1. Multicast architecture in Linux
Laurentiu Barza
Sujet
Après une évolution lente de l’Internet, nous assistont à sa croissance exponentielle, générée par l’utilisation des réseaux dans le commerce électronique, domaine mondial qui ne cesse de croître. Mais quel est le rôle exact joué par l’Internet dans le développement des autoroutes de l’Information ? Des exemples de services d’informations ainsi que les nouveaux outils logiciels nécessaires (évolution des protocoles, intermédiation, télé-paiement,...) illustrent cette présentation.
Feb. 22, 2001 1

2. Conformance levels Level 0: no support for multicast
Level 1: sending, but not receiving
Level 2: full support for IP multicasting

3. Linux multicast routing & forwarding
(4)
Linux
kernel
Forwarding
(3)
(1)
(2)
Multicast
routing
algorithm
Multicast
routing
table

4. Linux multicast programming
int setsockopt (int s, int level, int optname, const void* optval, int optlen);
int getsockopt (int s, int level, int optname, void* optval, int* optlen);
s: the socket the system call applies to
level: layer which handle the option
optname: identifies the option we are setting/getting
optval: the value taken by the option
optlen: the size of data structure optval

5. Linux multicast programming
The optname values involved in multicast programming:
IP_MULTICAST_IF set/get IP multicast interface.
IP_MULTICAST_TTL set/get IP multicast ttl
IP_MULTICAST_LOOP set/get IP multicast loopback
IP_ADD_MEMBERSHIP add an IP group membership
IP_DROP_MEMBERSHIP drop an IP group membership

6. Linux multicast programming - IGMPv3 specific options -
For some applications all the sources are accepted, for others only souces in a given list are allowed.
IP_BLOCK_SOURCE mute a specific source
IP_UNBLOCK_SOURCE un-mute the source
IP_ADD_SOURCE_MEMBERSHIP add a specific source
IP_DROP_SOURCE_MEMBERSHIP drop a specific souce
IP_DROP_MEMBERSHIP drop all sources
IP_MULTICAST_FILTER set multicast filter

7. MGEN test tool
IP network performance measurements using UDP/IP unicast and multicast traffic
generate real traffic patterns: periodic, poisson
possibility to control packet size and transmission rate, RSVP, TOS settings
fixed-parameter mode, script mode
distributed with utility programs: parses log files and outputs statistics

8. MGEN test scenarios Unicast: source -> receiver
Multicast one-to-one
Multicast one-to-many: all the receivers in the same network
Multicast one to many: the receivers are in different networks

9. SSM current developments
IGMPv3 by Sprint
IGMPv3 lite by Cisco:
solution for application developers to immediately start programming SSM applications
URD host signaling
allows existing IP multicast receiver applications to be used with SSM without the need to modify the application

10. Future work Context : the Internet is changing
Content Distribution Networks (CDN) = an overlay for the Internet
performance: lower latency
bandwidth arbitrage: push the content where the bandwidth is cheaper
flash crowd control: load balancing
bandwidth multiplication

11. Future work Utilize multicast (SSM) in CDN networks user cache
Main site
(source)
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