1. Wide Area Ethernet Services Using GELS Architecture Zartash Afzal Uzmi Department of Computer Science School of Science and Engineering Lahore University of Management Sciences (LUMS) Lahore, Pakistan

2. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS2 What we are going to talk about? Question –Is it feasible and/or better to use newly proposed GELS architecture instead of traditional (STP) solution? Given –A network of nodes and communication links Problem “Optimally” place traffic on the given network Options (1) use 25+ years old STP in the network (2) use a newly proposed GELS architecture

3. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS3 What is GELS? GMPLS control for Ethernet label switching Ethernet uses IEEE 802.3 data plane Control plane Current (old): STP and its variants Proposed: GMPLS (proposed by GELS!) To evaluate GELS, we need to understand: STP and its variants such as Rapid STP (RSTP) GMPLS (generalized MPLS!)

4. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS4 Tutorial Agenda PART-I Introduction to MPLS and MPLS Terminology Setting up a simulated MPLS network (Hands-on) PART-II Introduction to STP for Bridges PART-III GMPLS and the GELS Architecture Comparison of GELS with Rapid STP (Hands-on) PART-IV Restoration and Protection Routing with MPLS PART-V Comparison of GELS with RSTP (Hands-on)

5. PART-I Introduction to MPLS and MPLS Terminology Setting up a simulated MPLS Network

6. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS6 Outline Traditional IP Routing Forwarding and routing Problems with IP routing Motivations behind MPLS MPLS Terminology and Operation MPLS Label, LSR and LSP, LFIB Vs FIB Transport of an IP packet over MPLS More MPLS terminology

7. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS7 Outline Traditional IP Routing Forwarding and routing Problems with IP routing Motivations behind MPLS MPLS Terminology and Operation MPLS Label, LSR and LSP, LFIB Vs FIB Transport of an IP packet over MPLS More MPLS terminology

8. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS8 Forwarding and routing Forwarding: Passing a packet to the next hop router Routing: Computing the “best” path to the destination IP routing – includes routing and forwarding Each router makes the forwarding decision Each router makes the routing decision MPLS routing Only one router (source) makes the routing decision Intermediate routers make the forwarding decision

9. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS9 IP versus MPLS routing IP routing Each IP datagram is routed independently Routing and forwarding is destination-based Routers look at the destination addresses May lead to congestion in parts of the network MPLS routing A path is computed “in advance” and a “virtual circuit” is established from ingress to egress An MPLS path from ingress to egress node is called a label switched path (LSP)

10. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS10 How IP routing works Searching Longest Prefix Match in FIB (Too Slow)

11. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS11 Problems with IP routing Too slow IP lookup (longest prefix matching) “was” a major bottleneck in high performance routers This was made worse by the fact that IP forwarding requires complex lookup operation at every hop along the path Too rigid – no flexibility Routing decisions are destination-based Not scalable in some desirable applications When mapping IP traffic onto ATM

12. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS12 IP routing rigidity example Packet 1: Destination A Packet 2: Destination B S computes shortest paths to A and B; finds D as next hop Both packets will follow the same path Leads to IP hotspots! Solution? Try to divert the traffic onto alternate paths 11 12 A B C A B S D

13. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS13 IP routing rigidity example Increase the cost of link DA from 1 to 4 Traffic is diverted away from node D A new IP hotspot is created! Solution(?): Network Engineering Put more bandwidth where the traffic is! Leads to underutilized links; not suitable for large networks 14 12 A B C S A B D

14. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS14 Motivations behind MPLS Avoid [slow] IP lookup Led to the development of IP switching in 1996 Provide some scalability for IP over ATM Evolve routing functionality Control was too closely tied to forwarding Evolution of routing functionality led to some other benefits Explicit path routing Provision of service differentiation (QoS)

15. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS15 IP routing versus MPLS routing Traditional IP Routing Multiprotocol Label Switching (MPLS) SD 54 3 21 MPLS allows overriding shortest paths!

16. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS16 Outline Traditional IP Routing Forwarding and routing Problems with IP routing Motivations behind MPLS MPLS Terminology and Operation MPLS Label, LSR and LSP, LFIB Vs FIB Transport of an IP packet over MPLS More MPLS terminology

17. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS17 MPLS label To avoid IP lookup MPLS packets carry extra information called “Label” Packet forwarding decision is made using label-based lookups Labels have local significance only! How routing along explicit path works? IP DatagramLabel

18. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS18 Routing along explicit paths Idea: Let the source make the complete routing decision How is this accomplished? Let the ingress attach a label to the IP packet and let intermediate routers make forwarding decisions only On what basis should you choose different paths for different flows? Define some constraints and hope that the constraints will take “some” traffic away from the hotspot! Use CSPF instead of SPF (shortest path first)

19. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS19 Label, LSP and LSR Label Router that supports MPLS is known as label switching router (LSR) An “Edge” LSR is also known as LER (edge router) Path which is followed using labels is called LSP Label = 20 bits Exp = Experimental, 3 bits S = Bottom of stack, 1bit TTL = Time to live, 8 bits 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 Label | Exp|S| TTL

20. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS20 LFIB versus FIB Labels are searched in LFIB whereas normal IP Routing uses FIB to search longest prefix match for a destination IP address Why switching based on labels is faster? LFIB has fewer entries Routing table FIB has larger number of entries??? In LFIB, label is an exact match In FIB, IP is longest prefix match

21. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS21 Mpls Flow Progress LSR1 LSR2 LSR3 LSR5 LSR6 R1R2LSR4 D 1 - R1 receives a packet for destination D connected to R2 R1 and R2 are regular routers D destination

22. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS22 Mpls Flow Progress LSR1 LSR2 LSR3 LSR5 LSR6 R1R2LSR4 D 2 - R1 determines the next hop as LSR1 and forwards the packet (Makes a routing as well as a forwarding decision) D destination

23. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS23 Mpls Flow Progress LSR1 LSR2 LSR3 LSR5 LSR6 R1R2LSR4 D 3 – LSR1 establishes a path to LSR6 and “PUSHES” a label (Makes a routing as well as a forwarding decision) D destination 31

24. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS24 Mpls Flow Progress LSR1 LSR2 LSR3 LSR5 LSR6 R1R2LSR4 D 4 – LSR3 just looks at the incoming label LSR3 “SWAPS” with another label before forwarding D destination 17 Labels have local signifacance!

25. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS25 MPLS Flow Progress LSR1 LSR2 LSR3 LSR5 LSR6 R1R2LSR4 D 5 – LSR6 looks at the incoming label LSR6 “POPS” the label before forwarding to R2 D destination 17 Path within MPLS cloud is pre-established: LSP (label-switched path)

26. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS26 MPLS and explicit routing recap Who establishes the LSPs in advance? Ingress routers (usually!) How do ingress routers decide not to always take the shortest path? Ingress routers use CSPF (constrained shortest path first) instead of SPF Examples of constraints: Do not use links left with less than 7Mb/s bandwidth Do not use blue-colored links for this request Use a path with delay less than 130ms

27. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS27 CSPF What is the mechanism? (in typical cases!) First prune all links not fulfilling constrains Now find shortest path on the rest of the topology Requires some reservation mechanism Changing state of the network must also be recorded and propagated For example, ingress needs to know how much bandwidth is left on links The information is propagated by means of routing protocols and their extensions

28. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS28 More MPLS terminology 172.68.10/24 LSR1LSR2 UpstreamDownstream Data

29. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS29 Label advertisement Always downstream to upstream label advertisement and distribution 171.68.32/24 LSR1 LSR2 Use label 5 for destination 171.68.32/24 MPLS Data Packet with label 5 travels Upstream Downstream

30. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS30 Label advertisement Label advertisement can be downstream unsolicited or downstream on-demand 171.68.32/24 LSR1 LSR2 Sends label Without any Request Upstream Downstream 171.68.32/24 LSR1LSR2 Sends label ONLY after receiving request Request For label Upstream Downstream

31. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS31 Setting up a simulated MPLS Network Need a simulator TOTEM with additional modules Need a network Use famous European and NA networks Need a traffic matrix Bandwidth for input-output pairs Place traffic matrix on the network using TOTEM simulator!

32. PART-II Introduction to STP for Bridges

33. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS33 Transparent Bridging … Bridge For stations, the two topologies are the same  transparent bridging stations Ethernet LAN Segment

34. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS34 Transparent Bridge Functions Promiscuous Listening Every packet passed up to software Store and Forward Based on a forwarding database Filtering Also based on forwarding database

35. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS35 Example 1: Learning and Forwarding Transmission order A  D Ports 2, 3 D  A Port 1 Q  A Filtered Z  C Ports 1, 3 B Port 1 Port 2 Port 3 AQ ZC DM

36. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS36 Example 2: Two Bridges B1 Port 1Port 2 B2 Port 1Port 2 AQDMKT What are the Station Caches after “complete” learning?

37. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS37 Topologies with Loops Problems Frames proliferate Learning process unstable Multicast traffic loops forever B1B2B3 LAN 1 LAN 2 A

38. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS38 Spanning Tree Algorithm A distributed Algorithm Elects a single bridge to be the root bridge Calculates the distance of the shortest path from each bridge to the root bridge (cost) For each LAN segment, elects a “designated” bridge from among the bridges residing on that segment The designated bridge for a LAN segment is the one closest to the root bridge And…

39. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS39 Spanning Tree Algorithm For each bridge Selects ports to be included in spanning tree The ports selected are: The root port --- the port that gives the best path from this bridge to the root The designated ports --- ports connected to a segment on which this bridge is designated Ports included in the spanning tree are placed in the forwarding state All other ports are placed in the blocked state

40. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS40 Forwarding frames along the spanning tree Forward and Blocked States of Ports Data traffic (from various stations) is forwarded to and from the ports selected in the spanning tree Incoming data traffic is always discarded (this is different from filtering frames. Why?) and is never forwarded on the blocked ports

41. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS41 Root Selection: Bridge ID Each port on the Bridge has a unique LAN address just like any other LAN interface card Bridge ID is a single bridge-wide identifier that could be: A unique 48-bit address Perhaps the LAN address of one of its ports Root Bridge is the one with lowest Bridge ID B Port Address

42. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS42 Path Length (Cost) Path length is the number of hops from a bridge to the root While forming a spanning tree, we are interested in the least cost path to the root Cost can also be specified based on the speed of the link Not fair to treat a 10Mb/s link the same as a 1Gb/s link A guideline for cost selection is in Table 8.5 of the latest IEEE 802.1D standard

43. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS43 Example Topology 1 457 1068 112 0

44. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS44 After algorithm execution 1 457 1068 112 0 DP RP BP RP DP RP DP RP DP RP BP RP DP RP DP RP: Root Port DP: Designated Port BP: Blocked Port

45. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS45 The Spanning Tree 1 457 1068 112 0 DP RP BP RP DP RP DP RP DP RP BP RP DP RP DP RP: Root Port DP: Designated Port BP: Blocked Port

46. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS46 Setting up a simulated STP Network Need a simulator TOTEM with additional modules Need a network Use famous European networks Need a traffic matrix Bandwidth for input-output pairs Compromised CSPF algorithm Paths over a shared medium network

47. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS47 STP and wide area networks Traditionally, STP is used in Bridged Ethernet local area networks (LANs) Ethernet means two things: Physical and MAC layer standard (CSMA/CD) A frame format Use of Ethernet [from format] is becoming popular in wide area networks STP can be used in wide area networks to come up with a loop free network topology

48. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS48 Applying STP on a wide area network

49. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS49 Applying STP on a wide area network Things will work okay but we would like to do better!

50. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS50 Ethernet Dominant LAN transport technology Speed and reach grew substantially in the last 25 years Very flexible and cost-effective transport Ethernet is seeing increasing deployment in service provider networks

51. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS51 Ethernet in the core - challenges Existing control plane (STP) Network link utilization – Low Resilience mechanism – Slow Rudimentary support for QoS and TE Spanning tree computed Spanning tree recomputed Link failure

52. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS52 Ethernet in the Core Ethernet LANs use STP (or RSTP/MSTP) Use of STP in Core Network leads to challenges Can we use an alternate control plane? GELS Architecture For Core Networks, use GMPLS as the Ethernet control plane

53. PART-III GMPLS and the GELS Architecture Comparison of GELS with Rapid STP (Hands-on)

54. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS54 MPLS challenges Newer devices are capable of switching on the basis of: Interface (FSC) Wavelength (LSC) TDM timeslot MPLS works with packet switch devices only Looks at the label and forwards an incoming packet Solution: Generalize MPLS to GMPLS (RFC 3945) Incompatibility of MPLS with newer devices GMPLS offers a control plane for devices with ANY data plane

55. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS55 GMPLS: Introduction Extends MPLS to support non-packet based interfaces (like TDM, OTN, Ethernet etc.) Concept of LSP and label is generalized Such as timeslots as labels or layer 2 LSP Provides a unified control plane for various data planes

56. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS56 GMPLS: Supported Interfaces Packet Switch Capable Interfaces (PSC) Interfaces that recognize packet boundaries and forward data based on packet headers Example: IP GMPLS labels are based on packet header values

57. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS57 GMPLS: Supported Interfaces Layer-2 Switch Capable (L2SC) Interfaces Interfaces that recognize frame/cell boundaries and forward data based on frame/cell headers Examples: Ethernet, ATM GMPLS labels are based on frame/cell header values

58. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS58 GMPLS: Supported Interfaces Time Division Multiplex Capable (TDM) Interfaces Interfaces that switch data based on the data’s time slot Examples: SONET/SDH GMPLS labels are actual time slots

59. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS59 GMPLS: Supported Interfaces Lambda Switch Capable (LSC) Interfaces Interfaces that switch data based on the wavelength or waveband on which data is received Examples: Photonic Cross-Connect (PXC), Optical Cross- Connect (OXC) GMPLS labels are either wavelength (value of lambda), or (waveband id + lambda range)

60. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS60 GMPLS: Supported Interfaces Fiber Switch Capable (FSC) Interfaces Interfaces that switch data based on the physical media Examples: PXC and OXC that can operate at the level of single or multiple fibers GMPLS labels are actual fibers

61. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS61 GMPLS: Enhancements to MPLS GMPLS incorporates enhancements to MPLS including: Constraining Label Choices Out of Band Signaling Reducing Signaling Latency Link Management Protocol

62. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS62 Constraining Label Choices What is meant by constraining label choices? In MPLS, the upstream node requests a label and the downstream node assigns one from the available set of labels In GMPLS, the downstream node can be constrained to select a specific label or a label from a given label set Why constrain label choices? Some optical switches may not have the capability to switch wavelengths or may not prefer too much switching (wavelength conversion introduces distortion) Nodes may need to assign a specific label which is chosen by a centralized server

63. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS63 Constraining Label Choices Two ways of constraining label choices Label Set: Upstream node specifies a label set to the downstream node which selects a label from this set Explicit Label Set: A central node, having complete information about label assignments in network, can select labels on each link for each LSP; all nodes along the LSP have to assign the pre-selected labels

64. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS64 Out of Band Signaling Protocol Layers for data and control plane: In MPLS, IP is used for communicating data as well as control messages. Thus, data and control channels are at the same protocol layer In GMPLS, control messages are still communicated at IP layer, while the GMPLS supported forwarding (data) planes can be at lower layers Granularity of Layers Lower layers have coarse granularity e.g., thousands of MPLS LSPs traverse a single wavelength Assigning a separate wavelength or fiber for a single control channel may not be efficient

65. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS65 Out of Band Signaling In GMPLS out of band signaling is preferred due to: difference in control and data protocol layers possible wastage of resources if control channel uses the data plane at relatively lower layers Control channels use IP which may run over any transport such as ethernet etc. Process of identifying data and control paths for an LSP: First, we calculate the data path for an LSP request Then, we calculate the control path that traverses all nodes in the data path Since control channel topology may be different from the data topology, the data and control paths MAY be different

66. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS66 Out of Band Signaling Control path Data path Forward Reserve

67. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS67 Out of Band Signaling: Issues In in-band signaling, all nodes that receive the control message for resource reservation have to reserve resources on the same interface on which the control message is received However, in out of band signaling: If the node that receives the control message is not in the data path it should simply forward the message to the next control node. If the node is in the data path, it has to identify the data interface on which the reservation is required GMPLS handles the above issues through extensions in resource reservation protocols

68. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS68 Signaling Latency: Problem In MPLS/GMPLS, actual switching/label assignment decision is made during the return path of signaling request Configuring a IP/MPLS router for switching is not too time consuming However, configuring an OXC for switching requires extra time micro mirrors have to be adjusted subsequent wait time for the resulting movement vibrations to damp away

69. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS69 Reducing Signaling Latency Suggested Label Upstream node suggests a label to the downstream node It configures its switching based on this label Downstream node is not constrained to select this label but should prefer this assignment If another label is assigned by the downstream node, the configuration is done for the actual label Reduces signaling latency in general

70. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS70 Suggested label: Example Used labels 10 15 20 Used labels 11 16 21 Use label 11 Use label 12 12

71. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS71 GMPLS/MPLS with Ethernet GMPLS support for Ethernet Ethernet control plane is replaced by GMPLS control plane Ethernet over MPLS Ethernet frames are carried over an MPLS cloud, giving a virtual LAN type environment MPLS over Ethernet MPLS packets are carried over an Ethernet transport

72. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS72 GELS is in draft stages in IETF No quantitative performance comparison available so far Proposes to use GMPLS control plane for the Ethernet data plane! GELS Ethernet Bridge

73. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS73 GMPLS Support for Ethernet GMPLS control plane dictates the forwarding of ethernet frames Provides a connection oriented ethernet service Spanning tree protocols are replaced by GMPLS constraint based routing Allows traffic engineering and rerouting of ethernet connections.

74. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS74 GMPLS controlled Ethernet Label Switching (GELS) Architecture GMPLS enabled bridges in the core that switch the Ethernet frame based on a ‘label’ Bridges could be part of a multi-layer network --- nodes are called Ethernet Label Edge Routers (E-LER) and Ethernet Label Switched Routers (E-LSR) regardless of the type/number of layers Typical GELS layers: IP, Ethernet, and Lambda i.e. IP over Ethernet over Lambda E-LERs and E-LSRs need not have IP layer i.e. only have functionality of layer 2 and below

75. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS75 GELS- Architecture Ethernet Label Edge Router (E-LER) ingress or egress points of a GMPLS Ethernet network at the ingress: takes an incoming native frame, adds an Ethernet label, and forwards it to the appropriate label controlled interface at the egress: removes the label and forwards it to a non-label controlled interface Ethernet Label Switched Router (E-LSR) takes an incoming labeled ethernet frame and forwards the frame to the appropriate label controlled interface

76. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS76 E-LER and E-LSR functionality Ethernet E-LER E-LSR

77. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS77 Services offered by GELS Metro Ethernet Forum has defined two service types: Ethernet Line Service (ELS) and Ethernet LAN Service (E-LAN) ELS Point to Point Ethernet Service Similar to Frame Relay or ATM Virtual Circuit E-LAN Multipoint to Multipoint Ethernet Service (like a normal Ethernet LAN) A new site automatically gains access to all previously existing sites

78. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS78 ELS and E-LAN Initial scope of GELS is limited to Point to Point Ethernet LSPs

79. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS79 GELS --- Choice of Label The selection of label has been the most controversial issue in GELS --- still no consensus What are the considerations? Label should not require changes in data plane IETF’s role is restricted to GMPLS which mandates changes in control plane ONLY Any change in data plane is unlikely to be supported by IEEE. The label should allow large number of nodes to be addressed i.e., label space should be sufficient It should allow co-working of 802.1 bridges having VLAN capability with GMPLS enabled Ethernet Routers Should be scalable --- the forwarding table entries and changes to OSPF-TE and RSVP-TE should be manageable

80. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS80 Label Options: VLAN ID VLAN ID can be used as a label with MAC learning switched off This ensures that switching is done on the basis of VLAN id Pros Doesn’t require changes in Data Plane Cons VLAN id cannot be used within LANs --- their functionality would be lost Limited label space --- 12 bits

81. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS81 Label Options: VLAN ID (Q in Q) Stack VLAN ids: use separate VLAN ids for metro/core while preserving the ids used in individual LANs Example: Cisco’s Q in Q (used for metro Ethernet but doesn’t use GMPLS control plane) Pros VLAN functionality is not lost Cons Requires modification in data plane since stacking of VLAN ids is not supported

82. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS82 Label Options: MPLS shim label Already defined in MPLS to be used with Ethernet as layer 2 technology Pros Doesn’t require changes in data plane Cons Doesn’t work at the Ethernet level (layer 2) --- works at MPLS layer which means that MPLS/IP layer functionality has to be added to ethernet switches. Then why not use ethernet over MPLS?

83. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS83 Label Options: Use of proprietary MAC addresses Use different/proprietary MAC addresses for forwarding in the GMPLS core First three bytes of MAC address are the Organizational Unit Identifier (OUI) Reserve OUI for use in GELS Pros Large label space No changes required in E-LSR Cons MAC address has to be overwritten at the E-LER, thereby requiring change in the data plane

84. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS84 Label Options: Use of new tag protocol identifier (tpid) First two bytes of Q-tag are tpid e.g, value of 0x8100 in the first two bytes indicate a (C-)VLAN in the next two bytes idea is to use a different tpid for the GMPLS label Acreo have built a tpid based solution for GELS Pros Large label space (2 bytes) Cons Require changes in data plane

85. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS85 Label Options: Use of MAC address + VLAN id Use a combination of Destination MAC address + VLAN id as the label Pros Large label space Cons Require changes in data plane Labels cannot be link local

86. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS86 GELS: Future Work Need a consensus on the choice of label Evaluate the several proposals that have been made already and possibly some new ones as well Based on the choice of label and other GELS requirement, design appropriate extensions to OSPF-TE and RSVP-TE Design a mechanism to interoperate traditional MAC learning/flooding with GMPLS based control plane

87. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS87 GELS Evaluation Simulation based evaluation of GELS Rapid STP (RSTP) versus GMPLS How does old control plane compare with new control plane? Considered: 1. Normal network operation 2. Single element failures

88. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS88 Methodology Develop software tools for: (1) simulating GELS architecture (2) simulating traditional solution Consider a well known network (e.g., European COST266) Compare old and new solutions (STP vs. GELS) Network behaves normally Portion of Network fails Which solution places more traffic on the network? Which solution recovers faster from the failure? Compare results STP vs. GELS Approach for Evaluation of GELS

89. PART-IV Restoration and Protection with MPLS

90. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS90 IP versus MPLS (recall) In IP Routing, each router makes its own routing and forwarding decisions In MPLS: source router makes the routing decision Intermediate routers make forwarding decisions A path is computed and a “virtual circuit” is established from ingress router to egress router An MPLS path or virtual circuit from source to destination is called an LSP (label switched path)

91. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS91 Protection and Restoration Restoration On-demand recovery – no preset backup paths Example: existing recovery in IP networks Protection Pre-determined recovery – backup paths “in advance” Primary and backup are provisioned at the same time IP supports restoration Because it is datagram service MPLS supports restoration as well as protection Because it is virtual-circuit service

92. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS92 Restoration in IP network In traditional IP, what happens when a link or node fails? Failure information needs to be disseminated in the network During this time, packets may go in loops Restoration latency is in the order of seconds We look for protection possibilities in an MPLS network, but… First we need to look at the QoS requirements

93. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS93 QoS Requirements Bandwidth Guaranteed Primary Paths Bandwidth Guaranteed Backup Paths BW remains provisioned in case of network failure Minimal “Protection or Restoration Latency” Protection/Restoration latency is the time that elapses between: “the occurrence of a failure”, and “the diversion of network traffic on a new path” Restoration is generally SLOWER than protection

94. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS94 Protection in MPLS First we define Protection level Path protection Also called end-to-end protection For each primary LSP, a node-disjoint backup LSP is set up Upon failure, ingress node diverts traffic on the backup path Local Protection Upon failure, node immediately upstream the failed element diverts the traffic on a “local” backup path Path Protection  More Latency Local Protection  Less Latency

95. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS95 Protection in MPLS S123D Primary Path Backup Path Path Protection This type of “path Protection” still takes 100s of ms. We may explore “Local Protection” to quickly switch onto backup paths!

96. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS96 Local Protection: Fault Models ABCD Link Protection ABCD ABCD Node Protection Element Protection

97. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS97 Reliability in Core Networks In Core Networks, we can use GELS with: Protection, or Restoration With this background on network recovery, we are now ready to compare STP with the GMPLS control plane

98. PART-V Comparison of GELS with RSTP (Hands-on)

99. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS99 GELS Evaluation Simulation based evaluation of GELS Rapid STP (RSTP) versus GMPLS How does old control plane compare with new control plane? Considered: 1. Normal network operation 2. Single element failures

100. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS100 Evaluation Criteria Evaluation criteria Normal network condition Failed network condition Total bandwidth placed Number of LSPs placed Average link utilization Single link failure Single node failure RSTP convergence time GELS recovery Restoratio n Protection GELS recovery schemes How efficiently can we use the network? How quickly can we recover from failure?

101. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS101 GMPLS with Compromised CSPF Evaluation challenges How to compare contention-based Ethernet with reservation based GMPLS? Allow partial placement of LSPs in GMPLS instead of YES/NO placement Request: 25 Placed: 0 GMPLS with CSPF Placed: 15 LSP placed Bandwidth placed: 60% LSP not placed Bandwidth placed: 0% Capacit y: 100 Available: 15 Available : 0

102. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS102 Switch traffic onto new LSP t sw : Switching delay GELS: Convergence time Link failure Failure notification sent to ingress t sig : Signaling delay Compute new LSP t proc : Processing delay Potential new path Reserve new LSP t res : Reservation delay Ingres s Egres s LSP Restoration: t rest = t sig + t proc + t res + t sw Protection: t prot = t sig + t sw Nearest upstream node to the failure

103. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS103 Timing parameter values t sig (Signaling delay): Based on 1ms/200 km link propagation delay t proc (Processing delay): 5ms t res (Reservation delay): Based on 1ms/200 km link propagation delay t sw (Switching delay): 1ms

104. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS104 GELS restoration recovery time LSP 1 LSP 2 Ingress has lost multiple LSPs Nearest upstream node for LSP 2 Nearest upstream node for LSP 1 Failure signaled to ingress Link failure 1.Compute 2.Reserve 3.Switch Sequentially Or In parallel Sequentially Convergence time is t min Convergence time is t max

105. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS105 GELS Centralized restoration Some deployments may use centralized instead of distributed failure recovery A central server handles restoration of LSPs affected by a failure Two options: Path Computation Element (PCE) Network Management System (NMS)

106. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS106 Path Computation Element (PCE) PCE is an entity responsible for path computation on request from a Path Computation Client (PCC) It could be a node or a process PCE may or may not reside on the same node as the PCC PCE PCC Node A PCC Node B PCE Node C

107. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS107 Path Computation Element (PCE) PCC sends a targeted request to a PCE PCC may not broadcast a request The PCE may compute the end-to-end path itself A PCE may cooperate with other PCEs to determine intermediate loose hops PCCPCE

108. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS108 Our PCE scenario A single central PCE server for the routing domain Nearest upstream node to the point of failure sends restoration request to PCE upon a failure event PCE computes the new path and sends this path to the ingress Ingress reserves the new LSP Ingress switches traffic onto new LSP

109. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS109 Switch traffic onto new LSP t sw : Switching delay GELS centralized restoration: PCE Link failure Failure notification sent to PCE t sig 1 : Signaling delay Potential new path Reserve new LSP t res : Reservation delay Ingres s Egres s LSP Restoration: t rest = t sig 1 + t proc + t sig 2 + t res + t sw Nearest upstream node to the failure PCE Compute new LSP t proc : Processing delay Notify the ingress of the new path t sig 2: signaling delay

110. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS110 GELS restoration: PCE Central PCEs are typically high end multiprocessor platforms Router platforms are not as fast as central PCEs Centralized PCEs should be able to compute paths more quickly than routers Centralized PCEs should also be able to perform multiple path computations simultaneously

111. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS111 GELS restoration: NMS NMS is also a centralized restoration scenario Here, the central server performs path computation as well as reservation It may use SNMP for path reservation Once path has been reserved, the ingress is notified Ingress switches traffic onto new LSP

112. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS112 Switch traffic onto new LSP t sw : Switching delay GELS centralized restoration: NMS Link failure Failure notification sent to NMS t sig 1 : Signaling delay Potential new path Ingres s Egres s LSP Restoration: t rest = t sig 1 + t proc + t sig 2 + t res + t sw Nearest upstream node to the failure NMS Compute new LSP t proc : Processing delay Reserve resources along the new path t sig 2: signaling delay Notify the ingress of the new LSP

113. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS113 Timing parameter values t sig (Signaling delay): Based on 1ms/200 km link propagation delay t proc (Processing delay): 1ms t res (Reservation delay): Based on 1ms/200 km link propagation delay t sw (Switching delay): 1ms

114. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS114 Simulation setup - networks Milan (11) Copenhagen (1) London (2)Amsterdam (3)Berlin (4) Brussels (5)Luxembourg (6)Prague (7) Paris (8)Zurich (9)Vienna (10) COST 239: 11 nodesCOST 266: 50 nodes

115. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS115 Traffic matrices LSP requests arrive one-by-one Randomly chosen ingress and egress nodes Bandwidth request 1, 2 or 3 Gb/s chosen with equal probability

116. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS116 Simulation environment Based on: Bridgesim 1 for native Ethernet TOTEM 2 for GMPLS-controlled Ethernet Enhancements to simulators: Implementation of C-CSPF Computation of recovery time 1: http://www.cs.cmu.edu/~acm/bridgesim/index.html 2: http://totem.info.ucl.ac.be/

117. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS117 A famous European network (COST266) How much traffic can be placed?

118. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS118 Black links indicate no traffic! Results: Using old solution (STP)

119. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS119 There are no black links! Results: Using new solution (GELS)

120. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS120 Comparison Graph: Taken from IEEE Globecom 2007 paper Comparative Performance

121. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS121 Results: LSP placement percentage GELS with restoration places more LSPs than RSTP GELS with protection places fewer LSPs than RSTP

122. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS122 Results: Bandwidth placement GELS with protection places less (primary) bandwidth than RSTP GELS with restoration places more bandwidth than RSTP

123. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS123 Results: Average link utilization RSTP has lowest average link utilization GELS with protection quickly approaches almost full link utilization GELS approaches 92% average link utilization

124. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS124 Results: RSTP convergence time vs cost to root RSTP convergence time is highest if the root bridge fails Convergence time decreases as cost to root increases

125. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS125 Single link failure average convergence time TopologyRSTP (ms) Restoration (ms) PCE (ms) NMS (ms) Protection (ms) t min t max t min t max t min t max 11 nodes0.732.6741.6123.5381.7529.3699.683.89 50 nodes102.438.1339.6139.1464.6552.498.316.18 Results: Single link failure convergence time More links closer to root bridge in COST 266 More LSPs were restored in COST 239

126. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS126 Single link failure average convergence time TopologyRSTP (ms) Restoration (ms) PCE (ms) NMS (ms) Protection (ms) t min t max t min t max T min t max 11 nodes485030.0739.3422.2162.3429.8195.252.56 50 nodes336542.2544.2437.4176.1352.73111.836.1 Results: Node failure convergence time t 1 - t 10 are in milliseconds t 1 – t 49 are in milliseconds 50+ 11 Small value 50+ 50 Small value

127. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS127 Summary About 45% improvement with GELS over native Ethernet in: LSP acceptance Bandwidth placement Failure recovery time orders of magnitude less for GELS than for native Ethernet

128. March 30, 2008AICCSA 2008: Wide Area Ethernet Services Using GELS128 Conclusion Ethernet is a flexible, cost effective and efficient transport mechanism for metro/core networks GMPLS promises to be a useful control plane for Ethernet in metro/core Tremendous administrative benefits of using a single control plane Vendors actively working on standardization of GELS