From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joe Stringer Subject: Re: Maximum MPLS labels on Linux network stack Date: Wed, 3 May 2017 13:21:16 -0700 Message-ID: References: <149211493832787@web33j.yandex.ru> <5a408c23-d3e2-aa3e-4574-82521b2255b0@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Cc: =?UTF-8?B?0JDQu9C10LrRgdC10Lkg0JHQvtC70LTRi9GA0LXQsg==?= , netdev To: David Ahern Return-path: Received: from relay4-d.mail.gandi.net ([217.70.183.196]:60376 "EHLO relay4-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754355AbdECUVl (ORCPT ); Wed, 3 May 2017 16:21:41 -0400 Received: from mfilter17-d.gandi.net (mfilter17-d.gandi.net [217.70.178.145]) by relay4-d.mail.gandi.net (Postfix) with ESMTP id BFE211720C8 for ; Wed, 3 May 2017 22:21:39 +0200 (CEST) Received: from relay4-d.mail.gandi.net ([IPv6:::ffff:217.70.183.196]) by mfilter17-d.gandi.net (mfilter17-d.gandi.net [::ffff:10.0.15.180]) (amavisd-new, port 10024) with ESMTP id 0z-CH7A0b0lD for ; Wed, 3 May 2017 22:21:38 +0200 (CEST) Received: from mail-qk0-f177.google.com (mail-qk0-f177.google.com [209.85.220.177]) (Authenticated sender: joe@ovn.org) by relay4-d.mail.gandi.net (Postfix) with ESMTPSA id 50BCF1720A9 for ; Wed, 3 May 2017 22:21:38 +0200 (CEST) Received: by mail-qk0-f177.google.com with SMTP id q1so613299qkd.2 for ; Wed, 03 May 2017 13:21:38 -0700 (PDT) In-Reply-To: <5a408c23-d3e2-aa3e-4574-82521b2255b0@gmail.com> Sender: netdev-owner@vger.kernel.org List-ID: On 3 May 2017 at 11:14, David Ahern wrote: > On 5/3/17 11:33 AM, Алексей Болдырев wrote: >> I watched one forum, there is listed in the properties of one license for Cisco, it says: >> >> Layer 3 VPN • Multi-VRF CE (VRF-lite); requires IP Services Feature license >> • MPLS VPN; requires Advanced IP Feature license >> • 26 VRFs > > There is no direct limit on the number of VRFs the kernel allows you to > create. There are indirect ones -- total memory in the system and limits > such as /proc/sys/net/ipv6/route/max_size. By increasing the latter I > have created 4k VRFs in a system. > > >> • 8192 MPLS labels >> >> Especially interested in the figure 8192 MPLS Labels. > > 8192 labels added in one pass is absurd. There is no reason to support > such a number. With the latest version of the MPLS stack in the kernel > you can add up to 30 labels in a single route. If you want more you have > to either recirculate the packet using routes or recompile the kernel > and increase the memory limit and the number of labels limit. > >> >> As I understand it, is it either a limit on the number of labels on the stack or the total number of labels? >> >> In Linux, for example, you can specify a common col- lection of labels through /proc/sys/net/mpls/platforms_labels > > that just allocates the size of an array which dictates the max label > number for that namespace. The array needs to be converted to a hash > table at some point. > >> >> Also I would like to know if the openvswitch has a limit of 3 tags in the stack or the total number of MPLS labels that can send? >> > > someone familiar with OVS needs to answer that. That would be 3 tags in a stack. When we spoke to people involved in the design and usage of MPLS in practice, we got the impression that it's very rare for anyone to configure a setup where more than that is used concurrently on a packet. If you believe the contrary, then I imagine it's not hard to bump that limit. There is no limit on which labels can be used from OVS, it's just a number in an action attached to a flow.