Jakub Kicinski <kuba@xxxxxxxxxx> wrote:
On Wed, 23 Mar 2022 08:35:03 -0600 David Ahern wrote:The summary (from my perspective) is that the alb/rlb technology
On 3/23/22 6:09 AM, Sun Shouxin wrote:What I'm not sure of is why this gets reposted after Jiri nacked
This patch is implementing IPV6 RLB for balance-alb mode.net-next is closed, so this set needs to be delayed until it re-opens.
it. A conclusion needs to be reached on whether we want this
functionality in the first place. Or someone needs to explain
to me what the conclusion is if I'm not reading the room right :)
more or less predates LACP, and is a complicated method to implement
load balancing across a set of local network peers. The existing
implementation for IPv4 uses per-peer tailored ARP messages to "assign"
particular peers on the subnet to particular bonding interfaces. I do
encounter users employing the alb/rlb mode, but it is uncommon; LACP is
by far the most common mode that I see, with active-backup a distant
second.
The only real advantage alb/rlb has over LACP is that the
balance is done via traffic monitoring (i.e., assigning new peers to the
least busy bond interface, with periodic rebalances) instead of a hash
as with LACP. In principle, some traffic patterns may end up with hash
collisions on LACP, but will be more evenly balanced via the alb/rlb
logic (but this hasn't been mentioned by the submitter that I recall).
The alb/rlb logic also balances all traffic that will transit through a
given router together (because it works via magic ARPs), so the scope of
its utility is limited.
As much as I'm all in favor of IPv6 being a first class citizen,
I haven't seen a compelling use case or significant advantage over LACP
stated for alb/rlb over IPv6 that justifies the complexity of the
implementation that will need to be maintained going forward.
-J
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-Jay Vosburgh, jay.vosburgh@xxxxxxxxxxxxx