BGP Traffic Engineering

These questions assume that you have read the following article :

B. Quoitin, S. Uhlig, C. Pelsser, L. Swinnen and O. Bonaventure. Interdomain traffic engineering with BGP IEEE Communications Magazine Internet Technology Series, 41(5):122-128, May 2003. http://inl.info.ucl.ac.be/publications/interdomain-traffic-engineering-bgp

Paste this command into your terminal:

The password to connect is

Please answer to all the questions. Internal error {} has not a valid extension. {} is too heavy.

Question 1: BGP Attributes inserted in the import filterWhich of the BGP attributes are typically inserted by import files to influence the selection of the BGP routes inside an AS ?

Which of the BGP attributes are typically inserted by import filters to influence the selection of the BGP routes inside an AS ?

Multi Exit Discriminator

AS Path

local-pref

Originator_Id

The IGP cost

Question 2: BGP Attributes inserted in the export filter

Which of the BGP attributes are typically inserted by export filters to influence the selection of the BGP routes inside the remote AS ?

The CLUSTER_LIST

The IGP cost

The Multi Exit Discriminator

local-pref

Question 3: Control of the outgoing traffic

Which of the following traffic engineering techniques can be used to control the outgoing traffic of a stub network ?

Setting the value of the Multi-Exit Discriminator attribute in the import filter of eBGP sessions

Tune the IGP link weights

Add several times your own AS in the AS-Path attribute in the export filter

Setting the value of the local-pref attribute in the export filter of eBGP sessions

Setting the value of the local-pref attribute in the import filter of eBGP sessions

Question 4: Control of the incoming traffic

Which of the following traffic engineering techniques can be used to control the incoming traffic of a stub network ?

Tune the IGP link weights

Setting the value of the local-pref attribute in the import filter of eBGP sessions

Advertising more specific prefixes

Add several times your own AS in the AS-Path attribute in the export filter

Setting the value of the Multi-Exit Discriminator attribute in the import filter of eBGP sessions

Setting the value of the Multi-Exit Discriminator attribute in the export filter of eBGP sessions

Question 5: BGP Communities for traffic engineering

Several network operators have defined BGP Communities that can be used by their customers to control how the routes that they advertise will be ranked inside their own network.

As an example, consider the BGP policy that is specified by Sprint and is described in https://www.sprint.net/index.php?p=policy_bgp

Google's AS number is 15169. Assuming that Google is connected to Sprint, which of the following sentences are valid for a route advertised by a stub that has two links to Sprint.

To implement a backup service, the stub should attach BGP community 1239:100 to the routes sent over the primary link and 1239:80 over the secondary link.

If BGP Communities 65010:15169 and 65070:15169 are attached to a route, Sprint will not readvertise the route towards Google in Asia and North America

If BGP Communities 65010:15169 and 65070:15169 are attached to a route, Sprint will advertise this route towards Google in Asia and North America but not elsewhere

If BGP community 65001:15169 is attached to a route, this route will not be announced to Google.

Question 6: Internet traffic engineering exercise

You are responsible for AS1. Assume that the Internet topology is the followin g:

AS1 --- AS2 ---- AS4 ----- AS6
 +       +                 +
 +----- AS3 -- AS5 --- AS7 --+

For political reasons, the CEO of your company wants to ensure that AS6 never has a route towards prefix p advertised by AS1. How do you implement this political decision with BGP knowing that your two providers do not support any BGP communities.

You configure the import filters of your routers to attach a low local-pref attribute on all routes originated by AS6.

You use AS-Path prepending on the link with both AS3 and AS2 and advertise prefix p with AS-Path AS1:AS1:AS1:AS1

You quit your job because this cannot be implemented in BGP.

You use AS-Path prepending on the link with both AS3 and AS2 and advertise prefix p with AS-Path AS1:AS6

Author(s)	Olivier Bonaventure
Deadline	No deadline
Submission limit	No limitation

Information

Sign in