Intel ER8100STUS - Express 8100 Router, Reference Manual

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Reference.bok : Chapter10 103 Wed Apr 22 10:58:08 1998
103
How Bridging Works
WAN Bridging Services
Processing by the
Source Forwarding Table
Packets which are passed by the Destination Forwarding Table are then checked
by the Source Forwarding Table as follows:
1
If a table entry for both the Source MAC address and the incoming link
exist, the packet is labelled for forwarding on the outgoing link(s) allowed
by both the Destination and Source Forwarding Tables. The packet is then
passed to the Type Forwarding Table for further processing.
For example, if an entry in the Destination Forwarding Table allows a
packet from the LAN link to be forwarded on WAN link 1 and an entry in
the Source Forwarding Table only allows the packet from the LAN link to
be forwarded on WAN link 2, the packet received on the LAN link is dis-
carded.
Note
If a table entry for the packet defines the outgoing link as
None
,
the packet is discarded.
2 If a table entry exists for the Source MAC address but the incoming link
does not correspond with that of the packet, the packet is discarded.
3
If Source Forwarding Table is set to
Discard Multicast
. If the packet is
a Multicast packet and the Source MAC address for the packet is not found
in the table, the packet is discarded.
4
If no entry is found for the Source MAC address and the Default Action of
the Source Forwarding Table is set to Pass, the packet is labelled for for-
warding on the link(s) defined during processing by the Destination For-
warding Table. The packet is then passed to the Type Forwarding Table for
further processing.
Processing by the Type
Forwarding Table
Packets which have been passed by the Destination and Source Forwarding Ta-
bles are checked against the entries in the Type Forwarding Table as follows:
1
If table entries for both the Ethernet packet type and the incoming link
exist, the packet is forwarded on the outgoing link allowed by the Destina-
tion, Source and Type Forwarding Table entries except for the link on
which it was received.
Note
If entries exist in the Destination, Source and Type Forwarding
Tables, the outgoing link in these entries must be the same or the
packet is discarded.
Note
If a table entry for the packet defines the outgoing link as
None
,
the packet is discarded.
2
If a table entry exists for the Ethernet packet type but the incoming link
does not correspond with that of the packet, the packet is discarded.
3
If no entry is found for the Ethernet packet type and the Default Action of
the Type Forwarding Table is set to
Discard
, the packet is discarded.