ITEC4610 Network Switching and Routing

1. ITEC4610Network Switching and Routing ดร. ประวิทย์ ชุมชู หัวหน้าสาขาวิชาวิศวกรรมสารสนเทศและการสื่อสาร(ICE) MUT Email: prawit@mut.ac.th ห้องทำงาน: F402 เบอร์โทรศัพท์ที่ทำงาน: (02)9883655 ต่อ 220 เบอร์โทรศัพท์เคลื่อนที่: 065343850

2. ClassIXMulticasting ดร. ประวิทย์ ชุมชู หัวหน้าสาขาวิชาวิศวกรรมสารสนเทศและการสื่อสาร(ICE) MUT Email: prawit@mut.ac.th ห้องทำงาน: F402 เบอร์โทรศัพท์ที่ทำงาน: (02)9883655 ต่อ 220 เบอร์โทรศัพท์เคลื่อนที่: 065343850

3. Multicasting • Multicast Applications • Group Management Protocols • Multicast Routing Algorithm • Multicast Routing Protocols

4. Multicast Applications • Software Distribution • Replicated database update • Command and control systems • Audio/video conferencing • Distributed games • Distributed interactive simulation (DIS) • Distribution of news • Distance Learning

5. Fundamental issues in multicast • Joining and leaving a group • Multicast sessions learning • Group members discovery • Dynamic group membership • Efficient transmission of multicast traffic • Resource optimization • Delivery tree maintenance • Time-sensitive delivery of multicast traffic • Data sequence maintenance • Synchronization

6. Fundamental issues in multicast (Cont.) • Guaranteed arrival of multicast traffic • RTP • RMP • Scalability • Feedback implosions • The use of groups • Security • The exchange of cryptographic keys • UDP-based multicasting protocols

7. Multicasting • Multicast Applications • Group Management Protocols • Multicast Routing Algorithm • Multicast Routing Protocols

8. Group Management Protocols • IGMPv1 • IGMPv2 • IGMPv3

9. IGMPv1(RFC1054) • Multicast router: periodically sends a query message to the all-hosts address (224.0.0.1) • A host sends a report in reply on a per grou basis, thereby refreshing the tentative states • IGMP v1 supports suppression for periodical refresh report messages. • IGMP v1 hosts send unsolicited reports upon joining a group, but leaves the group silently

10. IGMPv2(RFC2236) • IGMP v2 maintains two types of query: general query and group-specific query; • Periodical refresh report suppression is supported as well. • The approach to lower leave latency

11. IGMPv3(RFC 3376) • IGMP v3 maintains three types of query: general query, group-specific query, and group-and-source specific query • IGMP v3 maintains four reports: join, leave, state change, and refresh • No periodical refresh report suppression is supported • The approach to support source filtering: (group-id, filter mode, source list)

12. Position of IGMP in the network layer

13. GROUPMANAGEMENT IGMP is a protocol that manages group membership. The IGMP protocol gives the multicast routers information about the membership status of hosts (routers) connected to the network. .

14. Note: IGMP is a group management protocol. It helps a multicast router create and update a list of loyal members related to each router interface.

15. IGMPMESSAGES IGMP has three types of messages: the query, the membership report, and the leave report. There are two types of query messages, general and special. The topics discussed in this section include: Message Format

16. IGMP message types

17. IGMP message format

18. IGMP type field

19. IGMP OPERATION A multicast router connected to a network has a list of multicast addresses of the groups with at least one loyal member in that network. For each group, there is one router that has the duty of distributing the multicast packets destined for that group. The topics discussed in this section include: Joining a Group Leaving a Group Monitoring Membership

20. IGMP operation

21. Membership report

22. Note: In IGMP, a membership report is sent twice, one after the other.

23. Leave report

24. Note: The general query message does not define a particular group.

25. General query message

26. Example 1 Imagine there are three hosts in a network as shown in the following Figure A query message was received at time 0; the random delay time (in tenths of seconds) for each group is shown next to the group address. Show the sequence of report messages. See Next Slide

27. Example 1

28. Example 1 (Continued) SolutionThe events occur in this sequence: a.Time 12: The timer for 228.42.0.0 in host A expires and a membership report is sent, which is received by the router and every host including host B which cancels its timer for 228.42.0.0. b.Time 30: The timer for 225.14.0.0 in host A expires and a membership report is sent, which is received by the router and every host including host C which cancels its timer for 225.14.0.0. c.Time 50: The timer for 238.71.0.0 in host B expires and a membership report is sent, which is received by the router and every host. See Next Slide

29. Example 1 (Continued) d.Time 70: The timer for 230.43.0.0 in host C expires and a membership report is sent, which is received by the router and every host including host A which cancels its timerfor 230.43.0.0. Note that if each host had sent a report for every group in its list, there would have been seven reports; with this strategy only four reports are sent.

30. ENCAPSULATION The IGMP message is encapsulated in an IP datagram, which is itself encapsulated in a frame. The topics discussed in this section include: IP Layer Data Link Layer Netstat Utility

31. Encapsulation of IGMP packet

32. Note: The IP packet that carries an IGMP packet has a value of 2 in its protocol field.

33. Note: The IP packet that carries an IGMP packet has a value of 1 in its TTL field.

34. Destination IP addresses

35. Mapping class D to Ethernet physical address

36. Note: An Ethernet multicast physical address is in the range01:00:5E:00:00:00to 01:00:5E:7F:FF:FF.

37. Example 2 Change the multicast IP address 230.43.14.7 to an Ethernet multicast physical SolutionWe can do this in two steps: a. We write the rightmost 23 bits of the IP address in hexadecimal. This can be done by changing the rightmost 3 bytes to hexadecimal and then subtracting 8 from the leftmost digit if it is greater than or equal to 8. In our example, the result is 2B:0E:07. b. We add the result of part a to the starting Ethernet multicast address, which is (01:00:5E:00:00:00). The result is 01:00:5E:2B:0E:07

38. Example 3 Change the multicast IP address 238.212.24.9 to an Ethernet multicast address. Solution a. The right-most three bytes in hexadecimal are D4:18:09. We need to subtract 8 from the leftmost digit, resulting in 54:18:09.. b. We add the result of part a to the Ethernet multicast starting address. The result is 01:00:5E:54:18:09

39. Tunneling For WAN, there is no physical multicast support

40. Example 4 We use netstat with three options, -n, -r, and -a. The -n option gives the numeric versions of IP addresses, the -r option gives the routing table, and the -a option gives all addresses (unicast and multicast). Note that we show only the fields relative to our discussion. $ netstat -nraKernel IP routing tableDestination Gateway Mask Flags Iface153.18.16.0 0.0.0.0 255.255.240.0 U eth0169.254.0.0 0.0.0.0 255.255.0.0 U eth0127.0.0.0 0.0.0.0 255.0.0.0 U lo224.0.0.0 0.0.0.0 224.0.0.0 U eth00.0.0.0 153.18.31.254 0.0.0.0 UG eth0 Any packet with a multicast address from 224.0.0.0 to 239.255.255.255 is masked and delivered to the Ethernet interface.

41. IGMP PACKAGE We can show how IGMP can handle the sending and receiving of IGMP packets through our simplified version of an IGMP package. In our design an IGMP package involves a group table, a set of timers, and four software modules. The topics discussed in this section include: Group Table Timers Group-Joining Module Group-Leaving Module Input Module Output Module

42. IGMP package

43. Group table States: Free: There are no process left in the group Delaying: There is timer for for sending a report Idle: There is no timer Reference count: The number of process still interested in the group

44. Group-Joining Module • Receive: a request from a process to join a group • Look for the corresponding entry in the table • If (found) • Increment the reference count • If (not found) • Create an entry with reference count set one • Add the entry to the table • Request a membership report from the output module • Inform the data link layer to update its configuration table • Return

45. Group-Leaving Module • Receive: a request from a process to leave a group • Look for the corresponding entry in the table • If (found) • Decrease the reference count • If (reference count is zero) • If(any timer for this entry) • Cancel the timer • Change state to free • Request a leave report from the output module • Return

46. Input Module • Receive: an IGMP message • Check the message type • If (query) • Start a timer for each entry in the table with the state IDLE • Change each IDLE state to Delaying • Return • If (membership report) • Look for the corresponding entry in the table • If (found any state is Delaying) • Cancel the timer for the entry • Change the state to IDLE • Return

47. Output Module • Receive: a signal from a timer or a request from joining or leaving module • If the message comes from a timer • If (found and state is DELAYING) • Create a member ship report. • Reset the state to IDLE • If the message comes from the group-joining module • Create a membership report • If the message comes from the group-leaving module • Create a leave report • Send the message • Return

48. Multicasting • Multicast Applications • Group Management Protocols • Multicast Routing Algorithms • Multicast Routing Protocols

49. Multicast Routing algorithms • Source-based tree • Multicast link state routing • Multicast Distance Vector routing • Group-based tree

50. Unicasting