From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 50022C4338F for ; Fri, 6 Aug 2021 01:44:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 25BC661184 for ; Fri, 6 Aug 2021 01:44:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241075AbhHFBoy (ORCPT ); Thu, 5 Aug 2021 21:44:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55018 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229510AbhHFBox (ORCPT ); Thu, 5 Aug 2021 21:44:53 -0400 Received: from mail-qk1-x72b.google.com (mail-qk1-x72b.google.com [IPv6:2607:f8b0:4864:20::72b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 227B9C061798 for ; Thu, 5 Aug 2021 18:44:38 -0700 (PDT) Received: by mail-qk1-x72b.google.com with SMTP id c9so8328465qkc.13 for ; Thu, 05 Aug 2021 18:44:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ziepe.ca; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=UjUg2cUQb95U3OFdHhs6XgieXL4GS3upA0q60oAkd4U=; b=jhyg8H870XIJQYMmxwY5rQvAJQw25ZfSnTT48qMiwceGkFfyx4sQlKt87V1PA7XHti egaCYXMsbvj76ijKBe2JM9OhiG9nlxU1vKA4GiOy0q1K6GhB9bWoajsgpp9QuDSWvtCy jec3M0gfD5E0rFYL3tofcYMA4F3cWcDX7CUGZj2HsTvBvpD/K2cZM80TgI/+TymIW5M6 jRJgzb4tCv+/l1V3gmDjXrgBBvveTRpRm2Xc1SWH3u4rEBVaeO4D6/AEKPMtZyM03/Pi PtO/8nj1Pa0cP6ulQczuCkH3aro+p27vfoj1TbvAhi4qwkmxtSgi6LZBRe0Jb1FYQhRl TCkQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=UjUg2cUQb95U3OFdHhs6XgieXL4GS3upA0q60oAkd4U=; b=XM9bwcYZyeZgs9aYPrTgbQ78fFEUphNn70MlFX2zbC364maGJc1dNcrg7uABcWcbnM 8reDS//3qfuzdfIXoE/QTBICYFZztOVUcnkDJDB0jxEvIo4YIL1R1rj2IE9jUQ75S3Zu 82U0KINA9LRDmELch8Up/T/YdWkbU29vRZibAJfUMEZJ5cdgF/FDjd8JynFG4Uyj/2Vw sCfRs+MREJVkDWhdiusYCA6BiTvPtfiVyrW8mxj/l0+f0+U9owvP6yapHGww+SDWfKDy V81wFUTcdTsJdzY7/TFOSVpjErcWHEu2vo8/nCD0UrqBwM368BNvrF8mnjp2EIuumr0S 5F0g== X-Gm-Message-State: AOAM532awbDHYC5rN8DbvFQ2Pq7WGw6rklkY29TSUp7AJVsniIdvGOFS NNu20ZWkVPFH8DHe80OiPgAMKw== X-Google-Smtp-Source: ABdhPJx3JUJGcie9wVKgF4BC79/12zv+ZofpglFGOGeSZo9JdU4tQyyxkDPekm69j7O+A0qChC4W6Q== X-Received: by 2002:a05:620a:2446:: with SMTP id h6mr7659106qkn.497.1628214277352; Thu, 05 Aug 2021 18:44:37 -0700 (PDT) Received: from ziepe.ca (hlfxns017vw-142-162-113-129.dhcp-dynamic.fibreop.ns.bellaliant.net. [142.162.113.129]) by smtp.gmail.com with ESMTPSA id u19sm2852096qtx.48.2021.08.05.18.44.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 05 Aug 2021 18:44:36 -0700 (PDT) Received: from jgg by mlx with local (Exim 4.94) (envelope-from ) id 1mBoua-00Dvf5-6c; Thu, 05 Aug 2021 22:44:36 -0300 Date: Thu, 5 Aug 2021 22:44:36 -0300 From: Jason Gunthorpe To: Olga Kornievskaia Cc: linux-rdma Subject: Re: Help understand use of MAC address resolution in RDMA Message-ID: <20210806014436.GL543798@ziepe.ca> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org On Thu, Aug 05, 2021 at 10:38:42AM -0400, Olga Kornievskaia wrote: > Hi folks, > > Can somebody help me understand how RoCE (this is probably RDMA core > and not specific to RoCE but I'm not sure) manages destination MAC > addresses for its connection? > > Specifically the problem being observed is a server initiates an RDMA > CM disconnect (client replies), client tries to reconnect. Server > sends an ARP advertising a different MAC for the IP that the RDMA > connection was using. RDMA code keeps sending the RDMA CM connect > message to the old MAC for a certains period of time (90-100sec) then > it finally sends it to the new MAC address. > > Question: how does the core RDMA layer manage the MAC address for the > connection. Why does it seem like it ignores the ARP updates? RDMA objects acquire a MAC adress when they are created and do not synchronize with the neighbor cache after. What you are seeing is that the CM_ID object holds the bad mac until it is destoroyed and likely a new CM_ID object gets created that holds the updated MAC Jason