Prepend prefix is community received from peer is 65003:1000

[axelhauguel]

Hello,

I'm looking for something that I can't find in cisco:

I would like if my BGP neighbor sends BGP community 65003:1000 on a prefix, it would be prepended 3 times on one of my neighbor.

How to do this?

Also, I would like if it sends 65535:666 on a /32, I would like to automatically modify the next hop.

Anyone have any documentation? At Juniper, this is called "Policy options"

My equipment is a Cisco Nexus 9000.

Thank you !

Axel HAUGUEL

[MHM Cisco World]

...

[axelhauguel]

Hi ! 

Thanks for reply, but I cannot integrate this directly on route-map ?

ip prefix-list PFX-AS50046-IRR-V4 seq 10 permit 45.152.70.0/24
ip prefix-list PFX-AS50046-IRR-V4 seq 95 permit 0.0.0.0/0 ge 32 
ip prefix-list PFX-AS50046-IRR-V4 seq 100 deny 0.0.0.0/0 le 32

ip prefix-list PFX-AS212815-IRR-V4 seq 67 permit 45.152.70.0/24
 
route-map RPL-AS210578-CUST-IN-V4 permit 100
  description "AS210578 Florian MISFUD"
  match ip address prefix-list PFX-AS210578-IRR-V4 
   set community 999:100 999:200 999:300 additive 
route-map RPL-AS210578-CUST-OUT-V4 permit 100

  template peer NBRGRP-AS210578-CUST-V4
    remote-as 210578
    remove-private-as
    address-family ipv4 unicast
      send-community
      route-map RPL-AS210578-CUST-IN-V4 in
      route-map RPL-AS210578-CUST-OUT-V4 out
      maximum-prefix 20
      soft-reconfiguration inbound always

  neighbor 185.171.202.237
    inherit peer NBRGRP-AS210578-CUST-V4
    description Cust: AS210578 XXX
    no shutdown

Maybe I must play with permit XXX ?

Because actually, route-map is "RPL-AS210578-CUST-IN-V4". If I apply a community directly on this route-map, it will be applied on the customer on all prefixes received.

Me, I want customer can announce prefix and my route-map match and prepared ONLY IF CUSTOMER SEND PREFIX WITH THE COMMUNITY MATCHED

[Georg Pauwen]

Hello, 

can you break this down logically ?

--> customer sends what (give an example)

--> you announce what ?

[axelhauguel]

Hi

Example :

A client sends me:

193.234.222.0/24 with no community
112.111.111.0/24 with no community
213.221.241.0/24 with community 65003:1000

I would like if the client sends me a prefix with the following community:

65001:1000 -> Prefix is only prepended once
65002:1000 -> The prefix prepends 2 times
65003:1000 -> The prefix prepends 3 times

Thanks

Axel

[Georg Pauwen]

Hello,

I think you need one prefix list and route map for each prefix. That way you can specify what to do with each prefix. This would look something like below:

route-map A_RM permit 10
match ip address prefix-list A_PFX
set community 65001:1000 additive
!
route-map A_RM permit 20
match ip address prefix-list B_PFX
set community 65002:1000 65002:1000 additive
!
route-map A_RM permit 30
match ip address prefix-list C_PFX
match community C_LIST
set community 65003:1000 65003:1000 65003:1000 additive

EDIT: one route map with three sequences...

[axelhauguel]

Hi,

Humm, I see I think.

ip prefix-list PFX-AS50046-IRR-V4 seq 10 permit 45.152.70.0/24
ip prefix-list PFX-AS50046-IRR-V4 seq 95 permit 0.0.0.0/0 ge 32 
ip prefix-list PFX-AS50046-IRR-V4 seq 100 deny 0.0.0.0/0 le 32

ip prefix-list PFX-AS212815-IRR-V4 seq 67 permit 45.152.70.0/24
 

route-map RPL-AS210578-CUST-IN-V4 permit 100
  description "AS210578
  match ip address prefix-list PFX-AS210578-IRR-V4 
   set community 999:100 999:200 999:300 additive 

route-map RPL-AS210578-CUST-IN-V4 permit 200
  description "AS210578"
  match ip address prefix-list PFX-AS210578-IRR-V4 
  match community 65001:1000
   set community 999:100 999:200 999:300 additive 
  set as-path prepend last-as 1
route-map RPL-AS210578-CUST-IN-V4 permit 300
  description "AS210578"
  match ip address prefix-list PFX-AS210578-IRR-V4 
  match community 65002:1000
   set community 999:100 999:200 999:300 additive 
  set as-path prepend last-as 2

route-map RPL-AS210578-CUST-IN-V4 permit 400
  description "AS210578"
  match ip address prefix-list PFX-AS210578-IRR-V4 
  match community 65003:1000
   set community 999:100 999:200 999:300 additive 
  set as-path prepend last-as 3

route-map RPL-AS210578-CUST-OUT-V4 permit 100

  template peer NBRGRP-AS210578-CUST-V4
    remote-as 210578
    remove-private-as
    address-family ipv4 unicast
      send-community
      route-map RPL-AS210578-CUST-IN-V4 in
      route-map RPL-AS210578-CUST-OUT-V4 out
      maximum-prefix 20
      soft-reconfiguration inbound always

  neighbor 185.171.202.237
    inherit peer NBRGRP-AS210578-CUST-V4
    description Cust: AS210578 XXX
    no shutdown

It will be working?

Thanks ! 

[paul driver]

Hello
Why are you adding prepending on ingress prefixes are you readvertising them?

[MHM Cisco World]

...

[axelhauguel]

Hi MHM,

This configuration is correct.

      route-map RPL-AS210578-CUST-IN-V4 in
      route-map RPL-AS210578-CUST-OUT-V4 out

 "RPL-AS210578-CUST-IN-V4" -> Prefixes received to my router, from customer

"RPL-AS210578-CUST-OUT-V4" -> Fullview distribued to customer from my router

I do not understand that : 

R2 will use 
route-map IN 
match community 
set prepend

I don't understand how to use this.

Because currently I already have "RPL-AS210578-CUST-IN-V4" which exists.

However, if I apply match + community on this RPL, it will apply to prefixes received with community 6500X:1000.

Also, prefixes that don't have this community, which route-map will they use?

[MHM Cisco World]

ip communuty list standard X 6500:100
!
route-map CommModify permit
match community-list X
set community 6500:100 6500:100 6500:100 additive 

!
!
template peer-session BasePolicy

route-map CommModify OUT
exit
!

neighbor x.x.x.x remote-as AS

address-family ipv4 unicast

inherit peer-policy BasePolicy

we all assume you receive bgp and resend it BUT here there are template Peer, so you need peer-session command. 


hope this work for you. 
good luck friend