Deploying IP/MPLS VPN - Cisco Networkers 2010

BRKMPL-2102
Rajiv Asati, Technical Leader
Designing MPLS Layer3 VPN Networks

© 2010 Cisco and/or its affiliates. All rights reserved. Cisco ConfidentialPresentation_ID 2
Abstract
 Multi Protocol Label Switching (MPLS) has been
widely adopted by the Network Operators to
provide scalable L2, L3 VPN, traffic engineering
services etc. Enterprises are fast adopting this
technology to address network segmentation and
traffic separation needs.
 This session covers MPLS Layer3 VPN, which is
the most adopted MPLS application. The session
will cover:
• MPLS VPN Technology Overview (RFC2547/RFC4364)
• MPLS/VPN Configuration Overview
• MPLS/VPN-based services (multihoming, Hub&Spoke,
extranet, Internet, NAT, VRF-lite, etc.)
• Best Practices

Other MPLS-Related Sessions
Session-ID Session Name
BRKRST-1101 Introduction to MPLS
BRKRST-2103 Migration Considerations when
Buying MPLS VPN Service
BRKRST-2105 Inter-AS MPLS Solutions
BRKRST-3101 Advanced Topics and Future
Directions in MPLS

Agenda
 MPLS VPN Overview
 MPLS VPN Services
 Best Practices
 Conclusion

Prerequisites
 Must understand basic IP routing, especially BGP
 Must understand MPLS basics (push, pop, swap,
label stacking)
 Should understand MPLS VPN basics
 Must keep the speaker engaged…
…by asking bad questions 
Reference

Terminology
 LSR: label switch router
 LSP: label switched path
The chain of labels that are swapped at each hop to get from one LSR to another
 VRF: VPN routing and forwarding
Mechanism in Cisco IOS® used to build per-customer RIB and FIB
 MP-BGP: multiprotocol BGP
 PE: provider edge router interfaces with CE routers
 P: provider (core) router, without knowledge of VPN
 VPNv4: address family used in BGP to carry MPLS-VPN routes
 RD: route distinguisher
Distinguish same network/mask prefix in different VRFs
 RT: route target
Extended community attribute used to control import and export policies
of VPN routes
 LFIB: label forwarding information base
 FIB: forwarding information base
Reference

Agenda
 MPLS VPN Overview
Technology (how it works)
Configuration
 MPLS-VPN Services
 Best Practices
 Conclusion

MPLS-VPN Technology
 More than one routing and forwarding tables
 Control plane—VPN route propagation
 Data or forwarding plane—VPN packet forwarding

MPLS-VPN Technology
MPLS VPN Connection Model
PE
MPLS Backbone
MP-iBGP Session
PE
P P
P P
CE CE
CE
CE
P Routers
Sit inside the network
Forward packets by looking
at labels
P and PE routers share a
common IGP
PE Routers
Sit at the Edge
Use MPLS with P routers
Uses IP with CE routers
Distributes VPN information
through MP-BGP to other PE
routers

CE2
MPLS-VPN Technology
Separate Routing Tables at PE
Global Routing Table
 Created when IP routing is
enabled on PE.
 Populated by OSPF, ISIS, etc.
inside the MPLS backbone
 “show ip route”
PE
CE1
VPN 1
VPN 2
MPLS Backbone IGP (OSPF, ISIS)
Customer Specific Routing Table
 Routing (RIB) and forwarding table
(CEF) dedicated to VPN customer
VPN1 routing table
VPN2 routing table
 Referred to as VRF table for the
<named VPN>.
 “show ip route vrf <name>”

MPLS-VPN Technology
Virtual Routing and Forwarding Instance (1)
 What’s a Virtual Routing and Forwarding (VRF) ?
Representation of VPN customer inside the SP MPLS network
Each VPN is associated with at least one VRF
 VRF configured on each PE and associated with PE-CE interface(s)
Privatize an interface, i.e., coloring of the interface
 VRF-aware routing protocol (static, RIP, BGP, EIGRP, ISIS, OSPF)
 No changes needed at CE
PE(conf)#interface Ser0/0
PE(conf)#ip vrf forwarding blue
PE(conf)#ip vrf blue
CE2
PE
CE1
VPN 1
VPN 2
VRF Blue
VRF Green
Ser0/0

MPLS-VPN Technology
Virtual Routing and Forwarding Instance (2)
 PE installs the backbone routes (IGP) in global routing table
 PE installs the VPN routes in VRF routing table(s).
VPN routes are learned from CE routers or remote PE routers
 VPN customers can use overlapping IP addresses
BGP plays a key role. Let’s understand few BGP specific details..…
CE2
PE
CE1
VPN 1
VPN 2
EBGP, OSPF, RIPv2, Static

MPLS-VPN Technology: Control Plane
MP-BGP Customizes the VPN customer Routing Information as per
the locally configured VRF information at the PE -
 Route Distinguisher (RD)
 Route Target (RT)
 Label
8 Bytes
Route-Target
3 Bytes
Label
MP-BGP UPDATE message showing
only VPNv4 address, RT, Label
1:1
8 Bytes 4 Bytes
RD IPv4
VPNv4
10.1.1.0
The Control Plane for MPLS VPN Is Multi-Protocol BGP

MPLS-VPN Technology: Control Plane
MP-BGP UPDATE Message Capture
 Visualize how the
BGP UPDATE
message advertising
VPNv4 routes looks
like.
 Notice the Path
Attributes.
VPNv4 prefix with label is
encoded in this attribute.
Route Target 3:3
Reference

MPLS VPN Control Plane
MP-BGP Update Components: RD & VPNv4 Address
 VPN customer IPv4 address (10.1.1.0, say) is converted into a
VPNv4 address by appending the RD to the IPv4 address
=>1:1:10.1.1.0
Makes the customer’s IPv4 address unique inside the SP MPLS network.
 Route Distinguisher (RD) is configured inside the VRF at PE
RD is not a BGP attribute, just a field.
8 Bytes
Route-Target
3 Bytes
Label
MP-BGP update showing RD, RT, and label
1:1
8 Bytes 4 Bytes
RD IPv4
VPNv4
10.1.1.0
!
ip vrf green
rd 1:1
!* After 12.4(3)T, 12.4(3) 12.2(32)S, 12.0(32)S etc., RD Configuration within
VRF Has Become Optional. Prior to that, It Was Mandatory.

MP-BGP Update Components: Route-Target
 Route-target (RT): identifies the VRF for the received
VPNv4 prefix. It is an 8-byte extended community attribute.
 Each VRF is configured with a set of RT(s) at the PE
RT identifies which VRF(s) keep which VPN route
 Export RT(s) attached to VPN routes in PE->PE
advertisements
!
ip vrf green
route-target import 1:1
route-target export 1:2
!
8 Bytes
Route-Target
3 Bytes
Label
MP-BGP update showing RD, RT, and Label
1:1
8 Bytes 4 Bytes
RD IPv4
VPNv4
10.1.1.0 1:2

MP-BGP Update Components: Label
 PE assigns a label for the VPNv4 prefix; Label is not an attribute.
Next-hop-self towards MP-iBGP neighbors by default i.e. PE sets the NEXT-
HOP attribute to its own address (loopback)
 PE addresses used as BGP next-hop must be uniquely known in
the backbone IGP
Do not summarize the PE loopback addresses in the core
3 Bytes
Label
MP-BGP update showing RD, RT, and label
1:1
8 Bytes 4 Bytes
RD IPv4
VPNv4
10.1.1.0 2:2 50
8 Bytes
Route-Target

MPLS VPN Control Plane:
Putting It All Together
1. PE1 receives an IPv4 update (eBGP/OSPF/ISIS/RIP/EIGRP)
2. PE1 translates it into VPNv4 address and constructs the MP-
iBGP UPDATE message
Associates the RT values (export RT =1:2, say) per VRF configuration
Rewrites next-hop attribute to itself
Assigns a label (100, say); Installs it in the MPLS forwarding table.
3. PE1 sends MP-iBGP update to other PE routers
10.1.1.0/24
Next-Hop=CE-1
MP-iBGP Update:
RD:10.1.1.0
Next-Hop=PE-1
RT=1:2, Label=100
1
3
10.1.1.0/24
PE1 PE2
P
P P
P
CE2
MPLS Backbone
Site 1 Site 2
CE1
2

MPLS VPN Control Plane:
Putting It All Together
4. PE2 receives and checks whether the RT=1:2 is locally configured as
‘import RT’ within any VRF, if yes, then
PE2 translates VPNv4 prefix back in IPv4 prefix
Updates the VRF CEF Table for 10.1.1.0/24 with label=100
5. PE2 advertises this IPv4 prefix to CE2 (using whatever routing protocol)
5
10.1.1.0/24
Next-Hop=CE-1
MP-iBGP Update:
RD:10.1.1.0
Next-Hop=PE-1
RT=1:2, Label=100
10.1.1.0/24
Site 1 Site 2
10.1.1.0/24
Next-Hop=PE-2
1
3
PE2
PP
P P
MPLS Backbone
CE1
2 4
CE2
PE1

Global Forwarding Table
(show ip cef)
 Stores Next-hop routes with associated
labels
 Next-hop routes learned through IGP
 Label learned through LDP/TDP
VRF Forwarding Table
(show ip cef vrf <vrf>)
 Stores VPN routes with associated labels
 VPN routes learned through BGP
 Labels learned through MP-BGP
10.1.1.0/24
Site 1 Site 2
VRF Green Forwarding Table
Dest  NextHop
10.1.1.0/24-PE1, label: 100
PE1 PE2
P4
P1 P2
P3
CE2CE1
Global Routing/Forwarding Table
Dest  Next-Hop
PE2  P3, Label: 50
Global Routing/Forwarding Table
Dest  Next-Hop
PE1  P2, Label: 25
MPLS-VPN Forwarding Plane
Review

10.1.1.0/24
PE1 PE2
CE2
CE1
Site 1 Site 2
10.1.1.1
10.1.1.110050
MPLS-VPN Forwarding Plane
Packet Forwarding
 PE2 imposes two labels (MPLS headers) for each packet going to
the VPN destination 10.1.1.1.
Outer label is LDP learned; Corresponds derived from an IGP route
Inner label is learned via MP-BGP; corresponds to the VPN address
 PE1 recovers the IP packet (from the received MPLS packet) and
forwards it to CE1.
10.1.1.1
10.1.1.1100
10.1.1.1 10025
IP Packet
MPLS Packet
IP Packet
P4
P1 P2
P3

MPLS-VPN Technology: Forwarding Plane
MPLS Packet Capture
 This capture
might be helpful
if you never
captured an
MPLS packet
before.
Inner Label
Outer Label
IP packet
Ethernet Header
Reference

Agenda
 MPLS VPN Explained
Technology
Configuration
 Best Practices
 Conclusion

MPLS VPN Sample Configuration (IOS)
PE-P Configuration
ip vrf VPN-A
rd 1:1
interface Serial0
ip address 192.168.10.1 255.255.255.0
ip vrf forwarding VPN-A
VRF Definition
PE1
10.1.1.0/24
PE1
CE1
Site 1
192.168.10.1
Se0
Interface Serial1
ip address 130.130.1.1 255.255.255.252
mpls ip
router ospf 1
network 130.130.1.0 0.0.0.3 area 0
PE1
Se0
P
PE1 s1
Reference

PE: MP-IBGP Config
RR: MP-IBGP Config
router bgp 1
neighbor 1.2.3.4 remote-as 1
neighbor 1.2.3.4 update-source loopback0
!
address-family vpnv4
neighbor 1.2.3.4 activate
neighbor 1.2.3.4 send-community both
!
PE1
router bgp 1
no bgp default route-target filter
!
neighbor 1.2.3.6 route-reflector- client
!
RR
PE1 PE2
RR
PE1 PE2
RR
Reference

router bgp 1
!
address-family ipv4 vrf VPN-A
exit-address-family
!
PE-CE Routing: BGP
PE-CE Routing: OSPF
router ospf 1
!
router ospf 2 vrf VPN-A
network 192.168.10.0 0.0.0.255 area 0
redistribute bgp 1 subnets
!
PE1
PE1
10.1.1.0/24
PE1
CE1
Site 1
192.168.10.1
192.168.10.2
10.1.1.0/24
PE1
Site 1
192.168.10.1
192.168.10.2
CE1
Reference

router rip
!
version 2
no auto-summary
network 192.168.10.0
redistribute bgp 1 metric transparent
!
PE-CE Routing: RIP
PE-CE Routing: EIGRP router eigrp 1
!
no auto-summary
network 192.168.10.0 0.0.0.255
autonomous-system 1
redistribute bgp 1 metric 100000 100
255 1 1500
!
10.1.1.0/24
PE1
CE1
Site 1
192.168.10.1
192.168.10.2
10.1.1.0/24
PE1
Site 1
192.168.10.1
192.168.10.2
CE1
Reference
PE1
PE1

ip route vrf VPN-A 10.1.1.0 255.255.255.0
192.168.10.2
PE-CE Routing: Static
PE-CE: MB-iBGP Routes to VPN
router rip
version 2
redistribute bgp 1 metric transparent
no auto-summary
network 192.168.10.0
exit-address-family
If PE-CE Protocol Is non-BGP (such as RIP), then Redistribution of
VPN Routes from MP-IBGP Is Required (Shown Below for RIP) -
10.1.1.0/24
PE1
CE1
Site 1
192.168.10.1
192.168.10.2
PE1
RR
CE1
Site 1
Reference
PE1
PE1

 For config hands-on, please attend “Configuring MPLS
VPNs” Lab session.
 Having familiarized with IOS based config, let’s glance
through the IOS-XR based config for VPNs
router bgp 1
neighbor 1.2.3.4 update-source loopback 0
redistribute {rip|connected|static|eigrp|ospf}
PE-RR (VPN Routes to VPNv4)
If PE-CE Protocol Is non-BGP, then Redistribution of Local
VPN Routes into MP-IBGP Is Required (Shown Below)
PE1
RR
CE1
Site 1
Reference
PE1

MPLS VPN Sample Configuration (IOX)
vrf VPN-A
router-id 192.168.10.1
address-family ipv4 unicast
import route-target 100:1
export route-target 100:1
export route-policy raj-exp
interface Serial0
vrf VPN-A
ipv4 address 192.168.10.1/24
VRF Definition
PE1
router bgp 1
vrf VPN-A
rd 1:1
redistribute connected
!
neighbor 192.168.10.2
remote-as 2
route-policy raj-temp in
!
!
!
!
PE-CE Routing: BGP
PE1
10.1.1.0/24
PE1
CE1
Site 1
192.168.10.1
Se0
10.1.1.0/24
PE1
Site 1
192.168.10.1
192.168.10.2
CE1
Reference

Agenda
1. Load-Sharing for Multihomed VPN Sites
2. Hub and Spoke Service
3. MPLS VPN Extranet Service
4. Internet Access Service
5. VRF-Aware NAT Services
6. VRF-Selection Based Services
7. Remote VPN Access Service
8. QoS Service
9. Multicast VPN Service
10. MPLS/VPN over IP Transport
11. IPv6 VPN Service
12. Multi-VRF CE Service
 Best Practices
 Conclusion

PE11
PE2
MPLS Backbone
PE12
CE1
Site A
171.68.2.0/24
Site B
CE2
RR
MPLS VPN Services:
1. Loadsharing for the VPN Traffic
 VPN sites (such as Site A) could be multihomed
 VPN customer may demand the traffic (to the
multihomed site) be loadshared
Route Advertisement

MPLS VPN Services:
1. Loadsharing for the VPN Traffic: Cases
PE2
MPLS Backbone
CE2
Traffic Flow
1 CE 2 PEs
CE1
Site A
171.68.2.0/24
PE11
RR
PE12
Site B
Site A
171.68.2.0/24
2 CEs  2 PEs
PE11
PE2
MPLS Backbone
PE12
Site B
CE2
RR
Traffic Flow
CE2
CE1

MPLS VPN Services:
1. Loadsharing for the VPN Traffic: Deployment
 Configure unique RD per VRF per PE for multihomed site/interfaces
Assuming RR exists
 Enable BGP multipath within the relevant BGP VRF address-family
at remote PE routers such as PE2 (why PE2?).
PE11
PE2
MPLS Backbone
PE12
CE1
Site A
171.68.2.0/24
Site B
CE2
RR
ip vrf green
rd 300:11
route-target both 1:1
1
ip vrf green
rd 300:12
1
router bgp 1
address-family ipv4 vrf green
maximum-paths eibgp 2
2
ip vrf green
rd 300:13
1

!
ip vrf green
rd 300:11
protection local-prefixes
!
MPLS VPN Services:
1. VPN Fast Convergence—PE-CE Link Failure
 In a classic multi-homing case, PE11, upon detecting the PE-CE
link failure, sends BGP message to withdraw the VPN routes
towards other PE routers.
This results in the remote PE routers selecting the alternate bestpath
(if any), but until then, they keep sending the MPLS/VPN traffic to PE11,
which keeps dropping the traffic.
 Cisco has implemented a fast local repair feature (referred to as
BGP local convergence) to minimize the loss due to the PE-CE
link failure from sec to msec .
PE11
PE2
MPLS Backbone
PE12
171.68.2.0/24
RR VPN Traffic
Redirected VPN Traffic
Traffic Is
Dropped
by PE11
CE1 CE2
Site A Site B

MPLS VPN Services:
1. VPN Fast Convergence—PE-CE Link Failure
 ‘BGP Local Convergence’ feature helps PE11 to minimize the traffic loss
from sec to msec, during local PE-CE link failure
PE11 immediately reprograms the forwarding entry with the alternate BGP best path (which
is via PE12)
PE11 redirects the CE1 bound traffic to PE12 (with the right label)
 In parallel, PE11 sends the ‘BGP withdraw message’ to RR/PE2, which
will run the bestpath algorithm and removes the path learned via PE11,
and then adjust their forwarding entries via PE12
 This feature is independent of whether multipath is enabled on PE2
or not, however, dependent on VPN site multihoming
PE2
MPLS Backbone
PE12
171.68.2.0/24
Traffic Is
Redirected
by PE11
VPN Traffic
Redirected VPN Traffic
Site A Site B
CE2CE1
PE11
RR

Agenda
8. QoS Service
 Best Practices
 Conclusion

MPLS-VPN Services:
 Many VPN deployments need to be hub and spoke
Spoke to spoke communication via Hub site only
 Despite MPLS VPN’s implicit any-to-any, i.e.,
full-mesh connectivity, hub and spoke service
can easily be offered
Done with import and export of route-target (RT) values
Requires unique RD per VRF per PE
 PE routers can run any routing protocol with VPN
customer’ hub and spoke sites independently

MPLS-VPN Services:
 Two configuration Options :
1. 1 PE-CE interface to Hub & 1 VRF;
2. 2 PE-CE interfaces to Hub & 2 VRFs;
 Use option#1 if Hub site advertises default or
summary routes towards the Spoke sites, otherwise
use Option#2
 HDVRF feature* allows the option#2 to use just one
PE-CE interface
* HDVRF feature is discussed later

MPLS-VPN Services:
2. Hub and Spoke Service: Configuration – Option#1
PE-SA
PE-Hub
MPLS VPN Backbone
PE-SB
CE-SA
CE-SBSpoke B
Spoke A
171.68.1.0/24
171.68.2.0/24
Eth0/0
ip vrf green-spoke1
description VRF for SPOKE A
rd 300:111
ip vrf green-spoke2
description VRF for SPOKE B
rd 300:112
ip vrf HUB
description VRF for HUB
rd 300:11
Note: Only VRF Configuration Is Shown Here
CE-Hub
Import and export RT
values must be different

MPLS-VPN Services:
PE-SA
PE-Hub
MPLS VPN Backbone
PE-SB
CE-SA
CE-SBSpoke B
Spoke A
171.68.1.0/24
171.68.2.0/24
Eth0/0.2
Eth0/0.1
ip vrf green-spoke1
rd 300:111
ip vrf green-spoke2
rd 300:112
ip vrf HUB-OUT
description VRF for traffic to HUB
rd 300:12
ip vrf HUB-IN
description VRF for traffic from HUB
rd 300:11
CE-Hub
Import and export RT
values must be different
Note: Only VRF Configuration Is Shown Here

MPLS-VPN Services:
 If BGP is used between every PE and CE, then
allowas-in and as-override* knobs must be used at
the PE_Hub**
Otherwise AS_PATH looping will occur
* Only if Hub and Spoke sites use the same BGP ASN
** Configuration for this Is Shown on the Next Slide

router bgp <ASN>
address-family ipv4 vrf HUB-OUT
neighbor <CE> allowas-in 2
MPLS-VPN Services:
PE-SA
PE-Hub
MPLS VPN Backbone
PE-SB
CE-SA
CE-SB
Spoke B
Spoke A
171.68.1.0/24
171.68.2.0/24
Eth0/0.2
Eth0/0.1
ip vrf green-spoke1
rd 300:111
ip vrf green-spoke2
rd 300:112
ip vrf HUB-OUT
rd 300:12
router bgp <ASN>
address-family ipv4 vrf HUB-IN
neighbor <CE> as-override
ip vrf HUB-IN
rd 300:11
CE-Hub

MPLS-VPN Services:
2. Hub and Spoke Service: Control Plane (Option#2)
 Two VRFs at the PE-Hub:
VRF HUB-IN to learn every spoke routes from remote PEs
VRF HUB-OUT to advertise spoke routes or summary 171.68.0.0/16 routes to
remote PEs
PE-SA
MPLS Backbone
PE-SB
CE-SA
CE-SB
Spoke B
Spoke A
VRF HUB-OUT
VRF HUB-IN
VRF HUB-IN FIB and LFIB
Destination NextHop Label
171.68.1.0/24 PE-SA 40
171.68.2.0/24 PE-SB 50
171.68.1.0/24
171.68.2.0/24
VRF HUB-OUT FIB
Destination NextHop
171.68.0.0/16 CE-H1
MP-iBGP update
171.68.0.0/16
Label 35
Route-Target 2:2
FIB—IP Forwarding Table
LFIB—MPLS Forwarding Table
MP-iBGP update
171.68.2.0/24
Label 50
Route-Target 1:1
MP-iBGP update
171.68.1.0/24
Label 40
Route-Target 1:1
PE-Hub
CE-Hub
VRF FIB and LFIB
Destination NextHop Label
171.68.0.0/16 PE-Hub 35
171.68.1.0/24 CE-SA
VRF FIB and LFIB
171.68.0.0/16 PE-Hub 35
171.68.2.0/24 CE-SB

PE-SA
PE-Hub
MPLS Backbone
MPLS-VPN Services:
2. Hub and Spoke Service: Forwarding Plane (option#2)
PE-SB
CE-SA
CE-SB
Spoke B
Spoke A
VRF HUB-OUT
VRF HUB-IN
171.68.1.0/24
171.68.2.0/24
L1 35 171.68.1.1
L2 40 171.68.1.1
171.68.1.1
L1 Is the Label to Get to PE-Hub
L2 Is the Label to Get to PE-SA
This Is How The Spoke-to-Spoke Traffic Flows
171.68.1.1
171.68.1.1
171.68.1.1
CE-Hub

MPLS-VPN Services:
2. What if many spoke sites connect to the same PE router?
 If more than one spoke router (CE) connects to the
same PE router (within the same VRF), then such
spokes can reach other without needing the hub.
Defeats the purpose of hub and spoke 
 Half-duplex VRF is the answer
Uses two VRFs on the PE (spoke) router :
A VRF for spoke->hub communication (upstream)
A VRF for spoke<-hub communication (downstream)
Note- 12.2(33)SRE supports any interface type (Eth, Ser etc.)
PE-SA
CE-SA1
CE-SA2
CE-SA3
PE-Hub

PE-SA
PE-Hub
MPLS Backbone
MPLS-VPN Services:
2. Hub and Spoke Service: Half-Duplex VRF
CE-SA
CE-SB
Spoke B
Spoke A
171.68.1.0/24
171.68.2.0/24
PE-SA installs the spoke routes only in downstream VRF i.e. green-down
PE-SA forwards the incoming IP traffic (from Spokes) using the upstream
VRF i.e. green-up routing table.
ip vrf HUB-OUT
rd 300:12
Int virtual-template1
….
ip vrf forward green-up downstream green-down
…
Upstream VRF Downstream VRF
ip vrf green-up
description VRF – upstream flow
rd 300:111
ip vrf green-down
description VRF – downstream flow
rd 300:112
route-target export 1:1 ip vrf HUB-IN
rd 300:11
CE-Hub

Agenda
8. QoS Service
 Best Practices
 Conclusion

MPLS-VPN Services
3. Extranet VPN
 MPLS VPN, by default, isolates one VPN customer
from another
Separate virtual routing table for each VPN customer
 Communication between VPNs may be required
i.e., extranet
External intercompany communication (dealers with
manufacturer, retailer with wholesale provider, etc.)
Management VPN, shared-service VPN, etc.
 Needs to share the import and export route-target
(RT) values within the VRFs of extranets.
Export-map or import-map may be used for advanced
extranet.

VPN_B Site#1
180.1.0.0/16
MPLS-VPN Services
3. Extranet VPN – Simple Extranet
71.8.0.0/16 PE1 PE2
MPLS Backbone
VPN_A Site#2
P
VPN_A Site#1
ip vrf VPN_A
rd 3000:111
ip vrf VPN_B
rd 3000:222
192.6.0.0/16
All Sites of Both VPN_A and VPN_B can Communicate
with Each Other.

VPN_B Site#1
180.1.0.0/16
MPLS-VPN Services
3. Extranet VPN – Advanced Extranet
71.8.0.0/16 PE1 PE2
MPLS Backbone
VPN_A Site#2
P
VPN_A Site#1
ip vrf VPN_A
rd 3000:111
import map VPN_A_Import
export map VPN_A_Export
!
route-map VPN_A_Export permit 10
match ip address 1
set extcommunity rt 3000:2 additive
!
route-map VPN_A_Import permit 10
match ip address 2
!
access-list 1 permit 71.8.0.0 0.0.0.0
ip vrf VPN_B
rd 3000:222
import map VPN_B_Import
export map VPN_B_Export
!
route-map VPN_B_Export permit 10
match ip address 2
set extcommunity rt 3000:1 additive
!
route-map VPN_B_Import permit 10
match ip address 1
!
192.6.0.0/16
Only Site #1 of Both VPN_A and VPN_B Would Communicate
with Each Other.
Lack of ‘additive’
would result in
3000:222 being
replaced with
3000:1. We don’t
want that.

Agenda
8. QoS Service to VPNs
 Best Practices
 Conclusion

MPLS-VPN Services
4. Internet Access Service to VPN Customers
 Internet access service could be provided as
another value-added service to VPN customers
 Security mechanism must be in place at both
provider network and customer network
To protect from the Internet vulnerabilities
 VPN customers benefit from the single point of
contact for both Intranet and Internet connectivity

MPLS-VPN Services
4. Internet Access: Design Options
Four options to Provide the Internet Service -
1. VRF specific default route with “global” keyword
2. Separate PE-CE sub-interface (non-VRF)
3. Extranet with Internet-VRF
4. VRF-aware NAT

MPLS-VPN Services
4. Internet Access: Design Options
1. VRF specific default route
1.1 Static default route to move traffic from VRF to Internet
(global routing table)
1.2 Static routes for VPN customers to move traffic from Internet (global
routing table) to VRF
2. Separate PE-CE subinterface (non-VRF)
May run BGP to propagate Internet routes between PE and CE
3. Extranet with Internet-VRF
VPN packets never leave VRF context; issue with overlapping VPN
address
4. Extranet with Internet-VRF along with VRF-aware NAT
VPN packets never leave VRF context; works well with overlapping
VPN address

192.168.1.2
 A default route, pointing to the
ASBR, is installed into the site
VRF at each PE
 The static route, pointing to the
VRF interface, is installed in the
global routing table and
redistributed into BGP
PE1
ASBR
CE1
MPLS Backbone
192.168.1.1
Internet GW
SO
P
PE1#
ip vrf VPN-A
rd 100:1
Interface Serial0
ip address 192.168.10.1 255.255.255.0
Router bgp 100
no bgp default ipv4-unicast
redistribute static
neighbor 192.168.1.1 remote 100
neighbor 192.168.1.1 next-hop-self
ip route vrf VPN-A 0.0.0.0 0.0.0.0 192.168.1.1 global
ip route 71.8.0.0 255.255.0.0 Serial0
Site1
Internet71.8.0.0/16
MPLS-VPN Services: Internet Access
4.1 Option#1: VRF Specific Default Route

Cons
 Using default route
for Internet
 Routing does not allow any other
default route for intra-VPN routing
Increasing size
of global routing table by leaking
VPN routes
 Static configuration (possibility of
traffic blackholing)
4.1 Option#1: VRF Specific Default Route
(Forwarding)
71.8.0.0/16
PE1 PE2S0
P
PE1: VRF Routing/FIB Table
Destination Label/Interface
0.0.0.0/0 192.168.1.1 (global)
Site-1 Serial 0
PE1: Global Routing/FIB Table
192.168.1.1/32 Label=30
71.8.0.0/16 Serial 0
Internet
(5.1.0.0/16)
PE2: Global Table and LFIB
192.168.1.2/32 Label=35
71.8.0.0/16 192.168.1.2
5.1.0.0/16 Serial 0
192.168.1.2
Pros
 Different Internet gateways
 Can be used for
different VRFs
 PE routers need not to
hold the Internet table
 Simple configuration
Site1
S0
MPLS Backbone
192.168.1.1
5.1.1.130
MPLS Packet
5.1.1.1
IP Packet
71.8.1.135
5.1.1.1
IP Packet
71.8.1.1 IP Packet71.8.1.1
MPLS Packet
71.8.1.1
IP Packet

 PE1-CE1 has one sub-interface
associated to a VRF for VPN routing
 PE1-CE has another subinterface
(global) for Internet routing
 PE1 may have eBGP peering with
CE1 over the global interface and
advertise full Internet routes or a
default route to CE1
 PE2 must advertise VPN/site1 routes
to the Internet.
ip vrf VPN-A
rd 100:1
Interface Serial0.1
ip address 192.168.20.1 255.255.255.0
frame-relay interface-dlci 100
!
Interface Serial0.2
ip address 71.8.10.1 255.255.0.0
frame-relay interface-dlci 200
!
Router bgp 100
no bgp default ipv4-unicast
71.8.0.0/16
CE1
MPLS Backbone
Internet GW
Se0.2
P
iBGP
Site1
Se0.1
InternetInternet
4.2 Option#2: Separate PE-CE Subinterfaces
192.168.1.2
192.168.1.1
PE1 PE2

CE Routing Table
VPN Routes Serial0.1
Internet Routes Serial0.2
PE1 Global Table and FIB
Internet Routes 192.168.1.1
192.168.1.1 Label=30
Pros
1. CE is dual-homed and can
perform Optimal Routing
2. Traffic Separation Done
by CE
Cons
1. PE to Hold Full Internet Routes
or default route via the Internet
GW
. BGP Complexities Introduced at
CE; CE1 May Need to Aggregate
to Avoid AS_PATH Looping
71.8.0.0/16
MPLS Backbone
PE-Internet GW
S0.2
P
Site1
S0.1
InternetInternet
4.2 Option#2: Separate PE-CE Subinterfaces
(Forwarding)
192.168.1.2
192.168.1.1
PE1 PE2
5.1.1.1
IP Packet
5.1.1.130
MPLS Packet 5.1.1.1
IP PacketCE1

4.3 Option#3: Extranet with Internet-VRF
 The Internet routes could be placed within the VRF
at the Internet-GW i.e., ASBR
 VRFs for customers could ‘extranet’ with the
Internet VRF and receive either default, partial or
full
Internet routes
 Be careful if multiple customer VRFs, at the same
PE, are importing full Internet routes
 Works well only if the VPN customers don’t have
overlapping addresses

4.4 Option#4: Using VRF-Aware NAT
 If the VPN customers need Internet access without
Internet routes, then VRF-aware NAT can be used
at the Internet-GW i.e., ASBR
 The Internet GW doesn’t need to have Internet
routes either
 Overlapping VPN addresses is no longer a problem
 More in the “VRF-aware NAT” slides…

Agenda
8. QoS Service
 Best Practices
 Conclusion

MPLS-VPN Services
 VPN customers could be using ‘overlapping’ IP
address i.e.,10.0.0.0/8
 Such VPN customers must NAT their traffic before
using either “Extranet” or “Internet” or any shared*
services
 PE is capable of NATting the VPN packets
(eliminating the need for an extra NAT device)
* VoIP, Hosted Content, Management, etc.

MPLS-VPN Services
 Typically, inside interface(s) connect to private
address space and outside interface(s) connect to
global address space
NAT occurs after routing for traffic from inside-to-outside
interfaces
NAT occurs before routing for traffic from outside-to-inside
interfaces
 Each NAT entry is associated with the VRF
 Works on VPN packets in the following switch
paths: IP->IP, IP->MPLS and MPLS->IP

Internet
217.34.42.2.1
MPLS-VPN Services:
5. VRF-Aware NAT Services: Internet Access
PE-ASBR
MPLS Backbone
CE1
Blue VPN Site
10.1.1.0/24
CE2
10.1.1.0/24
Green VPN Site
IP NAT Inside
IP NAT Outside
VRF-Aware NAT Specific ConfigVRF Specific Config
ip nat pool pool-green 24.1.1.0 24.1.1.254 prefix-length 24
ip nat pool pool-blue 25.1.1.0 25.1.1.254 prefix-length 24
ip nat inside source list vpn-to-nat pool pool-green vrf green
ip nat inside source list vpn-to-nat pool pool-blue vrf blue
ip access-list standard vpn-to-nat
permit 10.1.1.0 0.0.0.255
ip route vrf green 0.0.0.0 0.0.0.0 217.34.42.2 global
ip route vrf blue 0.0.0.0 0.0.0.0 217.34.42.2 global
ip vrf green
rd 3000:111
ip vrf blue
rd 3000:222
router bgp 3000
address-family ipv4 vrf green
network 0.0.0.0
address-family ipv4 vrf blue
network 0.0.0.0
P
PE11
PE12

MPLS-VPN Services:
MPLS Backbone
P
Traffic Flows
Internet
Src=10.1.1.1
Dest=Internet
Src=24.1.1.1
Dest=Internet
Src=10.1.1.1
Dest=Internet
Label Stack 30
Src=10.1.1.1
Dest=Internet
IP Packet
MPLS Packet
NAT Table
VRF IP Source Global IP VRF-Table-Id
10.1.1.1 24.1.1.1 green
10.1.1.1 25.1.1.1 blue
 PE-ASBR removes the label from the
received MPLS packets per LFIB
 Performs NAT on the resulting
IP packets
 Forwards the packet to the internet
 Returning packets are NATed and
put back in the VRF context and
then routed
 This is also one of the ways to provide
Internet access to VPN customers
with or without overlapping addresses
PE11
PE12
PE-ASBR
CE1
Green VPN Site
10.1.1.0/24
CE2
Blue VPN Site
10.1.1.0/24
Src=25.1.1.1
Dest=Internet
IP Packet
Label Stack 40
Src=10.1.1.1
Dest=Internet

MPLS-VPN Services:
 The previous example uses one of many variations
of NAT configuration
 Other variations (few below) work fine as well
Extended vs. standard ACL for traffic classification
PAT (e.g. overload config)
Route-map instead of ACL for traffic classification
Single NAT pool instead of two pools
Reference

Agenda
8. QoS Service
 Best Practices
 Conclusion

MPLS VPN Service
6. VRF-Selection
 The common notion is that a single VRF must be
associated to an interface
 “VRF-selection” breaks this association and
enables multiple VRFs associated to an interface
 Each packet on PE-CE interface is classified in
real-time and mapped to one of many VRFs
Classification criteria could be source/dest IP address, ToS,
TCP port, etc. specified in the ACL
 Voice and data traffic on a single PE-CE interface
can be separated out into different VRFs at the PE;
service enabler
Reference

MPLS VPN Service
6. VRF-Selection: Based on Source IP Address
PE1 PE2MPLS Backbone
(Cable Company)
CE1
RR
44.3.12.1 66.3.0.0/16
VPN Green
33.3.14.1
44.3.0.0/16
VPN Yellow
Global Interface
Se0/0
Cable
Setup
VRF Interfaces
Traffic Flows
ip vrf red
rd 3000:111
!
ip vrf yellow
rd 3000:222
!
ip vrf green
rd 3000:333
route-map PBR-VRF-Selection permit 10
match ip address 40
set vrf red
!
match ip address 50
set vrf yellow
!
match ip address 100
set vrf green
interface Serial0/0
ip address 215.2.0.6 255.255.255.252
ip policy route-map PBR-VRF-Selection
ip vrf receive red
ip vrf receive yellow
ip vrf receive green
!
access-list 100 permit udp 33.3.1.0 0.0.0.255 any
dscp ef range 30000 31000
!
ip route vrf red 33.3.14.0 0.0.0.255 Se0/0
ip route vrf yellow 44.3.1.0 0.0.0.255 Se2/0
ip route vrf green 33.3.1.0 0.0.0.255 Se2/0
33.3.0.0/16
VPN Brown
Reference
33.3.1.25

Agenda
8. QoS Service
 Best Practices
 Conclusion

MPLS VPN Service
7. Remote Access Service
 Remote access users i.e., dial users, IPSec users could
directly be terminated in VRF
PPP users can be terminated into VRFs
IPSec tunnels can be terminated into VRFs
 Remote access services integration with MPLS VPN opens up
new opportunities for providers and VPN customers
BRKSEC-3005 Deploying Remote-Access IPSec/SSL VPNs
BRKSEC-3006 Deploying Site-to-site VPN with DMVPN
 “Remote Access” is not to be confused by “GET VPN” that
provides any-to-any (CE-based) security service
BRKSEC-2007 Site to Site VPN with GET VPN
Reference

Internet
MPLS VPN Service
7. Remote Access Service: IPSec to MPLS VPN
Corporate IntranetBranch
Office
Access
Remote Users/
Telecommuters
MPLS VPNIPSec SessionIP IP
Cable/DSL/
ISDN ISP
IP/MPLS/Layer 2
Based Network
VPN A
VPN B
SP Shared Network
Customer B
Customer A
Head Office
Customer C
PE
PE
VPN C
SOHO
Local or
Direct
Dial ISP
Cisco IOS VPN
Routers or Cisco
Client 3.x or higher
Customer A
Branch Office
PE
SP AAA Customer
AAAPE+IPSec
Aggregator
VPN A
IKE_ID is
used to map
the IPSec
tunnel to
the VRF
(within the
ISAKMP
profile)
Reference

Agenda
6. Remote VPN Access
8. QoS Service
 Best Practices
 Conclusion

MPLS-VPN Services:
8. Providing QoS to VPN Customers
 VPN customers may want SLA so as to treat
real-time, mission-critical and best-effort traffic appropriately
 QoS can be applied to VRF interfaces
- Just like any global interface
- Same old QoS mechanisms are applicable
 Remember—IP precedence bits are copied to MPLS EXP bits
(default behavior)
 MPLS Traffic-Eng could be used to provide the bandwidth-on-
demand or Fast Rerouting to VPN customers
BRKIPM-2104 Deploying MPLS Traffic Engineering
BRKIPM-3071 Advanced MPLS Designs
BRKIPM-2018 QoS Decomposed
Reference

Agenda
6. Remote VPN Access
8. QoS Service
 Best Practices
 Conclusion

MPLS-VPN Services:
9. Providing Multicast Service to VPNs
 Multicast VPN service is also available for
deployment
Current deployment model utilizes GRE encapsulation
(not MPLS) within SP network
 Multicast VPN also utilizes the existing 2547
infrastructure
 MPLS multicast i.e., mLDP and P2MP TE, is not far
away either
 Please see the following session for details on
mVPN:
BRKIPM-2261 Deploying IP Multicast
BRKIPM-3261 Advances in IP Multicast
Reference

Agenda
6. Remote Access MPLS VPN
9. Multicast Service to VPNs
 Best Practices
 Conclusion

MPLS-VPN Services:
10. Providing MPLS/VPN over IP Transport
 MPLS/VPN (rfc2547) can also be deployed using
IP transport
No MPLS needed in the core
 PE-to-PE IP tunnel is used, instead of MPLS tunnel,
for sending MPLS/VPN packets
MPLS labels are still allocated for VPN prefixes by PE
routers and used only by the PE routers
MPLS/VPN packet is encapsulated inside an IP header
 IP tunnel could be GRE, mGRE etc.
Reference
http://www.cisco.com/en/US/docs/ios/interface/configuration/guide/ir_mplsvpnomgre.html

IP Header
GRE Header
VPN Label
src add
dst add
data
src add
dst add
data
src add
dst add
data
IP
CE1 CE2PE1 PE2
VRF
MPLS-VPN Services:
10. Providing MPLS/VPN over IP Transport
 GRE/IP header and VPN label imposed on VPN traffic by PE1
 VPN traffic is forwarded towards egress PE using IP forwarding
 Egress PE2 decapsulates, and uses VPN label to forward packet to CE2
GRE/IP Tunnel
Reference
VRF
http://www.cisco.com/en/US/docs/ios/interface/configuration/guide/ir_mplsvpnomgre.html
IP Packet

Agenda
 Best Practices
 Conclusion

MPLS-VPN Services:
 Similar to IPv4 VPN, IPv6 VPN can also be offered.
Referred to as “IPv6 VPN Provider Edge (6VPE)”.
 No modification on the MPLS core.
IPv4 and IPv6 VPNs can be offered on the same interface
 Config and operation of IPv6 VPN are similar to IPv4 VPN
P
P
P
P
iBGP Sessions in VPNv4 and
VPNv6 address-families
VPN B
VPN A
v4 and v6
VPN A
v6 Only
v4 and v6
VPN B
VPN A
v6 Only
v4 and v6
MPLS/VPN
Network
PE PE
PE PE
CE
CE
CE
CE
CE

MPLS-VPN Services:
P
P
P
P
iBGP Sessions in VPNv4 and
VPNv6 address-families
VPN B
VPN A
v4 and v6
VPN A
v6 Only
v4 and v6
VPN B
VPN A
v6 Only
v4 and v6
MPLS/VPN
Network
PE PE
PE PE
CE
CE
CE
CE
CE
PE#
!
vrf definition v2
rd 2:2
!
address-family ipv4
exit-address-family
!
address-family ipv6
exit-address-family
!
!
router bgp 1
!
exit-address-family
!
exit-address-family
!
address-family ipv4 vrf v2
exit-address-family
!
address-family ipv6 vrf v2
neighbor 200::2 remote-as 30000
neighbor 200::2 activate
exit-address-family
!

Agenda
 Best Practices
 Conclusion

MPLS-VPN Services:
12. Providing Multi-VRF CE Service
 Is it possible for an IP router to keep multiple customer
connections separated ?
Yes, “multi-VRF CE” a.k.a. vrf-lite can be used
 “Multi-VRF CE” provides multiple virtual routing tables
(and forwarding tables) per customer at the CE router
Not a feature but an application based on VRF implementation
Any routing protocol that is supported by normal VRF can be used in
a multi-VRF CE implementation
 No MPLS functionality needed on CE, no label exchange
between CE and any router (including PE) 
 One deployment model is to extend the VRFs to the CE,
another is to extend it further inside the Campus =>
Virtualization

MPLS-VPN Services:
12. Providing Multi-VRF CE Service
Campus
PE
MPLS
Network
Multi-VRF
CE Router
SubInterface
Link *
PE
Router
Campus
One Deployment Model—Extending MPLS/VPN to CE
Vrf Green
Vrf Red
Vrf
Green
ip vrf green
rd 3000:111
ip vrf blue
rd 3000:222
ip vrf red
rd 3000:333
Vrf Green
Vrf Red
*SubInterface Link—Any Interface Type that Supports Sub Interfaces, FE-Vlan,
Frame Relay, ATM VCs
Vrf
Red
ip vrf green
rd 3000:111
ip vrf blue
rd 3000:222
Ip vrf red
rd 3000:333

Agenda
 Best Practices
 Conclusion

Best Practices
1. Use RR to scale BGP; deploy RRs in pair for the redundancy
Keep RRs out of the forwarding paths and disable CEF (saves memory)
2. Choose AS format for RT and RD i.e., ASN: X
Reserve first few 100s of X for the internal purposes such as filtering
3. Consider unique RD per VRF per PE,
Helpful for many scenarios such as multi-homing, hub&spoke etc.
4. Don’t use customer names (V458:GodFatherNYC32ndSt) as the
VRF names; nightmare for the NOC.
Consider v101, v102, v201, v202, etc. and Use description for naming
5. Utilize SP’s public address space for PE-CE IP addressing
Helps to avoid overlapping; Use /31 subnetting on PE-CE interfaces
6. Limit the number of prefixes per-VRF and/or per-neighbor on PE
Max-prefix within the VRF configuration; Do suppress the inactive routes
Max-prefix per neighbor within the BGP VRF af (if BGP on the PE-CE)

Best Practices
7. Leverage BGP Prefix Independent Convergence (PIC) for fast
convergence
• PIC Core and PIC Edge
• Best-external advertisement
• Next-hop tracking (ON by default)
8. Consider RT-constraint for Route-reflector scalability

Agenda
 Best Practices
 Conclusion

Conclusion
 MPLS VPN is becoming a cheaper and faster alternative to
traditional l2vpn
Secured VPN
 Straightforward to configure any-to-any VPN topology
Partial-mesh, Hub and Spoke topologies can also be
easily deployed
 VRF-aware services could be deployed to maximize
the investment
CsC and Inter-AS could be used to expand into
new markets.
 MPLS-VPN paves the way for virtualization.
Benefits whether SP or Enterprise.

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Additional Slides
Advanced MPLS VPN Topics
Inter-AS and CsC

Agenda
 Advanced MPLS VPN Topics
Inter-AS MPLS-VPN
CsC Carrier Supporting Carrier

What Is Inter-AS?
VPN-A VPN-A
PE-1
PE2
CE2CE-1
AS #1 AS #2
149.27.2.0/24
MP-iBGP Update:
BGP, OSPF, RIPv2
149.27.2.0/24, NH=CE-1
Problem:
How Do Provider
X and Provider Y
Exchange VPN
Routes?
???
ASBR1 ASBR2
RR2RR1
Provider X Provider Y

4. Non-VPN Transit Provider
1. Back-to-Back VRFs
(Option A)
2. MP-eBGP for VPNv4
(Option B)
3. Multihop MP-eBGP Between RRs
(Option C)
Inter-AS Deployment Scenarios
PE1 PE2
CE2
Following Options/Scenarios
for Deploying Inter-AS:
AS #1 AS #2
ASBR1 ASBR2
CE1
Each Option Is Covered in Additional Slides
VPN-A VPN-A

Scenario 1: Back-to-Back VRF
Control Plane
PE-1 PE-2
VPN-B
CE-2 CE-3
VPN-B
VRF-to-VRF Connectivity Between ASBRs
ASBR-1 ASBR-2
10.1.1.0/24
BGP, OSPF, RIPv2
10.1.1.0/24,NH=CE-2
VPN-v4 Update:
RD:1:27:10.1.1.0/24
NH=PE-1
RT=1:1, Label=(29)
VPN-B VRF
Import routes with
Route-Target 1:1
VPN-v4 Update:
RD:1:27:10.1.1.0/24,
NH=ASBR-2
RT=1:1, Label=(92)
BGP, OSPF, RIPv2
10.1.1.0/24,NH=PE-2
VPN-B VRF
Import Routes with
Route-Target 1:1
BGP, OSPF, RIPv2
10.1.1.0/24
NH=ASBR-2

 Not scalable. # of interface on both
ASBRs is directly proportional to #VRF.
 No end-to-end MPLS
 Unnecessary memory consumed in
RIB/(L)FIB
 Dual-homing of ASBR makes
provisioning worse
Scenario 1: Back-to-Back VRF
Forwarding Plane
PE-1 PE-2
VPN-B
CE-2 CE-3
VPN-B
ASBR-1 ASBR-2
10.1.1.0/24
10.1.1.1
10.1.1.1
10.1.1.1
10.1.1.12930
10.1.1.19220
P2
P1
10.1.1.192
IP Packets
Between ASBRs
 Per-customer QoS is possible
 It is simple and elegant since no need
to load the Inter-AS code (but still not
widely deployed)
Pros Cons

Cisco IOS Configuration
Scenario 1: Back-to-Back VRF Between ASBRs
AS #1 AS #2
VRF Routes Exchange via
any Routing Protocol
1.1.1.0/30
ip vrf green
rd 1:1
!
Router bgp x
Address-family ipv4 vrf green
neighbor 1.1.1.x activate
ASBR VRF and BGP config
VPN-A
PE1
CE-1
VPN-A
CE-2
PE2
ASBR1 ASBR2
Note: ASBR Must Already Have MP-iBGP Session with iBGP Neighbors such as RRs or PEs

Scenario 2: MP-eBGP Between ASBRs
to Exchange VPNv4 Routes
 New CLI “no bgp default route-target filter” is
needed on the ASBRs
 ASBRs exchange VPN routes using eBGP (VPNv4
af)
 ASBRs store all VPN routes
But only in BGP table and LFIB table
Not in routing nor in CEF table
 ASBRs don’t need
VRFs to be configured on them
LDP between them

PE-1 PE-2
VPN-B
CE-2 CE-3
VPN-B
ASBR-1 ASBR-2
10.1.1.0/24
BGP, OSPF, RIPv2
10.1.1.0/24, NH=CE-2
MP-iBGP Update:
RD:1:27:10.1.1.0/24,
NH=PE-1
RT=1:1, Label=(40)
MP-iBGP Update:
RD:1:27:10.1.1.0/24,
NH=ASBR-2
RT=1:1, Label=(30)MP-eBGP Update:
RD:1:27:10.1.1.0/24,
NH=ASBR-1
RT=1:1, Label=(20)
BGP, OSPF, RIPv2
10.1.1.0/24, NH=PE-2
Scenario 2: MP-eBGP bet ASBRs
for VPN Control Plane

Scenario 2: MP-eBGP bet ASBRs
for VPN Forwarding Plane
 More scalable
Only one interface between
ASBRs routers
No VRF configuration on ASBR.
Less memory consumption (no RIB/FIB memory)
 MPLS label switching between providers
Still simple, more scalable & works today
PE-1
VPN-B
CE-2 CE-3
VPN-B
ASBR-1 ASBR-2
10.1.1.0/24
10.1.1.1
10.1.1.13020
10.1.1.130
P2
20 10.1.1.1
MPLS Packets
Between ASBRs
10.1.1.14030
10.1.1.140
10.1.1.1
Pros Cons
 Automatic route filtering must
be disabled
But we can apply BGP filtering
 ASBRs are still required to hold
VPN routes

Scenario 2: External MP-BGP between ASBRs for
VPN
AS #1 AS #2
1.1.1.0/30
VPN-A
PE1
CE-1
VPN-A
CE-2
PE2
ASBR1 ASBR2
MP-eBGP for
VPNv4
Label Exchange
Between ASBRs
Using MP-eBGP
Router bgp x
no bgp default route-target filter
neighbor 1.1.1.x remote-as x
!
neighbor 1.1.1.x activate
neighbor 1.1.1.x send-com extended
ASBR MB-EBGP Configuration
Note: ASBR Must Already Have MP-iBGP Session with iBGP Neighbors such as RRs or PEs

Scenario 3: Multihop MP-eBGP Between
RRs to Exchange VPNv4 Routes
 Exchange VPNv4 prefixes via the Route Reflectors
Requires Multihop MP-eBGP (with next-hop-unchanged)
 Exchange IPv4 routes with labels between directly
connected ASBRs using eBGP
Only PE loopback addresses need to be exchanged (they
are BGP next-hop addresses of the VPN routes)

RRs for VPN Routes: Control Plane
PE-1 PE-2
VPN-B
CE-2
CE-3
VPN-B
ASBR-1
RR-2
AS#2
ASBR-2
RR-1
IP-v4 Update:
Network=PE-1
NH=ASBR-1
Label=(20)BGP, OSPF, RIPv2
10.1.1.0/24,NH=CE-2
10.1.1.0/24
VPN-v4 Update:
RD:1:27:10.1.1.0/24,
NH=PE-1
RT=1:1, Label=(90)
VPN-v4 Update:
RD:1:27:10.1.1.0/24,
NH=PE-1
RT=1:1, Label=(90)
VPN-v4 Update:
RD:1:27:10.1.1.0/24,
NH=PE-1
RT=1:1, Label=(90)
BGP, OSPF, RIPv2
10.1.1.0/24,NH=PE-2
AS#1
IGP+LDP:
Network=PE-1
NH=ASBR-2
Label=(30)
Note: Instead of IGP+Label, iBGP+Label Can Be Used to Exchange PE Routes/Label.
Please see Scenario#5 on slide#49 and 50.
IGP+LDP:
Network=PE-1
NH=PE-1
Label=(40)

RRs for VPN Routes: Forwarding Plane
PE-1
PE-2
VPN-B
CE-2 CE-3
VPN-B
RR-2
ASBR-2
RR-1
10.1.1.0/24
10.1.1.1
20 90 10.1.1.1
10.1.1.190
10.1.1.1
50 90 10.1.1.1
40 90 10.1.1.1
ASBR-1
P1 P2
Note: Instead of IGP+Label, iBGP+Label Can Be Used to Exchange PE Routes/Label.
90 10.1.1.130

Scenario 3: Pros/Cons
 More scalable than Scenario 1
and 2
Separation of control and
forwarding planes
 Route Reflector exchange
VPNv4 routes+labels
RR hold the VPNv4
information anyway
 ASBRs now exchange only
IPv4 routes+labels
ASBR forwards MPLS packets
 Advertising PE addresses
to another AS may not be
acceptable to few providers
Pros Cons

Scenario 3: Multihop MP-eBGP between RRs for VPN
VPN-A
PE1
VPN-A
PE2
CE-2CE-1
ASBR-1
RR-2
AS #1 AS #2
Multihop MP-eBGP
for VPNv4 with
next-hop-unchange
ASBR-2
RR-1
eBGP IPv4 + Labels
iBGPipv4+label Could Also Be Used in Within Each AS (Instead of
“network <x.x.x.x>”) to Propagate the Label Information for PEs
router ospf x
redistribute bgp 1 subnets
!
router bgp x
neighbor < ASBR-x > remote-as x
!
address-family ipv4
Network <PEx> mask 255.255.255.255
Network <RRx> mask 255.255.255.255
neighbor < ASBR-x > activate
neighbor < ASBR-x > send-label
router bgp x
neighbor <RR-x> remote-as x
neighbor <RR-x> ebgp-multihop
neighbor <RR-x> update loopback 0
!
neighbor <RR-x> activate
neighbor <RR-x> send-com extended
neighbor <RR-x> next-hop-unchanged
RR Configuration ASBR Configuration

Scenario 4: Non-VPN Transit Provider
 Two MPLS VPN providers may exchange routes via
one or more transit providers
Which may be non-VPN transit backbones just running
MPLS
 Multihop MP-eBGP deployed between edge
providers
With the exchange of BGP next-hops via the transit
provider

Scenario 4: Non-VPN Transit Provider
PE1
PE2VPN-B
CE-2
VPN-B
ASBR-1
RR-2
Non-VPN MPLS
Transit Backbone
Multihop MP-eBGP OR
MP-iBGP for VPNv4
ASBR-2
RR-1
ASBR-3
ASBR-4
next-hop-unchanged
eBGP IPv4 + Labels
eBGP IPv4 + Labels
MPLS VPN
Provider #1
MPLS VPN
Provider #2
iBGP IPv4 + Labels
CE-3
iBGP IPv4 + Labels

Route-Target Rewrite at ASBR
 ASBR can add/delete route-target associated with a
VPNv4 prefix
 Secures the VPN environment
ASBR(conf)#router bgp 1000
ASBR(conf-router)#neighbor 1.1.1.1 route-map route-target-deletion
out
ASBR(conf-router)#exit
ASBR(conf)#route-map route-target-delete
ASBR(conf-route-map)#match extcommunity 101
ASBR(conf-route-map)#set extcomm-list 101 delete
ASBR(conf-route-map)#set extcommunity rt 123:123 additive
ASBR(conf)# ip extcommunity-list 101 permit rt 100:100

Inter-AS Deployment Guidelines
1. Use ASN in the Route-target i.e., ASN:xxxx
2. Max-prefix limit (both BGP and VRF) on PEs
3. Security (BGP MD5, BGP filtering, BGP max-
prefix, etc.) on ASBRs
4. End-to-end QoS agreement on ASBRs
5. Route-target rewrite on ASBR
6. Internet connectivity on the same ASBR??

Agenda
 Advanced MPLS VPN Topics
Inter-AS MPLS-VPN
Carrier Supporting Carrier (CsC)

MPLS/VPN Networks Without CsC
 Number of VPN routes is one of the biggest limiting
factors in scaling the PE router
Few SPs are running into this scaling limitation
 If number of VPN routes can be reduced somehow
(without loosing the functionality), then the existing
investment can be protected
The same PE can still be used to connect more VPN
customers
 Carrier Supporting Carrier (CsC) provides the
mechanism to reduce the number of routes from
each VRF by enabling MPLS on the PE-CE link

CsC Deployment Model
PE1
PE2
ISP PoP
Site-1
CE-1 CE-2
ISP PoP
Site-2
MP-iBGP for VPNv4
Carrier’s MPLS Core
P1
ASBR-2
R1 R2
ISP Customers =
External Routes
Full-Mesh iBGP
for External Routes
ASBR-1
Internal Routes =
IGP Routes
Internal Routes =
IGP Routes
IGP+LDP
IGP+LDP
Internet
C1
MPLS-Enabled VRF Int
IPv4 Routes with
Label Distribution
IPv4 Routes with
Label Distribution

Benefits of CsC
 Provide transport for ISPs ($)
No need to manage external routes from ISPs
 Build MPLS Internet Exchange (MPLS-IX) ($$)
Media Independence; POS/FDDI/PPP possible
Higher speed such OC192 or more
Operational benefits
 Sell VPN service to subsidiary companies that
provide VPN service ($)

What Do I Need to Enable CsC ?
1. Build an MPLS-VPN enabled carrier’s network
2. Connect ISP/SPs sites (or PoPs) to the Carrier’s
PEs
3. Exchange internal routes + labels between
Carrier’s PE and ISP/SP’s CE
4. Exchange external routes directly between
ISP/SP’s sites

Internet
CsC Deployment Models
PE1
PE2
ISP PoP
Site-1
CE-1
CE-2
ISP PoP
Site-2
MP-iBGP for VPNv4
Carrier’s MPLS Core
P1
ASBR-2
R1
R2
ISP Customers =
External Routes
Full-Mesh iBGP
for External Routes
IPv4 Routes with
Label Distribution
ASBR-1
internal Routes
= IGP Routes
IGP+LDP
IGP+LDP
MPLS-Enabled VRF int
C1
Internal Routes =
IGP Routes
IPv4 Routes with
Label Distribution

CsC Deployment Models
1. Customer-ISP not running MPLS
2. Customer-ISP running MPLS
3. Customer-ISP running MPLS-VPN
Model 1 and 2 Are Less Common Deployments.
Model 3 Will Be Discussed in Detail.

PE1 PE2
ISP PoP
Site-1
CE-1
CE-2
ISP PoP
Site-2
MP-iBGP Update:
1:1:30.1.61.25/32, RT=1:1
NH =PE-1, Label=51
Carrier’s Core
P1
ASBR_PE-1
30.1.61.25/32
ASBR_PE-2
R1
R2Network =
10.1.1.0/24
MP-iBGP Update:
1:1:10.1.1.0/24, RT=1:1
NH =30.1.61.25/32, Label = 90
VPN Site-2
10.1.1.0/24, NH=R1
10.1.1.0/24, NH
=ASBR_PE-2 IGP+LDP,
30.1.61.25/32
NH=C1, Label=70
VPN Site-1
C1
CsC: ISP Sites Are Running MPLS-VPN
Hierarchical MPLS-VPN Control Plane
IGP+LDP
30.1.61.25/32,Label = pop
30.1.61.25/32,
NH=PE-2, Label = 52
30.1.61.25/32,
NH=CE-1, Label = 50
IGP+LDP,
Net=PE-1,
Label = 16
IGP+LDP,
Net=PE-1,
Label = pop
IGP+LDP,
30.1.61.25/32
NH=CE-2, Label=60

PE1
PE2
ISP PoP
Site-1
CE-1 CE-2
ISP PoP
Site-2
Carrier’s Core
P1
ASBR-1 ASBR-2
R1 R2Network =
10.1.1.0/24
10.1.1.1905116
VPN Site-1
VPN Site-2
C1
CsC: ISP Sites Are Running MPLS-VPN
Hierarchical MPLS-VPN Forwarding Plane
10.1.1.110.1.1.1 10.1.1.19070
10.1.1.190
10.1.1.19060
10.1.1.19052
10.1.1.19051
10.1.1.19050

Deploying IP/MPLS VPN - Cisco Networkers 2010

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