On 3 May 2017 at 11:14, David Ahern <[email protected]> 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.
