If, after a series of reconfigurations, RSMLT peers do not transition to the up state, use the following procedure to troubleshoot the issue. You can observe this issue on dual-stack VLANs after multiple delete and re-adds of IPv4 interfaces.
show ip rsmlt peer
enable
configure terminal
interface vlan <1–4059>
no ip rsmlt
ip rsmlt
Display the RSMLT configuration:
Switch:1>enable
Switch:1#configure terminal
Switch:1(config)#interface vlan 1
Switch:1(config-if)#show ip rsmlt peer
=====================================================================
                       Ip Rsmlt Peer Info - GlobalRouter
=====================================================================
VID   IP              MAC                ADMIN   OPER  HDTMR  HUTMR
---------------------------------------------------------------------
1     192.0.2.1     00:1f:ca:1e:d3:1e	   Enable	  Up	  60  180
2     198.51.100.1  00:1b:ca:1d:e3:1d	   Enable	  Up	  60  180
VID   HDT REMAIN  HUT REMAIN  SMLT ID
---------------------------------------------------------------------
1     60   180     10
2     60   180     10, 16
VID   IPv6            MAC                ADMIN   OPER  HDTMR  HUTMR
---------------------------------------------------------------------
VID   HDT REMAIN  HUT REMAIN  SMLT ID
--------------------------------------------------------------------
Switch:1(config-if)#no ip rsmlt
Switch:1(config-if)#ip rsmlt