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=-3.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED 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 AAB23C4338F for ; Wed, 18 Aug 2021 21:15:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 86C2D61106 for ; Wed, 18 Aug 2021 21:15:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233865AbhHRVQ0 (ORCPT ); Wed, 18 Aug 2021 17:16:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60534 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229531AbhHRVQX (ORCPT ); Wed, 18 Aug 2021 17:16:23 -0400 Received: from mail-pj1-x102e.google.com (mail-pj1-x102e.google.com [IPv6:2607:f8b0:4864:20::102e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7B517C061764 for ; Wed, 18 Aug 2021 14:15:48 -0700 (PDT) Received: by mail-pj1-x102e.google.com with SMTP id 28-20020a17090a031cb0290178dcd8a4d1so5983159pje.0 for ; Wed, 18 Aug 2021 14:15:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=networkplumber-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=90MMNM2r4CjphxAeo54pw6vnPLieplOCTTcZNyLDLgA=; b=wkJ4uKbMiApqLxs5CcE6b5KdZ5deT4fk/HrZaukSvuH3oZMUbQPzOsaVdpjBr3c0uZ h+Iom++16pEJ+AjUD2KhMWwPqDRC8gzkEsMFi82mvr9zyHViv9PmP7yc3fTtXJ1lyD3a hNDLX6KPX/iDxMvDrWJd+j0o8W2xTai5gCQ31PNG1YxEdMwNJu3MjVbaHychgXiYw7/n ZxzMTLUyoBiTWqjFqwQIm6UJb1B77a70r6xnRZtLQqy11FF/bCF2woMaeRNA5ZKHseI9 K0/xNND3kzWxGpscwBB6w7beGsGQiTz796gfgmfvMNFdf7mD+6lEpl3bQk2b5pXzBi7T PSxQ== 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:in-reply-to :references:mime-version:content-transfer-encoding; bh=90MMNM2r4CjphxAeo54pw6vnPLieplOCTTcZNyLDLgA=; b=nNBjKE9UiAdiCYA/oGXnGjiNvTutk6T7j9879P1E1ayLd9x+0T6ToooATg5mcLscIW nVqyfRNCiWpW3ighmXapFY5wt0Ksleho1SETpD/4wx86FRd13XeLS1VxIhlfYdxHPGkR rivUaKmLAQ76mGoTe7GjLLooaX0ez2h5NhxoW549l65EDM0kgkjpuM7gSVUsv1R/erFI u6DCAmGM1N/YGUq55JCAMjH9bAa4/JFauUmPm7hsGiFzRS5H0R9/V9nmocFuiqBLJ4wM 3aiajiJ4Emb5Qqyp3hJILLOOUW461/YCYtlgYJM8jPxivAJH2wze3/pfPlmURiQ0b6mE CEsA== X-Gm-Message-State: AOAM532d/V1gQFRKC7TCR+ktW0C/5WdM50Ru21CAP+HaR27/Vrr2mx0Y J591eB3xStuMz7fDAPPBgW6EkQ== X-Google-Smtp-Source: ABdhPJyxhrVMBek40ffKErWj1RpAdhPvF2cpni8b6snTj9JGzKbMpw0eFeS0B+saf4JJaqQ7boEwMw== X-Received: by 2002:a17:90a:404a:: with SMTP id k10mr11443555pjg.145.1629321347950; Wed, 18 Aug 2021 14:15:47 -0700 (PDT) Received: from hermes.local (204-195-33-123.wavecable.com. [204.195.33.123]) by smtp.gmail.com with ESMTPSA id n22sm721730pff.57.2021.08.18.14.15.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 18 Aug 2021 14:15:47 -0700 (PDT) Date: Wed, 18 Aug 2021 14:15:44 -0700 From: Stephen Hemminger To: Willy Tarreau Cc: Thorsten Glaser , Oleg , netdev@vger.kernel.org Subject: Re: ipv6 ::1 and lo dev Message-ID: <20210818141544.75b15e93@hermes.local> In-Reply-To: <20210818201755.GA4899@1wt.eu> References: <20210818165919.GA24787@legohost> <20210818201755.GA4899@1wt.eu> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Wed, 18 Aug 2021 22:17:55 +0200 Willy Tarreau wrote: > On Wed, Aug 18, 2021 at 07:47:37PM +0200, Thorsten Glaser wrote: > > On Wed, 18 Aug 2021, Oleg wrote: > > > > > I try to replace ::1/128 ipv6 address on lo dev with ::1/112 to > > > access more than 1 address(like with ipv4 127.0.0.1/8). But i get > > > > AIUI this is not possible in IPv6, only :: and ::1 are reserved, > > the rest of ::/96 is IPv4-compatible IPv6 addresses. > > > > I never understood why you'd want more than one address for loopback > > anyway (in my experience, the more addresses a host has, the more > > confused it'll get about which ones to use for what). > > It's because you've probably never dealt with massive hosting :-) > Sometimes binding a full /24 (or smaller) on the loopback, be it > for listening addresses or to be used as sources to connect to > next hops, is extremely useful. > > Willy In the large scale routing world addresses are assigned to loopback interface because it keeps routing protocols happy. If interface goes down loopback stays around.