[ovs-discuss] Strange behavior with paths longer than 5 hops.

Jesse Gross jesse at nicira.com
Wed Jul 18 02:54:25 UTC 2012


If you remove it at some point the machine will crash.  I think your
time is better spent reducing the number of hops that you have.  I
don't know what your goal is but your current design is extremely
inefficient.

On Tue, Jul 17, 2012 at 7:41 PM, Vjekoslav Brajkovic
<balkan at cs.washington.edu> wrote:
> Would you happen to know what needs to be patched in order to
> modify/remove this behavior?
>
> On Tue, Jul 17, 2012 at 7:38 PM, Jesse Gross <jesse at nicira.com> wrote:
>> On Tue, Jul 17, 2012 at 7:32 PM, Vjekoslav Brajkovic
>> <balkan at cs.washington.edu> wrote:
>>> Hi,
>>>
>>> I ran into this problem and I think it might be a bug. The problem is
>>> most likely somewhere on the datapath, as it appears to be happening
>>> with and without a controller.  Here are the steps to reproduce it.
>>>
>>> (container 0) <--> sw0 <--> sw1 <--> sw2 <--> sw3 <--> sw4 <--> sw5
>>> <--> sw6 <--> sw7 <--> (container 1)
>>>
>>> It appears to be happening with paths that are above 5 hops. Both with
>>> OVS 1.4.2 and 1.6.1.
>>
>> It's not a bug, it's intentional behavior.  In order to avoid blowing
>> out the kernel stack in the event of a loop or excessive number of
>> hops we limit the number of times a packet can traverse the datapath
>> to 5.



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