MPLS: Change MTU - - The MPLS MTU to support Jumbo frames

PE1#sh mpls forwarding-table de
Local Outgoing Prefix Bytes Label Outgoing Next Hop
Label Label or VC or Tunnel Id Switched interface
16 Pop Label 10.1.1.2/32 0 Fa0/0.21 172.16.12.2
MAC/Encaps=18/18, MRU=1504, Label Stack{} --> Default
CA040FE80008CA030FE80008810000158847
No output feature configured

PE1(config-if)#mtu 9216
% Interface FastEthernet0/0 does not support user settable mtu.

PE1(config-if)#mpls mtu ?
<1501-1524> MTU (baby giants bytes)
<64-1500> MTU (bytes)

PE1(config-if)#mpls mtu 1524

PE1#sh mpls forwarding-table de
Local Outgoing Prefix Bytes Label Outgoing Next Hop
Label Label or VC or Tunnel Id Switched interface
16 Pop Label 10.1.1.2/32 0 Fa0/0.21 172.16.12.2
MAC/Encaps=18/18, MRU=1504, Label Stack{} --> Default, Stll no change ? Why
CA040FE80008CA030FE80008810000158847
No output feature configured


Now lets change it on subinterface


PE1(config)#int f0/0.31
PE1(config-subif)#mpls mtu 1524
PE1(config-subif)#^Z
PE1#
00:55:38: %SYS-5-CONFIG_I: Configured from console by console
PE1#sh mpls forwarding-table de
Local Outgoing Prefix Bytes Label Outgoing Next Hop
Label Label or VC or Tunnel Id Switched interface
16 Pop Label 10.1.1.2/32 0 Fa0/0.21 172.16.12.2
MAC/Encaps=18/18, MRU=1528, Label Stack{} -->Changes show up,
CA040FE80008CA030FE80008810000158847
No output feature configured