BGP Route Reflection

These questions assume that you have read the following article :

Jong Han Park et al, BGP Route Reflection Revisited, IEEE Communications Magazine, June 2012, http://irl.cs.ucla.edu/~j13park/rr-commag.pdf

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

Which of the BGP attributes are only used when there are BGP Route Reflectors inside a network ?

CLUSTER_LIST

ORIGINATOR_ID

Multi-Exit Discriminator (MED)

local-pref

Question 2: Number of iBGP sessions

Consider the network whose topology is shown by the ASCII drawing below.

R1------R2----R6
|       |
R3------R4----R5

All these routers belong to the same AS. If one of them is a Route Reflector, how many iBGP sessions do you need to create ?

Question 3: Number of iBGP sessions

Consider the network whose topology is shown by the ASCII drawing below.

R1------R2----R6
|       |
R3------R4----R5

All these routers belong to the same AS. If R2 and R4 are redundant route reflectors, how many iBGP sessions do you need to create inside this AS ?

Question 4: Basics of BGP Route Reflection

Consider the simple network shown in the ASCII figure below.

    +                  +
Rx -+- R1 --- RR --- R2 -+- Ry
    +                  +

In this network, R1, RR and R2 belong to AS1. R1 and R2 are clients of the Route Reflector RR. Rx belongs to AS2 and Ry to AS3. These two ASes are connected to AS4 that advertises prefix p. This implies that :

Rx advertises prefix p with AS-Path:`AS2:AS4 to R1
Ry advertises prefix p with AS-Path:`AS3:AS4 to R2

If link R1-RR has a cost of 1 and link RR-R2 a cost of 2, what are the BGP routes known by these three routers ? (routes marked with * are the best ones, we assume that BGP Nexthop self is not used)

R1's RIB
 *p via RX AS2:AS4
 p via RY AS3:AS4

RR's RIB
  p via RX AS2:AS4
 *p via RY AS3:AS4

R2's RIB
  p via RX AS3:AS4
 *p via RX AS2:AS4

R1's RIB
 *p via RX AS2:AS4
  p via RY AS3:AS4

RR's RIB
 *p via RX AS2:AS4
  p via RY AS3:AS4

R2's RIB
  p via RX AS2:AS4
 *p via RY AS3:AS4

R1's RIB
 *p via RX AS2:AS4

RR's RIB
 *p via RX AS2:AS4
  p via RY AS3:AS4

R2's RIB
 *p via RY AS3:AS4

R1's RIB
 *p via RX AS2:AS4

RR's RIB
 *p via RX AS2:AS4
  p via RY AS3:AS4

R2's RIB
 *p via RY AS3:AS4
  p via RX AS2:AS4

Question 5: Basics of BGP Route Reflection

Consider the simple network shown in the ASCII drawing below.

    +                  +
Rx -+- R1 --- RR --- R2 -+- Ry
    +                  +

In this network, R1, RR and R2 belong to AS1. R1 and R2 are clients of the Route Reflector RR. Rx belongs to AS2 and Ry to AS3. Rx advertises prefix p with AS-Path:`AS2:AS4 to R1

If link R1-RR has a cost of 1 and link RR-R2 a cost of 1, what are the BGP routes known by these three routers ? (routes marked with * are the best ones, BGP Nexthop self is not used in this network)

R1's RIB
 *p via RX AS2:AS4

RR's RIB
 *p via R1 AS2:AS4

R2's RIB
 *p via RR AS2:AS4

Ry's RIB
 *p via R2 AS1:AS3:AS4

R1's RIB
 *p via RX AS2:AS4

RR's RIB
 *p via RX AS2:AS4

R2's RIB
 *p via RX AS2:AS4

Ry's RIB
 *p via R2 AS1:AS3:AS4

R1's RIB
 *p via RX AS2:AS4

RR's RIB
 *p via R1 AS2:AS4

R2's RIB
 *p via R1 AS2:AS4

Ry's RIB
 *p via R2 AS1:AS3:AS4

R1's RIB
 *p via Rx AS2:AS4

RR's RIB
 *p via Rx AS2:AS4

R2's RIB
 *p via Rx AS2:AS4

Ry's RIB
 *p via Rx AS1:AS3:AS4

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

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