Other Types

Besides wired, wireless and VPN interfaces, there are also some other, virtual interfaces, as well as some miscellaneous interface-related. These options can be found under Interfaces ‣ Other types. This document briefly explains these options.

Bridge

Bridging allows to create a connection between separate networks, allow traffic on network A destined for network B (where both networks are connected to your OPNsense device) to reach it via this bridge. Note that this does not include DHCP services—this needs to set using DHCP relaying.

A bridge works like a (layer-2) switch, forwarding traffic from one interface to another. Multicast and broadcast packets are always forwarded to all interfaces that are part of the bridge. For unicast traffic, the bridge learns which MAC addresses are associated with which interfaces and will forward the traffic selectively.

Optionally a bridge can be configured to support (Rapid) Spanning Tree Protocol (RSTP/RTP) to prevent loops in the network topology. These options are provided in the “advanced” section of the configuration and include the following settings:

Option

Description

Enable

Enable the (Rapid) Spanning Tree Protocol

Protocol

Protocol to use, rapid or regular spanning tree

STP interfaces

The interfaces tith [R]STP enabled, from the ones in the bridge

Valid time (maxage)

Set the time that a Spanning Tree Protocol configuration is valid. The default is 20 seconds.

Forward time (fwddelay)

Set the time that must pass before an interface begins forwarding packets when Spanning Tree is enabled. The default is 15 seconds.

Hello time (hellotime)

Set the time between broadcasting of Spanning Tree Protocol configuration messages. The hello time may only be changed when operating in legacy STP mode. The default is 2 seconds.

Priority

Set the bridge priority for Spanning Tree. The default is 32768. The minimum is 0 and the maximum is 61440.

Hold count (holdcnt)

Set the transmit hold count for Spanning Tree. This is the number of packets transmitted before being rate limited. The default is 6. The minimum is 1 and the maximum is 10.

[interface] Priority (ifpriority)

Set the Spanning Tree priority of interface to value. The default is 128. The minimum is 0 and the maximum is 240. Increments of 16.

[interface] Path cost (ifpathcost)

Set the Spanning Tree path cost of interface to value. The default is calculated from the link speed. To change a previously selected path cost back to automatic, set the cost to 0. The minimum is 1 and the maximum is 200000000.

Other advanced options available in the bottom section of the screen and include the following settings:

Option

Description

Cache size (maxaddr)

Set the size of the bridge address cache to size. The default is 2000 entries.

Cache entry expire time (timeout)

Set the timeout of address cache entries to this number of seconds. If seconds is zero, then address cache entries will not be expired. The default is 1200 seconds.

Span port

Span ports transmit a copy of every frame received by the bridge. This is most useful for snooping a bridged network passively on another host connected to one of the span ports of the bridge.

Edge ports

Set interface as an edge port. An edge port connects directly to end stations and cannot create bridging loops in the network; this allows it to transition straight to forwarding.

Auto Edge ports

Allow interface to automatically detect edge status. This is the default for all interfaces added to a bridge, selecting interfaces will disable auto mode.

PTP ports

Set the interface as a point-to-point link. This is required for straight transitions to forwarding and should be enabled on a direct link to another RSTP-capable switch.

Auto PTP ports

Automatically detect the point-to-point status on interface by checking the full duplex link status. This is the default for interfaces added to the bridge, selecting interfaces will disable auto mode.

Sticky ports

Mark an interface as a “sticky” interface. Dynamically learned address entries are treated as static once entered into the cache. Sticky entries are never aged out of the cache or replaced, even if the address is seen on a different interface.

Private ports

Mark an interface as a “private” interface. A private interface does not forward any traffic to any other port that is also a private interface.

GIF

GIF (gif(4), Generic Tunnel Interface) can be used to tunnel IPv6 via IPv4 connections. A common use for this is the IPv6 tunnel of Hurricane Electric (he.net).

Note

In Configure IPv6 Tunnel Broker you can find information on how to setup a tunnel using Hurricane Electric

As with all tunnel types, the most important settings relate to how both ends connect and which addressing will be used to route traffic over the tunnel. The rest of the settings usually are best left to their defaults.

Option

Description

Parent interface

Actually the source address the tunnel will use to connect from.

GIF remote address

Peer address where encapsulated gif packets will be sent.

GIF tunnel local address

The tunnel’s local address which will be configured on the interface.

GIF tunnel remote address

The tunnel’s remote address which will be configured on the interface.

Disable Ingress filtering

Ingress filtering on outer tunnel source can break tunnel operation in an asymmetrically routed networks, in which case this can be disabled by marking this option.

ECN friendly behavior

Note that the ECN friendly behavior violates RFC2893. This should be used in mutual agreement with the peer.

Description

User friendly description for this tunnel

GRE

GRE (gre(4), Generic Routing Encapsulation) is used to create a virtual point-to-point connection, through which encapsulated packages can be sent. This can be used to utilise (OSI-layer 3) protocols between devices over a connection that does not normally support these protocols.

Since the GRE protocol was designed by Cisco, it is often used as default tunnel technology when using their solutions.

A common use-case of GRE is also to forward (no routable) multicast traffic, although this will need additional software such as IGMP-proxy or PIMD, which are less commonly used on OPNsense.

The available settings are similar to those described for the GIF tunnel type:

Option

Description

Parent interface

Actually the source address the tunnel will use to connect from.

GRE remote address

Peer address where encapsulated gif packets will be sent.

GRE tunnel local address

The tunnel’s local address which will be configured on the interface.

GRE tunnel remote address

The tunnel’s remote address which will be configured on the interface.

Description

User friendly description for this tunnel

LAGG

LAGG (lagg(4)) allows for link aggregation, bonding and fault tolerance. This works best if your network switches support. Only unassigned interfaces can be added to LAGG.

The userinterface supports the following options:

Option

Description

Parent interface

Members of the link aggregation

Lag proto

Protocol to use for aggregation, available options are described in the next table. LACP is most commonly used.

Description

User friendly description for this interface

Fast timeout

Enable lacp fast-timeout on the interface.

Use flowid

Use the RSS hash from the network card if available, otherwise a hash is locally calculated. The default depends on the system tunable in net.link.lagg.default_use_flowid.

Hash Layers

Set the packet layers to hash for aggregation protocols which load balance.

Use strict

Enable lacp strict compliance on the interface. The default depends on the system tunable in net.link.lagg.lacp.default_strict_mode.

MTU

MTU size, when unset the smallest mtu of this laggs children will be used.

Available protocols

Name

Description

failover

Sends and receives traffic only through the master port. If the master port becomes unavailable, the next active port is used. The first interface added is the master port; any interfaces added after that are used as failover devices.

fec

Supports Cisco EtherChannel. This is a static setup and does not negotiate aggregation with the peer or exchange frames to monitor the link.

lacp

Supports the IEEE 802.3ad Link Aggregation Control Protocol (LACP) and the Marker Protocol. LACP will negotiate a set of aggregable links with the peer in to one or more Link Aggregated Groups. Each LAG is composed of ports of the same speed, set to full-duplex operation. The traffic will be balanced across the ports in the LAG with the greatest total speed, in most cases there will only be one LAG which contains all ports. In the event of changes in physical connectivity, Link Aggregation will quickly converge to a new configuration.

loadbalance

Balances outgoing traffic across the active ports based on hashed protocol header information and accepts incoming traffic from any active port. This is a static setup and does not negotiate aggregation with the peer or exchange frames to monitor the link. The hash includes the Ethernet source and destination address, and, if available, the VLAN tag, and the IP source and destination address.

roundrobin

Distributes outgoing traffic using a round-robin scheduler through all active ports and accepts incoming traffic from any active port.

none

This protocol is intended to do nothing: It disables any traffic without disabling the lagg interface itself.

Loopback

Loopbacks are logical virtual interfaces which emulate real interfaces and can be used for different setup scenario’s, which require always-on interfaces. Below you will find some scenario’s for which these types of interfaces are used.

  • Administrative access to services on your machine, which can bind to an address configured on top of the loopback.

  • Using loopback addresses as router IDs for OSPF or BGP, which helps to identify your nodes and eases administration

VLAN

VLANs (Virtual LANs) can be used to segment a single physical network into multiple virtual networks. This can be done for QoS purposes, among other things. For this reason, most ISP-issued IPTV devices utilise VLANs.

The following settings are available for these interface types:

Name

Description

Parent interface

The interface to use as parent which it will send/receive vlan tagged traffic on

VLAN tag

802.1Q VLAN tag (between 1 and 4094)

VLAN priority

802.1Q VLAN PCP (priority code point)

Description

User friendly description for this interface

VXLAN

Virtual eXtensible Local Area Networks (VXLANs) are used to overlay virtualized layer 2 networks over layer 3 networks as described by rfc7348.

Tunnels can be setup in point to point (parameter Remote address) or multicast (parameters Multicast group and Device). The Source address must be an existing (statically assigned) address assigned at this firewall, which will be used as source in the encapsulating IPv4/IPv6 header.

Note

Since the vxlan interface encapsulates the Ethernet frame with an IP, UDP, and vxlan header, the resulting frame may be larger than the MTU of the physical network. The vxlan specification recommends the physical network MTU be configured to use jumbo frames to accommodate the encapsulated frame size. Alternatively, the MTU size on the vxlan interface might be reduced to allow the encapsulated frame to fit in the current MTU of the physical network.