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1. Interdomain Routing algorithm with advantages and disadvantages
PRESENTED BY:-
AYUSH MISHRA-(ROLL NO-2106047)
VIJAY KUMAR-(ROLL NO-2106059)
SAURABH KUMAR-(ROLL NO-2106074)
1

2. 2
ON THE AGENDA
1. INTRODUCTION
2. BORDER GATEWAY PROTOCOL
3.PEER LINKING
4. ADVANTAGES
5. DISADVANTAGES
6. REFRENCES

3. INTRODUCTION
•Interdomain Routing
algorithm works within and
between domains.
•It need to know only about
other routers within and
between their domain.
•Protocols used in
interdomain routing are
known as Exterior-gateway
protocols.
3

4. • In this Routing, routing takes
place between the
autonomous networks.
• Interdomain routing protocol
assumes that the internet
contains the collection of
interconnected
AS(autonomous systems).
4

5. • Popular Protocols of this
routing is BGP(Border
Gateway Protocol) used to
connect two or more
AS(autonomous system).
5

6. 6

7. 7
•The network is partitioned into
Autonomous Systems (ASes) each
owned by an economic entity.
•Within ASes routing is cooperative
•Between ASes inherently non-
cooperative
AT&T
Qwest
Comcast
UUNET
My link to UUNET is for
backup purposes only.
Load-balance my
outgoing traffic.
Always choose
shortest paths.
Avoid routes
through AT&T if at
all possible.

8. 8
ON THE AGENDA
1. INTRODUCTION
2. BORDER GATEWAY PROTOCOL
3.PEER LINKING
4. ADVANTAGES
5. DISADVANTAGES
6. REFRENCES

9. BORDER
GATEWAY
PROTOCOL
•Path vector protocol
•BGP router advertises its best route to each
destination. The only protocol currently used
to establish routes between ASes
(interdomain routing):
The Border Gateway Protocol (BGP).
•The computation by each node is an infinite
sequence of actions:
9
receive routes
from
neighbors
choose
“best”
neighbor
send updates
to neighbors

10. 10
Source:https://www.google.com/url?sa=i&url=https%3A%2F%2Fwww.networkcomputing.com%2Fdata-centers%2Fbgp-basics-internal-and-external-
bgp&psig=AOvVaw0szPQDJDMVg8JoMcONTA8r&ust=1680939277677000&source=images&cd=vfe&ved=0CBAQjRxqFwoTCJCg7PSgl_4CFQAAAAAdAAAAABAY

11. 11
• Principles
• BGP relies on the
incremental exchange of
path vectors
BGP : PRINCIPLES

12. 12
Source:https://www.google.com/url?sa=i&url=https%3A%2F%2Fnetworkingtales.com%2Fbgp-path-selection-part-
i%2F&psig=AOvVaw0szPQDJDMVg8JoMcONTA8r&ust=1680939277677000&source=images&cd=vfe&ved=0CBAQjRxqFwoTCJCg7PSgl_4CFQAAAAAdAAAAABAQ

13. 13
• UPDATE (Path Vector)
• Advertises A Route
Towards One Prefix
• Destination Address/Prefix
• Interdomain Path (As-path)
• Nexthop
• WITHDRAW
BGP :BASICS

14. 14
• A Previously Announced
Route Is Not Reachable
Anymore
• Unreachable Destination
Address/Prefix

15. 15
Source:https://www.google.com/imgres?imgurl=https%3A%2F%2Fwww.researchgate.net%2Fpublication%2F272485008%2Ffigure%2Ffig3%2FAS%3A667838033448977%401536236403995%2FBorder-Gateway-
Protocol-BGP.ppm&tbnid=TsaN0uanTLNoAM&vet=12ahUKEwjcmNn5o5f-AhX6_TgGHX1KBOIQMygRegUIARDjAQ..i&imgrefurl=https%3A%2F%2Fwww.researchgate.net%2Ffigure%2FBorder-Gateway-
Protocol-BGP_fig3_272485008&docid=pb5P664L-4--0M&w=850&h=587&q=bgp%20routers%20images&ved=2ahUKEwjcmNn5o5f-AhX6_TgGHX1KBOIQMygRegUIARDjAQ

16. How to prefer routes ?
RPSL-like policy for AS1
• aut-num: AS1
• import: from AS2 RA at R1 set
localpref=100;
from AS2 RB at R1 set localpref=200;
accept ANY
• export: to AS2 RA at R1 announce AS1
to AS2 RB at R1 announce AS1
RPSL-like policy for AS2
• aut-num: AS2
• import: from AS1 R1 at RA set
localpref=100;
from AS1 R1 at RB set localpref=200; accept
AS1
• export: to AS1 R1 at RA announce ANY
to AS2 R1 at RB announce ANY
Source:https://www.google.com/imgres?imgurl=https%3A%2F%2Fi
mage.slidesharecdn.com%2F10-routing-bgp-
210507084643%2F85%2Fpart-10-routing-in-ip-networks-and-
interdomain-routing-with-bgp-58-
320.jpg%3Fcb%3D1668843428&tbnid=_KAXrXkInGwPaM&vet=12a
hUKEwiR8dXvpZf-
AhWCGbcAHQCjCDgQMygfegUIARD3AQ..i&imgrefurl=https%3A%
2F%2Fwww.slideshare.net%2Fobonaventure%2Fpart-10-routing-in-
ip-networks-and-interdomain-routing-with-
bgp&docid=0av0ygD9JtgCRM&w=320&h=240&itg=1&q=how%20to
%20prefer%20routes%20images&ved=2ahUKEwiR8dXvpZf-
AhWCGbcAHQCjCDgQMygfegUIARD3AQ

17. ON THE AGENDA
1. INTRODUCTION
2. BORDER GATEWAY PROTOCOL
3. PEER LINKING
4. ADVANTAGES
5. DISADVANTAGES
6. REFRENCES

18. Peer
Linking
•An agreement is peering when two peer ISPs
exchange traffic between themselves without its
pay.
•Two ISPs can decide to do peering agreement if
they determine that costs for direct
interconnection are lower than the costs for
buying transit from each other.
18

19. 19
Fig.a Interdomain link
Fig.b Interdomain exchange
Source:https://www.google.com/imgres?imgurl=https%3A%2F%2Fimage.slidesharecdn.com%2F10-routing-bgp-210507084643%2F85%2Fpart-10-routing-in-ip-networks-and-interdomain-routing-with-bgp-29-
320.jpg%3Fcb%3D1668843428&tbnid=7lvqEJo_usEltM&vet=12ahUKEwi00dblpJf-AhUFDbcAHTBXD4YQMygdegUIARDxAQ..i&imgrefurl=https%3A%2F%2Fwww.slideshare.net%2Fobonaventure%2Fpart-10-routing-in-ip-
networks-and-interdomain-routing-with-bgp&docid=0av0ygD9JtgCRM&w=320&h=240&itg=1&q=interdomain%20link%20images&ved=2ahUKEwi00dblpJf-AhUFDbcAHTBXD4YQMygdegUIARDxAQ

20. 20
• In theory BGP allows each domain to define its
own routing policy...
• In practice there are two common policies
• Customer-provider peering - Customer c
buys Internet connectivity from provider P
• Shared-cost peering - Domains x and y agree
to exchange packets without any payment
Routing policies

21. 21

22. 22

23. ON THE AGENDA
1. INTRODUCTION
2. BORDER GATEWAY PROTOCOL
3. PEER LINKING
4. ADVANTAGES
5. DISADVANTAGES
6. REFRENCES

24. ADVANTAGES
•Interdomain routing algorithms have several
advantages such as scalability, flexibility, and
reliability.
•These algorithms can handle large and complex
networks with thousands of ASes and routers
using techniques like route aggregation, filtering,
and policy-based routing to reduce the size and
complexity of routing tables.
24

25. 25
• EGP protocols also provide the flexibility to
accommodate different IGP protocols and
network architectures, as well as support
hierarchical, flat, or hybrid routing model.
• Furthermore, EGP protocols can enhance the
reliability and availability of interdomain
routing by providing multiple paths and
backup routes.
• Mechanisms such as route preference, load
balancing, and multipath routing are used for
the best path.

26. 26

27. BGP
SECURITY •BGP is a critical protocol for the operation of
the Internet, and it is essential that it is
secured to ensure the integrity of routing
information. Here are some security issues
associated with BGP:
•Route hijacking: This occurs when an attacker
advertises a false BGP route to a router,
causing traffic to be redirected to the attacker's
network. 27

28. •Route leaks: This occurs when a BGP router
sends routing information to a neighboring
router that it should not have sent.
•BGP session hijacking: This occurs when an
attacker takes control of a BGP session
between two routers and sends false routing
information.
28

29. •BGP prefix hijacking: This occurs when an
attacker advertises a prefix that it does not
own to a BGP router, causing traffic to be
redirected to the attacker's network.
29
Source:https://www.google.com/imgres?imgurl=https%3A%2F%2Fcsirt.lacnic.net%2Fwp-content%2Fuploads%2F201703_Articulo_BPG_AC_DG-1-1.png&tbnid=mmoD-lruRrGEzM&vet=12ahUKEwjwupSrpZf-
AhXKD7cAHY4cBBEQMyhWegUIARCDAQ..i&imgrefurl=https%3A%2F%2Fcsirt.lacnic.net%2Fen%2Fnews-articles%2Fbgp-to-filter-or-not-to-filter-by-network-size-that-is-the-
question&docid=aVt08I9Hqg054M&w=1317&h=777&q=bgp%20prefix%20hijack%20images&ved=2ahUKEwjwupSrpZf-AhXKD7cAHY4cBBEQMyhWegUIARCDAQ

30. ON THE AGENDA
1. INTRODUCTION
2. BORDER GATEWAY PROTOCOL
3. PEER LINKING
4. ADVANTAGES
5. DISADVANTAGES
6. REFRENCES

31. DISADVANTAGES
EGP protocols are used for interdomain
routing and have certain disadvantages.
• One of the disadvantages is that they are less
secure than static routing. EGP protocols are
vulnerable to spoofing, hijacking, denial-of-
service, and man-in-the-middle attacks.
•Man-in-the-middle attack is when an attacker
intercepts communication between two hosts. 31

32. •EGP protocols do not have built-in
authentication or encryption mechanisms.
Another disadvantage of EGP protocols is
that they can take longer to converge than
IGP protocols because they rely on slow
convergence mechanisms like route flapping
detection and hold-down timers.
32

33. • Complexity-wise, EGP protocols can be
difficult to configure and manage due to
their large-scale and distributed nature.
33

34. ON THE AGENDA
1. INTRODUCTION
2. BORDER GATEWAY PROTOCOL
3. PEER LINKING
4. ADVANTAGES
5. DISADVANTAGES
6. REFRENCES

35. REFERENCES
35
• BOOKS:-
• WEBPAGES:-
• Data communication and networking, fifth edition, Author:
Behrouz A. Forouzan, Mc Graw Hill(2012)
• Computer Networking: A Top-Down Approach, sixth edition,
Author: James F. Kurose, and Keith W. Ross., Pearson(2018)
• Wikipedia:https://en.wikipedia.org/wiki/Inter-domain_routing
• Geeks for geeks:https://www.geeksforgeeks.org/differences-
between-intradomain-and-interdomain-routing
• TechTarget:https://www.techtarget.com/searchnetworking/definitio
n/CIDR