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authorJarod Wilson <jarod@redhat.com>2021-01-19 04:09:27 +0300
committerJakub Kicinski <kuba@kernel.org>2021-01-20 06:30:32 +0300
commit7b8fc0103bb51d1d3e1fb5fd67958612e709f883 (patch)
treea270badd5579c8e8f7c4bfdc98d23a2835fecc4a /Documentation/networking
parent00b229f762b020eebf55a52b984aec76ae0ad966 (diff)
downloadlinux-7b8fc0103bb51d1d3e1fb5fd67958612e709f883.tar.xz
bonding: add a vlan+srcmac tx hashing option
This comes from an end-user request, where they're running multiple VMs on hosts with bonded interfaces connected to some interest switch topologies, where 802.3ad isn't an option. They're currently running a proprietary solution that effectively achieves load-balancing of VMs and bandwidth utilization improvements with a similar form of transmission algorithm. Basically, each VM has it's own vlan, so it always sends its traffic out the same interface, unless that interface fails. Traffic gets split between the interfaces, maintaining a consistent path, with failover still available if an interface goes down. Unlike bond_eth_hash(), this hash function is using the full source MAC address instead of just the last byte, as there are so few components to the hash, and in the no-vlan case, we would be returning just the last byte of the source MAC as the hash value. It's entirely possible to have two NICs in a bond with the same last byte of their MAC, but not the same MAC, so this adjustment should guarantee distinct hashes in all cases. This has been rudimetarily tested to provide similar results to the proprietary solution it is aiming to replace. A patch for iproute2 is also posted, to properly support the new mode there as well. Cc: Jay Vosburgh <j.vosburgh@gmail.com> Cc: Veaceslav Falico <vfalico@gmail.com> Cc: Andy Gospodarek <andy@greyhouse.net> Cc: Thomas Davis <tadavis@lbl.gov> Signed-off-by: Jarod Wilson <jarod@redhat.com> Link: https://lore.kernel.org/r/20210119010927.1191922-1-jarod@redhat.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'Documentation/networking')
-rw-r--r--Documentation/networking/bonding.rst13
1 files changed, 13 insertions, 0 deletions
diff --git a/Documentation/networking/bonding.rst b/Documentation/networking/bonding.rst
index adc314639085..5f690f0ad0e4 100644
--- a/Documentation/networking/bonding.rst
+++ b/Documentation/networking/bonding.rst
@@ -951,6 +951,19 @@ xmit_hash_policy
packets will be distributed according to the encapsulated
flows.
+ vlan+srcmac
+
+ This policy uses a very rudimentary vlan ID and source mac
+ hash to load-balance traffic per-vlan, with failover
+ should one leg fail. The intended use case is for a bond
+ shared by multiple virtual machines, all configured to
+ use their own vlan, to give lacp-like functionality
+ without requiring lacp-capable switching hardware.
+
+ The formula for the hash is simply
+
+ hash = (vlan ID) XOR (source MAC vendor) XOR (source MAC dev)
+
The default value is layer2. This option was added in bonding
version 2.6.3. In earlier versions of bonding, this parameter
does not exist, and the layer2 policy is the only policy. The