1. CS 4594 Broadband
PNNI Signaling

2. PNNI PNNI = Private Network to Network Interface
Can be used for both public and private networks

3. Two Parts of PNNI
Topology Distribution Protocol: Establish structure on an unstructured network
Signaling Protocol: Establish a connection in a network

4. PNNI – ATM Forum
From the ATM Forum af-pnni : PNNI consists of:
A protocol is defined for distributing topology information between switches and clusters of switches. This information is used to compute paths through the network. A hierarchy mechanism ensures that this protocol scales well for large world-wide ATM networks. A key feature of the PNNI hierarchy mechanism is its ability to automatically configure itself in networks in which the address structure reflects the topology. PNNI topology and routing is based on the well-known link-state routing technique.
A second protocol is defined for signaling, that is message flows used to establish point-to-point and point-to-multipoint connections across the ATM network. This protocol is based on the ATM Forum UNI signaling, with mechanisms added to support source routing, crankback, and alternate routing of call setup requests in case of connection setup failure.

5. Functions of the PNNI routing protocol
Discovery of neighbors and link status.
Election of PGLs. (Peer Group Leader)
Construction of the routing hierarchy.
Synchronization of topology databases.

6. Hello – establishes local topology
Each node exchanges Hello packets with its immediate neighbors and thereby determines its local state information. This state information includes the identity and peer group membership of the node’s immediate neighbors, and the status of its links to the neighbors. Each node then bundles its state information in “PNNI Topology State Elements” (PTSEs), which are reliably flooded throughout the peer group.

7. Example Network – No Hierarchical Structure
B.1.1
B.2.1
B.1.2
B.2.3
Source
A.1.2.x
B.2.2
B.3.2
B.1.3
A.2.1
B.3.1
B.3.3
B.3.4
A.2.2
A.2.3
B.3.5
A.1.1
A.3.2
A.3.3
A.1.2
A.3.4
Destination
B.3.3.y
A.3.1
Level 96
Level 96

8. Structure Peer Groups are determined by addressing.
Address levels are determined by how many bits are allocated to the peer group part of the address.
Peer Group Leaders are determined by election.
Reachability information is determined by exchange of information among nodes.
Uplinks are established using physical links between members of different peer groups.

9. The Network Structured
Level 64 A C B
A.2
Level 80
Level 96
B.1
B.2
B.3
C.1
C.2
A.1
A.3
B.1.1
B.2.1
Level 72
B.1.2
B.2.3
B.2.2
B.3.2
B.1.3
A.2.1
B.3.1
B.3.3
Level 96
Level 96
B.3.4
A.2.2
A.2.3
B.3.5
A.1.1
A.3.2
Level 96
A.3.3
Level 104
A.1.2
A.3.4
A.3.1
Level 96
Level 96

10. Some Uplinks Level 64 A C B A.2 Level 80 Level 96 B.1 B.2 B.3 C.1 C.2

11. The Logical Links are Supported by Uplinks
Level 64 A C B
A.2
Level 80
Level 96
B.1
B.2
B.3
C.1
C.2
A.1
A.3
B.1.1
B.2.1
Level 72
B.1.2
B.2.3
Source
A.1.2.x
B.2.2
B.3.2
B.1.3
A.2.1
B.3.1
B.3.3
Level 96
Level 96
B.3.4
A.2.2
A.2.3
B.3.5
A.1.1
A.3.2
Level 104
Level 96
A.3.3
A.1.2
A.3.4
Destination
B.3.3.y
A.3.1
Level 96
Level 96

12. Problem: Establish a Route
Given: Source and Destination and Network as it is known at each node.
Establish a route.

13. The Source and Destination
Level 64 A C B
A.2
Level 80
Level 96
B.1
B.2
B.3
C.1
C.2
A.1
A.3
B.1.1
B.2.1
Level 72
B.1.2
B.2.3
Source
A.1.2.x
B.2.2
B.3.2
B.1.3
A.2.1
B.3.1
B.3.3
Level 96
Level 96
B.3.4
A.2.2
A.2.3
B.3.5
A.1.1
A.3.2
Level 104
Level 96
A.3.3
A.1.2
A.3.4
Destination
B.3.3.y
A.3.1
Level 96
Level 96

14. Possible Route 1A Source A.1.2.x Destination B.3.3.y Level 64 A C B

15. Possible Route 1B Source A.1.2.x Destination B.3.3.y Level 64 A C B

16. Possible Route 2A Source A.1.2.x Destination B.3.3.y Level 64 A C B

17. Yet Another Route (3A) Source A.1.2.x Destination B.3.3.y Level 64 A C

18. Basic Concepts Designated Transit List (DTL) Call SETUP Message
DTLs map out routes.
DTLs work at different levels.
A stack keeps track of the levels.
Call SETUP Message
is passed to next node.
is saved at nodes that add new routes.

19. Some Problems
The link between A.3.3 and B.1.2 is blocked (even though PNNI routing says it is OK)
The link between A.3.3 and B.2.3 cannot support the high peak cell rate requested.

20. The Network with Problems
Level 64 A C B
A.2
Level 80
Level 96
B.1
B.2
B.3
C.1
C.2
A.1
A.3
B.1.1
B.2.1
Level 72
B.1.2
B.2.3
Source
A.1.2.x
B.2.2
B.3.2
B.1.3
A.2.1
B.3.1
B.3.3
Level 96
Level 96
B.3.4
A.2.2
A.2.3
B.3.5
A.1.1
A.3.2
Level 96
A.3.3
Level 104
A.1.2
A.3.4
Destination
B.3.3.y
A.3.1
Level 96
Level 96

21. Begin at the Source, Use Route 1
Level 64 A C B
A.2
Level 80
Level 96
B.1
B.2
B.3
C.1
C.2
A.1
A.3
B.1.1
B.2.1
Level 72
B.1.2
B.2.3
Source
A.1.2.x
B.2.2
B.3.2
B.1.3
A.2.1
B.3.1
B.3.3
Level 96
Level 96
B.3.4
A.2.2
A.2.3
B.3.5
A.1.1
A.3.2
Level 104
Level 96
A.3.3
A.1.2
A.3.4
Destination
B.3.3.y
A.3.1
Level 96
Level 96

22. Find Route Through A and A.1
Level 64 A C B
A.2
Level 80
Level 96
B.1
B.2
B.3
C.1
C.2
A.1
A.3
B.1.1
B.2.1
Level 72
B.1.2
B.2.3
Source
A.1.2.x
B.2.2
B.3.2
B.1.3
A.2.1
B.3.1
B.3.3
Level 96
Level 96
B.3.4
A.2.2
A.2.3
B.3.5
A.1.1
A.3.2
Level 104
Level 96
A.3.3
A.1.2
A.3.4
Destination
B.3.3.y
A.3.1
Level 96
Level 96

23. Call SETUP Begins SETUP Message saved at A.2.1
Message forwarded to next node.

24. Push Route from A to B DTL: [A, B], pointer-1 Source A.1.2.x Level 64

25. Push Route Through A DTL: [A.1, A.2, A.3], pointer-1
DTL: [A, B], pointer-1
Level 64 A C
Source
A.1.2.x B
A.2
A.1.1
A.1
A.3
A.1.2
Level 72

26. Push Route Through A.1 DTL: [A.1.2, A.1.1], pointer-1
DTL: [A.1, A.2, A.3], pointer-1
DTL: [A, B], pointer-1
Level 64 A C
Source
A.1.2.x B
A.2
A.1.1
A.1
A.3
A.1.2
Level 72

27. Move to Next Node in top DTL
DTL: [A.1.2, A.1.1], pointer-2
DTL: [A.1, A.2, A.3], pointer-1
DTL: [A, B], pointer-1
Level 64 A C
Source
A.1.2.x B
A.2
A.1.1
A.1
A.3
A.1.2
Level 72

28. Pop DTL Stack and Move to A.2
DTL: [A.1, A.2, A.3], pointer-2
DTL: [A, B], pointer-1
Level 64 A C B
A.2
A.1
A.3
Level 72

29. Push a Route through A.2 DTL: [A.2.2, A.2.3], pointer-1
DTL: [A.1, A.2, A.3], pointer-2
DTL: [A, B], pointer-1
Level 64 A C B
A.2
A.2.1
A.1
A.3
A.2.2
A.2.3
Level 72
Level 96

30. Call SETUP saved at node
New route, so save SETUP message at node A.2.2.

31. Move through A.2 DTL: [A.2.2, A.2.3], pointer-2
DTL: [A.1, A.2, A.3], pointer-2
DTL: [A, B], pointer-1
Level 64 A C B
A.2
A.2.1
A.1
A.3
A.2.2
A.2.3
Level 72
Level 96

32. Route Through A.2 Source A.1.2.x Destination B.3.3.y Level 64 A C B

33. Pop DTL Stack and Move to A.3
DTL: [A.1, A.2, A.3], pointer-3
DTL: [A, B], pointer-1
Level 64 A C B
A.2
A.1
A.3
Level 72

34. Push a Route through A.3 DTL: [A.3.4, A.3.2, A.3.3], pointer-1
DTL: [A, B], pointer-1
Level 64 A C B
A.2
A.3.2
A.3.3
A.1
A.3
A.3.4
A.3.1
Level 72
Level 96

35. Save Call SETUP
New route, so save SETUP message at A.3.4.

36. Move to next node DTL: [A.3.4, A.3.2, A.3.3], pointer-2
DTL: [A, B], pointer-1
Level 64 A C B
A.2
A.3.2
A.3.3
A.1
A.3
A.3.4
A.3.1
Level 72
Level 96

37. Go to end of A.3 DTL: [A.3.4, A.3.2, A.3.3], pointer-3
DTL: [A, B], pointer-1
Level 64 A C B
A.2
A.3.2
A.3.3
A.1
A.3
A.3.4
A.3.1
Level 72
Level 96

38. Pop DTL Stack DTL: [A.1, A.2, A.3], pointer-3 DTL: [A, B], pointer-1
Level 64 A C B
A.2
A.1
A.3
Level 72

39. Pop DTL Stack, Look for B
DTL: [A, B], pointer-2
Level 64 A C B

40. Call is Blocked
At this point the call is blocked – A.3.3 finds it cannot use the connection to B.1.2

41. Route 1 is Blocked into B Source A.1.2.x Destination B.3.3.y Level 64

42. Crankback begins at A.3.3 Source A.1.2.x Destination B.3.3.y Level 64

43. Crankback
It cranks back to A.3.4 which attempts alternate routing.

44. Crankback to A.3.4 Source A.1.2.x Destination B.3.3.y Level 64 A C B

45. Crankback A.3.4 cannot find a route.
It cranks back to A.1.2 which then attempts alternate routing.
RELEASE message.

46. Crankback to A.1.2 Source A.1.2.x Destination B.3.3.y Level 64 A C B

47. Find an Alternate Route from A.1.2 to B
Level 64 A C B
A.2
Level 80
Level 96
B.1
B.2
B.3
C.1
C.2
A.1
A.3
B.1.1
B.2.1
Level 72
B.1.2
B.2.3
Source
A.1.2.x
B.2.2
B.3.2
B.1.3
A.2.1
B.3.1
B.3.3
Level 96
Level 96
B.3.4
A.2.2
A.2.3
B.3.5
A.1.1
A.3.2
Level 104
Level 96
A.3.3
A.1.2
A.3.4
Destination
B.3.3.y
A.3.1
Level 96
Level 96

48. Push DTLs Through A and A.1
DTL: [A.1.2, A.1.1], pointer-2
DTL: [A.1, A.2], pointer-1
DTL: [A, B], pointer-1
Level 64 A C
Source
A.1.2.x B
A.2
A.1.1
A.1
A.3
A.1.2
Level 72

49. Pop A.1 and Move to A.2 DTL: [A.1, A.2], pointer-1
DTL: [A, B], pointer-1
Level 64 A C
Source
A.1.2.x B
A.2
A.1.1
A.1
A.3
A.1.2
Level 72

50. Push Route through A.2 DTL: [A.2.2, A.2.1], pointer-2
DTL: [A, B], pointer-1
Level 64 A C B
A.2
A.2.1
A.1
A.3
A.2.2
A.2.3
Level 72
Level 96

51. Pop A.2 DTL: [A.1, A.2], pointer-2 DTL: [A, B], pointer-1 Level 64 A C

52. Pop A.2
DTL: [A, B], pointer-2
Level 64 A C B

53. Continue the Path Into B
Level 64 A C B
A.2
Level 80
Level 96
B.1
B.2
B.3
C.1
C.2
A.1
A.3
B.1.1
B.2.1
Level 72
B.1.2
B.2.3
B.2.2
B.3.2
B.1.3
A.2.1
B.3.1
B.3.3
Level 96
Level 96
B.3.4
A.2.2
A.2.3
B.3.5
A.1.1
A.3.2
Level 96
A.3.3
Level 104
A.1.2
A.3.4
A.3.1
Level 96
Level 96

54. Push DTLs Through B and B.1
DTL: [B.1.1, B.1.3], pointer-2
DTL: [B.1, B.2, B.3], pointer-1
DTL: [A, B], pointer-2
Level 64 A C B
Level 80
B.1.1
B.1
B.2
B.3
B.1.2
B.1.3
Level 96

55. The Path Continues through B.1
Level 64 A C B
A.2
Level 80
Level 96
B.1
B.2
B.3
C.1
C.2
A.1
A.3
B.1.1
B.2.1
Level 72
B.1.2
B.2.3
B.2.2
B.3.2
B.1.3
A.2.1
B.3.1
B.3.3
Level 96
Level 96
B.3.4
A.2.2
A.2.3
B.3.5
A.1.1
A.3.2
Level 96
A.3.3
Level 104
A.1.2
A.3.4
A.3.1
Level 96
Level 96

56. Pop B.1, Push Through B.2 DTL: [B.2.2, B.2.1, B.2.3], pointer-2
DTL: [A, B], pointer-2
Level 64 A C B
Level 80
B.1
B.2
B.3
B.2.1
B.2.3
B.2.2

57. Move to End of B.2 DTL: [B.2.2, B.2.1, B.2.3], pointer-2
DTL: [A, B], pointer-2
Level 64 A C B
Level 80
B.1
B.2
B.3
B.2.1
B.2.3
B.2.2

58. The Path Continues through B.2
Level 64 A C B
A.2
Level 80
Level 96
B.1
B.2
B.3
C.1
C.2
A.1
A.3
B.1.1
B.2.1
Level 72
B.1.2
B.2.3
B.2.2
B.3.2
B.1.3
A.2.1
B.3.1
B.3.3
Level 96
Level 96
B.3.4
A.2.2
A.2.3
B.3.5
A.1.1
A.3.2
Level 96
A.3.3
Level 104
A.1.2
A.3.4
A.3.1
Level 96
Level 96

59. Pop B.2, Push Through B.3 DTL: [B.3.4, B.3.1, B.3.3], pointer-2
DTL: [A, B], pointer-2
Level 64 A C B
B.3.2
B.3.1
Level 80
B.3.3
B.1
B.2
B.3
B.3.4
B.3.5
Level 104

60. Move to End of B.3 DTL: [B.3.4, B.3.1, B.3.3], pointer-2
DTL: [A, B], pointer-2
Level 64 A C B
B.3.2
B.3.1
Level 80
B.3.3
B.1
B.2
B.3
B.3.4
B.3.5
Level 104

61. Pop the Stack Pop B.3 Pop B At the destination
Now stack is empty and we are done.

62. Send back CONNECT message

63. The Path Is Established
Level 64 A C B
A.2
Level 80
Level 96
B.1
B.2
B.3
C.1
C.2
A.1
A.3
B.1.1
B.2.1
Level 72
B.1.2
B.2.3
Source
A.1.2.x
B.2.2
B.3.2
B.1.3
A.2.1
B.3.1
B.3.3
Level 96
Level 96
B.3.4
A.2.2
A.2.3
B.3.5
A.1.1
A.3.2
Level 96
A.3.3
Level 104
A.1.2
A.3.4
Destination
B.3.3.y
A.3.1
Level 96
Level 96