From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C321610949 for ; Thu, 29 Jun 2023 11:12:45 +0000 (UTC) Received: from out4-smtp.messagingengine.com (out4-smtp.messagingengine.com [66.111.4.28]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2A98D125 for ; Thu, 29 Jun 2023 04:12:44 -0700 (PDT) Received: from compute2.internal (compute2.nyi.internal [10.202.2.46]) by mailout.nyi.internal (Postfix) with ESMTP id 0095F5C0117; Thu, 29 Jun 2023 07:12:40 -0400 (EDT) Received: from mailfrontend2 ([10.202.2.163]) by compute2.internal (MEProxy); Thu, 29 Jun 2023 07:12:40 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-type:content-type:date:date :feedback-id:feedback-id:from:from:in-reply-to:in-reply-to :message-id:mime-version:references:reply-to:sender:subject :subject:to:to:x-me-proxy:x-me-proxy:x-me-sender:x-me-sender :x-sasl-enc; s=fm2; t=1688037159; x=1688123559; bh=ukfwBVdtsxIn4 shVj8CUA3yoKBUYzs3tebDftyZdP3g=; b=fcgqHl+5g3IdeCpxIvvaB7vQzLAus c0I8s5wSFKUQ0555imppMu824xABNXB9MRhBTULlSPZCzFrEjeUUnteqJikefrlZ bn/cOfaIiDT+3PzPLX/QgQ8SHCznn3HDGDnwPmWrD3TmX4k0JihMGnWHhv58Jg2w EjJmsu7Aqin5BNSLJyY88azERADrZDaTVcYRwmYmBnF5bu0sHPFMVCXISrnvMVg5 NbM/iOjqjPSfZXkYtv8DOwAZ5T+hyJuN2FpES9p+W3Fu+zZ5vQyyP0leAxF4x/Bp 2p/ezPpbyxn2FfBg6922VHW6WRAu5DLh6OXQbx+L8L4PPYXBKqqnFuI9Q== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedviedrtdeggdefkecutefuodetggdotefrodftvf curfhrohhfihhlvgemucfhrghsthforghilhdpqfgfvfdpuffrtefokffrpgfnqfghnecu uegrihhlohhuthemuceftddtnecunecujfgurhepfffhvfevuffkfhggtggujgesthdtre dttddtvdenucfhrhhomhepkfguohcuufgthhhimhhmvghluceoihguohhstghhsehiugho shgthhdrohhrgheqnecuggftrfgrthhtvghrnhepvddufeevkeehueegfedtvdevfefgud eifeduieefgfelkeehgeelgeejjeeggefhnecuvehluhhsthgvrhfuihiivgeptdenucfr rghrrghmpehmrghilhhfrhhomhepihguohhstghhsehiughoshgthhdrohhrgh X-ME-Proxy: Feedback-ID: i494840e7:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Thu, 29 Jun 2023 07:12:39 -0400 (EDT) Date: Thu, 29 Jun 2023 14:12:35 +0300 From: Ido Schimmel To: Nayan Gadre Cc: netdev@vger.kernel.org Subject: Re: Routing in case of GRE interface under a bridge Message-ID: References: Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Spam-Status: No, score=-2.6 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,RCVD_IN_DNSWL_LOW,RCVD_IN_MSPIKE_H3,RCVD_IN_MSPIKE_WL, SPF_HELO_PASS,SPF_NONE,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net On Wed, Jun 28, 2023 at 07:06:45PM +0530, Nayan Gadre wrote: > I have a "l2gre0" and "eth0" interface under the bridge "br0". I assume "l2gre0" is a gretap, not ipgre. > If a packet comes to eth0 interface with a destination IP address say > 10.10.10.1 which is not known on the Linux system, as there is no > route for 10.10.10.1, will the l2gre0 interface encapsulate this > packet and send it across the tunnel ? The bridge doesn't care about IP addresses when forwarding unicast packets. Forwarding happens based on DMAC. Packet will be transmitted through "l2gre0" if the bridge has a matching FDB entry for the DMAC with "l2gre0" as the destination bridge port or if there is no FDB entry at all, in which case the packet will be flooded. One of the attributes of the GRE device is the remote address, which is the encapsulating destination IP. Linux needs to have a route telling it how to reach this destination address or the packet will be dropped. > The other endpoint is on a different Linux system with another l2gre0 > interface having IP address 10.10.10.1 > > Thanks > N Gadre >