Example: APS for a Layer 2 Circuit Configuration
Figure 1: APS for a Layer 2 Circuit Topology Diagram
Figure 1 shows that APS is configured on a PE router to protect a PE-CE link in a Layer 2 circuit. This example shows only the PE router configuration and assumes that you have preconfigured a full Layer 2 circuit topology. For more information about configuring Layer 2 circuits, see Junos Layer 2 Circuits Feature Guide.
On Router PE1, configure ATM2 IQ interface at-0/0/1 as an APS protect circuit and ATM2 IQ interface at-1/3/1 as a working circuit. Also, configure the working circuit interface as the primary interface for your Layer 2 circuit and configure the protect circuit interface as the protected interface for your Layer 2 circuit.
Router PE1
Verifying Your Work
To verify proper operation of APS for Layer 2 circuits, use the following command:
After you configure the Layer 2 circuit and the APS working and protect circuits, you can see which APS circuit is active for the Layer 2 circuit with the show l2circuit connections command. The first local interface that is displayed is always the active circuit. If the second local interface field indicates Protect-Inactive, the working circuit is active, as shown in this output sample.
user@PE0> show l2circuit connectionsLayer-2 Circuit Connections: Legend for connection status (St) EI -- encapsulation invalid NP -- interface h/w not present MM -- mtu mismatch Dn -- down EM -- encapsulation mismatch VC-Dn -- Virtual circuit Down CM -- control-word mismatch Up -- operational OL -- no outgoing label XX -- unknown NC -- intf encaps not CCC/TCC CB -- rcvd cell-bundle size bad Legend for interface status Up -- operational Dn -- down Neighbor: 10.255.17.4 Interface Type St Time last up # Up trans at-1/3/1.0(vc 100) rmt Up Sep 3 17:48:25 2003 1 Local interface: at-1/3/1.0, Status: Up, Encapsulation: ATM CELL (PORT Mode) Remote PE: 10.255.17.4, Negotiated control-word: Yes (Null) Incoming label: 100368, Outgoing label: 100112 Local interface: at-0/0/1.0, Status: Dn, Encapsulation: ATM CELL (PORT Mode), Protect-Inactive
Conversely, if the first local interface is marked with the Protect-Active indicator, and the second local interface indicates Primary-Inactive, the protect circuit is active, as shown here:
user@PE0> show l2circuit connections Layer-2 Circuit Connections:
Legend for connection status (St)
EI -- encapsulation invalid NP -- interface h/w not present
MM -- mtu mismatch Dn -- down
EM -- encapsulation mismatch VC-Dn -- Virtual circuit Down
CM -- control-word mismatch Up -- operational
OL -- no outgoing label XX -- unknown
NC -- intf encaps not CCC/TCC
CB -- rcvd cell-bundle size bad
Legend for interface status
Up -- operational
Dn -- down
Neighbor: 10.255.17.4
Interface Type St Time last up # Up trans
at-1/3/1.0(vc 100) rmt Up Sep 3 17:51:06 2003 2
Local interface: at-0/0/1.0, Status: Up, Encapsulation: ATM CELL (PORT Mode),
Protect-Active
Remote PE: 10.255.17.4, Negotiated control-word: No
Incoming label: 100368, Outgoing label: 100112
Local interface: at-1/3/1.0, Status: Dn, Encapsulation: ATM CELL (PORT Mode),
Primary-Inactive
