From patchwork Wed Apr 7 18:03:31 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrea Mayer X-Patchwork-Id: 12189141 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=-11.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 7B866C433ED for ; Wed, 7 Apr 2021 18:10:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5034561363 for ; Wed, 7 Apr 2021 18:10:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1348411AbhDGSKn (ORCPT ); Wed, 7 Apr 2021 14:10:43 -0400 Received: from smtp.uniroma2.it ([160.80.6.16]:32878 "EHLO smtp.uniroma2.it" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1348221AbhDGSKj (ORCPT ); Wed, 7 Apr 2021 14:10:39 -0400 X-Greylist: delayed 350 seconds by postgrey-1.27 at vger.kernel.org; Wed, 07 Apr 2021 14:10:38 EDT Received: from localhost.localdomain ([160.80.103.126]) by smtp-2015.uniroma2.it (8.14.4/8.14.4/Debian-8) with ESMTP id 137I49dc014753 (version=TLSv1/SSLv3 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT); Wed, 7 Apr 2021 20:04:09 +0200 From: Andrea Mayer To: "David S. Miller" , Hideaki YOSHIFUJI , David Ahern , Jakub Kicinski , linux-kernel@vger.kernel.org, netdev@vger.kernel.org Cc: Stefano Salsano , Paolo Lungaroni , Ahmed Abdelsalam , Andrea Mayer Subject: [RFC net-next 0/1] seg6: Counters for SRv6 Behaviors Date: Wed, 7 Apr 2021 20:03:31 +0200 Message-Id: <20210407180332.29775-1-andrea.mayer@uniroma2.it> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 X-Virus-Scanned: clamav-milter 0.100.0 at smtp-2015 X-Virus-Status: Clean Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org X-Patchwork-State: RFC This patch provides counters for SRv6 Behaviors as defined in [1], section 6. For each SRv6 Behavior instance, counters defined in [1] are: - the total number of packets that have been correctly processed; - the total amount of traffic in bytes of all packets that have been correctly processed; In addition, this patch introduces a new counter that counts the number of packets that have NOT been properly processed (i.e. errors) by an SRv6 Behavior instance. Counters are not only interesting for network monitoring purposes (i.e. counting the number of packets processed by a given behavior) but they also provide a simple tool for checking whether a behavior instance is working as we expect or not. Counters can be useful for troubleshooting misconfigured SRv6 networks. Indeed, an SRv6 Behavior can silently drop packets for very different reasons (i.e. wrong SID configuration, interfaces set with SID addresses, etc) without any notification/message to the user. Due to the nature of SRv6 networks, diagnostic tools such as ping and traceroute may be ineffective: paths used for reaching a given router can be totally different from the ones followed by probe packets. In addition, paths are often asymmetrical and this makes it even more difficult to keep up with the journey of the packets and to understand which behaviors are actually processing our traffic. When counters are enabled on an SRv6 Behavior instance, it is possible to verify if packets are actually processed by such behavior and what is the outcome of the processing. Therefore, the counters for SRv6 Behaviors offer an non-invasive observability point which can be leveraged for both traffic monitoring and troubleshooting purposes. [1] https://www.rfc-editor.org/rfc/rfc8986.html#name-counters Troubleshooting using SRv6 Behavior counters -------------------------------------------- Let's make a brief example to see how helpful counters can be for SRv6 networks. Let's consider a node where an SRv6 End Behavior receives an SRv6 packet whose Segment Left (SL) is equal to 0. In this case, the End Behavior (which accepts only packets with SL >= 1) discards the packet and increases the error counter. This information can be leveraged by the network operator for troubleshooting. Indeed, the error counter is telling the user that the packet: (i) arrived at the node; (ii) the packet has been taken into account by the SRv6 End behavior; (iii) but an error has occurred during the processing. The error (iii) could be caused by different reasons, such as wrong route settings on the node or due to an invalid SID List carried by the SRv6 packet. Anyway, the error counter is used to exclude that the packet did not arrive at the node or it has not been processed by the behavior at all. Turning on/off counters for SRv6 Behaviors ------------------------------------------ Each SRv6 Behavior instance can be configured, at the time of its creation, to make use of counters. This is done through iproute2 which allows the user to create an SRv6 Behavior instance specifying the optional "count" attribute as shown in the following example: $ ip -6 route add 2001:db8::1 encap seg6local action End count dev eth0 per-behavior counters can be shown by adding "-s" to the iproute2 command line, i.e.: $ ip -s -6 route show 2001:db8::1 2001:db8::1 encap seg6local action End packets 0 bytes 0 errors 0 dev eth0 #################################################### Impact of counters for SRv6 Behaviors on performance ==================================================== To determine the performance impact due to the introduction of counters in the SRv6 Behavior subsystem, we have carried out extensive tests. We chose to test the throughput achieved by the SRv6 End.DX2 Behavior because, among all the other behaviors implemented so far, it reaches the highest throughput which is around 1.5 Mpps (per core at 2.4 GHz on a Xeon(R) CPU E5-2630 v3) on kernel 5.12-rc2 using packets of size ~ 100 bytes. Three different tests were conducted in order to evaluate the overall throughput of the SRv6 End.DX2 Behavior in the following scenarios: 1) vanilla kernel (without the SRv6 Behavior counters patch) and a single instance of an SRv6 End.DX2 Behavior; 2) patched kernel with SRv6 Behavior counters and a single instance of an SRv6 End.DX2 Behavior with counters turned off; 3) patched kernel with SRv6 Behavior counters and a single instance of SRv6 End.DX2 Behavior with counters turned on. All tests were performed on a testbed deployed on the CloudLab facilities [2], a flexible infrastructure dedicated to scientific research on the future of Cloud Computing. Results of tests are shown in the following table: Scenario (1): average 1504764,81 pps (~1504,76 kpps); std. dev 3956,82 pps Scenario (2): average 1501469,78 pps (~1501,47 kpps); std. dev 2979,85 pps Scenario (3): average 1501315,13 pps (~1501,32 kpps); std. dev 2956,00 pps As can be observed, throughputs achieved in scenarios (2),(3) did not suffer any observable degradation compared to scenario (1). Comments, suggestions and improvements are very welcome! Thanks, Andrea [2] https://www.cloudlab.us Andrea Mayer (1): seg6: add counters support for SRv6 Behaviors include/uapi/linux/seg6_local.h | 8 ++ net/ipv6/seg6_local.c | 133 +++++++++++++++++++++++++++++++- 2 files changed, 139 insertions(+), 2 deletions(-)