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Advertise a /32 via BGP when I only have the /24 connected

Ozan1
Level 1
Level 1

So I have a BDI on an ASR, and it is a /24. Let's call it 192.168.1.0/24. I have an ASA connected it to it and its outside IP is 192.168.1.100

 

I want to advertise to my ISP 192.168.1.100/32 via BGP and not the whole /24. How do I accomplish this?

 

I did add the 192.168.1.100/32 ge 0 to my "prefix-list" but it didn't get advertised, when I checked advertised routes until I put in

ip route 192.168.1.100 255.255.255.255 null 0.

 

But then, the traffic got dropped. 

2 Accepted Solutions

Accepted Solutions

Harold Ritter
Level 12
Level 12

Hi @Ozan1 ,

 

You need to specify the BDI as the next hop.

 

ip route 192.168.1.100 255.255.255.255 BDIxxx

 

Regards,

Harold Ritter
Sr Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México
Paseo de la Reforma 222
Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México

View solution in original post

Giuseppe Larosa
Hall of Fame
Hall of Fame

Hello @Ozan1 

 

>>>> ip route 192.168.1.100 255.255.255.255 null 0

 

this is a black hole !  a sink that says silenty packets for the host t be simply discarded !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

 

follow @Harold Ritter auggestions !

 

Hope to help

Giuseppe

View solution in original post

4 Replies 4

balaji.bandi
Hall of Fame
Hall of Fame

we need to know your  BGP config how you doing peering with other side. :

 

But high level below may syntax may help you : ( make sure you understand syntax and test it)

 

 

ip prefix-list MyList permit 192.168.1.100/32

router bgp XXX
neighbor x.x.x.x prefix-list MyList out

 

BB

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Harold Ritter
Level 12
Level 12

Hi @Ozan1 ,

 

You need to specify the BDI as the next hop.

 

ip route 192.168.1.100 255.255.255.255 BDIxxx

 

Regards,

Harold Ritter
Sr Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México
Paseo de la Reforma 222
Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México

I think this is it! Thank you. I knew I was missing a specific route. 

Giuseppe Larosa
Hall of Fame
Hall of Fame

Hello @Ozan1 

 

>>>> ip route 192.168.1.100 255.255.255.255 null 0

 

this is a black hole !  a sink that says silenty packets for the host t be simply discarded !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

 

follow @Harold Ritter auggestions !

 

Hope to help

Giuseppe

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