[j-nsp] Filter created from bgp route tag ?

[Pedro Roque Marques]

Ezequiel Carson wrote:
> Pedro,
> 
>             Can i use this for emulating the Cisco's QPPB feature.

 From what i can see from cisco documentation qppb sounds like DCU 
without 1/2 the functionality. So i guess the answer is yes.

>  Im 
> trying to apply a policer for the incomming traffic when the 
> destionation ip address matches with a BGP community.

Yes, you can do that with DCU.

> 
>             I understand that Junos can not do this in a easy way

I don't understand why you make that comment.

>, since 
> the policer is applied before the routing lookup.
> 

You can configure policers in any point at which you can configure a 
firewall filter. That can be done in several different points of a 
packet data path throuth the box.

It helps to have a top level idea of the packet forwarding path. In a 
centralized architecture box (Martini chipset, i.e. all Mxx platforms), 
this is something like:


if1 ---> if1-input-filter \
		           -- [ scu / rpf ] -- [ftf] -- dst lookup
if2 ---> if2-input-filter /


			 if x output filter -- encaps --- [out]
		      /
           dst lookup
                       \
			 if y output filter -- encaps --- [out]


So if you configure an output filter that gets executed after the 
destination lookup.

On T-series, it gets a little bit trickier... one can achieve this today 
(> 7.0) w/ some tricks. More recent releases will have a clean way to 
get this to work.

   Pedro.