CCIE R&S Techtorial MPLS

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CCIE R&S Techtorial MPLS Ing. Tomáš Kelemen Partner Systems Engineer CCIE #24395 Ing.

2 Agenda Introduction to MPLS What is MPLS? Why it was developed? How MPLS works What are priciples of MPLS? What are uses of MPLS? MPLS in action Q&A Basic MPLS L3 VPN config MPLS L3 VPN verification 2011 Cisco Systems, Inc. All rights reserved. 2

4 What Is MPLS? Multi Protocol Label Switching is a technology to deliver IP services - MPLS enables network services such as VPN and traffic engineering Forwarding of data packets is via labels MPLS enabled routers do not look into IP header to forward packets MPLS is known as OSI layer 2.5 Label info is inserted between Data link and Network layer and this is sometimes called shim header Ethernet MPLS IP Data MPLS works over most Layer 2 technologies such as ATM, FR, PPP, POS, Ethernet 2011 Cisco Systems, Inc. All rights reserved. 4

5 Why it was developed? Network infrastructure convergence MPLS enabled network allows to carry different kind of traffic (IPv4, IPv6, Layer2 frames) across single network infrastructure No need to have BGP enabled on all routers Very important for scaling lare networks because MPLS forwarding is done via labels, we do not need to keep all destination IP addresses in routing tables CE BGP session P P CE MPLS network CE P P CE BGP session 2011 Cisco Systems, Inc. All rights reserved. 5

6 Why it was developed? New approach to VPN technologies Allows use of overlapping IPv4 address space Allows optimal traffic flow CE CE routing peering ATM/FR VC routing peering routing peering CE CE Traditional ATM/FR VPN CE MPLS VPN CE 2011 Cisco Systems, Inc. All rights reserved. 6

7 Why it was developed? Traffic engineering Preffered path is least cost path determined by IGP Basic idea is to use links in network infrastructure efficiently MPLS needs to be able to provide mechanism to divert traffic to other links beside preffered path Preffered, least cost path MPLS network with TE enabled Traffic engineered path 2011 Cisco Systems, Inc. All rights reserved. 7

9 What are principles of MPLS? Main building stones of MPLS: Label 32bit value inserted between Layer 2 and Layer Label 20bits EXP S TTL-8bits COS/EXP = Class of Service: 3 Bits; S = Bottom of Stack; TTL = Time to Live LSR Label Switch Router (eg., P) LSP Label Switched Path IGP Interior Gateway Protocol LDP Label Distribution Protocol LIB, LFIB Label Information Base, Label Forwarding Information Base MP-BGP, RSVP Protocols for MPLS VPN and MPLS TE 2011 Cisco Systems, Inc. All rights reserved. 9

10 What are principles of MPLS? Life of a packet in MPLS network: 2. Core LSR label swapping 1. Ingress LSR label imposition P LSP P 3. Egress LSR label disposition CE CE P P Egress LSR not always performs label disposition - PHP (Penultimate Hop Popping) signaled via implicit null label (LDP advertising MPLS label of value three) 2011 Cisco Systems, Inc. All rights reserved. 10

11 What are principles of MPLS? Assigning and distributing MPLS labels Each LSR needs to run IGP to learn IP prefixes (eg. neighbor loopbacks, BGP next hops) Each LSR then forms LDP neighborship between its directly connected LSR Once LDP neighborship is formed, each LSR uses LDP to assign labels to IP prefixes it knows about each LSR does this independently and advertises its labels to its LDP neighbors LDP is standards based RFC 3035 and RFC 3036 LDP uses UDP for session discovery (port 646 and destination IP ) LDP uses TCP (port 646 and destination IP of its LDP peer) for rest of the messages (label advertisement, label withdrawal, session maintenance, session teardown) 2011 Cisco Systems, Inc. All rights reserved. 11

12 What are principles of MPLS? Forwarding MPLS packets which label to use? RIB stores IP prefixes, LIB stores MPLS labels LFIB is created from both RIB and LIB and used to forward MPLS tagged packets Example for LSR in bottom picture: - RIB has /32 learned via IGP over e0/0 interface - LIB has label L for prefix /32 learned from its LDP peer - LFIB has: to forward packet to /32, use label L and send packet using peer LDP nexthop over e0/0 interface e0/ /32 LSR 2011 Cisco Systems, Inc. All rights reserved. 12

13 What are uses of MPLS? Label stacking Labeling does not make forwarding of packets faster Label stacking is the primary use of MPLS that enables use of MPLS L2 and L3 VPNs, traffic engineering and other services Most used examples of label stacking: - 2 labels for MPLS VPN bottom label indicates which VPN this packet belongs to, outer is used by core LSRs for packet forwarding - 3 labels for MPLS TE the most upper label is used to indicate which TE tunnel to forward this packet Outer Label TE Label LDP Label VPN Label Inner Label IP Header 2011 Cisco Systems, Inc. All rights reserved. 13

14 What are uses of MPLS? Use of MPLS to build Layer 3 VPN MPLS VPN is set of sites that communicate with each other these sites can be connected to MPLS infrastructure at various routers LSR acts as aggregation router in MPLS VPN each site is identified by its own VRF (Virtual Routing and Forwarding) instance, which is logically separated and by default communication between VRF is not allowed Each router assigns distinct MPLS label for each VRF it communicates with other routers this label is not assigned by LDP, but by MP-BGP, and is used to know which VRF site remote needs to send packet to VPN RED MPLS network VPN BLUE VPN GREEN 2011 Cisco Systems, Inc. All rights reserved. 14

15 What are uses of MPLS? Use of MPLS to build Layer 3 VPN RD (Route Distinguisher) is attached to each IP prefix exchanged in VPN to make them unique RD + prefix = VPN prefix RD allows to use overlapping IP addresses among VPNs RD length is 64 bits and is in formant X:Y, where X is usually Autonomous System Number or IP address usually one RD is assigned per one customer RT (Route Target) governs which VPN prefixes are allowed to be imported or exported out of particular VPN Using RT you create intranet or extranet - Intranet different sites of same VPN can communicate - Extranet different sites of different VPNs can communicate In order to bring L3 VPN into life, you need to exchange both RD and RT this is done by MP-BGP 2011 Cisco Systems, Inc. All rights reserved. 15

16 What are uses of MPLS? MPLS Layer 3 VPN Intranet for customer in VPN RED ip vrf RED rd 100:1 route-target export 1:1 route-target import 1:1 ip vrf RED rd 100:1 route-target export 1:1 route-target import 1:1 VPN RED MPLS network VPN BLUE VPN GREEN ip vrf RED rd 100:1 route-target export 1:1 route-target import 1: Cisco Systems, Inc. All rights reserved. 16

17 What are uses of MPLS? MPLS Layer 3 VPN Intranet for customer in VPN GREEN ip vrf GREEN rd 100:2 route-target export 2:1 route-target import 2:1 ip vrf GREEN rd 100:2 route-target export 2:1 route-target import 2:1 VPN RED MPLS network VPN BLUE VPN GREEN ip vrf GREEN rd 100:2 route-target export 2:1 route-target import 2: Cisco Systems, Inc. All rights reserved. 17

18 What are uses of MPLS? MPLS Layer 3 VPN Intranet for customer in VPN BLUE ip vrf BLUE rd 100:3 route-target export 3:1 route-target import 3:1 VPN RED MPLS network VPN BLUE VPN GREEN ip vrf BLUE rd 100:3 route-target export 3:1 route-target import 3:1 ip vrf BLUE rd 100:3 route-target export 3:1 route-target import 3: Cisco Systems, Inc. All rights reserved. 18

19 What are uses of MPLS? MPLS Layer 3 VPN Extranet between customer VPN RED and VPN BLUE ip vrf RED rd 100:1 route-target export 1:1 route-target import 1:1 route-target import 3:1 VPN RED MPLS network VPN BLUE VPN GREEN ip vrf BLUE rd 100:3 route-target export 3:1 route-target import 3:1 route-target import 1: Cisco Systems, Inc. All rights reserved. 19

20 What are uses of MPLS? Exchanging RD, RT and VPN label over MPLS network Each router forms ibgp session with other router Over this ibgp sessions, routers exchange VPN prefixes Each VPN prefix is exchanged with its associated RT and VPN label RT is for importing routes into VRF RIB, VPN label is for actual packet forwarding MPLS network 2011 Cisco Systems, Inc. All rights reserved. 20

21 What are uses of MPLS? Packet forwarding with MPLS Layer 3 VPN IGP label is assigned by LDP VPN label is assigned by MP-BGP IP IGP VPN IP IGP VPN IP VPN IP IP Site 1 of VPN BLUE 1 P1 P2 2 Site 2 of VPN BLUE 1.) 1 receives IP packet on VRF interface assigned to site 1 of VPN BLUE. 2.) 1 looks up VPN and IGP label, imposes this label stack to IP packet and forwards it to MPLS network. IGP label is known based on ibgp next hop, which is IP address of 2. 3.) P1 router swaps IGP label based on its LFIB table. 4.) P2 removes IGP label due to PHP, but does not touch VPN label. 5.) 2 router receives IP packet with VPN label, which it uses to select correct outgoing VPN site 6.) 2 then strips off VPN label, makes lookup in its VRF RIB for particular VPN site to get the outgoing interface to send received packet to Cisco Systems, Inc. All rights reserved. 21

24 MPLS demo lab topology Site 1 of VPN RED s2/0 s2/0 Site 2 of VPN RED s2/0 s2/0 Site 1 of VPN BLUE s3/0 s3/0 e0/0 e0/0 e1/0 e1/0 1 P1 P2 e0/0 e0/0 2 s3/0 s3/0 Site 2 of VPN BLUE - VPN Red site 1 s2/0: /30 lo0: /24-1 s2/0: /30 s3/0: /30 e0/0: /24 - P1 e0/0: /24 e1/0: /24 lo0: /32 - VPN Blue site 1 s3/0: /30 lo0: /24 lo0: /32 - P2 e0/0: /24 e1/0: /24 lo0: / VPN Red site 2 s2/0: /30 s2/0: /30 s3/0: /30 lo0: /24 e0/0: /24 lo0: /32 - VPN Blue site 1 s3/0: /30 lo0: / Cisco Systems, Inc. All rights reserved. 24

26 Basic MPLS L3 VPN config 1.) Configuring core LSR for MPLS switching P1(config)#mpls ldp router-id loop0 P1(config)#int e0/0 P1(config-if)#mpls ip P1(config-if)#int e1/0 P1(config-if)#mpls ip P1(config-if)#router ospf 100 P1(config-router)#network area 0 P1(config-router)#network area 0 P1(config-router)#network area 0 Loopback interface must be routable for LDP to form adjacencies P2(config)#mpls ldp router-id loop0 P2(config)#int e0/0 P2(config-if)#mpls ip P2(config-if)#int e1/0 P2(config-if)#mpls ip P2(config-if)#router ospf 100 P2(config-router)#network area 0 P2(config-router)#network area 0 P2(config-router)#network area Cisco Systems, Inc. All rights reserved. 26

27 Basic MPLS L3 VPN config 2.) Configuring edge LSR for MPLS switching 1(config)#mpls ldp router-id loop0 1(config)#int e0/0 1(config-if)#mpls ip 1(config-if)#router ospf 100 1(router)#network area 0 1(router)#network area 0 Loopback interface must be routable for LDP to form adjacencies 2(config)#mpls ldp router-id loop0 2(config)#int e0/0 2(config-if)#mpls ip 2(config-if)#router ospf 100 2(router)#network area 0 2(router)#network area Cisco Systems, Inc. All rights reserved. 27

28 Basic MPLS L3 VPN config 3a.) Configuring edge LSR 1 for MPLS L3 VPN ip vrf blue rd 100:3 route-target export 3:1 route-target import 3:1! ip vrf red rd 100:1 route-target export 1:1 route-target import 1:1! interface Serial2/0 ip vrf forwarding red! interface Serial3/0 ip vrf forwarding blue 2011 Cisco Systems, Inc. All rights reserved. 28

29 Basic MPLS L3 VPN config 3b.) Configuring edge LSR 1 for MPLS L3 VPN router bgp 100 no bgp default ipv4-unicast bgp log-neighbor-changes neighbor remote-as 100 neighbor update-source Loopback0! address-family ipv4 no synchronization no auto-summary exit-address-family! address-family vpnv4 neighbor activate neighbor send-community extended exit-address-family! address-family ipv4 vrf blue no synchronization redistribute static exit-address-family! address-family ipv4 vrf red no synchronization redistribute static exit-address-family! ip route vrf red Serial2/0 ip route vrf blue Serial3/0 VPNv4 for exchange of VPNv4 prefixes that includes RD and RT to CE connectivity 2011 Cisco Systems, Inc. All rights reserved. 29

30 Basic MPLS L3 VPN config 4a.) Configuring edge LSR 2 for MPLS L3 VPN ip vrf blue rd 100:3 route-target export 3:1 route-target import 3:1! ip vrf red rd 100:1 route-target export 1:1 route-target import 1:1! interface Serial2/0 ip vrf forwarding red! interface Serial3/0 ip vrf forwarding blue 2011 Cisco Systems, Inc. All rights reserved. 30

31 Basic MPLS L3 VPN config 4b.) Configuring edge LSR 2 for MPLS L3 VPN router bgp 100 no bgp default ipv4-unicast bgp log-neighbor-changes neighbor remote-as 100 neighbor update-source Loopback0! address-family ipv4 no synchronization no auto-summary exit-address-family! address-family vpnv4 neighbor activate neighbor send-community extended exit-address-family! address-family ipv4 vrf blue no synchronization redistribute static exit-address-family! address-family ipv4 vrf red no synchronization redistribute static exit-address-family! ip route vrf red Serial2/0 ip route vrf blue Serial3/0 VPNv4 for exchange of VPNv4 prefixes that includes RD and RT to CE connectivity 2011 Cisco Systems, Inc. All rights reserved. 31

32 Basic MPLS L3 VPN config 5.) Configuring CE- connectivity on CE1 and CE2 site_1_vpn_blue(config)#ip route Serial3/0 site_2_vpn_blue(config)#ip route Serial3/0 site_1_vpn_red(config)#ip route Serial2/0 site_2_vpn_red(config)#ip route Serial2/ Cisco Systems, Inc. All rights reserved. 32

34 MPLS L3 VPN verification 1.) IGP peerings formed in core P1#show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface FULL/BDR 00:00: Ethernet1/ FULL/DR 00:00: Ethernet0/0 P2#show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface FULL/DR 00:00: Ethernet1/ FULL/DR 00:00: Ethernet0/ Cisco Systems, Inc. All rights reserved. 34

35 MPLS L3 VPN verification 2.) MPLS LDP peerings formed in core P1#show mpls ldp discovery Local LDP Identifier: :0 Discovery Sources: Interfaces: Ethernet0/0 (ldp): xmit/recv LDP Id: :0 Ethernet1/0 (ldp): xmit/recv LDP Id: :0 P2#show mpls ldp discovery Local LDP Identifier: :0 Discovery Sources: Interfaces: Ethernet0/0 (ldp): xmit/recv LDP Id: :0 Ethernet1/0 (ldp): xmit/recv LDP Id: : Cisco Systems, Inc. All rights reserved. 35

36 MPLS L3 VPN verification 3.) VRF tables and interfaces defined on routers 1#show ip vrf Name Default RD Interfaces blue 100:3 Se3/0 red 100:1 Se2/0 1#show ip vrf interfaces Interface IP-Address VRF Protocol Se3/ blue up Se2/ red up 2#show ip vrf Name Default RD Interfaces blue 100:3 Se3/0 red 100:1 Se2/0 2#show ip vrf interfaces Interface IP-Address VRF Protocol Se3/ blue up Se2/ red up 2011 Cisco Systems, Inc. All rights reserved. 36

37 MPLS L3 VPN verification 4.) ibgp session formed between routers 1#show bgp vpnv4 unicast all summary BGP router identifier , local AS number 100 BGP table version is 9, main routing table version 9 4 network entries using 564 bytes of memory 4 path entries using 272 bytes of memory 5/4 BGP path/bestpath attribute entries using 380 bytes of memory 2 BGP extended community entries using 48 bytes of memory 0 BGP route-map cache entries using 0 bytes of memory 0 BGP filter-list cache entries using 0 bytes of memory BGP using 1264 total bytes of memory BGP activity 4/0 prefixes, 4/0 paths, scan interval 15 secs Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd :27: Cisco Systems, Inc. All rights reserved. 37

38 MPLS L3 VPN verification 5a.) IGP labels assigned by LDP path from 1 to 2 1#traceroute Type escape sequence to abort. Tracing the route to [MPLS: Label 19 Exp 0] 8 msec 0 msec 0 msec [MPLS: Label 16 Exp 0] 4 msec 0 msec 0 msec msec * 4 msec 1#show mpls forwarding Local Outgoing Prefix Bytes Label Outgoing Next Hop Label Label or VC or Tunnel Id Switched interface /32 0 Et0/ P1#sh mpls forwarding-table Local Outgoing Prefix Bytes Label Outgoing Next Hop Label Label or VC or Tunnel Id Switched interface / Et1/ P2#show mpls forwarding-table Local Outgoing Prefix Bytes Label Outgoing Next Hop Label Label or VC or Tunnel Id Switched interface 16 Pop Label / Et0/ Cisco Systems, Inc. All rights reserved. 38

39 MPLS L3 VPN verification 5b.) IGP labels assigned by LDP path from 2 to 1 2#traceroute Type escape sequence to abort. Tracing the route to [MPLS: Label 18 Exp 0] 4 msec 4 msec 0 msec [MPLS: Label 16 Exp 0] 0 msec 4 msec 0 msec msec * 0 msec 2#show mpls forwarding-table Local Outgoing Prefix Bytes Label Outgoing Next Hop Label Label or VC or Tunnel Id Switched interface /32 0 Et0/ P2#show mpls forwarding-table Local Outgoing Prefix Bytes Label Outgoing Next Hop Label Label or VC or Tunnel Id Switched interface / Et1/ P1#show mpls forwarding-table Local Outgoing Prefix Bytes Label Outgoing Next Hop Label Label or VC or Tunnel Id Switched interface 16 Pop Label / Et0/ Cisco Systems, Inc. All rights reserved. 39

40 MPLS L3 VPN verification 6.) VPN labels assigned by BGP 1#show bgp vpnv4 unicast vrf red labels Network Next Hop In label/out label Route Distinguisher: 100:1 (red) /nolabel nolabel/21 1#show bgp vpnv4 unicast vrf blue labels Network Next Hop In label/out label Route Distinguisher: 100:3 (blue) / /nolabel / nolabel/22 2#show bgp vpnv4 unicast vrf red labels Network Next Hop In label/out label Route Distinguisher: 100:1 (red) nolabel/ /nolabel 2#show bgp vpnv4 unicast vrf blue labels Network Next Hop In label/out label Route Distinguisher: 100:3 (blue) / nolabel/ / /nolabel 2011 Cisco Systems, Inc. All rights reserved. 40

41 MPLS L3 VPN verification 7a.) End-to-end connectivity between VPN RED sites site_1_vpn_red#traceroute source Type escape sequence to abort. Tracing the route to msec 20 msec 20 msec [MPLS: Labels 19/21 Exp 0] 40 msec 40 msec 40 msec [MPLS: Labels 16/21 Exp 0] 40 msec 40 msec 40 msec msec 20 msec 20 msec msec * 40 msec site_2_vpn_red#traceroute source Type escape sequence to abort. Tracing the route to msec 20 msec 20 msec [MPLS: Labels 18/17 Exp 0] 40 msec 36 msec 40 msec [MPLS: Labels 16/17 Exp 0] 40 msec 40 msec 40 msec msec 20 msec 16 msec msec * 40 msec 2011 Cisco Systems, Inc. All rights reserved. 41

42 MPLS L3 VPN verification 7b.) End-to-end connectivity between VPN BLUE sites site_1_vpn_blue#traceroute source Type escape sequence to abort. Tracing the route to msec 12 msec 20 msec [MPLS: Labels 19/22 Exp 0] 40 msec 40 msec 40 msec [MPLS: Labels 16/22 Exp 0] 40 msec 40 msec 40 msec msec 20 msec 20 msec msec * 40 msec site_2_vpn_blue#traceroute source Type escape sequence to abort. Tracing the route to msec 12 msec 20 msec [MPLS: Labels 18/24 Exp 0] 40 msec 40 msec 40 msec [MPLS: Labels 16/24 Exp 0] 40 msec 40 msec 40 msec msec 20 msec 20 msec msec * 28 msec 2011 Cisco Systems, Inc. All rights reserved. 42

Multiprotocol Label Switching Virtual Private Network

Anas Al-Selwi Multiprotocol Label Switching Virtual Private Network Helsinki Metropolia University of Applied Sciences Bachelor of Engineering Information Technology Thesis 08 May 2013 Abstract Author(s)