iBGP

These questions assume that you have read the iBGP section of the first edition of the Computer Networking: Principles, Protocols and Practice ebook.

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 Decision process

What is the first rule of the BGP decision process ?

Prefer routes learned via eBGP sessions over routes learned via iBGP sessions

Prefer routes having the smallest MED

Ignore routes having an unreachable BGP nexthop

Prefer routes having the shortest AS-Path

Prefer routes having the highest local-pref

Question 2: Hot potato routing

In the list below, which rules of the BGP Decision process corresponds to hot potato routing ?

Prefer routes having the shortest AS-Path

Prefer routes having the smallest MED

Ignore routes having an unreachable BGP nexthop

Prefer routes learned via eBGP sessions over routes learned via iBGP sessions

Prefer routes having the closest next-hop

Prefer routes having the highest local-pref

Question 3: BGP Decision process

The BGP Decision Process starts with the following rules

1. Ignore routes having an unreachable BGP nexthop
2. Prefer routes having the highest local-pref
3. Prefer routes having the shortest AS-Path

What are the next rules of the BGP decision process ?

4. Prefer routes having the smallest MED
5. Prefer routes learned via eBGP sessions over routes learned via iBGP sessions
6. Prefer routes having the closest next-hop
7. Tie breaking rules prefer routes learned from the router with lowest router id

4. Prefer routes having the closest next-hop
5. Prefer routes learned via eBGP sessions over routes learned via iBGP sessions
6. Prefer routes having the smallest MED
7. Tie breaking rules prefer routes learned from the router with lowest router id

4. Prefer routes learned via eBGP sessions over routes learned via iBGP sessions
5. Prefer routes having the closest next-hop
6. Prefer routes having the smallest MED
7. Tie breaking rules prefer routes learned from the router with lowest router id

4. Prefer routes learned via eBGP sessions over routes learned via iBGP sessions
5. Prefer routes having the smallest MED
6. Prefer routes having the closest next-hop
7. Tie breaking rules prefer routes learned from the router with lowest router id

Question 4: Cold potato routing

Cold potato routing relies on the utilisation of a specific BGP attribute. Which one ?

The AS-Path

The BGP Communities

The Multi-Exit Discriminator (MED)

The BGP Nexthop

The local-preference

Question 5: Number of iBGP sessions

Consider a transit network that is composed of k different transit routers. What many iBGP sessions do you need to create inside this network ?

\(k \times (k-1)\)

\(\frac{k \times (k-1)}{2}\)

\(k\)

\(\frac{k}{2}\)

Author(s)	Olivier Bonaventure
Deadline	No deadline
Submission limit	3 submissions

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Question 1: BGP Decision process

Question 2: Hot potato routing

Question 3: BGP Decision process

Question 4: Cold potato routing

Question 5: Number of iBGP sessions

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iBGP Collapse context

Question 1: BGP Decision process

Question 2: Hot potato routing

Question 3: BGP Decision process

Question 4: Cold potato routing

Question 5: Number of iBGP sessions

iBGP