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([2a01:e0a:410:bb00:304d:64e9:99ee:68e4]) by smtp.gmail.com with ESMTPSA id u6sm3320011wrn.95.2020.08.26.00.47.55 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 26 Aug 2020 00:47:55 -0700 (PDT) Reply-To: nicolas.dichtel@6wind.com Subject: Re: [PATCH net-next v2] gtp: add notification mechanism To: Harald Welte Cc: davem@davemloft.net, kuba@kernel.org, pablo@netfilter.org, osmocom-net-gprs@lists.osmocom.org, netdev@vger.kernel.org, Gabriel Ganne References: <20200825143556.23766-1-nicolas.dichtel@6wind.com> <20200825155715.24006-1-nicolas.dichtel@6wind.com> <20200825170109.GH3822842@nataraja> From: Nicolas Dichtel Organization: 6WIND Message-ID: Date: Wed, 26 Aug 2020 09:47:54 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20200825170109.GH3822842@nataraja> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Le 25/08/2020 à 19:01, Harald Welte a écrit : > Hi Nicolas, > > thanks a lot for your patch. > > On Tue, Aug 25, 2020 at 05:57:15PM +0200, Nicolas Dichtel wrote: >> Like all other network functions, let's notify gtp context on creation and >> deletion. > > While this may be in-line with typical kernel tunnel device practises, I am not > convinced it is the right way to go for GTP. > > Contrary to other tunneling mechansims, GTP doesn't have a 1:1 rlationship between > tunnels and netdev's. You can easily have tens of thousands - or even many more - > PDP contexts (at least one per subscriber) within one "gtp0" netdev. Also, the state > is highly volatile. Every time a subscriber registers/deregisters, goes in or out of > coverage, in or out of airplane mode, etc. those PDP contexts go up and down. > > Sending (unsolicited) notifications about all of those seems quite heavyweight to me. There is no 'unsolicited' notifications with this patch. Notifications are sent only if a userspace application has subscribed to the gtp mcast group. ip routes or conntrack entries are notified in the same way and there could a lot of them also (more than 100k conntrack entries for example).