FortiGate
FortiGate Next Generation Firewall utilizes purpose-built security processors and threat intelligence security services from FortiGuard labs to deliver top-rated protection and high performance, including encrypted traffic.
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Staff
Description

This article describes why the BGP advertised and received routes have no subnet mask included.

Scope FortiGate.
Solution

If the advertised and received routes have no subnet mask included, this means that the network is a classful subnet and hitting the boundary. So in the below example, the 172.16.0.0 and 172.16.31.0 are using a /16  subnet mask. This is a class B subnet. The class A boundary is /8 while class C is /24.

 

FGT (BGP_1) # get router info bgp neighbors 1.1.1.2 advertised-routes

VRF 0 BGP table version is 2, local router ID is 1.1.1.1

Status codes: s suppressed, d damped, h history, * valid, > best, i - internal

Origin codes: i - IGP, e - EGP, ? - incomplete

 

   Network          Next Hop            Metric     LocPrf Weight RouteTag Path

*> 172.16.0.0       1.1.1.1                       100  32768        0 i <-/->

 

FGT (BGP_1) # get router info bgp neighbors 1.1.1.2 received-routes

VRF 0 BGP table version is 4, local router ID is 1.1.1.1

Status codes: s suppressed, d damped, h history, * valid, > best, i - internal

Origin codes: i - IGP, e - EGP, ? - incomplete

 

   Network          Next Hop            Metric     LocPrf Weight RouteTag Path

*> 172.31.0.0       1.1.1.2                                0        0 2 i <-/->

 

The subnet mask will be only included on the advertised and received routes that are not hitting the boundary and if the network is a classless subnet. Below is an example.

 

FGT (BGP_1) # get router info bgp neighbors 1.1.1.2 advertised-route

VRF 0 BGP table version is 4, local router ID is 1.1.1.1

Status codes: s suppressed, d damped, h history, * valid, > best, i - internal

Origin codes: i - IGP, e - EGP, ? - incomplete

 

   Network          Next Hop            Metric     LocPrf Weight RouteTag Path

*> 10.1.0.0/24      1.1.1.1                       100  32768        0 i <-/->

 

PAULO_FWF60E (BGP_1) # get router info bgp neighbors 1.1.1.2 received-routes

VRF 0 BGP table version is 4, local router ID is 1.1.1.1

Status codes: s suppressed, d damped, h history, * valid, > best, i - internal

Origin codes: i - IGP, e - EGP, ? - incomplete

 

   Network          Next Hop            Metric     LocPrf Weight RouteTag Path

*> 10.2.0.0/24      1.1.1.2                                0        0 2 i <-/->

 

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