5-8
S
UMMIT
S
WITCH
I
NSTALLATION
AND
U
SER
G
UIDE
V
IRTUAL
LAN
S
(VLAN
S
)
In
Figure 5-4
and
Figure 5-5
:
¥
The trunk port on each Switch carries trafÞc for both VLAN
Marketing
and VLAN
Sales
.
¥
The trunk port on each Switch is tagged.
¥
The server connected to port 1 on Switch 1 has a NIC that supports 802.1Q tagging.
¥
The server connected to port 1 on Switch 1 is a member of both VLAN
Marketing
and VLAN
Sales
.
¥
All other stations use untagged trafÞc.
As data passes out of the Switch, the Switch determines if the destination port requires
the frames to be tagged or untagged. All trafÞc coming from and going to the server is
tagged. TrafÞc coming from and going to the trunk ports is tagged. The trafÞc that
comes from and goes to the other stations on this network is not tagged.
M
IXING
P
ORT
-
BASED
AND
T
AGGED
VLAN
S
You can conÞgure the Summit using a combination of port-based and tagged VLANs. A
given port can be a member of multiple VLANs, with the stipulation that only one of its
VLANs uses untagged trafÞc. In other words, a port can simultaneously be a member of
one port-based VLAN and multiple tag-based VLANs.
For the purposes of VLAN classification, packets arriving on a port with an
802.1Q tag containing a VLAN ID of zero are treated as untagged.
P
ROTOCOL
-B
ASED
VLAN
S
Protocol-based VLANs enable you to deÞne a packet Þlter that the Summit uses as the
matching criteria to determine if a particular packet belongs to a particular VLAN.
Protocol-based VLANs are most often used in situations where network segments
contain hosts running multiple protocols. For example, in
Figure 5-6
, the hosts are
running both the IP and NetBIOS protocols.
SUMMIT.BK Page 8 Thursday, September 25, 1997 12:33 PM
