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Example: APS for a Layer 2 Circuit Configuration

Figure 1: APS for a Layer 2 Circuit Topology Diagram

Image g017218.gif

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

[edit]chassis {fpc 0 {pic 0 { atm-l2circuit-mode { cell; # This dedicates FPC 0 PIC 0 to cell-relay mode.}}}fpc 1 {pic 3 { atm-l2circuit-mode { cell; # This dedicates FPC 1 PIC 3 to cell-relay mode.}}}}interfaces {at-0/0/1 {description "To CE1 at-0/1/2";encapsulation atm-ccc-cell-relay;sonet-options {aps { protect-circuit TEST; # This interface is the APS protect circuit.}}atm-options {pic-type atm2;promiscuous-mode;}unit 0 {allow-any-vci;}}at-1/3/1 {description "To CE1 at-0/1/1";encapsulation atm-ccc-cell-relay;sonet-options {aps { working-circuit TEST; # This interface is the APS working circuit.}}atm-options {pic-type atm2;promiscuous-mode;}unit 0 {allow-any-vci;}}}protocols {l2circuit {neighbor 10.255.17.4 { interface at-1/3/1.0 { # The Layer 2 circuit interface is the working circuit. protect-interface at-0/0/1.0; # The protect-interface is the protect circuit.virtual-circuit-id 100;}}}}

Verifying Your Work

To verify proper operation of APS for Layer 2 circuits, use the following command:

show l2circuit connections

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 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 17:48:25 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

Published: 2010-04-15

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