Specifications

Watson 5 Ethernet
Operating Manual
W5-Ethernet-Manual.doc
Version 2.0-01
3-14 Revision: 2006-04-27
Server
4 LAN interfaces
One MAC
address
Watson 5 Ethernet
Plugin
A B C D
ETH1 .. ETH4
DSL1 .. DSL4
Watson 5 Ethernet
Tabletop
2 3 4
1
1 2 3 4
1 2 3 4
1 2 3 4
1
1
Default VLAN Tag
VLAN Port Membership
If SVL is used:
1 – Server transmits an Ethernet packet to client A. MAC
address of Server is learned at port ETH1.
2 – Client B tries to send a packet to Server. Packets from
client B are tagged with VID 2. If SVL is used then this
packet will be forwarded to port ETH1 (where the Server
MAC address has been learned) but it cannot egress
there because ETH1 is member of VLAN 1.
Communication between client B and Serve is interrupted
(until Server sends a packet to client B).
Conclusion:
Each VLAN must use its individual forwarding database (IVL)
Figure 3-9: Individual VLAN learning (IVL) example
For IVL operation each VLAN is configured to use its own forwarding database.
SVL is used e.g. in asymmetric VLAN configurations. Asymmetric VLANs together with Port-based
tagging allow several clients to access a common server while prohibiting the clients from talking to
each other:
Server
Watson 5 Ethernet
Plugin
A B C D
ETH1
DSL1 .. DSL4
Watson 5 Ethernet
Tabletop
5
1,5 2,5 3,5 4,5
1 2 3 4
1
1
Default VLAN Tag
VLAN Port Membership
Upstream VLANs: 1, 2, 3, 4
Downstream VLAN: 5
Upstream: Any packet being sent to the Server from any client will
always will always egress at ETH1 regardless of its VID but cannot
reach any other client because their ports are in different VLANs. The
MAC address of the Clients are learned at ports DSL1 .. DSL4 for all
VLANs.
Downstream: All packets are tagged with VID 5 and will be sent to
the correct client port (the client MAC address has been learnt when
the first packet was sent upstream to the server). The shared FDB
ensures that the Server MAC addresses is learnt at port ETH1 for all
VLANs.
1, 2, 3, 4, 5
Figure 3-10: Shared VLAN learning (SVL) example
For SVL operation several VLANs are configured to use the same forwarding database.
Notes: ! The Watson 5 Ethernet tabletop modems do not support VLAN tagging. They are transparent
for VLANs, i.e. VLAN tags are preserved during transmission over the DSL.
! The Watson 5 Ethernet tabletop modem has a single address learning database which does
not take VIDs into account.