APNIC elearning: Introduction to MPLS

Transcription

1 2/5/5 ANIC elearning: Introduction to MLS 3 MAY 25 3: M AEST Brisbane (UTC+) Issue Date: Revision: Introduction resenter Sheryl Hermoso Training Officer [email protected] Specialties: Network Security DNS/DNSSEC Iv6 Routing Internet Resource Mgmt Reminder: lease take time to fillup the survey

2 2/5/5 Limitation of Traditional I Routing Routing protocols are used to distribute Layer 3 routing information Forwarding is based on the destination address only Routing lookups are performed on every hop. 3 Limitation of Traditional I Routing Every router may need full Internet routing information Global Internet routing table size 5,+ routes Destinationbased routing lookup is needed on every hop. 4 2

3 2/5/5 Limitation of Traditional I Routing Traffic Engineering Most traffic goes between large sites A and B, and uses only the primary link Destinationbased routing does not provide any mechanism for load balancing across unequal paths. olicybased routing can be used to forward packets based on other parameters, but this is not a scalable solution. 5 How MLS Enhances Traditional I Routing Limitation MLS is a new forwarding mechanism in which packets are forwarded based on labels. s usually correspond to I destination networks (equal to traditional I forwarding). s can also correspond to other parameters, such as QoS or source address. MLS was designed to support forwarding of other protocols as well. 6 3

4 2/5/5 Basic MLS Concepts Only the edge routers will perform a routing lookup Core routers switch packets based on simple label lookups and swap labels 7 Traffic Engineering with MLS Traffic can be forwarded based on other parameters (QoS, source, and so on) Load sharing across unequal paths can be achieved. TE determines the path at the source based on additional parameters, such as available resources and constraints in the network 8 4

5 2/5/5 So What is MLS? Brief Summary It s all about labels Use the best of both worlds Layer2 (ATM/FR): efficient forwarding and traffic engineering Layer3 (I): flexible and scalable MLS forwarding plane Use of labels for forwarding Layer2/3 data traffic ed packets are being switched instead of routed Leverage layer2 forwarding efficiency MLS control/signaling plane Use of existing I control protocols extensions + new protocols to exchange label information Leverage layer3 control protocol flexibility and scalability 9 MLS Reference Architecture Different Type of Nodes in a MLS Network (rovider) router switching router (LSR) Switches MLSlabeled packets E MLS Domain E E (rovider Edge) router Edge router (LER) Imposes and removes MLS labels E E (Customer Edge) router Connects customer network to MLS network switched traffic 5

6 2/5/5 LER & LSR Router Functions Different Type of Nodes in a MLS Network LSR () primarily forwards labeled packets (label swapping). Edge LSR (E) primarily labels I packets and forwards them into the MLS domain, or removes labels and forwards I packets out of the MLS domain. routers are not aware about MLS. They work on traditional I routing protocol MLS s MLS technology is intended to be used anywhere regardless of Layer media and Layer 2 protocol. MLS uses a 32bit label field that is inserted between Layer 2 and Layer 3 headers (framemode MLS). MLS over ATM uses the ATM header as the label (cellmode MLS) 2 6

7 2/5/5 MLS Shim s Definition and Encapsulation s used for making forwarding decision Multiple labels can be used for MLS packet encapsulation Creation of a label stack Outer label always used for switching MLS packets in network Remaining inner labels used to specific services (e.g., VNs) MLS # 2bits T C S TTL8bits TC = Traffic Class: 3 Bits; S = Bottom of Stack; TTL = Time to Live MLS Encapsulation LAN MAC Header MAC Header LAN MAC Header MAC Header MLS Stack S Layer 3 acket Layer 3 acket Bottom of Stack Bit Set 3 Basic MLS Forwarding Operations How s Are Being Used to Establish Endtoend Connectivity imposition (USH) By ingress E router; classify and label packets Based on Forwarding Equivalence Class (FEC) swapping or switching By router; forward packets using labels; indicates service class & destination disposition (O) By egress E router; remove label and forward original packet to destination L2/L3 acket Imposition (ush) E E L Swap L L2 Swap L2 L3 Disposition (o) L3 E E 4 7

8 2/5/5 I acket Forwarding Example Basic I acket Forwarding I routing information exchanged between nodes Via IG (e.g., OSF, ISIS) ackets being forwarded based on destination I address Lookup in routing table (RIB) Forwarding Table Address refix Data I/F Data Forwarding Table Address refix I/F Address refix Forwarding Table I/F Data Data MLS ath (LS) Setup Step : I Routing (IG) Convergence Exchange of I routes OSF, ISIS, EIGR, etc. Establish I reachability Forwarding Table Forwarding Table Forwarding Table In Address refix I face You Can Reach and 7.69 Thru Me In Address refix I face In Address refix I face You Can Reach Thru Me Routing Updates (OSF, EIGR, ) You Can Reach 7.69 Thru Me

9 2/5/5 MLS ath (LS) Setup Step 2A: Assignment of Local s Each MLS node assigns a local label to each route in local routing table In label Forwarding Table Forwarding Table Forwarding Table In Address refix I face In Address refix I face In 3 Address refix I face MLS ath (LS) Setup Step 2B: Assignment of Remote s Local label mapping are sent to connected nodes Receiving nodes update forwarding table Out label Forwarding Table Forwarding Table Forwarding Table In Address refix I face Use 2 for and Use 2 for In Address refix I face 3 36 In 3 Address refix I face Use 3 for Distribution rotocol (LD) (Downstream Allocation) Use 36 for

10 2/5/5 MLS Traffic Forwarding Hopbyhop Traffic Forwarding Using s Ingress E node adds label to packet (push) Via forwarding table Downstream node use label for forwarding decision (swap) Outgoing interface Out label Egress E removes label and forwards original packet (pop) Forwarding Table Forwarding Table Forwarding Table In Address refix I face Data Data In Address refix Forwarding based on I face 3 36 In 3 Address refix Data 7.69 I face Data 9 MLS VN Models Technology Options MLS Layer3 VNs eering relationship between and E MLS Layer2 VNs Interconnect of layer2 Attachment Circuits (ACs) MLS Layer2 VNs ointtooint Layer2 VNs connected to E via p2p L2 connection (FR, ATM) s peer with each other (I routing) via p2p layer2 VN connection routing; no S involvement MLS VN Models Multioint Layer2 VNs connected to E via Ethernet connection (VLAN) s peer with each other via fully/partial mesh Layer2 VN connection routing; no S involvement MLS Layer3 VNs connected to E via Ibased connection (over any layer2 type) Static routing E routing protocol; ebg, OSF, ISIS routing has peering relationship with E router; E routers are part of customer routing E routers maintain customerspecific routing tables and exchange customer=specific routing information 2

11 2/5/5 Virtual Routing and Forwarding Instance Virtual Routing Table and Forwarding to Separate Customer Traffic Virtual routing and forwarding table On E router Separate instance of routing (RIB) and forwarding table Typically, VRF created for each customer VN Separates customer traffic VRF associated with one or more customer interfaces VRF has its own routing instance for E configured routing protocols E.g., ebg VN VN 2 VRF Green E VRF Blue MLS Backbone 2 VN Route Distribution Exchange of VN olicies Among E Routers Full mesh of BG sessions among all E routers BG Route Reflector Multirotocol BG extensions (MiBG) to carry VN policies E routing options Static routes ebg OSF ISIS E Link Blue VN olicy Red VN olicy E E BG Route Reflector Switched Traffic E E E Link BlueVN olicy` Red VN olicy 22

12 2/5/5 VN Control lane rocessing VRF arameters Make customer routes unique: Route Distinguisher (RD): 8byte field, VRF parameters; unique value to make VN I routes unique VNv4 address: RD + VN I prefix Selective distribute VN routes: Route Target (RT): 8byte field, VRF parameter, unique value to define the import/ export rules for VNv4 routes MiBG: advertises VNv4 prefixes + labels 23 VN Control lane rocessing Interactions Between VRF and BG VN Signaling. redistribute Iv4 route to E via ebg 2. E allocates VN label for prefix learnt from to create unique VNv4 route 3. E redistributes VNv4 route into MiBG, it sets itself as a next hop and relays VN site routes to E2 4. E2 receives VNv4 route and, via processing in local VRF (green), it redistributes original Iv4 route to 2 ebg: 6./6 I Subnet E BG advertisement: VNIv4 Addr = RD:6./6 BG NextHop = E Route Target = : =42 Blue VN ip vrf bluevpn VRF RD : parameters: Name routetarget = bluevpn export : RD = : Import routetarget RouteTarget import = : : Export RouteTarget = : ebg: 6./6 I Subnet E

13 2/5/5 VN Forwarding lane rocessing Forwarding of Layer3 MLS VN ackets. 2 forwards Iv4 packet to E2 2. E2 imposes preallocated VN label to Iv4 packet received from 2 Learned via MIBG 3. E2 imposes outer IG label A (learned via LD) and forwards labeled packet to nexthop router 2 4. routers and 2 swap outer IG label and forward label packet to E A>B (2) and B>C () 5. Router E strips VN label and IG labels and forwards Iv4 packet to Iv4 Iv4 acket E IG C VNv4 Iv4 IG B VNv4 Iv4 2 Blue VN IG A ip vrf bluevpn VRF RD parameters: : Name routetarget = bluevpn export : RD = : Import routetarget RouteTarget import = : : Export RouteTarget = : VNv4 Iv4 Iv4 Iv4 acket E Service rovider Deployment Scenario MLS Layer3 VNs for Offering Layer3 Business VN Services Deployment Use Case Delivery of I VN services to business customers Benefits Leverage same network for multiple services and customers (CAEX) Highly scalable Service enablement only requires edge node configuration (OEX) Different I connectivity can be easily configured; e.g., full/ partial mesh Managed VN Service Unmanaged VN Service CE Edge Core Core VN Edge CE Network Segment CE Edge Core MLS Node E Typical latforms ASRK ISR/G2 ASR9K 76 ASRK ASR93 ME38X CRS GSR ASR9K 26 3

14 2/5/5 Enterprise Deployment Scenario MLS Layer3 VNs for Implementing Network Segmentation Deployment Use Case Segmentation of enterprise network to provide selective connectivity for specific user groups and organizations Benefits Network segmentation only requires edge node configuration Flexible routing; different I connectivity can be easily configured; e.g., full/partial mesh Access Edge MLS VNs for L3 Network Segmentation Core VN Core Edge Network Segment Access Edge Core MLS Node E Access 27 Data Center Deployment Scenario MLS Layer3 VNs for Segmented L3 Data Center Access and Interconnect Deployment Use Case Segmented WAN Layer3 at Data Center edge Layer3 segmentation in Data Center Benefits Only single Data Center edge node needed for segmented layer3 access Enables VLAN/Layer2 scale (> 4K) Access Top Of Rack Distribution Core Data Center MLS VNs terminating on DC aggregation Core Edge Network Segment Distribution Core Edge MLS Node or E or E MLS VNs at DC edge 28 4

15 2/5/5 Survey Link: s/apnic2553el3 Slides are available for download from ANIC FT. 29 ANIC Helpdesk Chat 3 5

16 2/5/5 Thank You! END OF SESSION 3 6