This section provides solution for this issue DECnet and HSRP do not work together on certain router platforms, which causes routing failures
DECnet, a proprietary protocol, is part of the Digital Network Architecture (DNA) protocol stack. DECnet routers are uniquely identified in the network by configuring an address comprising of the area.node identifier. To maintain backward compatibility with previous versions of the protocol, a DECnet router derives the MAC address of an interface from the configured area.node identifier. This is done instead of using the Burned-In MAC Address (BIA) of the interface.
The Hot Standby Router Protocol (HSRP) provides redundancy by allowing multiple routers on a single LAN to share a virtual IP and MAC address. This address is configured as the default gateway on the hosts. The MAC address that HSRP uses is a fixed address. This address is based on the HSRP group and used by the active router. Because certain router platforms do not have the required hardware to support multiple MAC addresses, DECnet and HSRP cannot work together on these platforms. This results in routing failures.
To configure DECnet and HSRP together, check whether the router platform supports multiple MAC addresses on the interface. You may also receive the %STANDBY-3-MISCONFIG: Attempt to change Ethernet0 MAC address to 0000.0c07.acxx when DECnet is already running error message. This can happen when HSRP tries to change the MAC address that has been derived by DECnet.
If the router platform does not support multiple MAC addresses on the interface, you can issue the standby use-bia command under the interface. This makes HSRP use the MAC address derived by DECnet as the virtual MAC. It also enables the MAC address to work along with DECnet.