User`s guide

Chapter 4: Examples
4-16 DIGITAL MultiSwitch 700 Port Based VLAN User’s Guide
4. When Switch 1 receives the tagged broadcast frame, it also examines
the tag and classifies the frame as belonging to the Red VLAN. This
broadcast frame is then sent to all ports eligible to receive Red VLAN
frames. In this case only the 1d trunk, port 3, is eligible, as it is
considered a member of all VLANs for forwarding purposes. The Tag
is stripped from the frame and the frame is transmitted out port 3 as
shown in Figure 4-10. The Source Address Table for Switch 1 is
updated to contain User B.
Figure 4-10 Switch 1 Forwards to 1d Trunk
5. The Mail Server receives the broadcast frame and recognizes it. The
Mail Server responds with a unicast frame to User B. This frame
crosses the 1d Trunk and is received by Switch 1. Switch 1 classifies
the unicast frame as belonging to the Default VLAN (the only
membership for the 1d Trunk port).
Switch 1 checks the Filtering Database for the MAC address of
User B. User B’s MAC address is located, and port 2 is identified as
User B’s location. The frame is then checked against the Egress List
for port 2. Since port 2 is a 1Q Trunk port, its Egress List contains all
VLANs. The frame is tagged and transmitted out port 2.
The switch also recognizes the MAC address of User B in its Source
Address Table and updates that table to contain the MAC address and
port combination of the Mail Server.
6. This tagged unicast frame is received by Switch 2. The frame is
already tagged as belonging to the Default VLAN, so no classification
needs to be done. The switch recognizes User B’s MAC address in its
Source Address Table and updates that table to contain the Mail
Server’s MAC address and port combination.
Floor 1
Floor 2
1
1
2
3
4
Mail Server
Green VLAN
Green, Inc.
2263n20