Subject: [Bier] overdue text on BEIR TE

From: Lou Berger <[email-masked]>
Date: Tue, 14 Apr 2020 08:46:43 -0400

Hi,

This is a bit overdue - but I somehow imagine that many will understand 
life hasn't been happening in a normal way recently.

I suggest the text enclosed below be incorporated into the BEIR TE 
draft, perhaps at the end of section 2 or a new section 3. Please excuse 
any typos, and I'm sure it will need some tweaking to best align with 
BIER terminology.

Lou

PS I'm triple booked during today's interim, but still hope to be there.

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2.5. Traffic Engineering Considerations

Traffic Engineering [RFC3272-Bis] provides performance optimization of 
operational IP networks while utilizing network resources economically 
and reliably.  The key elements needed to effect TE are policy, path 
steering and resource management. These elements require support at the 
control/controller level and within the forwarding plane.

Policy decisions are made within the BIER-TE control plane, i.e., within 
BIER-TE Controllers.  Controllers use policy when composing BitStrings 
(BFR flow state) and BFR BIFT state. The mapping of user/IP traffic to 
specific BitStrings/BEIR-TE flows is made based on policy. The specifics 
details of BIER-TE policies and how a controller uses such are out of 
scope of this document.

Path steering is supported  via the definition of a BitString. 
BitStrings used in BIER-TE are composed based on policy and resource 
management considerations.  When composing BIER-TE BitStrings, a 
Controller MUST take into account the resources available at each BFR 
and for each BP.  Resource availability is typically provided 
dynamically via routing protocol information, but may also be obtained 
via the BIER-TE control protocol.  The resource usage of an individual 
BP can be tracked on a Controller based on its local accounting and via 
routing or the BIER-TE control protocol. This implies that such 
information be collected by each BFR.

Resource management also has implications on the BFR forwarding plane.  
BIER-TE supporting BFRs  MAY support per BIFT entry resources and 
resource allocation. Example resources include buffers, policing and 
rate-shaping mechanisms which are typically supported via queuing.  This 
level of resource control, while optional, is important in networks that 
wish to support congestion management policies to control or regulate 
the offered traffic to deliver different levels of service and alleviate 
congestion problems, or those networks that wish to control latencies 
experienced by specific traffic flows.

[RFC3272-Bis] https://tools.ietf.org/html/draft-dt-teas-rfc3272bis