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Example: PPP to ATM TCC Configuration

Figure 85: TCC Interface Switching—PPP to ATM

Image g017139.gif

In Figure 85, Router A uses PPP to connect with Router B, while Router C connects with Router B through ATM. Router B acts as the Layer 2 virtual switch and transparently connects Router A to Router C.

On Router A, configure basic PPP encapsulation and any desired Layer 3 protocol families on the SONET/SDH interface.

Router A



[edit]
interfaces {


so-0/1/0 {
description "to Router B so-0/0/0";


unit 0 {
                   
encapsulation ppp;                 



family inet {
address 10.1.1.1/30;
}


}


}


}

Router B acts as the virtual Layer 2 switch. Here you configure the appropriate TCC encapsulations on the corresponding interfaces. In this case, encapsulation ppp-tcc is bound to physical interface so-0/0/0, and encapsulation atm-tcc-vc-mux is placed on VC 32 of interface at-1/1/0. Because the switching occurs at Layer 2, you cannot configure IP addresses or other Layer 3 family information on these interfaces.

You also need to configure MPLS and establish the cross-connect by adding the necessary interfaces to the interface-switch statement at the [edit protocols connections] hierarchy level.

Router B



[edit]
interfaces {


so-0/0/0 {
description "to Router A so-0/1/0";
                 
encapsulation ppp-tcc;               



unit 0 {
}




at-1/1/0 {
description "to Router C at-0/3/0";


atm-options {
vpi 0 maximum-vcs 2000;
}




unit 32 {
vci 32;
                     
encapsulation atm-tcc-vc-mux;                   

}


}


}




protocols {


mpls {
interface so-0/0/0.0;
interface at-1/1/0.32;
}




connections {


interface-switch PPP-to-ATM {
interface so-0/0/0.0;
interface at-1/1/0.32;
}


}


}


}

On Router C, the encapsulation option used to connect to the TCC-encapsulated ATM interface on Router B is atm-vc-mux. Since this ATM connection is switched at Layer 2 to reach the PPP link, it is transparent to Layer 3 addressing. As a result, the IP address must be configured in the same address space as Router A’s so-0/1/0 interface.

Router C



[edit]
interfaces {


at-0/3/0 {
description "to Router B at-1/1/0";


atm-options {
vpi 0 maximum-vcs 2000;
}




unit 32 {
vci 32;
encapsulation atm-vc-mux;


family inet {
address 10.1.1.2/30;
}


}


}


}

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