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DECnet and HSRP do not work together on certain router platforms, which causes routing failures




This section provides solution for this issue DECnet and HSRP do not work together on certain router platforms, which causes routing failures

Core Issue

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.


For more information, refer to these documents:




Problem Type

HSRP Issues


Multiple devices on different network


Multiple devices

Source And Destination Physical Connectivity

Source and destination exist on different subnetwork

Other Errors, Warnings and Log Messages