Cisco 3200 Series - Page 128

C-4
Cisco 3200 Series Router Hardware Reference
OL-5816-10
Appendix C Switch Port Functionality
Inter-VLAN Routing
Figure C-3 802.1Q Tag Format in an Ethernet Frame
Inter-VLAN Routing
In a VLAN network, traffic and stations for multiple network layer subnets (VLANs) can coexist on a
single physical LAN segment. In practice, a single VLAN corresponds to a network subnet, and a VLAN
trunking capable router is required to forward traffic from a first VLAN to a second VLAN for a Layer
2
switch.
The FESMIC enables the Cisco 3200 Series router to become one of first IOS Ethernet switching routers
to deliver intelligent Layer
2 switching capability and Layer 3 inter-VLAN routing in a single box
solution, as shown in
Figure C-4
Figure C-4 Switching Router Network Topology
82634
Len/Etype
Len/Etype
Data
Data
Tagged
Frame
Original
Frame
FCS
FCS
SrcDest
SrcDest Etype
Etype
Token-Ring Encapsulation Flag
VLAN-ID
VLAN-ID and
TR encapsulation are
802.IQ, not 802.IP.
Ta g
82635
Floor 1
Switching
Router
Switching
Router
Switching
Router
L2 Switch
L2 Switch
Router
Floor 2
Floor 3
Floor 1
Floor 2
Floor 3
VLAN1 VLAN2 VLAN3
VLAN1 VLAN2 VLAN3
L2 Switch
Traditional Switch and Router Topology. Switching Router Topology.