To configure AToM Graceful Restart, perform the following task.

There is no AToM-specific configuration for AToM GR. You enable LDP GR to assist a neighboring router configured with AToM NSF/SSO to maintain its forwarding state while the LDP session is disrupted. See the LDP Graceful Restart document for information about how LDP GR works and how you can customize it for your network.

The following example shows a Fast Ethernet VLAN over MPLS configuration. PE1 is configured with AToM Graceful Restart. PE2 is configured with AToM NSF/SSO. The commands for configuring AToM GR and NSF/SSO are shown in bold.

ip cef distributed
!
mpls label protocol ldp
mpls ldp graceful-restart
mpls ldp router-id Loopback0
!
pseudowire-class atom
encapsulation mpls
!
interface Loopback0
 ip address 10.1.1.2 255.255.255.255
!
interface FastEthernet2/1/1
 no ip address
!
interface FastEthernet2/1/1.2
 description "xconnect to PE2"
 encapsulation dot1Q 2 native
 xconnect 10.2.2.2 1002 pw-class mpls
!
! IGP for MPLS
router ospf 10
log-adjacency-changes
auto-cost reference-bandwidth 1000
network 10.1.1.2 10.0.0.0 area 0
network 10.1.1.0 10.0.0.255 area 0

redundancy
  mode sso
ip cef distributed
!
mpls label protocol ldp
mpls ldp graceful-restart
mpls ldp router-id Loopback0
!
pseudowire-class atom
encapsulation mpls
!
interface Loopback0
 ip address 10.2.2.2 255.255.255.255
!
interface FastEthernet0/3/2
 no ip address
!
interface FastEthernet0/3/2.2
 description "xconnect to PE1"
 encapsulation dot1Q 2
 xconnect 10.1.1.2 1002 pw-class mpls
!
! IGP for MPLS
router ospf 10
log-adjacency-changes
nsf cisco enforce global
auto-cost reference-bandwidth 1000
network 10.2.2.2 10.0.0.0 area 0
network 10.1.1.0 10.0.0.255 area 0

The following examples show the output of the show mpls l2transport vccommand during normal operation and when an LDP session is recovering from a disruption.

The following example shows the status of the VC on PE1 with AToM GR during normal operation:

Router# show mpls l2transport vc
Local intf     Local circuit        Dest address    VC ID      Status
-------------  -------------------- --------------- ---------- ----------
Fa2/1/1.2      Eth VLAN 2           10.2.2.2         1002       UP

The following example shows the status of the VC on PE1 with AToM GR while the VC is recovering from an LDP session disruption. The forwarding state for the circuit remains as it was before the disruption.

Router# show mpls l2transport vc
Local intf     Local circuit        Dest address    VC ID      Status
-------------  -------------------- --------------- ---------- ----------
Fa2/1/1.2      Eth VLAN 2           10.2.2.2         1002       RECOVERING

The following example shows the status of the VC on PE1 with AToM GR after the LDP session disruption was cleared. The AToM label bindings were advertised within the allotted time and the status returned to UP.

Router# show mpls l2transport vc
Local intf     Local circuit        Dest address    VC ID      Status
-------------  -------------------- --------------- ---------- ----------
Fa2/1/1.2      Eth VLAN 2           10.2.2.2         1002       UP

The following example shows the detailed status of the VC on PE1 with AToM GR during normal operation:

Router# show mpls l2transport vc detail
Local interface: Fa2/1/1.2 up, line protocol up, Eth VLAN 2 up
  Destination address: 10.2.2.2, VC ID: 1002, VC status: up
    Preferred path: not configured
    Default path: active
    Tunnel label: imp-null, next hop point2point
    Output interface: Se2/0/2, imposed label stack {16}
  Create time: 1d00h, last status change time: 1d00h
  Signaling protocol: LDP, peer 10.2.2.2:0 up
    MPLS VC labels: local 21, remote 16
    Group ID: local 0, remote 0
    MTU: local 1500, remote 1500
    Remote interface description: "xconnect to PE2"
  Sequencing: receive disabled, send disabled
  VC statistics:
    packet totals: receive 3466, send 12286
    byte totals:   receive 4322368, send 5040220
    packet drops:  receive 0, send 0

The following example shows the detailed status of the VC on PE1 with AToM GR while the VC is recovering.

Router# show mpls l2transport vc detail
Local interface: Fa2/1/1.2 up, line protocol up, Eth VLAN 2 up
  Destination address: 10.2.2.2, VC ID: 1002, VC status: recovering
    Preferred path: not configured
    Default path: active
    Tunnel label: imp-null, next hop point2point
    Output interface: Se2/0/2, imposed label stack {16}
  Create time: 1d00h, last status change time: 00:00:03
  Signaling protocol: LDP, peer 10.2.2.2:0 down
    MPLS VC labels: local 21, remote 16
    Group ID: local 0, remote 0
    MTU: local 1500, remote 1500
    Remote interface description: "xconnect to PE2"
  Sequencing: receive disabled, send disabled
  VC statistics:
    packet totals: receive 20040, send 28879
    byte totals:   receive 25073016, send 25992388
    packet drops:  receive 0, send 0