netdev - Re: [Discuss] IPv4 packets lost with macvlan over bond alb

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Date: Thu, 8 Jun 2023 11:43:31 +0800
From: Hangbin Liu <liuhangbin@...il.com>
To: Jay Vosburgh <jay.vosburgh@...onical.com>
Cc: netdev@...r.kernel.org
Subject: Re: [Discuss] IPv4 packets lost with macvlan over bond alb

Hi Jay, any thoughts?

Thanks
Hangbin
On Fri, Jun 02, 2023 at 04:09:00PM +0800, Hangbin Liu wrote:
> Hi Jay,
> 
> It looks there is an regression for commit 14af9963ba1e ("bonding: Support
> macvlans on top of tlb/rlb mode bonds"). The author export modified ARP to
> remote when there is macvlan over bond, which make remote add neighbor
> with macvlan's IP and bond's mac. The author expect RLB will replace all
> inner packets to correct mac address if target is macvlan, but RLB only
> handle ARP packets. This make all none arp packets macvlan received have
> incorrect mac address, and dropped directly.
> 
> In short, remote client learned macvlan's ip with bond's mac. So the macvlan
> will receive packets with incorrect macs and dropped.
> 
> To fix this, one way is to revert the patch and only send learning packets for
> both tlb and alb mode for macvlan. This would make all macvlan rx packets go
> through bond's active slave.
> 
> Another way is to replace the bond's mac address to correct macvlan's address
> based on the rx_hashtbl . But this may has impact to the receive performance
> since we need to check all the upper devices and deal the mac address for
> each packets in bond_handle_frame().
> 
> So which way do you prefer?
> 
> Reproducer:
> ```
> #!/bin/bash
> 
> # Source the topo in bond selftest
> source bond_topo_3d1c.sh
> 
> trap cleanup EXIT
> 
> setup_prepare
> bond_reset "mode balance-alb"
> ip -n ${s_ns} addr flush dev bond0
> 
> ip -n ${s_ns} link add link bond0 name macv0 type macvlan mode bridge
> ip -n ${s_ns} link set macv0 up
> 
> # I just add macvlan on the server netns, you can also move it to another netns for testing
> ip -n ${s_ns} addr add ${s_ip4}/24 dev macv0
> ip -n ${s_ns} addr add ${s_ip6}/24 dev macv0
> ip netns exec ${c_ns} ping ${s_ip4} -c 4
> sleep 5
> ip netns exec ${c_ns} ping ${s_ip4} -c 4
> ```
> 
> Thanks
> Hangbin