VPN - Vanguard Networks

Tunnel Support for
Bridge Traffic
Figure 2-3 shows an example of packet flow between the bridge, tunnel, and LCON
modules. The overall configuration guidelines of tunnel support for bridge traffic
are:
• Configure each tunnel with a unique Bridge Link Number. The Bridge Link
can be Transparent, Source Routing or Translational Bridge Traffic.
• All bridge packets intended for the remote side bridge, passing through the
tunnel are encapsulated with encrypted GRE and IP headers, and then sent
over the tunnel.
• On the remote side tunnel, the IP and GRE Headers are removed after
decryption and the original bridge packet is forwarded to the appropriate host.
• Source Routing Bridge, Transparent Bridge, and Translational Bridge traffics
can be tunneled.
• The Protocol Type field in GRE Header has separate identifiers for:
- Source Routing Bridge Packet
- Spanning Tree Protocol Entity packet
- Transparent Bridge packet (protocol type value = 6558)
• Tunnels support the transport of BPDU between the remote bridges for
spanning tree calculations.
• For SR Bridge Traffic over a LAN Tunnel, the “Link Mode” must be
configured as RFC1294 in the Bridge Link Configuration, corresponding to
the Tunnel.
(Normal) Bridge Link z
Ethernet
Packets
Tunnel Bridge Link x
Tunnel Bridge Link y
LCON
Module
Packet
Out
Bridge
Token Ring
Packets
Figure 2-3. Packet Flow between Bridge, Tunnel, and LCON Modules
Tunneling 2-3
T0103-10, Revision L Release 7.3