1 ISTANBUL 1.1 MPLS overview 1
1.1.1 Principle Use of a ATM core network 2 Overlay Network One Virtual Circuit per communication No routing protocol Scalability problem 2
1.1.1 Principle Weakness of overlay model Overlay Network Drawbacks 3 200 routers ISP core network 20,000 PVC s!!! 3
1.1.1 Principle Peer model Tunnels built between Edge routers 4 4
1.1.1 Principle router vs. ATM switch 5 ATM cell overhead approximately 20% of bandwidth 2.5Gb/s link wastes 498 Mbps in ATM cell overhead Current generation of routers have High speed, wire-rate interfaces Deterministic performance Software advances 5
1.1.1 Principle router vs. ATM switch 6 Solution MPLS Fuse best aspects of ATM PVCs with highperformance routing engines : Use low-overhead circuit mechanism Automate path selection and configuration Implement quick failure recovery 6
1.6.4 MPLS summary Other driving factor of MPLS 7 Offers scalability advantages Supports QoS Brodacast TV Vo Streaming Audio/video video conference MPLS network Allows Traffic Engineering Provides VPN services N.Y Best effort MPLS High priority data traffic Paris Voice traffic 7
1.1.1 Principle Classical routing 8 Dest. 47.1.0.0/16 47.2.0.0/16 47.3.0.0/16 Next Hop R4 R4 R1 if 1 1 3 3 R2 2 1 3 Dest. 47.1.0.0/16 47.2.0.0/16 47.3.0.0/16 R4 Next Hop -- R5 R1 2 1 if 1 2 3 47.1.0.0/16 47.3.0.0/16 3 R1 1 2 R3 R5 47.2.0.0/16 Dest. 47.1.0.0/16 47.2.0.0/16 47.3.0.0/16 Next Hop R2 R3 if 1 2 3 R6 R7 8
1.1.1 Principle Routing table scanning 9 Prefix Next Hop 192.168.0.0/16 R4 192.168.1.17 194.1.0.0 /16 194.1.16.0 /20 R1 R2 192.168.1.0/24 R3 Choice of the longest prefix Full scan of the routing table 9
1.1.1 Principle packet processing 10 1 47.1.2.3 Dest. Next Hop if 47.3.0.0/16 R1 3 47.2.0.0/16 R4 1 47.1.0.0/16 R4 1 3 4 R2 2 1 5 6 Dest. Next if Hop 47.3.0.0/16 R1 3 47.1.2.3 47.2.0.0/16 R5 2 47.1.0.0/16 -- 7 1 3 R4 2 1 47.1.0.0/16 47.3.0.0/16 3 R1 1 2 3 R3 R5 47.2.0.0/16 2 Dest. Next Hop if 47.3.0.0/16 3 47.2.0.0/16 R3 2 47.1.0.0/16 R2 1 R6 R7 10
1.1.1 Principle The solution : MPLS 11 Current problems : Backbone routing tables are increasing continuously (1994: 15,000 entries; 1998 : 50,000; 2003: 100,000; 2005 : 120,000) Level 3 prefix analysis request high processing capacity Solutions Replace these routing table by simple index searching Perform this process at the level 2 MPLS does not replace classical routing but optimizes it MPLS : Multiprotocol Label Switching 11
1.1.1 Principle Principle of the Label switching» 12 Switching Table In (port, label) Out (port, label) (1, 22) (2, 17) (1, 24) (3, 17) Data packet s: 154.1.2.3 d: 86.6.7.8 Label 25 (1, 25) (2, 23) (4, 19) (3, 12) Port 1 Port 2 packet Label Data s: 154.1.2.3 d: 86.6.7.8 19 Port 3 Port 4 12
1.1.1 Principle MPLS location 13 7 to 5 Applications 4 TCP UDP 3 2 MPLS Routing Table Destination Next Hop 134.5.0.0/16 200.5.1.5 134.5.1.0/24 200.2.3.4 MPLS Table In Out (2, 84) (2, 85) (4,12) (3, 99) PPP Ethernet Frame Relay ATM 1 Physical (Optical Electrical) 13
14 1.1.2 Definitions 14
1.1.2 Definitions : Label Switch Router 15 MPLS network Routing Label switching Routing Routeur Label Switching Routeur 15
1.1.2 Definitions LER : Label Edge Router 16 Transit processing traffic within the MPLS domain Forwards MPLS packets using label swapping (label swap) Ingress LER MPLS network LER Egress LER : Label Edge Router processing traffic as it enters the MPLS domain : examines inbound packets classifies packet for QoS Assigns initial label (label push) LER : Label Edge Router processing traffic as it leaves the MPLS domain: Removes label (label pop) 16
1.1.2 Definitions LSP : Label Switched Path 17 LSP Label : 21 Label : 56 LER MPLS network Label : 3 LER 17
1.1.2 Definitions Principle of FEC (Forward Equivalence Class) 18 1 A FEC may be a group of destination addresses using same LSP LER LER LSP 2 1 23 6 6 14 1 2 223 123 2 6 1 6 214 114 2 18
1.1.2 Definitions Flow aggregation LSP 19 FEC FEC Ingress Routing Table Destination Label 134.5.0.0/16 9 200.3.2.0/24 56.42.1.0/24 9 9 123.2.0.0/16 5 10.8.128.0/20 5 LER Aggregation can also be done : By protocol By application (destination port) By traffic priority By source address Label : 9 Label : 5 MPLS network LSP Label : 43 Label : 56 Label : 8 FEC : Forward Equivalence Class Label : 3 LER Label : 15 19
20 1.1.3 Labels 20
1.1.3 Labels MPLS Forwarding Example 21 Ingress Routing Table Destination Next Hop 134.5.0.0/16 LSP3 200.3.2.0/24 LSP5 MPLS Table Dest Proc Out LSP3 Push2, 84 LSP5 Push 3, 99 1 134.5.1.5 200.3.2.7 3 200.3.2.7 2 134.5.1.5 2 3 99 4 84 LSP5 5 LSP3 1 2 MPLS Table In Proc Out 2, 84 Swap 6, 3 2 6 200.3.2.7 56 134.5.1.5 3 5 6 3 1 2 200.3.2.7 134.5.6.1 9 134.5.1.5 3 200.3.1.1 134.5.1.5 Ingress Routing Table Destination Next Hop 134.5.0.0/16 134.5.6.1 200.3.2.0/24 200.3.1.1 MPLS Table In Proc Out 1, 3 Pop -- 7 2, 3 Pop -- 200.3.2.7 8 MPLS Table In Proc Out MPLS Table In Proc Out 1,99 Swap 2,56 3,56 Swap 5,3 200.3.2.7 21
1.1.3 Labels Types of labels ATM cell 22 ATM VPI/VCI Payload ATM header (5 Bytes) FR frame Frame-Relay DLCI Payload F-R header (2 Bytes) Eth MAC@ dest MAC@ src Ethernet header (14 Bytes) Ethertype 0x8847 Label Shim 4bytes header Payload FCS (4 Bytes) PPP Addr Ctl Prot 0x0281 PPP header (4 Bytes) Label shim Payload FCS (2 Bytes) 22
1.1.3 Labels MPLS shim label 23 1 2 3 4 5 6 7 8 bit Label (20 bits) EXP S TTL Time To Live Experimental use bottom of stack (explained in the following diagrams) 23
24 1.6.4 MPLS summary 24
1.6.4 MPLS summary MPLS reduces carrier operations costs 25 25
1.6.4 MPLS summary Other driving factor of MPLS 26 Offers scalability advantages Supports QoS Brodacast TV Vo Streaming Audio/video video conference MPLS network Allows Traffic Engineering Provides VPN services N.Y Best effort MPLS High priority data traffic Paris Voice traffic 26
27 1.6.1 VPN overview 27
1.6.1 VPN overview What is a VPN 28 Private Net. NetID: 10.10.10.0 @ : 10.10.10.8 Private Network Leased line @ : 10.10.20.4 Private Net NetID: 10.10.20.0 Private Net. NetID: 10.10.10.0 @ : 10.10.10.8 Virtual Private Network Tunneling Internet @ : 10.10.20.4 Private Net NetID: 10.10.20.0 28
1.6.1 VPN overview Overlay model 29 Overlay Model (or -to-) VPN Blue Site X (Hub) Typically Frame Relay or ATM VPN Red Site A VPN Red Site A VPN Blue Site Y (Spoke) VPN Red Site A VPN Blue Site Y (Spoke) VPN Blue Site Y (Spoke) : Customer Edge 29
1.6.1 VPN overview Example of overlay model at Layer 1 Layer 1 -based VPNs 30 PPP routing adjacency PPP SDH SDH SDH SDH Customer premises Access network Service Provider backbone Access network Customer premises 30
1.6.1 VPN overview Examples of overlay model at Layer 2 31 AAL5 ATM ATM Layer 2 -based VPNs ATM ATM ATM network ATM ATM ATM AAL5 ATM PPP PPP TP Tunnel : TP TP UDP network UDP 31
1.6.1 VPN overview Example of overlay model at Layer 3 Layer 3 -based VPNs routing adjacency 32 sec sec tunnel sec network Customer premises Access network Service Provider backbone Access network Customer premises 32
1.6.1 VPN overview Weakness of overlay model Overlay Network Drawbacks 33 200 routers 20,000 PVC s!!! 33
1.6.1 VPN overview Peer model 34 Peer model or -based VPNs VPN Blue Site X (Hub) Tunnels built from to Only one LSP between s Label Stack for VPN linked to VPN Red Site A VPN Red Site A VPN Blue Site Y (Spoke) VPN Blue Site Y (Spoke) VPN Red Site A VPN Blue Site Y (Spoke) 34
1.6.1 VPN overview Example of Peer model at Layer 2 35 Layer 2 -based VPNs routing adjacency Bridging Layer2 logical connection MPLS Tunnel (LSP) MPLS network MPLS Layer2 logical connection Customer premises Access network Service Provider backbone Access network Customer premises Layer 2 : PPP, FR, ATM, Ethernet, 35
1.6.1 VPN overview Example of Peer model at Layer 3 Layer 3 -based VPNs 36 M-BGP routing adjacency MPLS Tunnel (LSP) MPLS network MPLS routing adjacency Customer premises Access network Service Provider backbone Access network Customer premises Layer 3 : 36
1.6.1 VPN overview MPLS VPN topologies 37 VPN Layer 2 Layer 3 Overlay (-based) MPLS (-based) MPLS (-based) Overlay (-based) Ethernet ATM FR TP Pseudo Wire VPLS VPWS RFC 2547bis sec GRE / 37