Specifications

4-4
Cisco IGX 8400 Series Provisioning Guide, Release 9.3.3 and Later Releases
OL-1166-04
Chapter 4 Cisco IGX 8400 Series Trunks
Functional Overview
Note VPCs cannot be routed over a virtual trunk, due to the way virtual trunks are represented in the public
ATM network.
For information on virtual trunk support and compatibility, see the “Virtual Trunks Supported on the
IGX” section on page 4-5. For information on setting up a virtual trunk, see the “Configuring a Virtual
Trunk on the IGX” section on page 4-9.
Note Virtual trunks originating from the UXM and UXM-E URM cannot terminate on the BPX BNI card. For
information on virtual trunks and the BPX BNI card, see the “Virtual Trunking” section in Chapter 1,
“The BPX Switch: Functional Overview,” in the Cisco BPX 8600 Series Installation and Configuration
guide.
Figure 4-1 Typical ATM Hybrid Network Using Virtual Trunks
Note You cannot use a virtual trunk as an interface shelf (feeder) trunk; similarly, you cannot configure an
interface shelf trunk to act as a virtual trunk, nor can you terminate interface shelf (feeder) connections
on a virtual trunk.
Public ATM network
ATM-UNI
ATM-UNI
17712
BXM 4
IGX 10
4.3.1
10.2.1
4.3
10.2
VPCs within the cloud,
one for each virtual trunk
(virtual trunks can be
type CBR, VBR, or ABR)
BPX_A
IGX_A
BXM 5
BPX_B
4.3.2
10.2.3
5.1.1
5.1.2
5.1