Cisco's IOS calls it Administrative Distance, other vendors call it Default Preference, Distance, many vendors call it Priority. But what is this administrative distance?.

Administrative Distance or Priority is a networking operating system specific priority table for the supported routing protocols.

The protocol with the highest priority on this priority table, wins. The highest priority is in that case either 0 or 1 or a the smallest digit. Across all network operating systems in the overview below, the highest priority is always set to the directly connected network it is everywhere 0, or some kind of system or kernel route.

Here following acronyms would describe the following overview also good enough. These are my own ideas how it also could be named or described in short form cross-vendor:

• NOSSDAD - Network Operating System Specific Default Administrative Distance
• IDRPP - Implementation Dependent Routing Protocol Priority

RouterOS

MikroTik's (RouterOS) RouterOS - Route Distance

What is MME? Mesh Made Easy a RouterOS/MikroTik routing protocol based on B.A.T.M.A.N..

ArubaOS

Aruba's (ArubaOS) Administrative distance is found on docs for the 3810 and 5400R series routers. Aruba 3810 / 5400R Multicast and Routing Guide for ArubaOS-Switch 16.08

B.I.R.D.

linux's () - Control Plane for linux IP routing. No official documentation found yet.

* Update *

Interesting note on the default preference behaviour from the mailing list says:

Note though that the preference value in bird is inverted compared to
Cisco which uses administrative distance. Juniper seems to use the term
preference value but have the same semantics as Cisco administrative
distance.

Bird preference value: higher is more preferred
Cisco/Juniper AD value: lower is more preferred

* Last update 2023 *

This is the last update regarding B.I.R.D.

• B.I.R.D does not properly support the same route coming from multiple routing protocols; it's undefined behavior in B.I.R.D.
• B.I.R.D.'s official documentation is lacking ANY examples on how to configure and handle B.I.R.D. with different vendors routing implementations.

If you find out a way how to configure and operate B.I.R.D. with different vendors please write me an email. I have been searching for simple configuration examples on this topic now for a long time. The usersbase could not hint me into the "right" direction. I still do not know how to configure B.I.R.D. and how to operate it in a multi vendor network environement.

IOS/IOS-XE/IOS-XR/NX-OS

Cisco's - Internetwork Operating System (IOS) IOS/-XE/-XR/NX-OS - Administrative Distance

JUNOS

Juniper's (JUNOS) JUNOS - Default Preference

EXOS

ExtermeNetworks's (EXOS)

No online reference found yet. The output is taken from the EXOS cli. EXOS as the only network operating system has a protocol priorty range x > 256. The LOWEST priority is assigned to the *Bootp protocol to 5000. The directly connected network has a priority of 10, this is the highest priority setting.

FRR

linux's Free Range Routing (FRR) FRRouting - Administrative Distance

Comware

HP's (ComWare) ComWare's preference

ComWare has the lowest preference on BGP compared with other implementations.

SR OS

Nokia's - Service Router Operating System (SROS) Route Preference Defaults by Route Type

VRP

Huawei's - Versatile Routing Platform (VRP) Routing Protocol Preference

What is OSPF ASE? Did not find out yet. It might be some Stubby Area perhaps. No online documentation found. Interestingly, VRP has a much lower preference for static routes than any other implementations.