> On 11/15/24 08:15, Jun Wang via discuss wrote:
>> We are using OVS bond with the configuration as shown below. We found that
>> when the switch is configured in MLAG mode:
>>
>> 1. We tested sending 1000 UDP packets per second, with a total of 500,000
>> packets. The statistics show that there is occasionally a chance of losing a
>> few packets (background traffic is around 100,000 pps).
>> 2. We also tested the same scenario in a non-MLAG setup with the same
>> testing steps, and there was basically no packet loss (background traffic is
>> around 100,000 pps).
>>
>>
>> |ovs-vsctl --may-exist add-bond br-tun dpdk_tun_port tun_port_p0 tun_port_p1
>> \|
>> |bond_mode=balance-tcp lacp=active
>> other-config:bond-rebalance-interval=||1000|
>> |other_config:lb-output-action=||true| |\|
>> |-- set Interface tun_port_p0 type=dpdk \|
>> |options:dpdk-devargs=||0000||:ca:||00.0| |mtu_request=||1600| |\|
>> | ||options:n_rxq_desc=||2048|
>> |options:n_txq_desc=||2048| |\|
>> | ||options:n_rxq=||4| |\|
>> |-- set Interface tun_port_p1 type=dpdk \|
>> |options:dpdk-devargs=||0000||:ca:||00.1| |mtu_request=||1600| |\|
>> | ||options:n_rxq_desc=||2048|
>> |options:n_txq_desc=||2048| |\|
>> | ||options:n_rxq=||4|
>>
>> For the phenomenon described above, in the MLAG scenario, after adjusting
>> |bond-rebalance-interval=0|, we found that during
>> the test of sending 1000 UDP packets per second with a total of 500,000
>> packets, there was no packet loss. It is unclear whether
>> this is an issue related to OVS bond's support for MLAG, which might cause
>> packet loss under certain conditions. Therefore,
>> I found some relevant descriptions online that may explain this behavior.
>>
>> https://forum.proxmox.com/threads/solution-multiple-ovs-sdn-and-lacp-heartaches.120634/
>>
>> <https://forum.proxmox.com/threads/solution-multiple-ovs-sdn-and-lacp-heartaches.120634/>
>> The description is as follows:
>> “Since my original post, I've spent some more time on this, and discovered
>> that OVS is totally unsuitable for more enterprise-y setups,
>> and MLAG in particular. None of the MLAG implementations I've tried this
>> with expect distinct flows to flap between legs, and this does cause minor
>> issues.“
>>
>> In addition, the |bond-rebalance-interval=0| configuration can lead to
>> traffic imbalance between interfaces, which has a negative impact. Is there
>> a better solution to this issue?
>
>If the switches do not support traffic moving between legs of the MLAG,
>then disabling of the rebalancing sounds like the only option.
I have confirmed that the switch supports MLAG, but I occasionally encounter
packet loss, which is very frustrating and unacceptable.
>Note that the traffic will still be balanced based on the packet hash.
>So, as long as you have many light traffic streams the traffic should
>be well balanced. But if your traffic pattern involves having a couple
>heavy streams along many light ones, then it may not be fully balanced
>indeed.
I captured packets and confirmed that OVS is dropping packets. Observing the
coverage statistics,
I noticed an increase in datapath_drop_invalid_port. However, after setting
bond-rebalance-interval=0, the counter no longer increases.
>Is there a linux bond mode that works fine with this MLAG?
>
>>
>> ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
>> Jun Wang
>>
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>> disc...@openvswitch.org
>> https://mail.openvswitch.org/mailman/listinfo/ovs-discuss
Jun Wang
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