Figure 39: TCC Interface Switching—PPP to ATM
In Figure 39, 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;
- }
- }
- }
- }
To verify your TCC connection, use the show connections command on Router B:
user@router_b> show connections CCC and TCC connections [Link Monitoring On] Legend for status (St) Legend for connection types UN -- uninitialized if-sw: interface switching NP -- not present rmt-if: remote interface switching WE -- wrong encapsulation lsp-sw: LSP switching DS -- disabled Dn -- down Legend for circuit types -> -- only outbound conn is up intf -- interface <- -- only inbound conn is up tlsp -- transmit LSP Up -- operational rlsp -- receive LSP Connection/Circuit Type St Time last up # Up trans PPP-to-ATM if-sw Up Nov 30 08:57:53 1 at-1/1/0.32 intf Up so-0/0/0.0 intf Up
