query about determining ingress interface

Thu Jun 20 05:38:11 UTC 2002

On Thu, Jun 20, 2002 at 05:42:23PM -0400, Rajesh Talpade wrote:

> Is there a way for an ISP to determine the ingress router interface at 
> its network border that will carry IP traffic _from_ an IP address not 
> owned by it?
> 
> I don't want to assume the path is the same in both directions, and tools
> such as CAIDA's skitter plot paths from specific sources. One approach
> might be deriving network paths from CAIDA's data, perhaps someone has
> already done this? 

Rajesh,

Hi there..

Are you asking to determine the interface that "will" or "is" passing said
traffic?

I think it depends on what you're trying to do- Are you trying to track
an individual src at one given point, or collect some stats/trends on where
various srcs are entering your network?

I.e, for an individual src/dst (maybe you're tracing a DoS, etc..) there are
a number of ways to use filters and other mechanisms to log/count packets
matching some known charachteristics (src/dst, length, etc..)  

There are various ways to do things like this, it depends on what exactly you're
trying to track though.

..Dylan

-- 
  ,  Dylan Greene      ,
 +   Juniper Networks   +
 +   +1 617/407-6254    +
  `  dylan at juniper.net '