Technical Documentation

Example: ATM2 IQ-Based Layer 2 Circuit Configuration

Figure 1: ATM2 IQ-Based Layer 2 Circuit Topology Diagram

Image g017217.gif

Figure 1 shows a similar network topology to our previous two examples. In this example, Routers PE1 and PE2 use ATM cell-relay mode on a CE-facing interface and ATM AAL5 mode on a second CE-facing interface.

On Router CE1, configure the ATM2 IQ interfaces to handle ATM traffic. Interface at-0/0/1 handles standard ATM traffic while interface at-0/0/2 handles AAL5 traffic.

Router CE1

[edit]interfaces {at-0/0/1 {description "to PE1 at-0/1/0";atm-options { pic-type atm2; # Layer 2 circuits are compatible withvpi 0; # ATM2 IQ interfaces.}unit 0 {vci 32;family inet {address 10.1.1.1/30;}}}at-0/0/2 {description "to PE1 at-1/2/0";atm-options { pic-type atm2; # Layer 2 circuits are compatible withvpi 0; # ATM2 IQ interfaces.}unit 0 { encapsulation atm-vc-mux; vci 32;family inet {address 10.2.2.1/30;}}}}

On Router PE1, configure the ATM2 IQ-based CE-facing interfaces: one with ATM cell-relay mode CCC encapsulation and the other with ATM VC multiplexing CCC encapsulation. Also enable the corresponding Layer 2 circuit modes at the [edit chassis] hierarchy level. In this case, you must configure cell-relay mode on Physical Interface Card (PIC) 1 in Flexible PIC Concentrator (FPC) 0 and AAL5 mode on PIC 2 in FPC 1.

Establish your Layer 2 circuit with configuration of the l2circuit statement at the [edit protocols] hierarchy level. Remember to include in your Layer 2 circuit configuration the IP address of your remote PE neighbor (usually the loopback address of the neighbor), the interfaces connected to the CE router, and a virtual circuit identifier for each VC. In this case, you will establish one VC for cell-relay mode traffic and a second VC for AAL5 traffic. Then, configure MPLS, LDP, and an IGP (such as OSPF) to enable signaling for your Layer 2 circuit.

Router PE1

[edit]chassis {fpc 0 {pic 1 { atm-l2circuit-mode { cell; # This dedicates FPC 0 PIC 1 to cell-relay mode.}}}fpc 1 {pic 2 { atm-l2circuit-mode { aal5; # This dedicates FPC 1 PIC 2 to AAL5 mode.}}}}interfaces {at-0/1/0 {description "to CE1 at-0/0/1"; encapsulation atm-ccc-cell-relay; # Cell-relay requires cell-relay encapsulation.atm-options { cell-bundle-size 4; # This sets the cell bundle size for the interface. pic-type atm2; # Layer 2 circuits are compatible withvpi 0; # ATM2 IQ interfaces.}unit 0 { encapsulation atm-ccc-cell-relay; # Encapsulation for the logical interface.vci 32; cell-bundle-size 10; # The cell bundle size for the logical interface overrides}       # the physical interface setting.}at-1/2/0 {description "to CE1 at-0/0/2";atm-options { pic-type atm2; # Layer 2 circuits are compatible withvpi 0; # ATM2 IQ interfaces.}unit 0 { encapsulation atm-ccc-vc-mux; # AAL5 requires CCC VC MUX encapsulation.vci 32;}}so-0/1/0 {description "to P0 so-0/0/0";unit 0 {family inet {address 192.168.245.22/30;}family mpls; # Include the MPLS family on core-facing interfaces.}}lo0 {unit 0 {family inet {address 10.255.17.2/32;}}}}protocols {ospf {traffic-engineering;area 0.0.0.0 {interface so-0/1/0.0;interface lo0.0;}}ldp { # LDP is required as the signaling protocol for Layer 2 circuits.interface so-0/1/0.0;interface lo0.0;}l2circuit {neighbor 10.255.17.4 { # This points to the loopback of the PE neighbor.interface at-0/1/0.32 { # Here you include the local CE-facing interface.virtual-circuit-id 1; # Be sure this ID matches the ID of your PE neighbor.}}neighbor 10.255.17.4 { # This points to the loopback of the PE neighbor.interface at-1/2/0.32 { # Here you include the local CE-facing interface.virtual-circuit-id 2; # Be sure this ID matches the ID of your PE neighbor.}}}}

On Router P0, configure LDP, MPLS, and OSPF on the interfaces connected to the PE routers. The core router provides the MPLS backbone needed to tunnel Layer 2 traffic from the ingress PR router to the egress PE router.

Router P0

[edit]interfaces {so-0/0/0 {description "to PE1 so-0/1/0";unit 0 {family inet {address 192.168.245.21/30;}family mpls; # Include the MPLS family on core interfaces.}}so-0/2/1 {description "to PE2 so-1/1/0";unit 0 {family inet {address 192.168.245.17/30;}family mpls; # Include the MPLS family on core interfaces.}}lo0 {unit 0 {family inet {address 10.255.17.3/32;}}}}protocols {ospf {traffic-engineering;area 0.0.0.0 {interface so-0/0/0.0;interface so-0/2/1.0;}}ldp { # LDP is required as the signaling protocol for Layer 2 circuits.interface so-0/0/0.0;interface so-0/2/1.0;}}

On Router PE2, complete the Layer 2 circuit by configuring statements to match those previously set on Router PE1.

Configure the ATM2 IQ-based CE-facing interfaces: one with ATM cell-relay mode CCC encapsulation and the other with ATM VC multiplexing CCC encapsulation. Also enable the corresponding Layer 2 circuit modes at the [edit chassis] hierarchy level. In this case, you must configure cell-relay mode on PIC 1 in FPC 0 and AAL5 mode on PIC 2 in FPC 1.

Complete your Layer 2 circuit with configuration of the l2circuit statement at the [edit protocols] hierarchy level. Remember to include in your Layer 2 circuit configuration the IP address of your remote PE neighbor (Router PE1), the interfaces connected to the CE router, and a virtual circuit identifier for each VC. In this case, you will establish one VC for cell-relay mode traffic and a second VC for AAL5 traffic. Then, configure MPLS, LDP, and an IGP (such as OSPF) to enable signaling for your Layer 2 circuit.

Router PE2

[edit]chassis {fpc 0 {pic 1 {atm-l2circuit-mode {cell; # This dedicates FPC 0 PIC 1 to cell-relay mode.}}}fpc 1 {pic 2 {atm-l2circuit-mode {aal5; # This dedicates FPC 1 PIC 2 to AAL5 mode.}}}}interfaces {at-0/1/1 {description "to CE2 at-1/0/1";encapsulation atm-ccc-cell-relay; # Cell-relay requires cell-relay encapsulation.atm-options {cell-bundle-size 4; # This sets the cell bundle size for the physical interface.pic-type atm2; # Layer 2 circuits are compatible withvpi 0; # ATM2 IQ interfaces.}unit 0 {encapsulation atm-ccc-cell-relay; # Also configure the encapsulationvci 32; # on the logical interface.cell-bundle-size 10; # The cell bundle size for the logical interface overrides}          # the physical interface setting.}at-1/2/1 {description "to CE2 at-1/0/2";atm-options { pic-type atm2; # Layer 2 circuits are compatible withvpi 0; # ATM2 IQ interfaces.}unit 0 { encapsulation atm-ccc-vc-mux; # AAL5 requires CCC VC MUX encapsulation.vci 32;}}so-1/1/0 {description "to P0 so-0/2/1";unit 0 {family inet {address 192.168.245.18/30;}family mpls; # Include the MPLS family on core-facing interfaces.}}lo0 {unit 0 {family inet {address 10.255.17.4/32;}}}}protocols {ospf {traffic-engineering;area 0.0.0.0 {interface so-1/1/0.0;interface lo0.0;}}ldp {    # LDP is required as the signaling protocol for Layer 2 circuits.interface so-1/1/0.0;interface lo0.0;}l2circuit {neighbor 10.255.17.2 { # This points to the loopback of the PE neighbor.interface at-0/1/1.32 { # Here you include the local CE-facing interface.virtual-circuit-id 1; # Be sure this ID matches the ID of your PE neighbor.}}neighbor 10.255.17.2 { # This points to the loopback of the PE neighbor.interface at-1/2/1.32 { # Here you include the local CE-facing interface.virtual-circuit-id 2; # Be sure this ID matches the ID of your PE neighbor.}}}}

On Router CE2, configure the ATM2 IQ interfaces to handle ATM traffic. Interface at-1/0/1 handles standard ATM traffic while interface at-1/0/2 handles AAL5 traffic.

Router CE2

[edit]interfaces {at-1/0/1 {description "to PE2 at-0/1/1";atm-options {pic-type atm2; # Layer 2 circuits are compatible withvpi 0;    # ATM2 IQ interfaces.}unit 0 {vci 32;family inet {address 10.1.1.2/30;}}}at-1/0/2 {description "to PE2 at-1/2/1";atm-options {pic-type atm2; # Layer 2 circuits are compatible withvpi 0;   # ATM2 IQ interfaces.}unit 0 {encapsulation atm-vc-mux;vci 32;family inet {address 10.2.2.2/30;}}}}

Verifying Your Work

To verify proper operation of Layer 2 circuits, use the following commands:

  • ping mpls l2circuit interface interface-name
  • ping mpls l2circuit virtual-circuit virtual-circuit-id neighbor ip-address
  • show l2circuit connections
  • Options: [brief] | [down] | [extensive] | [history] | [instance] | [local-site] | [remote-site] |[status] | [summary] | [up] | [up-down]
  • show interfaces
  • show route table l2circuit.0
  • show ldp database l2circuit detail

This is what the operational command output looks like for cell-relay mode on Router PE1:


user@PE1> show l2circuit connections
Layer-2 Circuit Connections:

Legend for connection status (St)
EI -- encapsulation invalid      NP -- interface 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

Legend for interface status
Up -- operational
Dn -- down

Neighbor: 10.255.17.4
    Interface                 Type  St     Time last up          # Up trans
    at-0/1/0.0 (vc 32)        rmt   Up     Jan 22 15:15:52 2003           1
      Local interface: at-0/1/0.0, Status: Up, Encapsulation: ATM CELL (VC Mode)
      Remote PE: 10.255.17.4, Negotiated control-word: Yes (Non-null)
      Incoming label: 100000, Outgoing label: 100000

user@PE1>  show route table l2circuit.0 detail

l2circuit.0: 2 destinations, 2 routes (2 active, 0 holddown, 0 hidden)
10.255.17.4:CtrlWord:9:32:Local/96 (1 entry, 1 announced)
         *L2CKT   Preference: 7
                Next hop: via so-0/2/0.0 weight 1, selected
                Label-switched-path PE1-PE2
                Protocol next hop: 10.255.17.4 Indirect next hop: 85135e8 367
                State: <Active Int>
                Local AS:    69 
                Age: 2:34 
                 Task: l2 circuit
                Announcement bits (1): 0-LDP 
                AS path: I
                VC Label 100000, MTU 0,  cell-bundle size 80

10.255.17.4:CtrlWord:9:32:Remote/96 (1 entry, 1 announced)
         *LDP     Preference: 9
                Next hop type: Discard
                State: <Active Int>
                Local AS:    69 
                Age: 28:11 
                 Task: LDP
                Announcement bits (1): 1-l2 circuit 
                AS path: I
                VC Label 100000, MTU 0,  cell-bundle size 80

user@PE1>  show interfaces at-0/1/0.0 extensive
  Logical interface at-0/1/0.0 (Index 66) (SNMP ifIndex 40) (Generation 4)
    Flags: Point-To-Point SNMP-Traps  Encapsulation: ATM-CCC-Cell-Relay
     L2 circuit cell bundle size: 10 , bundle timeout: 125 usec, timeout count: 0
    L2 circuit out-of-sequence count: 0
    Traffic statistics:
[...]

user@PE1>  show interfaces media at-0/1/0
Physical interface: at-0/1/0, Enabled, Physical link is Up
 Interface index: 154, SNMP ifIndex: 50
 Link-level type: ATM-CCC-Cell-Relay,  MTU: 4482, Clocking: Internal, SONET mode,
 L2 circuit mode: Cell, Speed: OC12, Loopback: None
[...]

user@PE1>  show ldp database l2circuit detail
Input label database, 10.255.17.2:0--10.255.17.4:0
    Label     Prefix
   100000     L2CKT CtrlWord ATM CELL (VC Mode) VC 32
              Cell bundle size: 80
              State: Active
              Age: 9:48

Output label database, 10.255.17.2:0--10.255.17.4:0
    Label     Prefix
   100000     L2CKT CtrlWord ATM CELL (VC Mode) VC 32
              Cell bundle size: 80
              State: Active
              Age: 9:48

This is what the operational command output looks like on Router PE1 if AAL5 mode is used:


user@PE1> show l2circuit connections
Layer-2 Circuit Connections:

Legend for connection status (St)   
EI -- encapsulation invalid      NP -- interface 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

Legend for interface status
Up -- operational
Dn -- down

Neighbor: 10.255.17.4
    Interface                 Type  St     Time last up          # Up trans
    at-1/2/0.0 (vc 32)        rmt   Up     Feb 18 18:00:00 2003           1
      Local interface: at-1/2/0.0, Status: Up, Encapsulation: ATM AAL5
      Remote PE: 10.255.17.4, Negotiated control-word: Yes (Non-null)
      Incoming label: 100016, Outgoing label: 100032

user@PE1> show interfaces media at-0/1/0
Physical interface: at-0/1/0, Enabled, Physical link is Up
 Interface index: 154, SNMP ifIndex: 50
 Link-level type: ATM-PVC, MTU: 4482, Clocking: Internal, SONET mode,
 L2 circuit mode: AAL5, Speed: OC12, Loopback: None, Payload scrambler: Enabled
[...]

user@PE1>  show interfaces at-1/2/0.0 extensive
  Logical interface at-1/2/0.0 (Index 68) (SNMP ifIndex 40) (Generation 38)
    Flags: Point-To-Point SNMP-Traps  Encapsulation: ATM-CCC-VCMUX
    L2 circuit out-of-sequence count: 0
    Traffic statistics:[...]

Published: 2010-04-15