There are two possibilities: you can either ping something (eg the 
default router) _from_ the guest after it has migrated or you can set 
portfast on the switch.  The former just informs the switch that the 
originating MAC address is now on a different port; the latter makes the 
switch less willing to hold on to the MAC address/port association for a 
long time and is something that the network people can do.  You might 
want to try doing both.

jch



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Thank you so much  to both of you John and Matej.

Yes,  both of your  solution,  worked when I am live migrating the guest
from one  dom0 to  another dom0.

What i am doing now,

  -    In Host-B  , I am executing the command ,

                 ping  Guest-15a

   -   In the Host-A   ,  I am executing  the command

          xm  migrate --live  Guest-15a    Host-B

 The  result:

       * Live  migration went  very  well,  found  there is  just  1 sec
stop in between but I think that is  acceptable.*

Our network team says  that portfast is already configured at switch .

But as  the first option  worked , so  I  hope  I can move on  - right?  If
not please  advice....

My second question is,  mode=4  , ie  802.2ad ( link  aggregation ) did not
work still yet. I wanted to
set  the mode=4 as it is much faster. Found one document  , here is the url

http://wiki.oracle.com/page/Cisco+Systems+IOS-based+switches-+interface+bonding+and+trunking

It is very good .  In this  document  , the first line it is mentioned   :

*****   It is important that the native VLANs *be identical* on both sides
of the link

What does it mean  VLANs *be identical* on both sides of the link  ? Sorry
for the silly question though.

 Would you please explain , do I need to check /configure anything  on the
server side?     My configuration is  simple  enough ,

In my configuration I have used  eth0 and  eth1 bonded  to bond0, and  for
each subnet,  created  the

config files,  as   ifcfg-bond0.15, ifcfg-bond0.16,  ifcfg-bond0.17.   Then
in the /etc/xen/scripts  , I have created

a custom  file where I mentioned all the bridges  for  each  vlan tag.  And
this custom file is being called

from    /etc/xen/xend-config.sxp...


Please  advice,  do you need to proceed with aggregation link or  with
mode=1, which is now configured  and
you all helped me a work around...

Thanks again.




On Mon, Jul 5, 2010 at 6:25 AM, John Haxby <john.haxby@oracle.com> wrote:
>
>  On Sat, 2010-07-03 at 17:57 -0400, Srija G wrote:
>> Hi ,
>> [snip]
>>
>> Can anyone please advice , where to check?  Do you think it is the
switch
>> configuration issues?
>>
>>
>>
>
> It''s almost certainly a switch issue: the switch doesn''t
know that the MAC
> address for the recently migrated machine is on a different port.
>
> There are two possibilities: you can either ping something (eg the default
> router) _from_ the guest after it has migrated or you can set portfast on
> the switch.  The former just informs the switch that the originating MAC
> address is now on a different port; the latter makes the switch less
willing
> to hold on to the MAC address/port association for a long time and is
> something that the network people can do.  You might want to try doing
both.
>
> jch
>
>
>

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On Wednesday 07 July 2010 17:27:23 Srija G wrote:
> Thank you so much  to both of you John and Matej.
> 
> Yes,  both of your  solution,  worked when I am live migrating the guest
> from one  dom0 to  another dom0.
> 
> What i am doing now,
> 
>   -    In Host-B  , I am executing the command ,
> 
>                  ping  Guest-15a
> 
>    -   In the Host-A   ,  I am executing  the command
> 
>           xm  migrate --live  Guest-15a    Host-B
> 
>  The  result:
> 
>        * Live  migration went  very  well,  found  there is  just  1 sec
> stop in between but I think that is  acceptable.*
> 
> Our network team says  that portfast is already configured at switch .
> 
> But as  the first option  worked , so  I  hope  I can move on  - right?  If
> not please  advice....
> 
> My second question is,  mode=4  , ie  802.2ad ( link  aggregation ) did not
> work still yet. I wanted to
> set  the mode=4 as it is much faster. Found one document  , here is the url
> 
> http://wiki.oracle.com/page/Cisco+Systems+IOS-based+switches-+interface+bon
> ding+and+trunking
> 
> It is very good .  In this  document  , the first line it is mentioned   :
> 
> *****   It is important that the native VLANs *be identical* on both sides
> of the link
> 
> What does it mean  VLANs *be identical* on both sides of the link  ? Sorry
> for the silly question though.
> 
>  Would you please explain , do I need to check /configure anything  on the
> server side?     My configuration is  simple  enough ,
> 
> In my configuration I have used  eth0 and  eth1 bonded  to bond0, and  for
> each subnet,  created  the
> 
> config files,  as   ifcfg-bond0.15, ifcfg-bond0.16,  ifcfg-bond0.17.   Then
> in the /etc/xen/scripts  , I have created
> 
> a custom  file where I mentioned all the bridges  for  each  vlan tag.  And
> this custom file is being called
> 
> from    /etc/xen/xend-config.sxp...
> 
> 
> Please  advice,  do you need to proceed with aggregation link or  with
> mode=1, which is now configured  and
> you all helped me a work around...
> 
> Thanks again.
> 
> On Mon, Jul 5, 2010 at 6:25 AM, John Haxby <john.haxby@oracle.com>
wrote:
> >  On Sat, 2010-07-03 at 17:57 -0400, Srija G wrote:
> >> Hi ,
> >> [snip]
> >>
> >> Can anyone please advice , where to check?  Do you think it is the
> >> switch configuration issues?
> >
> > It''s almost certainly a switch issue: the switch
doesn''t know that the
> > MAC address for the recently migrated machine is on a different port.
> >
> > There are two possibilities: you can either ping something (eg the
> > default router) _from_ the guest after it has migrated or you can set
> > portfast on the switch.  The former just informs the switch that the
> > originating MAC address is now on a different port; the latter makes
the
> > switch less willing to hold on to the MAC address/port association for
a
> > long time and is something that the network people can do.  You might
> > want to try doing both.
> >
> > jch
> 
Why don''t you use multipathing in stead of bonding? 

B.

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