Subject: [RADIR] General TE definition

From: Jason Schiller <[email-masked]>
Date: Tue, 08 May 2007 15:08:40 -0400 (EDT)

Traffic engineering (TE) is accomplished by placing more specific routes
in the routing table and/or increasing the frequency of routing updates in
order to control inbound inter-AS traffic.

This is not exactly what I said on the call, and here is why:

1. I wanted to distingusih between internal traffic engineering done
primarily in the IGP vs. inter-AS traffic engineering at the inter-domain
level.

2. I included the word "inbound".  The extra more specifics, and the
frequency of changing them is an attempt to change inbound TE.  Outbound
TE is often a function of your IGP for shortest exit for equally good
routes, or some policy to depreference, or filter certain routes from
specific BGP peers.

___Jason

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---

From: Erik Nordmark <[email-masked]>
Date: Tue, 08 May 2007 12:51:01 -0700

> routes, or some policy to depreference, or filter certain routes from

Should we make #2 more specific in the text above i.e.
Inbound traffic engineering (TE) ...

and also add some text about Outbound traffic engineering saying that it 
doesn't (normally?) have any effects outside of the AS itself?

    Erik

---

From: Jason Schiller <[email-masked]>
Date: Tue, 08 May 2007 17:30:10 -0400 (EDT)

> doesn't (normally?) have any effects outside of the AS itself?

Erik,

I have no objections to either suggestion...  

In the call today we were discussing a short general definition of "TE'
for in the problem statement, and were planning on having a more detailed
description of TE in the "pressures on the routing table" section.  

I am happy to include your suggestions in either or both places.

I'm not sure how detailed we want to get but how is this:

Traffic engineering (TE) is artificially influencing the natural path that
traffic is forwarded on.  TE is usually divided into internal TE and
inter-AS TE.  

Internal TE is typically accomplished within the Interior Gateway Protocol
(IGP) and all information is kept local to the Autonomous System
(AS).  Since the amount of state in the IGP is relatively small, and the
information is kept local this is typically not a large factor in routing
scale.

Inter-AS TE is used at Autonomous System (AS) boundaries, and has a direct
impact on the routing table.  Inter-AS TE is typically divided into two
types inbound inter-AS TE and outbound inter-AS TE.

Inbound inter-AS TE is typically accomplished by placing more specific
routes in the routing table and/or increasing the frequency of routing
updates in order to control inbound traffic at the boundary of an
Autonomous system (AS).

Outbound inter-AS TE is typically accomplished but using the internal IGP
metrics to chooses the shortest exit for two equally good BGP
paths.  Tweaking the IGP metrics will cause more or less of the network to
choose a specific exit point as shorter for two equally good BGP
paths.  Additional traffic can be moved by applying some policy to
depreference, or filter certain routes from specific BGP peers.

-----

First attempt for reference

Traffic engineering (TE) is accomplished by placing more specific routes
in the routing table and/or increasing the frequency of routing updates in
order to control inbound traffic at the boundary of an Autonomous system
(AS).

notes from previous email:

___Jason

---

From: Erik Nordmark <[email-masked]>
Date: Tue, 08 May 2007 16:09:22 -0700

> depreference, or filter certain routes from specific BGP peers.

Works for me, but I no expert on TE.

    Erik

---

From: "John G. Scudder" <[email-masked]>
Date: Wed, 9 May 2007 11:21:43 +0300

Jason,

Either the shorter or longer version WFM.  I kind of like the shorter  
version because, well, it's shorter.  There's no need (IMO) to make  
this document a tutorial on all possible forms of TE -- it just needs  
to clarify what form of TE we are talking about.

One possible tweak to the shorter version to make this a bit more  
explicit:

"In this document, 'traffic engineering' (TE) refers to the current  
practice of inbound, inter-AS traffic engineering.  This is  
accomplished by placing more specific routes in the routing table and/ 
or increasing the frequency of routing updates in order to control  
inbound traffic at the boundary of an Autonomous system (AS)."

But any of the different versions are fine.

--John

---

From: Jason Schiller <[email-masked]>
Date: Wed, 09 May 2007 13:23:21 -0400 (EDT)

Those changes to the short version work for me... the longer version is
also fine if people think it useful

__Jason

On Wed, 9 May 2007, John G. Scudder wrote:

> Date: Wed, 09 May 2007 11:21:43 +0300
> From: John G. Scudder <[email-masked]>
> To: Jason Schiller <[email-masked]>
> Cc: Erik Nordmark <[email-masked]>, [email-masked],
>      Jason Schiller <[email-masked]>
> Subject: Re: [RADIR] General TE definition
> 
> Jason,
>