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111 © 2003 Cisco Systems, Inc. All rights reserved. Half Duplex VRFs, 12/03 HALF DUPLEX VRFs: A SCALABLE HUB & SPOKE IMPLEMENTATION DECEMBER 2003.

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Presentation on theme: "111 © 2003 Cisco Systems, Inc. All rights reserved. Half Duplex VRFs, 12/03 HALF DUPLEX VRFs: A SCALABLE HUB & SPOKE IMPLEMENTATION DECEMBER 2003."— Presentation transcript:

1 111 © 2003 Cisco Systems, Inc. All rights reserved. Half Duplex VRFs, 12/03 HALF DUPLEX VRFs: A SCALABLE HUB & SPOKE IMPLEMENTATION DECEMBER 2003

2 222 © 2003 Cisco Systems, Inc. All rights reserved. Half Duplex VRFs, 12/03 HALF DUPLEX VRFs (HDV) 222 © 2003 Cisco Systems, Inc. All rights reserved. Half Duplex VRFs, 12/03

3 333 © 2003 Cisco Systems, Inc. All rights reserved. Half Duplex VRFs, 12/03 Only way to implement hub and spoke topology is to put every spoke into a single and unique VRF Ensures that spokes do not communicate directly Single VRF model, which does not include HDV, impairs the ability to bind traffic on the upstream ISP Hub Why Half Duplex VRFs? Problem

4 444 © 2003 Cisco Systems, Inc. All rights reserved. Half Duplex VRFs, 12/03 HDV allows the wholesale Service Provider to provide true hub and spoke connectivity to subscribers, who can be connected to the: Same or different PE-router(s) Same or different VRFs, via the upstream ISP Why Half Duplex VRFs? Solution

5 555 © 2003 Cisco Systems, Inc. All rights reserved. Half Duplex VRFs, 12/03 Problem PE requires multiple VRF tables for multiple VRFs to push spoke traffic via hub If the spokes are in the same VRF (no HDV), traffic will be switched locally and will not go via the hub site Solution HDVs allows all the spoke site routes in one VRF Benefit Scalability for RA to MPLS connections Reduces memory requirements by using just two VRF tables Simplifies provisioning, management, and troubleshooting by reducing the number of Route Target and Route Distinguisher configuration Technical Justification

6 666 © 2003 Cisco Systems, Inc. All rights reserved. Half Duplex VRFs, 12/03 PE MPLS CORE ISP HUB VPN port VPNport VPNport A B All the spokes in the same VPN (yellow) Dedicated (separate) VRF per spoke is needed to push all traffic through upstream ISP Hub Spoke A VRF Spoke B VRF CE HUB Site PE Spoke Site PE Hub & Spoke Connectivity Without HDV Requires Dedicated VRF Tables Per Spoke

7 777 © 2003 Cisco Systems, Inc. All rights reserved. Half Duplex VRFs, 12/03 PE MPLS CORE ISP CE Service Loopback HUB VPNport VPNport VPN port A B If two subscribers of the same service terminate on the same PE-router, then traffic between them can be switched locally at the PE-router (as shown), which is undesirable All inter-subscriber traffic needs to follow the default route via the Home Gateway (located at upstream ISP). Single VRF table Hub Site PE Spoke Site PE Hub & Spoke Connectivity Without HDV Using A Single VRF

8 888 © 2003 Cisco Systems, Inc. All rights reserved. Half Duplex VRFs, 12/03 Upstream VRF Used to forward packets from Spokes to Hub Contains a static default route Downstream VRF Use to forward packets from Hub to Spoke Contains a /32 route to a subscriber (installed from PPP) Terminology

9 999 © 2003 Cisco Systems, Inc. All rights reserved. Half Duplex VRFs, 12/03 PE MPLS CORE ISP CE HUB VPN port VPN port VPN port A B If two subscribers of the same service terminate on the same PE-router, traffic between them is not switched locally All inter-subscriber traffic follows the default route via the Home Gateway (located at upstream ISP) Single VRF table HUB Site PE Spoke Site PE Hub & Spoke Connectivity With HDV Using A Single VRF

10 10 © 2003 Cisco Systems, Inc. All rights reserved. Half Duplex VRFs, 12/03 1.HDVs are used in only one direction by incoming traffic Ex: upstream toward the MPLS VPN backbone or downstream toward the attached subscriber 2.PPP client dial, and is authenticated, authorized, and assigned an IP address. 3.Peer route is installed in the downstream VRF table One single downstream VRF for all spokes in the single VRF 4.To forward the traffic among spokes (users), upstream VRF is consulted at the Spoke PE and traffic is forwarded from a Hub PE to Hub CE Return path: downstream VRF is consulted on the Hub PE before forwarding traffic to appropriate spoke PE and to the spoke (user) 5.Source address look up occurs in the downstream VRF, if unicast RPF check is configured on the interface on which HDV is enabled Half Duplex VRF Functionality

11 11 © 2003 Cisco Systems, Inc. All rights reserved. Half Duplex VRFs, 12/03 1.PPP user initiates a session with PPP session using a name and 2.LAC/PE-router sends username information to the WholesaleServiceProvider Radius Server 3.ISP-A (service name) is used to index into a profile that contains information on the IP address of the Radius server of the ISP-A and password is then forwarded from the Wholesale Provider Radius server (which acts as a "proxy-radius"), towards the ISP Radius 5.ISP-A Radius server authenticates and assigns IP address 6.ISP-A Radius server sends "Access-Accept" to Wholesale Service Provider Radius Server 7.The wholesale Service Provider Radius server adds authorization information to the Access- Accept, (based on the domain or servicename)and the VRF to be used by Subscriber-A, and forwards it to PE-WholesaleProvider-LAC router 8.PE-WholesaleProvider-LAC router creates temporary Virtual-Access interface (with associated /32 IP address) and places it into the appropriate VRF PE-WholeSale Provider-LAC PE-ISP PPP User Subscriber-A Wholesale Service Provider AAA Server ISP-A AAA Server MPLS Core Subscriber Connection Process

12 12 © 2003 Cisco Systems, Inc. All rights reserved. Half Duplex VRFs, 12/03 ! interface <> ip vrf forwarding [downstream ] ! vrf-name1: First VRF that the interface is associated with. vrf-name2: This is the downstream VRF. PPP peer route and per-user routes from AAA server are installed in this VRF. Configuration Command

13 13 © 2003 Cisco Systems, Inc. All rights reserved. Half Duplex VRFs, 12/03 ip vrf Internet-ISPA-upstream rd 10:26 route-target import 10:26 ! ip vrf Internet-ISPA-downstream rd 10:27 route-target export 10:27 Upstream VRF only requires a route-target import statement Imports the default route from the hub PE router Provider) Downstream VRF only requires a route-target export command Used to export all of the /32 (virtual-access ints) addresses toward the hub PE-router Each VRF is created on the Spoke PE-router (LAC) before PPPoA or PPPoE client connections are established Sample Configuration

14 14 © 2003 Cisco Systems, Inc. All rights reserved. Half Duplex VRFs, 12/03 Reverse Path Forwarding (RPF) Used by Service Provider determine the source IP address of an incoming IP packet and ascertain whether it entered the router via the correct inbound interface Concern HDV populates a different VRF than the one used for “upstream” forwarding Solution Extend the RPF mechanism so the “downstream” VRF is checked To enable RPF extension, configure: ip verify unicast reverse-path Reverse Path Forwarding Check

15 15 © 2003 Cisco Systems, Inc. All rights reserved. Half Duplex VRFs, 12/03 IP unnumbered any point-to-point interfaces, including virtual access/template interfaces Spokes connected to Spoke PE or the Hub PE Subscriber using single or multiple ISPs Reverse Path Forwarding Check HDV Supported Features

16 16 © 2003 Cisco Systems, Inc. All rights reserved. Half Duplex VRFs, 12/03 HDV-1 Base image: Release 12.2(14.6)T1 No unicast RPF support HDV-2 Base image: Release 12.2(15)T Unicast RPF support added HDV-3 Base image: Release 12.2(15)T2 Handles cases when downstream VRF is deleted Added support for distributed hardware; unicast RPF HDV info is propagated to linecards show ip vrf detail show ip interface show ip cef interface internal HDV-4 Same as HDV-3; based on Release 12.3(3) HDV Support: Cisco IOS Software Images

17 17 © 2003 Cisco Systems, Inc. All rights reserved. Half Duplex VRFs, 12/03 Software Only supports Virtual Access/Template interfaces –Must be configured with IP unnumbered –"ip address..." is not allowed on HDV interfaces PE-CE link: supports only static routing Hardware Release 12.3: feature will be available only on Cisco 6400 Series (NRP and NRP2 router blades) Restrictions

18 18 © 2003 Cisco Systems, Inc. All rights reserved. Half Duplex VRFs, 12/03 These commands highlight upstream / downstream VRFs bound to particular interfaces and give detailed information about VRFs PE-router# sh ip int vi 3 Virtual-Access3 is up, line protocol is up Interface is unnumbered. Using address of Loopback2 ( ) VPN Routing/Forwarding "U" Downstream VPN Routing/Forwarding "D" IP multicast fast switching is disabled Show Commands Partial output highlighting only HDV related information

19 19 © 2003 Cisco Systems, Inc. All rights reserved. Half Duplex VRFs, 12/03 PE-router#sh ip vrf detail D VRF D; default RD 1:8; default VPNID Description: Downstream VRF - to spokes No interfaces Interfaces using this VRF as downstream: Virtual-Access3 Virtual-Access4 Connected addresses are not in global routing table Export VPN route-target communities RT:1:100 No Import VPN route-target communities No import route-map No export route-map PE-router# sh cef interface vi 3 int Virtual-Access3 is up (if_number 35) Subblocks: ip verify: via=rx, acl=0, drop=0, sdrop=0, downstream VRF D Show Commands (Cont.)

20 20 © 2003 Cisco Systems, Inc. All rights reserved. Half Duplex VRFs, 12/03 CASE STUDY 20 © 2003 Cisco Systems, Inc. All rights reserved. Half Duplex VRFs, 12/03

21 21 © 2003 Cisco Systems, Inc. All rights reserved. Half Duplex VRFs, 12/03 Case Study Scenario Wholesale Service Provider and ISPs are offering services in partnership to the subscribers Subscribers connect to the Wholesale Service Provider network, which directs them to the appropriate ISP based on the Subscribed services Network topology and specification Multiple Spoke sites are connected to the same PE router in a Hub/Spoke topology over PPPoE Hub-PE is a separate PE router This topology serves PPP clients, who are authenticated and authorized by a Radius server via LNS (SpokeSitePE)

22 22 © 2003 Cisco Systems, Inc. All rights reserved. Half Duplex VRFs, 12/03 Topology SpokeSitePE (LNS1) MPLS Core HubSitePE SpokeSiteCE1(LAC1) Subscriber1 SpokeSiteCE2(LAC2) Subscriber2 ISP1_Hub_CE AAA Radius Server Subscribers

23 23 © 2003 Cisco Systems, Inc. All rights reserved. Half Duplex VRFs, 12/03 Topology (Cont.) SpokeSitePE (LNS1) MPLS Core HubSitePE SpokeSiteCE1 (LAC1) SpokeSiteCE 2 (LAC2) ISP1_Hub_CE AAA Radius Server ip vrf D rd 1:8 route-target export 1:100 ip vrf U rd 1:0 route-target import 1:0 ip vrf HUB rd 1:20 route-target export 1:0 route-target import 1:100 Subscriber1 Subscriber2

24 24 © 2003 Cisco Systems, Inc. All rights reserved. Half Duplex VRFs, 12/03 Configuration Steps To Enable HDV HubSitePE Regular VRF and VPNv4 configuration associated with HUB VRF SpokeSitePE (LNS) Create upstream & downstream VRFs Configure VPDN & AAA related configuration as usual Configure VPNv4 and VRFs as in basic MPLS VPN including upstream and downstream VRFs VPNv4 address-families SpokeSiteCE (LAC) Create upstream & downstream VRFs Configure VPDN & AAA related configuration as usual Bind VRF on appropriate interfaces (VirtualTemplate, Loopback) Radius Server Configure user profiles on a Radius Server

25 25 © 2003 Cisco Systems, Inc. All rights reserved. Half Duplex VRFs, 12/03 Radius Server Configuration DEFAULT Service-Type == Framed-User Framed-Protocol = PPP, cisco-avpair += "lcp:interface-config=ip vrf forwarding U downstream D", cisco-avpair += "lcp:interface-config=ip unnumbered loopback 2", cisco-avpair += "ip:addr-pool=U-pool", Fall-Through = Yes subscriber1 Auth-Type := Local, User-Password == “subscriber1" cisco-avpair += "ip:route= " subscriber2 Auth-Type := Local, User-Password == “subscriber2" cisco-avpair += "ip:route= " Spokes will inherit the default configuration

26 26 © 2003 Cisco Systems, Inc. All rights reserved. Half Duplex VRFs, 12/03 Configuration: HubSitePE ! router bgp 1 no bgp default ipv4-unicast bgp log-neighbor-changes neighbor remote-as 1 neighbor update-source Loopback0 no auto-summary ! address-family ipv4 multicast no auto-summary exit-address-family ! address-family vpnv4 neighbor activate neighbor send-community extended no auto-summary exit-address-family ! address-family ipv4 no auto-summary no synchronization exit-address-family ! address-family ipv4 vrf HUB neighbor remote-as 100 neighbor activate no auto-summary no synchronization exit-address-family ! ip vrf HUB rd 1:20 route-target export 1:0 route-target import 1:100 !

27 27 © 2003 Cisco Systems, Inc. All rights reserved. Half Duplex VRFs, 12/03 Configuration: SpokeSitePE(LNS) hostname SpokeSitePE aaa new-model ! aaa group server radius R server auth-port 1812 acct-port 1813 ! aaa authentication ppp default group radius aaa authorization network default group radius ! ip vrf D description Downstream VRF - to spokes rd 1:8 route-target export 1:100 ! ip vrf U description Upstream VRF - to hub rd 1:0 route-target import 1:0 ! ip cef vpdn enable ! vpdn-group U accept-dialin protocol pppoe virtual-template 1 ! interface Loopback2 ip vrf forwarding U ip address ! interface ATM2/0 description Mze ATM3/1/2 no ip address no atm ilmi-keepalive pvc 0/16 ilmi ! pvc 3/100 protocol pppoe ! pvc 3/101 protocol pppoe ! interface Virtual-Template1 no ip address ppp authentication chap ! router bgp 1 no synchronization no bgp default ipv4-unicast bgp log-neighbor-changes neighbor remote-as 1 neighbor update-source Loopback0 no auto-summary

28 28 © 2003 Cisco Systems, Inc. All rights reserved. Half Duplex VRFs, 12/03 Configuration: SpokeSitePE(LNS) ! address-family ipv4 multicast no auto-summary no synchronization exit-address-family ! address-family vpnv4 neighbor activate neighbor send-community extended no auto-summary exit-address-family ! address-family ipv4 vrf U no auto-summary no synchronization exit-address-family ! address-family ipv4 vrf D redistribute static no auto-summary no synchronization exit-address-family ! ip local pool U-pool ! radius-server host auth-port 1812 acct-port 1813 radius-server key cisco

29 29 © 2003 Cisco Systems, Inc. All rights reserved. Half Duplex VRFs, 12/03 Show Log: SpokeSitePE(LNS) SpokeSitePE#sh run int virtual-access 3 Building configuration... Current configuration : 92 bytes ! interface Virtual-Access3 ip vrf forwarding U downstream D ip unnumbered Loopback2 end SpokeSitePE#sh run int virtual-access 4 Building configuration... Current configuration : 92 bytes ! interface Virtual-Access4 ip vrf forwarding U downstream D ip unnumbered Loopback2 end Both subscribers available on the SpokeSitePE

30 30 © 2003 Cisco Systems, Inc. All rights reserved. Half Duplex VRFs, 12/03 Show Log: SpokeSitePE(LNS) (Cont.) SpokeSitePE#sh ip route vrf D Routing Table: D Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1, E2 - OSPF external type 2 i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area * - candidate default, U - per-user static route, o - ODR P - periodic downloaded static route Gateway of last resort is not set /8 is variably subnetted, 5 subnets, 2 masks U /32 [1/0] via S /8 is directly connected, Null0 U /32 [1/0] via C /32 is directly connected, Virtual-Access4 C /32 is directly connected, Virtual-Access3 Shows downstream VRF table

31 31 © 2003 Cisco Systems, Inc. All rights reserved. Half Duplex VRFs, 12/03 Show Log: SpokeSitePE(LNS) (Cont.) SpokeSitePE#sh ip route vrf U Routing Table: U Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1, E2 - OSPF external type 2 i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area * - candidate default, U - per-user static route, o - ODR P - periodic downloaded static route Gateway of last resort is to network /32 is subnetted, 1 subnets C is directly connected, Loopback2 B* /0 [200/0] via , 1w5d Shows upstream VRF table

32 32 © 2003 Cisco Systems, Inc. All rights reserved. Half Duplex VRFs, 12/03 Show Log: SpokeSitePE(LNS) (Cont.) SpokeSitePE#sh ip int vi 3 Virtual-Access3 is up, line protocol is up Interface is unnumbered. Using address of Loopback2 ( ) Broadcast address is Peer address is MTU is 1492 bytes Helper address is not set Directed broadcast forwarding is disabled Outgoing access list is not set Inbound access list is not set Proxy ARP is enabled Local Proxy ARP is disabled Security level is default Split horizon is enabled ICMP redirects are always sent ICMP unreachables are always sent ICMP mask replies are never sent IP fast switching is enabled IP fast switching on the same interface is enabled IP Flow switching is disabled IP CEF switching is enabled IP Feature Fast switching turbo vector IP VPN CEF switching turbo vector VPN Routing/Forwarding "U" Downstream VPN Routing/Forwarding "D" IP multicast fast switching is disabled IP multicast distributed fast switching is disabled IP route-cache flags are Fast, CEF Router Discovery is disabled IP output packet accounting is disabled IP access violation accounting is disabled TCP/IP header compression is disabled RTP/IP header compression is disabled Policy routing is disabled Network address translation is disabled WCCP Redirect outbound is disabled WCCP Redirect inbound is disabled WCCP Redirect exclude is disabled BGP Policy Mapping is disabled SpokeSitePE#sh cef interface vi 3 int Virtual-Access3 is up (if_number 35) Corresponding hwidb fast_if_number 35 Corresponding hwidb firstsw->if_number 35 Internet address is /0 Unnumbered interface. Using address of Loopback2 ( ) ICMP redirects are always sent Per packet load-sharing is disabled IP unicast RPF check is enabled Inbound access list is not set Outbound access list is not set IP policy routing is disabled BGP based policy accounting is disabled Interface is marked as point to point interface Hardware idb is Virtual-Access3 Fast switching type 7, interface type 21 IP CEF switching enabled IP Feature Fast switching turbo vector IP VPN Feature CEF switching turbo vector VPN Forwarding table "U" Input fast flags 0x5000, Output fast flags 0x0 ifindex 23(23) Slot -1 Slot unit 3 Unit 3 VC -1 Transmit limit accumulator 0x0 (0x0) IP MTU 1492 Subblocks: ip verify: via=rx, acl=0, drop=0, sdrop=0, downstream VRF D SpokeSitePE#sh ip vrf detail D VRF D; default RD 1:8; default VPNID Description: Downstream VRF - to spokes No interfaces Interfaces using this VRF as downstream: Virtual-Access3 Virtual-Access4 Connected addresses are not in global routing table Export VPN route-target communities RT:1:100 No Import VPN route-target communities No import route-map No export route-map

33 33 © 2003 Cisco Systems, Inc. All rights reserved. Half Duplex VRFs, 12/03 Configuration: SpokeSiteCE(LAC1) username subscriber1 password 0 subscriber1 username subscriber2 password 0 subscriber2 ! ip vrf D rd 1:8 route-target export 1:100 ! ip vrf U rd 1:0 route-target import 1:0 ! ip cef vpdn enable ! vpdn-group U accept-dialin protocol pppoe virtual-template 1 ! interface Loopback2 ip vrf forwarding U ip address ! ! interface ATM2/0 description Mze ATM3/1/2 no ip address no atm ilmi-keepalive pvc 0/16 ilmi ! pvc 3/100 protocol pppoe ! pvc 3/101 protocol pppoe ! ! interface Virtual-Template1 ip vrf forwarding U downstream D ip unnumbered Loopback2 peer default ip address pool U-pool ppp authentication chap ! ip local pool U-pool

34 34 © 2003 Cisco Systems, Inc. All rights reserved. Half Duplex VRFs, 12/03 BACKUP SLIDES 34 © 2003 Cisco Systems, Inc. All rights reserved. Half Duplex VRFs, 12/03

35 35 © 2003 Cisco Systems, Inc. All rights reserved. Half Duplex VRFs, 12/03 PE Home Gateway MPLS CORE ISP PECE Service Loopback Service Loopback HUB PE SPOKE 1 SPOKE 2 vpn port vpn port vpn port A B Upstream traffic (ie: traffic toward the upstream ISP or toward another subscriber) is sent to the hub PE-router and forwarded across the link between the wholesale SP and the ISP Subscriber traffic follows a default route within the VRF Traffic is forwarded towards and received from the wholesale Service Providers PE-router and the subscriber Topology I: Hub and Spoke Connectivity Between Distributed PE-Routers

36 36 © 2003 Cisco Systems, Inc. All rights reserved. Half Duplex VRFs, 12/03 Data flow between two subscribers that belong to different services goes through the hub location of the Service Provider Data will traverse through a network exchange point, either public or private, by following a default route within the subscriber VRF Topology II: Hub and Spoke Connectivity Between Subscribers Of Different Services

37 37 © 2003 Cisco Systems, Inc. All rights reserved. Half Duplex VRFs, 12/03 If two subscribers are terminated on the same PE-router and belong to different services, the data is required to traverse through the home gateways of both services. Topology III: Hub and Spoke Connectivity Via the Same PE-Router (Different Services)

38 38 © 2003 Cisco Systems, Inc. All rights reserved. Half Duplex VRFs, 12/03 38 © 2003 Cisco Systems, Inc. All rights reserved. Half Duplex VRFs, 12/03


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