Routing With Virtual Trunks; Figure 25-4 Virtual Trunks Across A Public Atm Network - Cisco BPX-BXM-155-8DX Installation And Configuration Manual

Chapter 25 Configuring BXM Virtual Trunks

Figure 25-4 Virtual Trunks across a Public ATM Network

BPX_A

Routing with Virtual Trunks

AutoRoute, PNNI, and MPLS each use different routing mechanisms. However, the routing
mechanisms meet the following criteria when dealing with virtual trunks:
•
•
•
The characteristics of a virtual trunk used by connection routing are maintained throughout the network.
This information—virtual trunk existence, traffic classes and connection channels—is sent to every
node to allow the routing algorithm to use the trunk correctly. Routing uses only those virtual trunks
that can support the traffic type of the connection.
Virtual trunking is supported by these features:
Release 9.3.0, Part Number 78-10674-01 Rev. D0, July 2001
BXM 4
4.3
ATM-UNI
4.3.2
Public ATM network
Virtual Trunk Existence
Routing has special restrictions and conid assignments for a virtual trunk. For example, VPC's may
not be routed over a virtual trunk.
Traffic Classes
The unique characteristics of CBR, VBR, and ABR traffic are maintained through the cloud as long
as the correct type of virtual trunk is used. You configure the traffic classes allowed per virtual
trunk by using cnftrk. The routing algorithm excludes virtual trunks whose traffic class is not
compatible with the candidate connection to be routed.
Connection Identifier (Conid) Capacity
Each virtual trunk has a configurable number of connection channels reserved from the card. The
routing algorithm checks for adequate channel availability on a virtual trunk before selecting the
trunk for a route.
VPCs within the cloud,
one for each virtual trunk
(Virtual trunks can be
type CBR, VBR, or ABR)
10.2.1
4.3.1
10.2.3
5.1.1
Cisco BPX 8600 Series Installation and Configuration
How Virtual Trunking Works
IGX 10
10.2
ATM-UNI
5.1.2
5.1
BXM 5
IGX_A
BPX_B
25-7