Brocade Multi-Service IronWare Switching Configuration Guide (Supporting R05.6.00) - Manual (Page 310)

280 Multi-Service IronWare Switching Configuration Guide
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Backbone Edge Bridge (BEB) operation
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Service instance
A Service Instance (SI) is also known as a bridging domain. It is defined as a single flooding domain
where any traffic that requires flooding is always flooded to all endpoints under the same SI. When
an unknown destination packet is received at a PBB endpoint it will cause flooding of this packet to
all the endpoints (source port suppressed). The following types of endpoints defined here are
supported by PBB.
Untagged endpoint
By default a port is configured with a Ethernet type (TPID) of 0x8100. If an untagged packet is
received by the port, it is accepted and switched within the PBB instance to the desired destination
MAC. If a 0x8100 tagged packet is received and the port is operating as untagged mode with the
default TPID of 0x8100, the packet will be dropped as an invalid packet.
Port-based untagged endpoint
Port-based untagged endpoint is defined to always accept whatever packet is received by the given
port whether there is any tag present in the packet received. As explained earlier, if the packet
received on an untagged mode interface where the received packet contains the tag that matches
the configured port Ethernet type value, it is dropped as an invalid packet. To achieve the desired
behavior of treating the entire packet as an untagged packet (no tag stripping/insertion), the user
must configure the Ethernet type of the port to a value that will not match the Ethernet type of any
packets sent to this port. This way, although the packet received may contain a tag its value will
never match to the configured TPID value of the port (avoid setting it to a known protocol Ethernet
type value) thus the tag will be treated as part of the customer payload. A suggested value of
0x9FFF can be used for this purpose as this value is not listed in the IEEE Ethernet Type Listing as
a reserved value for a known protocol at the time of this document creation. Please always refer to
IEEE Ethernet Type field public listing to avoid setting to a value that may conflict with a known
protocol.
C-Tagged endpoint
C-tagged endpoint is defined as an endpoint that considers all packets received with the top most
tag being the Customer Tag (C-Tag). This is achieved by configuring a tagged endpoint under the
PBB instance. The user must configure the Ethernet type of the port to match the C-Tag TPID value
of the received packets. Packets sent out through the C-tagged endpoint will have a C-tag with
C-VID 100 added at egress to the endpoint.
Example 1:
If the packet received has a C-VID of 100 and the destination is another C-Tagged endpoint
with C-VID 200, when the packet exits the destination C-Tagged endpoint, it will have the C-VID
of 200. The original C-VID 100 is “translated” in this case.
Example 2:
If the packet is destined to a port based untagged endpoint, the packet will be sent out without
the original C-VID 100 tag because it was removed at the ingress of the C-tagged endpoint.