Configure Asynchronous Transfer Mode (ATM)

ATM's structures are mostly from the X.25 and frame relay, but the objective is to run at a higher speed. However, with different frame relay is for 7,000 and 7,500 series routers specifically designed to work with ATM network adapter. It is also possible to configure an ATM using a serial interface (Federal information/HSSI) or serial interface (4000) NMP. This configuration details, please refer to the configuration guide, chapter 7th.

Configure the ATM interfaces specified at the beginning of the interface IP address (as shown earlier in this document). Frame relay ATM needs on the part of every host on the same subnet. Next configure the Pvc. There are two parts. First create a PVC "maps" on the interface. Second Protocol address images to each create a PVC. Pvc is described by the virtual circuit (VCD) is assigned to the given virtual path identifier (VPI) and virtual circuit identifier (VCI) is created. With a frame relay Dlci, for a given link, VCI assigned by the carrier. Creates a PVC on the General form of a given interface is the command

atm pvc <vcd> <vpi> <vci> <aal-encapsulation> [[<midlow> <midhigh>]
    [<peak> <avg> <burst> [oam <seconds>]]

VCD is specific to the router and the router is used to match VPI/VCI and can be used to determine the VPI and VCI numbers are different. It is also needs to be specified for ATM datagram encapsulated in the VCI. This is the ATM adaptation layer (AAL). Peak and average values used to specify where the PVC will be allowed connection bandwidth. When these values are ignored, and are assumed to be the highest possible connection rate.

Next, you need an image on an interface to create a protocol for each PVC. This is achieved by creating a list of maps. Each entry in this list have "<protocol> <address> ATM-VC <vcd> [radio]" where the IP or IPX protocol, or for example, AppleTalk. The address is on the Protocol address of the remote router is transmitting through a virtual connection.


Once the map is created, it need to be associated with a given ATM interface using the interface command "map-group <map name> 

An example configuration might look as follows

interface ATM1/0
 ip address 1.2.3.4 255.255.255.224
 ipx network 121
 atm pvc 32 0 3 aal5snap
 atm pvc 33 0 4 aal5snap
 map-group atm-map-1

map-list atm-map-1
 ip 1.2.3.5 atm-vc 3 broadcast
 ipx 121.0000.0c7e.a45.546 atm-vc 4

Two principle AAL package suitable for use with the data. First, as has already been shown to be aal5snap. This encapsulation allows multiprotocol routing on virtual circuits. Second meeting of encapsulates AAL5MUX. This encapsulation, a single agreement are committed to a virtual circuit. It has slightly less overhead than AAL5SNAP and may be useful, when you are connected to the network use charges for each datagram is set.

Current default is Cisco IOS AAL5SNAP. However, earlier versions of operating software AAL5NLPID specified as the default. Turntable is somewhat similar to run ATM over a serial interface (the HSSI) in an external ATM DSU is necessary often using multi-protocol encapsulation of the snap. This package is popular in exchange points such as Ameritech's NAP (AADS).