Cisco Systems 8540 CSR, 8510 CSR About ATM Uplinks Catalyst, About the ATM Uplink Interface

Chapter 4 Configuring Interfaces

About ATM Uplinks (Catalyst 8540)

SR1	72036	SR2	18806	SR3	0	SR4	0	SR5	0
MT1	15143	MT2	0	MT3	0	MT4	0	MT5	6
MT6	0	MT7	0	MT8	0	MT9	0
ST1	0	ST2	0
MRXS	262160	MTXS	16	SRXS 3		STXS 0

About ATM Uplinks (Catalyst 8540)

ATM uses cell-switching and multiplexing technology that combines the benefits of circuit switching (constant transmission delay and guaranteed capacity) with those of packet switching (flexibility and efficiency for intermittent traffic). ATM is a common network technology for enterprise backbones, MANs, and WANs. By using an ATM uplink, Layer 3 traffic can be routed over an ATM network. The ATM uplink facilitates this by segmenting packet data into fixed-size cells at the transmitting end and reassembling them into packets at the receiving end. This conversion process is defined by the ATM adaptation layer (AAL).

For further information about ATM and its implementation on the Catalyst 8540 MSR and

Catalyst 8510 MSR, refer to the Guide to ATM Technology.

About the ATM Uplink Interface

The ATM uplink interface allows the Catalyst 8540 switch router to be deployed as part of an existing network where a router with an ATM interface would otherwise have been utilized. Additionally, the ATM uplink interface allows a Catalyst 8540 deployed as a Layer 3 switch (CSR) to be connected to a Catalyst 8540 deployed as an ATM switch (MSR).

Figure 4-6shows an example application of the ATM uplink in which traffic from a LAN switch is aggregated at the Catalyst 8540 CSR and then passed to the ATM network over the ATM uplink. The Layer 3 enabled ATM uplink supports RFC 1483 (Multiprotocol Encapsulation over ATM), which provides for the mapping of Layer 3 addresses to ATM virtual circuits, and traffic shaping. Refer to the Guide to ATM Technology for additional information on RFC 1483.

Figure 4-6 Layer 3 Traffic with ATM Uplink

Wiring closet

	ATM uplink
Catalyst 8540 CSR		ATM network

	4Gb Ethernet
	Catalyst 8540 MSR
	32973
	Layer 3 Switching Software Feature and Configuration Guide
78-6235-04, Cisco IOS Release 12.0(10)W5(18)		4-27