Riverstone Networks RS Switch Router User Guide Release 8.0 5-19
Bridging Configuration Guide
Tunneling VLAN packets across MANs
5.12 TUNNELING VLAN PACKETS ACROSS MANS
The “stackable” VLAN feature on the RS allows you to tunnel multiple VLANs through a metropolitan area network
(MAN) over a single backbone VLAN. This feature provides the following benefits:
•
Traffic for multiple VLANs, or traffic for multiple customers, can be aggregated to run through a
MAN over a single backbone VLAN. The RS supports a maximum of 4094 customers or VLANs
and up to 4094 backbone VLANs.
•
Spanning tree and rapid spanning tree protocols can be run in customer-specific VLANs; no
reconfiguration of customer-specific VLANs is needed.
•
Per-VLAN spanning tree can be run in the backbone VLAN.
5.12.1
Stackable VLAN Components
The following figure illustrates the basic components of the stackable VLAN. Routers R1 and R2 switch traffic for
customers C1 and C2 through the MAN. Ports et.2.1 on R1 and et.6.1 on R2 belong to customer C1’s VLAN, “BLUE”
while ports et.3.1 on R1 and et. 7.1 on R2 belong to customer C2’s VLAN, “GREEN.” Traffic entering any of these
four ports are tagged with the appropriate customer VLAN ID (BLUE or GREEN) in an IEEE 802.1q header.
Figure 5-3 Stackable VLAN components
•
The VLAN RED is the
backbone VLAN
, which allows traffic from various VLANs to be tunneled
through the MAN.
•
Ports
et.4.1
on R1 and
et.5.1
on R2 are
tunnel backbone ports
, which are trunk ports through which
the VLAN traffic is tunneled. Tunnel backbone ports must be configured as trunk ports so that they
maintain the encapsulated 802.1q header. You configure these ports as both trunk ports and tunnel
backbone ports with the
stackable-vlan
option of the
vlan make trunk-port
CLI command.
•
Ports
et.2.1
and
et.3.1
on R1 are
tunnel entry ports
, which are access ports on which the VLAN
traffic to be tunneled enters R1. Ports
et. 6.1
and
et.7.1
on R2 are
tunnel exit ports
, which are access
ports on which the tunneled traffic exits R2. You configure the mapping of the tunnel entry and
tunnel exit ports to the backbone VLAN with the
vlan enable stackable-vlan
CLI command.
et.2.1
et.3.1
et.4.1
et.5.1
et.6.1
et.7.1
R1
R2
MAN
RED VLAN (backbone)
BLUE VLAN
GREEN VLAN
C1
C2
C1
C2
