Re: [PATCH RESEND net-next 0/2] ipvs: drop packet during rescheduling

To: Julian Anastasov <ja@xxxxxx>
Subject: Re: [PATCH RESEND net-next 0/2] ipvs: drop packet during rescheduling
Cc: lvs-devel@xxxxxxxxxxxxxxx, Jiri Bohac <jbohac@xxxxxxx>
From: Simon Horman <horms@xxxxxxxxxxxx>
Date: Fri, 12 Feb 2016 19:29:47 +0100
On Sun, Feb 07, 2016 at 01:07:30PM +0200, Julian Anastasov wrote:
> Jiri Bohac is reporting for a problem with the connection
> rescheduling mechanism added in 3.10 when new SYNs in
> connection to dead real server can be redirected to another
> real server. His solution is to drop SYNs until the IPVS
> connection and its conntrack are properly removed, so that
> a new connection can be established later from client's
> retransmissions. Alternative would be to redirect the
> conntrack (its reply direction) to the new real server but
> we do not see such solution.
> The second patch addresses another scenario: client restarts
> TCP connection by reusing the same IPVS connection:
> - IPVS conn is established, eg. FTP without persistence
> - restart client box
> - start new TCP connection from same port to reuse IPVS conn
> C: SYN with new SEQ
> S: ACK with ACK_SEQ=old SEQ
> retransmit pause
> C: SYN, still in CLOSE? => DROP, expire IPVS conn
> Expire IPVS connection
> retransmit pause
> C: SYN, create connection
> In this case we should allow rescheduling in CLOSE state.
> In the worst case for this scenario with initial RTO=3 secs
> the client can be delayed for 9 seconds.

Thanks, applied.
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