From: Godswill Oletu (oletu@inbox.lv)
Date: Sat Jul 16 2005 - 13:58:13 GMT-3
Your friend might be referring to something else, I haved as-path prepend in
live networks or real world networks and they work great, every time and all
the time. As-path is a well-known mandatory attribute and must be passed
from one AS to another, this is the best way to influence how others can
come into your AS.
MED is an optional non-transitive attribute, it is another way of telling
others how to reach you, but as you can see, it is 'optional' and it
'non-transitive', if your friend is referring to MED values, I will agree,
despite the fact that, it is non-transitive, one ISP can decide to send its
MED values, since it is optional, it is then upto the upstream ISP to
accept, reject or override those MED values with his own preferred values.
For as-path, it is mandatory so it must be included in your updates, it is
well-known and as such it must be accepted by the upstream ISP or AS.
As a side note, all the techniques or scenerios either to influence sometime
or to manipulate some networking behaviours, you see people in this group
discussed and especially related to the CCIE lab, works fine in the real
world networks. The only problem is that, most of them are bad network
design if implemented in the real world. That not withstanding, it is good,
because the primay objective of the CCIE Lab is not to teach the very best
network designs out there, but to see if you really understand how each of
the various technologies interract with each other.
Hope this helps.
Godswill Oletu
----- Original Message -----
From: <cciein2006@yahoo.com>
To: <ccielab@groupstudy.com>
Sent: Saturday, July 16, 2005 12:03 PM
Subject: Influencing Inbound Traffic in the Real World
> Hello All,
>
> I just had a discussion with my friend regarding multihomed internet
> connections and BGP.
>
> He said that most of the techniques used for influencing inbound traffic
> from multiple ISP's do not work in the real world. As an example he said
> that most ISP's don't accept as-path prepended routes and MED metrics are
> not passed between AS's (or are they passed but not compared by default?).
> Is this true?
>
> I wanted to know what has been people's experiences working with these
> scenarios in the real world and what techniques actually do work regarding
> influencing inbound internet traffic.
>
> TIA!
>
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