Technical Tip: FortiGate - Viewing FIB/RIB routing information in CLI

Description

This article describes how to view routing information.

Scope

FortiGate Routing.

Solution

View routing information on FortiGate CLI.

• All IP routing protocols submit the best routes for each destination to the routing table.

• The routing table manager then determines which route for a particular destination is to be submitted to the forwarding table. This includes directly connected, static routes, and dynamically learned routes.

• Packets are forwarded according to the forwarding table.

RIB vs FIB:

Routing Information Base (RIB):

• This is a database of routing prefixes that could potentially be installed into the forwarding table. 

• RIB is derived from the control plane, it is not used for forwarding. Every protocol such as OSPF, EIGRP, and BGP has its own RIB and selects its best candidates to try to install to global RIB so that it can then be selected for forwarding.

• The RIB is the input to the route computation.

Forwarding Information Base (FIB):

• It is a table that contains information necessary to forward IP datagrams - all active routes in the routing table must be present in the FIB.

• Entries contain interface identifiers and next-hop information for each reachable destination network prefix.

• The FIB may also include routes that are not in the routing table - such as dynamically added routes to reach SSL VPN users.

• The FIB is the output of the route computation.

• FIB is derived from RIB.

 
Viewing RIB in the CLI:

FGT # get router info routing-table all
Codes: K - kernel, C - connected, S - static, R - RIP, B - BGP
O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area
* - candidate default
C 10.27.0.0/20 is directly connected, port2
C 10.32.0.0/20 is directly connected, port3
C 10.37.0.0/20 is directly connected, port4
O 10.143.0.0/20 [110/2] via 10.27.9.50, port2, 03:53:48

2 Ways of viewing FIB in the CLI:

Forwarding table (Kernel routes/FIB):

get router info kernel

diagnose ip route list

tab=255 vf=0 scope=253 type=3 proto=2 prio=0 0.0.0.0/0.0.0.0/0->127.255.255.255/32 pref=127.0.0.1 gwy=0.0.0.0 dev=13(root)
tab=255 vf=0 scope=253 type=3 proto=2 prio=0 0.0.0.0/0.0.0.0/0->169.254.0.64/32 pref=169.254.0.66 gwy=0.0.0.0 dev=20(havdlink1)
tab=255 vf=0 scope=254 type=2 proto=2 prio=0 0.0.0.0/0.0.0.0/0->169.254.0.66/32 pref=169.254.0.66 gwy=0.0.0.0 dev=20(havdlink1)
tab=255 vf=0 scope=253 type=3 proto=2 prio=0 0.0.0.0/0.0.0.0/0->169.254.0.127/32 pref=169.254.0.66 gwy=0.0.0.0 dev=20(havdlink1)
tab=254 vf=0 scope=253 type=1 proto=2 prio=0 0.0.0.0/0.0.0.0/0->10.27.0.0/20 pref=10.27.11.96 gwy=0.0.0.0 dev=4(port2)
tab=254 vf=0 scope=253 type=1 proto=2 prio=0 0.0.0.0/0.0.0.0/0->10.32.0.0/20 pref=10.32.11.96 gwy=0.0.0.0 dev=5(port3)
tab=254 vf=0 scope=253 type=1 proto=2 prio=0 0.0.0.0/0.0.0.0/0->10.37.0.0/20 pref=10.37.11.96 gwy=0.0.0.0 dev=6(port4)
tab=254 vf=0 scope=0 type=1 proto=11 prio=0 0.0.0.0/0.0.0.0/0->10.143.0.0/20 pref=0.0.0.0 gwy=10.27.9.50 dev=4(port2)
tab=254 vf=0 scope=253 type=1 proto=2 prio=0 0.0.0.0/0.0.0.0/0->169.254.0.64/26 pref=169.254.0.66 gwy=0.0.0.0 dev=20(havdlink1)

FIB Type ID: Types of routing connection:

FIB Proto ID: This indicates where the route came from:

Other FIB values:

Related articles:

• Technical Tip: Routing in FortiGate (route-lookup-process)

• Technical Tip: Controlling how HA synchronizes routing table updates

• Technical Tip: How to display Kernel route

• Technical Tip: How to check VRF in a session table