Blocking 10.0.0.0/8 summary and 0.0.0.0 from MPLS BGP link

[mhudak]

Currently I use an access-list to block 0.0.0.0 and several class B addresses inbound from our MPLS BGP carrier.

ip access-list standard DEFAULT

deny 0.0.0.0

deny 10.96.0.0 0.0.255.255

deny 10.6.0.0 0.0.255.255

permit any

I now have to start blocking a 10.0.0.0/8 summary from them because we want to start advertising that address into the cloud.

I have made attemps to convert to a prefix-list with no success.

Does any have experience with this that could give me some advice for this configuration.

Thank you for your asistance.

Mhudak

[cadet alain]

I have made attemps to convert to a prefix-list with no success.

Can you post what you tried

Regards.

Alain.

[milan.kulik · Accepted solution]

Hi,

to translate the current ACL into the prefix-list:

ip prefix-list   DEFAULT seq 5 deny 0.0.0.0/0

ip prefix-list   DEFAULT seq 10 deny 10.96.0.0/16  le 32

ip prefix-list   DEFAULT seq 15 deny 10.6.0.0/16  le 32

ip prefix-list   DEFAULT seq 20 permit 0.0.0.0/0 le 32

If you want to block 10.0.0.0/8, too, just add

ip prefix-list   DEFAULT seq 18 deny 10.0.0.0/8

To understand 100%, note:

ip prefix-list   DEFAULT seq 10 deny 10.96.0.0/16  le 32   - blocks 10.96.0.0/16 plus all more specific subnets like 10.96.20.0/24

ip prefix-list   DEFAULT seq 18 deny 10.0.0.0/8  -   blocks   10.0.0.0/8, but does not block more specific subnets like   10.1.1.0/24

HTH,

Milan

[mhudak]

Tested and worked Great!

I appreciate your help.

Thank you

Mhudak