Generally, label switching routers (LSRs) use a label distribution protocol to dynamically learn the labels that they should use to label-switch packets. Examples of such protocols include:

• Label Distribution Protocol (LDP), the Internet Engineering Task Force (IETF) standard that is used to bind labels to network addresses

• Resource Reservation Protocol (RSVP), which is used to distribute labels for traffic engineering (TE)

• Border Gateway Protocol (BGP), which is used to distribute labels for MPLS virtual private networks (VPNs)

To use a learned label to label-switch packets, an LSR installs the label into its Label Forwarding Information Base (LFIB).

The static MPLS feature enables you to statically configure the following:

• The binding between a label and an IPv4 or IPv6 prefix

• The action corresponding to the binding between a label and an IPv4 or IPv6 prefix (label swap or pop)

• The contents of an LFIB cross-connect entry

Static MPLS has the following prerequisites:

• You must configure the ACL TCAM region size for MPLS, save the configuration, and reload the switch.

  Note	By default the MPLS region size is zero. You need to configure this region to 256 in order to support static MPLS.

Static MPLS has the following guidelines and limitations:

• Static MPLS and MPLS stripping cannot be enabled at the same time.

• Adjacency statistics are supported for Cisco Nexus 3100 Series switches but not for Cisco Nexus 3000 Series switches.

• Equal-cost multipath (ECMP) is not supported with label pop.

• Label pop and swap operations are supported, but label push operations are not.

• MPLS packets will be forwarded as long as the ingress label matches the configured label and the configured FEC (prefix) is in the routing table.

• The device performs as a label switching router (LSR). It performs as a label edge router (LER) only for penultimate hop popping (PHP), when the outermost label of an MPLS tagged packet is removed by an LSR before the packet is passed to an adjacent LER. This means that label switching router (LSR) functions with 2 (or more) incoming labels.

  The device generally performs as a label switching router (LSR). It performs as a label edge router (LER) for penultimate hop popping, by installing the explicit null label as the out-label in the label FIB (LFIB) by an LSR before the packet is passed to an adjacent LER. This means that label switching router (LSR) unctions with 1 or more labels.

  Note	If user intentionally uses implicit-null CLI on LSR, the output packet going to LER, will still have an explicit-null and the inner label.

• Static MPLS supports up to 128 labels.

• The backup path is supported only for a single adjacency and not for ECMP.

• The output for most of the MPLS commands can be generated in XML or JSON. See Verifying the Static MPLS Configuration for an example.

• VRFs, vPCs, FEX, and VXLAN are not supported with static MPLS.

• Subinterfaces are not supported for static MPLS.

• The Forwarding Equivalence Class (FEC) should exactly match routes in the routing table.

• When you configure fast reroute (backup), you can specify only the connected next hop (and not the recursive next hop) as the next-hop prefix in the backup configuration.

• When multiple FECs are sharing the backup (the same next-hop and interface), any change to the backup configuration requires a reconfiguration of all the other FECs that are sharing the backup configuration.

• When the backup path is active, the show mpls switching labels command will not show the out label/out interface/next hop and related statistics. You can use the show forwarding mpls label label stats platform command to check the statistics.

• If traffic ingresses or egresses on a non-default unit (where the default unit is unit0), the corresponding ULIB statistics will not be displayed in the output of the show mpls switching labels low-label-value [high-label-value] detail command. You can use the show forwarding mpls label label stats platform command to check the statistics.

• If the backup and primary paths are pointing to the same interface, the backup action swap takes precedence.

• Physical (Ethernet) and port channels are supported only for backup.

To display the static MPLS configuration, perform one of the following tasks:

This example shows sample output for the show mpls static binding all command:

1.255.200.0/32: (vrf: default) Incoming label: 2000
  Outgoing labels:
      1.21.1.1 implicit-null
      backup 1.24.1.1 2001

2000:1:255:201::1/128: (vrf: default) Incoming label: 3000
  Outgoing labels:
      2000:1111:2121:1111:1111:1111:1111:1 implicit-null
      backup 2000:1:24:1::1 3001

This example shows sample output for the show mpls switching detail command:

VRF default

IPv4 FEC
 In-Label                       : 2000
 Out-Label stack                : Pop Label
 FEC                            : 1.255.200.0/32
 Out interface                  : Po21
 Next hop                       : 1.21.1.1
 Input traffic statistics       : 0 packets, 0 bytes
 Output statistics per label    : 0 packets, 0 bytes
IPv6 FEC
 In-Label                       : 3000
 Out-Label stack                : Pop Label
 FEC                            : 2000:1:255:201::1/128
 Out interface                  : port-channel21
 Next hop                       : 2000:1111:2121:1111:1111:1111:1111:1
 Input traffic statistics       : 0 packets, 0 bytes
 Output statistics per label    : 0 packets, 0 bytes

This example shows normal, XML, and JSON sample output for the show mpls switching command when the switch is configured with a static IPv4 prefix:

switch# show run mpls static | sec 'ipv4 unicast'
address-family ipv4 unicast
local-label 100 prefix 192.168.0.1 255.255.255.255 next-hop auto-resolve out-label 200 

switch# show mpls switching
Legend:
(P)=Protected, (F)=FRR active, (*)=more labels in stack.
IPV4:
In-Label   Out-Label  FEC name           Out-Interface      Next-Hop
     
VRF default
100        200        192.168.0.1/32     Eth1/23            1.12.23.2


switch# show mpls switching | xml
<?xml version="1.0" encoding="ISO-8859-1"?> <nf:rpc-reply xmlns:nf="urn:ietf:params:xml:ns:netconf:base:1.0"
xmlns="http://w
ww.cisco.com/nxos:1.0:ulib">
 <nf:data>
  <show>
   <mpls>
    <switching>
     <__XML__OPT_Cmd_ulib_show_switching_cmd_labels>
      <__XML__OPT_Cmd_ulib_show_switching_cmd_detail>
       <__XML__OPT_Cmd_ulib_show_switching_cmd_vrf>
        <__XML__OPT_Cmd_ulib_show_switching_cmd___readonly__>
         <__readonly__>
          <TABLE_vrf>
           <ROW_vrf>
            <vrf_name>default</vrf_name>
            <TABLE_inlabel>
             <ROW_inlabel>
              <in_label>100</in_label>
              <out_label_stack>200</out_label_stack>
              <ipv4_prefix>192.168.0.1/32</ipv4_prefix>
              <out_interface>Eth1/23</out_interface>
              <ipv4_next_hop>1.12.23.2</ipv4_next_hop>
              <nhlfe_p2p_flag> </nhlfe_p2p_flag>
             </ROW_inlabel>
            </TABLE_inlabel>
           </ROW_vrf>
          </TABLE_vrf>
         </__readonly__>
        </__XML__OPT_Cmd_ulib_show_switching_cmd___readonly__>
       </__XML__OPT_Cmd_ulib_show_switching_cmd_vrf>
      </__XML__OPT_Cmd_ulib_show_switching_cmd_detail>
     </__XML__OPT_Cmd_ulib_show_switching_cmd_labels>
    </switching>
   </mpls>
  </show>
 </nf:data>
</nf:rpc-reply>
]]>]]>


switch# show mpls switching | json
{"TABLE_vrf": {"ROW_vrf": {"vrf_name": "default", "TABLE_inlabel":
{"ROW_inlabel
": {"in_label": "100", "out_label_stack": "200", "ipv4_prefix":
"192.168.0.1/32"
, "out_interface": "Eth1/23", "ipv4_next_hop": "1.12.23.2",
"nhlfe_p2p_flag": nu
ll}}}}}

To monitor static MPLS statistics, perform one of the following tasks:

This example shows sample output for the show forwarding adjacency mpls stats command:

FEC     								next-hop   interface  tx packets  tx bytes  Label info
--------------- ---------- ---------- ----------- --------- ----------
1.255.200.0/32  1.21.1.1   Po21       87388       10836236  POP 3
1.255.200.0/32  1.24.1.1   Po24       0           0         SWAP 2001
switch(config)#
switch(config)# show forwarding mpls drop-stats

Dropped packets : 73454
Dropped bytes : 9399304

This example shows sample output for the show forwarding ipv6 adjacency mpls stats command:

FEC                    next-hop        interface  tx packets  tx bytes  Label info
---------------------- --------------  ---------- ----------- --------- ----------- 
2000:1:255:201::1/128  2000:1.21.1.1   Po21       46604       5778896   POP 3
2000:1:255:201::1/128  2000:1:24:1::1  Po24       0           0         SWAP 3001

This example shows sample output for the show forwarding mpls label 2000 stats command:

--------+-----------+-------------------+----------------+-------------+-------
Local   |Prefix     |FEC                |Next-Hop        |Interface    |Out
Label   |Table Id   |(Prefix/Tunnel id) |                |             |Label
--------+-----------+-------------------+----------------+-------------+-------
2000    |0x1        |1.255.200.0/32     |1.21.1.1        |Po21         |Pop Label
 HH: 100008, Refcount: 1
Input Pkts : 77129                Input Bytes : 9872512
Output Pkts: 77223                Output Bytes: 9575652

This example shows sample output for the show mpls forwarding statistics command:

MPLS software forwarding stats summary:
    Packets/Bytes sent           : 0/0
    Packets/Bytes received       : 0/0
    Packets/Bytes forwarded      : 0/0
    Packets/Bytes originated     : 0/0
    Packets/Bytes consumed       : 0/0
    Packets/Bytes input dropped  : 0/0
    Packets/Bytes output dropped : 0/0

To clear the static MPLS statistics, perform these tasks:

This example shows how to reserve labels for static assignment:

switch# configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
switch(config)# mpls label range 17 99 static 100 10000
switch(config)# show mpls label range
Downstream Generic label region: Min/Max label: 17/99
Range for static labels: Min/Max Number: 100/10000

This example shows how to configure MPLS static label and IPv4 prefix binding in a top-of-rack configuration (swap configuration):

switch# configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
switch(config)# interface ethernet 1/1
switch(config-if)# mpls ip forwarding
switch(config-if)# mpls static configuration
switch(config-mpls-static)# address-family ipv4 unicast
switch(config-mpls-static-af)# local-label 2000 prefix 1.255.200.0/32
switch(config-mpls-static-af-lbl)# next-hop auto-resolve out-label 2000

This example shows how to configure MPLS static label and IPv6 prefix binding in a top-of-rack configuration (swap configuration):

switch# configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
switch(config)# interface ethernet 1/1
switch(config-if)# mpls ip forwarding
switch(config-if)# mpls static configuration
switch(config-mpls-static)# address-family ipv6 unicast
switch(config-mpls-static-af)# local-label 3001 prefix 2000:1:255:201::1/128
switch(config-mpls-static-af-lbl)# next-hop auto-resolve out-label 3001

This example shows how to configure MPLS static label and IPv4 prefix binding in an aggregator configuration (pop configuration):

switch# configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
switch(config)# interface ethernet 1/1
switch(config-if)# mpls ip forwarding
switch(config-if)# mpls static configuration
switch(config-mpls-static)# address-family ipv4 unicast
switch(config-mpls-static-af)# local-label 2000 prefix 1.255.200.0/32
switch(config-mpls-static-af-lbl)# next-hop 1.31.1.1 out-label implicit-null
switch(config-mpls-static-af-lbl)# next-hop backup Po34 1.34.1.1 out-label 2000

This example shows how to configure MPLS static label and IPv6 prefix binding in an aggregator configuration (pop configuration):

switch# configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
switch(config)# interface ethernet 1/1
switch(config-if)# mpls ip forwarding
switch(config-if)# mpls static configuration
switch(config-mpls-static)# address-family ipv6 unicast
switch(config-mpls-static-af)# local-label 3001 prefix 2000:1:255:201::1/128
switch(config-mpls-static-af-lbl)# next-hop 2000:1:31:1::1 out-label implicit-null
switch(config-mpls-static-af-lbl)# next-hop backup Po34 2000:1:34:1::1 out-label 3001