RuggedCom RuggedRouter RX1100 - Manual (Page 235)

26. Configuring Layer 2 Tunnels
Revision 1.14.3 235 RX1000/RX1100™
The Media Access Control (MAC) destination address of frames received from Ethernet is inspected
in order to determine which GOOSE group they are in. The frames are then encapsulated in network
headers and forwarded (with MAC source and destination addresses intact) to the network as GOOSE
packets.
IEC61850 recommends that the MAC destination address should be in the range 01:0c:cd:01:00:00
to 01:0c:cd:01:01:ff.
GOOSE Packets received from the network are stripped of their network headers and forwarded to
Ethernet ports configured for the same multicast address. The forwarded frames contain the MAC
source address or the originating device, and not that of the transmitting interface. The VLAN used
will be that programmed locally for the interface and may differ from the original VLAN. The frame will
be transmitted with the highest 802.1p priority level (p4).
Packets received from the network will also be forwarded to any other remote daemons included in
the group.
26.1.2. Generic Layer 2 Tunnel Fundamentals
The Layer 2 Tunnel Daemon also supports a generic mode of operation based on the Ethernet type
of Layer 2 data traffic seen by the router. Multiple tunnels may be configured, each one with:
• Ethernet type
• Tunnel ingress (Ethernet interface)
• Tunnel egress (either another locally connected Ethernet interface, or the remote IP address of
another Layer 2 Tunnel daemon instance running on another RuggedRouter)
26.1.2.1. Generic Tunnel Implementation Details
For each tunnel configured, the daemon monitors the specified Ethernet interface for Ethernet (Layer
2) frames of the specified type. If the configured egress is another local Ethernet port, frames are
simply forwarded on that port, unmodified.
If the configured tunnel egress is a remote IP address, the daemon encapsulates the frames and
forwards them to that address, where a corresponding Layer 2 Tunnel Daemon must be configured
to receive tunneled frames for local retransmission. Encapsulation headers are stripped in order that
the retransmitted frames are identical to those received at the tunnel ingress.
Other notes:
• Source and destination Ethernet MAC addresses are preserved, whether they are forwarded
locally or remotely.
• Packets received from the network will also be forwarded to any other remote daemons included
in the group.
• The UDP port number for inter-daemon communication must be the same throughout the
network
• Enabling Generic L2 Tunneling on an Ethernet interface does not interfere with other (Layer 3)
networking configuration on that interface, e.g. firewall rules, IP routing, etc.