MLS-RP in -null- domain

[sun816]

I have got catalyst 3550 as MLS-SE, cisco7204VXR as MLS-RP(IOS ver12.2)

to implement layer 3 switch.

When I input command as below I found I cannt let RP join the VTP I specificed.(I use MLS command following the order at cisco ducument)

Why the interface f0/0 belongs to the null domian ?I have tried to delete RP relatived configuration and set RP command again,the same phenomena occors.

cisco7200(config)#mls rp ip

cisco7200(config-if)#mls rp vlan 1

cisco7200(config-if)#mls rp vtp-domain silver ?

<cr>

cisco7200(config-if)#mls rp vtp-domain silver

interface FastEthernet0/0 currently in -null- domain

cisco7200#sho mls rp

ip multilayer switching is globally enabled

ipx multilayer switching is globally disabled

ipx mls inbound acl override is globally disabled

mls id is 0008.7cxx.xx

mls ip address x.x.x.x

mls ip flow mask is destination

mls ipx flow mask is unknown

number of domains configured for mls 1

vlan domain name: -null-

current ip flow mask: destination

[DALE FRANCIS]

This is a good gotcha from Cisco, the problem is that it is order dependant. DO NOT configure mls rp ip onthe interface 1st, first configure the mls rp vtp domain then configure the mls rp ip on the interface.

By default all interfaces are in domain null and when you type in mls rp ip on the interface it places it on the default null domain, so you have to change or create another domain by the mls rp vtp-domain then place the interface in that domain by configuring mls rp ip.

Also configure the mls rp managment-interface.