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.\" $OpenBSD: bpe.4,v 1.6 2022/09/12 09:15:29 jsg Exp $
.\"
.\" Copyright (c) 2018 David Gwynne <dlg@openbsd.org>
.\"
.\" Permission to use, copy, modify, and distribute this software for any
.\" purpose with or without fee is hereby granted, provided that the above
.\" copyright notice and this permission notice appear in all copies.
.\"
.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
.\"
.Dd $Mdocdate: September 12 2022 $
.Dt BPE 4
.Os
.Sh NAME
.Nm bpe
.Nd Backbone Provider Edge pseudo-device
.Sh SYNOPSIS
.Cd "pseudo-device bpe"
.Sh DESCRIPTION
The
.Nm bpe
driver creates IEEE 802.1Q Provider Backbone Bridge (PBB) networks
by acting as a Backbone Edge Bridge (BEB).
PBB, also known as mac-in-mac, was originally specified in
IEEE 802.1ah-2008 and became part of IEEE 802.1Q-2011.
.Pp
A Provider Backbone Bridge Network (PBBN) consists of BEBs
interconnected by Backbone Core Bridges (BCBs) to form an Ethernet
network for the transport of encapsulated Ethernet packets.
Where VLAN and SVLAN protocols add a shim to differentiate Ethernet
packets for different networks but retain the Ethernet addresses
of encapsulated traffic, PBB completely encapsulates Ethernet packets
for transmission between BEBs on a PBBN.
This removes the need for intermediate BCB devices on the backbone
network to learn the Ethernet addresses of devices on the encapsulated
network, but requires each BEB to maintain a mapping of addresses
on the encapsulated network to peer BEBs.
.Pp
A PBB packet consists of another Ethernet frame containing Ethernet
addresses for BEBs and the PBB Ethernet protocol type (0x88e7), a
32-bit Backbone Service Instance Tag (I-TAG), followed by the
encapsulated Ethernet frame.
The I-TAG contains a 24-bit Backbone Service Instance Identifier
(I-SID) to differentiate different PBBNs on the same backbone network
.Pp
IEEE 802.1Q describes customer VLANs being encapsulated by PBB,
which in turn uses an S-VLAN service.
This can be implemented with
.Xr vlan 4
using a
.Nm bpe
interface as the parent,
and with the
.Nm bpe
interface using
.Xr svlan 4
as the parent.
.Nm bpe
itself does not require this topology, therefore allowing flexible
deployment and network topologies.
.Pp
The
.Nm bpe
driver implements a learning bridge on each interface.
The driver will learn the mapping of BEPs to encapsulated Ethernet
address based on traffic received from other devices on the backbone
network.
Traffic sent to broadcast, multicast, or unknown unicast Ethernet
addresses will be flooded to a multicast address on the backbone network.
The multicast address used for each PBB Service Instance
will begin with 01:1e:83 as the first three octets, with the I-SID
as the last three octets.
For example, a
.Nm bpe
interface with a vnetid of 1024 (0x400 in hex) will have a multicast
group address of 01:1e:83:00:04:00.
The address learning in
.Nm bpe
only uses the Ethernet addresses of encapsulated traffic for its
forwarding decisions; it does not use VLAN or S-VLAN tags to
differentiate services.
.Pp
.Nm bpe
interfaces can be created at runtime using the
.Ic ifconfig bpe Ns Ar N Ic create
command or by setting up a
.Xr hostname.if 5
configuration file for
.Xr netstart 8 .
The interface itself can be configured with
.Xr ifconfig 8 ;
see its manual page for more information.
.Pp
.Nm bpe
interfaces must be configured with a parent Ethernet interface to
operate, and a virtual network identifier for use as the I-SID.
.Pp
The I-TAG includes a priority field.
By default, the value of the priority field in a transmitted packet
is based on the priority of packets sent over the interface, which
may be altered via
.Xr pf.conf 5 ;
see the
.Cm prio
option for more information.
Alternatively,
.Cm txprio
can set a specific priority for transmitted packets.
.Pp
.Nm bpe
interfaces support the following
.Xr ioctl 2 Ns s :
.Bl -tag -width indent -offset 3n
.It Dv SIOCSIFPARENT Fa "struct if_parent *"
Set the parent interface.
The parent may only be configured while the virtual interface is
administratively down.
.It Dv SIOCGIFPARENT Fa "struct if_parent *"
Get the currently configured parent interface.
.It Dv SIOCDIFPARENT Fa "struct ifreq *"
Delete the parent interface configuration.
The parent may only be removed while the virtual interface is
administratively down.
.It Dv SIOCSVNETID Fa "struct ifreq *"
Set the virtual network identifier.
Valid identifiers are 24-bit values in the range 0 to 16777215.
.It Dv SIOCGVNETID Fa "struct ifreq *"
Get the currently configured virtual network identifier.
.El
.Sh SEE ALSO
.Xr bridge 4 ,
.Xr inet 4 ,
.Xr ip 4 ,
.Xr netintro 4 ,
.Xr vlan 4 ,
.Xr hostname.if 5 ,
.Xr pf.conf 5 ,
.Xr ifconfig 8 ,
.Xr netstart 8
.Rs
.%T IEEE 802.1Q standard
.%U https://standards.ieee.org/standard/802_1Q-2018.html
.Re
.Rs
.%Q Provider Backbone Bridges
.%T IEEE 802.1ah standard
.Re
.Sh HISTORY
The
.Nm
driver first appeared in
.Ox 6.5 .
.Sh AUTHORS
.An David Gwynne Aq Mt dlg@openbsd.org .
|
