Filter
Top Products
16-2
ATM Switch Router Software Configuration Guide
OL-7396-01
Chapter 16 Configuring Tag Switching and MPLS
Hardware and Software Requirements and Restrictions (Catalyst 8540 MSR)
In a tag switching network, the Layer 3 header is analyzed just once. It is then mapped into a short
fixed-length tag. At each hop, the forwarding decision is made by looking only at the value of the tag.
There is no need to reanalyze the Layer 3 header. Because the tag is a fixed-length, unstructured value,
lookup is fast and simple.
For an overview of how tag switching works and its benefits, refer to the Guide to ATM Technology.
Hardware and Software Requirements and Restrictions
(Catalyst 8540 MSR)
The Catalyst 8540 MSR hardware requirements for tag switching include the following:
• The ATM switch router (used as a tag switch)
• A tag edged router such as a Cisco 7000 Route Switch Processor (RSP) with an Optical Carrier 3
(OC-3) ATM interface processor (AIP) installed
Tag switching has the following software restrictions:
• Open Shortest Path First (OSPF) is the only routing protocol currently supported.
• IP is the only network layer protocol supported.
• Hierarchical VP tunnels cannot co-exist on a physical interface with tag switching.
Hardware and Software Requirements and Restrictions
(Catalyst 8510 MSR and LightStream 1010)
The Catalyst 8510 MSR and LightStream 1010 ATM switch router hardware requirements for tag
switching include the following:
• The ATM switch router (used as a tag switch).
• A switch processor feature card installed on the route processor, if you want to enable VC merge
(multipoint-to-point connection). Note that FC-PFQ requires 64 MB of DRAM.
• A tag edged router such as a Cisco 7000 RSP with an OC-3 AIP installed.
Tag switching has the following software restrictions:
• Open Shortest Path First (OSPF) is the only routing protocol currently supported.
• IP is the only network layer protocol supported.
• Hierarchical VP tunnels cannot co-exist on a physical interface with tag switching.
Configuring Tag Switching
This section describes how to configure tag switching on ATM switch routers, and includes the following
procedures:
• Configuring a Loopback Interface, page 16-3
• Enabling Tag Switching on the ATM Interface, page 16-4
• Configuring OSPF, page 16-5