Why Does Enabling IPX EIGRP on a VLAN Interface Disable IPX MLS for That Respective Interface?
MLS IPX is disabled with EIGRP IPX since forwarding between RIP and EIGRP domains requires translations of the specific fields in the data portion (transmit control) of route packets. An IPX router interface when enabled for RIP/NLSP, will have the maximum hop count of 16. When a router is on the boundary of an NLSP/RIP and EIGRP routing domain, the interface is configured with both EIGRP and NLSP/RIP. It is necessary to remove MLS support for that interface if the maximum hop is configured to be 16 or less because in this case, the Transmit Control (TC) value will be translated instead of being incremented by 1 when a packet traverses from one routing domain to another. The MLS-SE does not have knowledge about the routing protocol being used and the MLS hardware will not be able to rewrite the Transmit Control (TC) field properly. “IPX mls will be disabled on Vlan
