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Way to resolve S9300 L3VPN disconnect issue.

Publication Date:  2014-12-30 Views:  262 Downloads:  0

Issue Description

Network information:
Users -------- firewall ------- S9306 (PE1) -------- S9303 (PE2) -------- user
Problem Description:
Two 9300 in the network, being as L3VPN PE devices, multiple users under them, a certain time the two PE device users experiencing service interruption problem.

Handling Process

1, both ends do ping test, found it is not pingable.

[S9303]ping -vpn-instance X 
  PING 56  data bytes, press CTRL_C to break
    Request time out
    Request time out
    Request time out
    Request time out
    Request time out

  --- ping statistics ---
    5 packet(s) transmitted
    0 packet(s) received
    100.00% packet loss

2. Check the device routing table information and found no abnormalities

<S9300>display  fib statistics  all
IPv4 FIB Total Route Prefix Count : 44951; Entry Count : 44958

IPv4 FIB Public Route Prefix Count : 1565; Entry Count : 1572
IPv4 FIB VPN-instance A Route Prefix Count : 172; Entry Count : 172
IPv4 FIB VPN-instance B Route Prefix Count : 129; Entry Count : 129
IPv4 FIB VPN-instance C Route Prefix Count : 189; Entry Count : 189
IPv4 FIB VPN-instance D Route Prefix Count : 167; Entry Count : 167
IPv4 FIB VPN-instance E Route Prefix Count : 14233; Entry Count : 14233
IPv4 FIB VPN-instance F Route Prefix Count : 14252; Entry Count : 14252
IPv4 FIB VPN-instance G Route Prefix Count : 355; Entry Count : 355
IPv4 FIB VPN-instance X Route Prefix Count : 13889; Entry Count : 13889

3. Enter diagnostic mode to check the forwarding of information and found the top of the private label value is 1840, the value of the underlying label is 1029, the wrong bottom label caused the business unavailable.

[S9300-diagnose]lsw-command 1 0 by-string d  egr_mpls_vc_and_swap_label_table 0x468

[S9300-diagnose]dis ip routing-table vpn-instance X verbose
Route Flags: R - relay, D - download to fib
Routing Table : X
Summary Count : 1

     Protocol: IBGP             Process ID: 0
   Preference: 255                    Cost: 0
      NextHop:     Neighbour:
        State: Active Adv Relied       Age: 16h32m40s
          Tag: 0                  Priority: low
        Label: 1840                QoSInfo: 0x0
   IndirectID: 0x217          
RelayNextHop:       Interface: Vlanif200
     TunnelID: 0xa026                Flags: RD

4, check the bottom of the label switching table resource view two switches on the device, found few resources left unoccupied

[S9300-diagnose]display  bcmfpi  X  slot 1  mpls vc-swap-table 
   Query Result:                                             
         EGR_MPLS_VC_AND_SWAP_LABEL_TABLE size:8192                                             
         EGR_MPLS_VC_AND_SWAP_LABEL_TABLE used:8151                                             

Root Cause

1, the network has increased the number of routes, it will result in a letter label switching table on the switch exceeds the specifications, after the super-size, will result in the index underlying chip resource allocation errors;
2, under the label switch table error is made by the label switching table super-size switch caused the entry after being filled, because they do not support the replication function, after the new entries made, the value of the package labeling error, resulting in service unavailable.


1, the routes for each side of the device to modify an instance of a label that each L3VPN VPN routes are posted with the same label, to reduce the occupancy switch label switch table quantities purposes;
2, if the client does not support routing publishing label of each instance of a function, it is recommended to do the same segment of the route aggregation, reduce the number of switches on the route to publish in order to achieve the purpose of reducing occupancy switch specifications;
3, if the label switching table is reduced to within specification, to resume operations by restarting the board.


consider carefully how many label switch can have during the design stage of the network.