Administrative distance / Route preference

Juniper and Cisco use different values for the administrative distance of routes from specific Routing protocols.
To illustrate the differences, i will show two tables taken directly from the vendors homepages.

Cisco

(taken from Cisco website)

Route Source Default Distance Values
Connected interface 0
Static route 1
Enhanced Interior Gateway Routing Protocol (EIGRP) summary route 5
External Border Gateway Protocol (BGP) 20
Internal EIGRP 90
IGRP 100
OSPF 110
Intermediate System-to-Intermediate System (IS-IS) 115
Routing Information Protocol (RIP) 120
Exterior Gateway Protocol (EGP) 140
On Demand Routing (ODR) 160
External EIGRP 170
Internal BGP 200
Unknown* 255

Juniper

(taken from Juniper website)

How Route Is Learned Default Preference Statement to Modify Default Preference
Directly connected network 0
System routes 4
Static 5 static
MPLS 7 MPLS preference in the JUNOS MPLS Applications Configuration Guide
LDF 8 LDF preference in the JUNOS MPLS Applications Configuration Guide
LDP 9 LDP preference in the JUNOS MPLS Applications Configuration Guide
OSPF internal route 10 OSPF export
IS-IS Level 1 internal route 15 IS-IS external-preference, preference
IS-IS Level 2 internal route 18 IS-IS external-preference, preference
Default 20
Redirects 30
Kernel 40
SNMP 50
Router Discovery 55
RIP 100 RIP preference
RIPng 100 RIPng preference
PIM 105 JUNOS Multicast Protocols Configuration Guide
DVMRP 110 JUNOS Multicast Protocols Configuration Guide
Routes to interfaces that are down 120
Aggregate 130 aggregate
OSPF AS external routes 150 OSPF external-preference, preference
IS-IS Level 1 external route 160 IS-IS external-preference, preference
IS-IS Level 2 external route 165 IS-IS external-preference, preference
BGP 170 BGP preference, export, import
MSDP 175 JUNOS Multicast Protocols Configuration Guide

Remark

As you can see, Juniper uses the same preference values for internal and external BGP.
This is due to the fact that JunOS prefers eBGP before iBGP without looking at the route preference.
–> concerning BGP, both vendors shows the same behaviour.

3 comments to Administrative distance / Route preference

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