This documentation has been moved - Dialing to Destinations with the Same IP Address for MPLS VPNs [Support]

Table Of Contents

Dialing to Destinations with the Same IP Address for MPLS VPNs

Contents

Prerequisites for Dialing to Destinations with the Same IP Address

Restrictions for Dialing to Destinations with the Same IP Address

Information About Dialing to Destinations with the Same IP Address

Introduction to Dialing to Destinations with the Same IP Address

Benefits of this Feature

How to Enable Dialing to Destinations with the Same IP Address

Mapping the VRF and Next-Hop Address to a Dial String

Prerequisites

Verifying the Configuration

Troubleshooting Tips

Configuration Examples for Dialing to Destinations with the Same IP Address

Additional References

Related Documents

Standards

MIBs

RFCs

Technical Assistance

Feature Information for Dialing to Destinations with the Same IP Address

Dialing to Destinations with the Same IP Address for MPLS VPNs

The dialer software in Cisco IOS prior to Release 12.2(8)T had no way to dial two different destinations with the same IP address. More specifically, in networks where a network access server (NAS) supports dialing clients with overlapping addresses, dial-out attempts fail. This module explains how to dial to more than one destination with the same IP address.

Module History

This module was first published on May 2, 2005, and last updated on May 2, 2005.

Finding Feature Information in This Module

Your Cisco IOS software release may not support all features. To find information about feature support and configuration, use the "Feature Information for Dialing to Destinations with the Same IP Address" section.

Contents

•Prerequisites for Dialing to Destinations with the Same IP Address

•Restrictions for Dialing to Destinations with the Same IP Address

•Information About Dialing to Destinations with the Same IP Address

•How to Enable Dialing to Destinations with the Same IP Address

•Configuration Examples for Dialing to Destinations with the Same IP Address

•Additional References

•Feature Information for Dialing to Destinations with the Same IP Address

Prerequisites for Dialing to Destinations with the Same IP Address

Before configuring this feature, you should understand how to configure the following network features:

•Virtual profiles with two-way AAA authentication

•MPLS VPNs

Refer to the documents listed in the "Additional References" section for information about configuring these features.

Restrictions for Dialing to Destinations with the Same IP Address

When configuring static routes in an MPLS or MPLS VPN environment, some variations of the ip route and ip route vrf commands are not supported. These variations of the commands are not supported in Cisco IOS releases that support the Tag Forwarding Information Base (TFIB), specifically Cisco IOS Releases 12.xT, 12.xM, and 12.0S. The TFIB cannot resolve prefixes when the recursive route over which the prefixes travel disappears and then reappears. However, the command variations are supported in Cisco IOS releases that support the MPLS Forwarding Infrastructure (MFI), specifically Cisco IOS Release 12.2(25)S and later. Use the following guidelines when configuring static routes.

Supported Static Routes in an MPLS Environment

The following ip route command is supported when you configure static routes in MPLS environment:

ip route destination-prefix mask interface next-hop-address

The following ip route commands are supported when you configure static routes in an MPLS environment and configure load sharing with static nonrecursive routes and a specific outbound interface:

ip route destination-prefix mask interface1 next-hop1
ip route destination-prefix mask interface2 next-hop2

Unsupported Static Routes in an MPLS Environment that Uses the TFIB

The following ip route command is not supported when you configure static routes in an MPLS environment:

ip route destination-prefix mask next-hop-address

The following ip route command is not supported when you configure static routes in an MPLS environment and enable load sharing where the next hop can be reached through two paths:

ip route destination-prefix mask next-hop-address

The following ip route command is not supported when you configure static routes in an MPLS environment and enable load sharing where the destination can be reached through two next hops:

ip route destination-prefix mask next-hop1
ip route destination-prefix mask next-hop2

Use the interface an next-hop arguments when specifying static routes.

Supported Static Routes in an MPLS VPN Environment

The following ip route vrf commands are supported when you configure static routes in a MPLS VPN environment, and the next hop and interface are in the same VRF:

–ip route vrf vrf-name destination-prefix mask next-hop-address

–ip route vrf vrf-name destination-prefix mask interface next-hop-address

–ip route vrf vrf-name destination-prefix mask interface1 next-hop1
ip route vrf vrf-name destination-prefix mask interface2 next-hop2

The following ip route vrf commands are supported when you configure static routes in a MPLS VPN environment, and the next hop is in the global table in the MPLS cloud in the global routing table. For example, these commands are supported when the next hop is pointing to the Internet Gateway.

–ip route vrf vrf-name destination-prefix mask next-hop-address global

–ip route vrf vrf-name destination-prefix mask interface next-hop-address
(This command is supported when the next hop and interface are in the core.)

The following ip route commands are supported when you configure static routes in a MPLS VPN environment and enable load sharing with static nonrecursive routes and a specific outbound interfaces:

ip route destination-prefix mask interface1 next-hop1
ip route destination-prefix mask interface2 next-hop2

Unsupported Static Routes in an MPLS VPN Environment that Uses the TFIB

The following ip route command is not supported when you configure static routes in a MPLS VPN environment, the next hop is in the global table in the MPLS cloud within the core, and you enable load sharing where the next hop can be reached through two paths:

ip route vrf destination-prefix mask next-hop-address global

The following ip route commands are not supported when you configure static routes in a MPLS VPN environment, the next hop is in the global table in the MPLS cloud within the core, and you enable load sharing where the destination can be reached through two next hops:

ip route vrf destination-prefix mask next-hop1 global
ip route vrf destination-prefix mask next-hop2 global

The following ip route vrf commands are not supported when you configure static routes in an MPLS VPN environment, and the next hop and interface are in the same VRF:

ip route vrf vrf-name destination-prefix mask next-hop1
ip route vrf vrf-name destination-prefix mask next-hop2

Supported Static Routes in an MPLS VPN Environment Where the Next Hop Resides in the Global Table on the CE Router

The following ip route vrf command is supported when you configure static routes in a MPLS VPN environment, and the next hop is in the global table on the CE side. For example, the following command is supported when the destination-prefix is the CE router's loopback address, as in EBGP multihop cases.

ip route vrf vrf-name destination-prefix mask interface next-hop-address

The following ip route commands are supported when you configure static routes in a MPLS VPN environment, the next hop is in the global table on the CE side, and you enable load sharing with static non-recursive routes and a specific outbound interfaces:

ip route destination-prefix mask interface1 nexthop1
ip route destination-prefix mask interface2 nexthop2

Information About Dialing to Destinations with the Same IP Address

Before configuring this feature, you should understand the following concepts:

•Introduction to Dialing to Destinations with the Same IP Address

•Benefits of this Feature

Introduction to Dialing to Destinations with the Same IP Address

The Cisco IOS dialer software can distinguish between two destinations with the same IP address using information stored in the VRF. This capability is provided to the dialer software by two existing Cisco IOS commands, dialer map and ip route, which have been enhanced to include VPN routing and forwarding (VRF) information.

In previous Cisco IOS releases, the dialer software obtained the telephone number for dial-out based on the destination IP address configured in the dialer map command. Now, the enhanced dialer map command supplies the name of the VRF so that the telephone number to be dialed is based on the VRF name and the destination IP address. The VRF is identified based on the incoming interface of the packet, and is used with the destination IP address defined in the dialer map command to determine the telephone number to be dialed.

The ip route configuration command also includes the VRF information. When a packet arrives in an incoming interface that belongs to a particular VRF, only those ip route commands that correspond to that particular VRF are used to determine the destination interface.

Benefits of this Feature

This feature allows the dialer software to dial out in an MPLS-based VPN. The MPLS VPN model simplifies network routing. For example, rather than needing to manage routing over a complex virtual network backbone composed of many virtual circuits, an MPLS VPN user can employ the backbone of the service provider as the default route in communicating with all other VPN sites.

This default route capability allows several sites to transparently interconnect through the service provider network. One service provider network can support several different IP VPNs, each of which appears to its users as a separate, private network. Within a VPN, each site can send IP packets to any other site in the same VPN, because each VPN is associated with one or more VRFs. The VRF is a key element in the VPN technology, because it maintains the routing information that defines a customer VPN site.

How to Enable Dialing to Destinations with the Same IP Address

This section includes the following procedures:

•Mapping the VRF and Next-Hop Address to a Dial String (required)

•Verifying the Configuration (optional)

Mapping the VRF and Next-Hop Address to a Dial String

Use the following procedure to map a VRF and next-hop address combination to a dial string and thereby allow the dialer software to be VRF-aware for an MPLS VPN.

Prerequisites

These commands are only part of the required configuration and show how to map a VRF and next-hop address combination to a dial string. Refer to the documents listed in the "Additional References" section and the example in the "Configuration Examples for Dialing to Destinations with the Same IP Address" section for details on where to include these commands in the network configuration.

SUMMARY STEPS

1. enable

2. configure terminal

3. interface dialer number

4. dialer map ip protocol-next-hop-address vrf vrf-name name host-name dial-string

5. end

6. ip route vrf vrf-name ip-address mask interface-type interface-number

DETAILED STEPS

Command or Action

Purpose

Step 1

enable
Example:

Router> enable

Enables privileged EXEC mode.

•Enter your password if prompted.

Step 2

configure terminal
Example:

Router# configure terminal

Enters global configuration mode.

Step 3

interface dialer number
Example:

Router(config)# interface dialer 1

Enters interface configuration mode and begins dialer configuration.

Step 4

dialer map ip protocol-next-hop-address vrf vrf-name name host-name dial-string
Example:

Router(config-if)# dialer map ip 60.0.0.12 vrf yellow name rubbertree02 5552171

Maps a VRF and next-hop address combination to a dial string (telephone number).

Step 5

end
Example:

Router(config-if)# end

(Optional) Exits interface configuration mode.

Step 6

ip route vrf vrf-name ip-address mask interface-type interface-number
Example:

Router(config)# ip route vrf blue 10.0.0.1 255.255.255.255 Dialer0

Configures a VRF and next hop address combination that points to the interface where the dialer software should make the connection.

Verifying the Configuration

To verify the configuration, use the following procedure.

SUMMARY STEPS

1. ping

2. show adjacency

DETAILED STEPS

Step 1 ping

Use this command on the customer edge NAS to place a call to a peer. The expected result is that the NAS successfully dials out to that peer.

Step 2 show adjacency

Use this command if the call fails to check Cisco Express Forwarding (CEF) adjacency table information.

Troubleshooting Tips

If you encounter problems with the feature, use the following debug privileged EXEC commands on the NAS to help you determine where the problem lies:

•debug aaa authentication

•debug aaa authorization

•debug dialer

•debug ppp authentication

•debug ppp negotiation

•debug radius

Configuration Examples for Dialing to Destinations with the Same IP Address

This section provides a configuration example of the feature for a simple network topology shown in Figure 1.

Figure 1 MPLS VPN Topology

Note The network addresses and telephone numbers used in the following configuration are examples only and will not work in an actual network configuration.

Customer Edge (CE) Router
!
hostname oaktree02
enable secret 5 !1!35Fg$Ep4.D8JGpg7rKxQa49BF9/
!
ip subnet-zero
no ip domain-lookup
!
controller T1 5/0
!
controller T1 5/1
!
interface FastEthernet0/0
 no ip address
 no ip mroute-cache
 duplex auto
 speed auto
!
interface FastEthernet0/1
 no ip address
 no ip mroute-cache
 shutdown
 duplex auto
 speed auto
!
interface Ethernet1/0
 ip address 10.0.58.11 255.255.255.0
 no ip mroute-cache
 half-duplex
!
interface Ethernet1/1
 ip address 50.0.0.2 255.0.0.0
 no ip mroute-cache
 half-duplex
!
interface Ethernet1/2
 no ip address
 no ip mroute-cache
 shutdown
 half-duplex
!
interface Ethernet1/3
 no ip address
 no ip mroute-cache
 shutdown
 half-duplex
!
interface Serial2/0
 no ip address
 no ip mroute-cache
 shutdown
 no fair-queue
 serial restart-delay 0
!
interface Serial2/1
 no ip address
 no ip mroute-cache
 shutdown
 serial restart-delay 0
!
interface Serial2/2
 no ip address
 no ip mroute-cache
 shutdown
 serial restart-delay 0
!
interface Serial2/3
 no ip address
 no ip mroute-cache
 shutdown
 serial restart-delay 0
!
interface FastEthernet4/0
 no ip address
 no ip mroute-cache
 shutdown
 duplex auto
 speed auto
!
ip classless
ip route 0.0.0.0 0.0.0.0 10.0.58.1
ip route 60.0.0.0 255.0.0.0 50.0.0.1
no ip http server
!
!
snmp-server manager
banner motd ^C  AV-8B    OAKTREE^C
alias exec r sh run
!
line con 0
 exec-timeout 0 0
line aux 0
 login
line vty 0 4
 no login
!
end
Provider Edge (PE) Router
hostname pinetree02
!
aaa new-model
!
!
aaa authentication login con-log none
aaa authentication ppp default group radius
aaa authorization network default group radius 
aaa session-id common
enable secret 5 $1$7KlA$xpC8l4dJCZogbzZvGUtFl/
!
username rubbertree02 password 0 Hello
ip subnet-zero
!
no ip domain-lookup
!
ip vrf yellow
 rd 100:1
ip cef
virtual-profile aaa
isdn switch-type primary-5ess
!
controller T1 3/0
 framing esf
 linecode b8zs
 pri-group timeslots 1-24
!
controller T1 3/1
 framing esf
 linecode b8zs
!
controller T1 3/2
 framing esf
 linecode b8zs
!
controller T1 3/3
 framing esf
 linecode b8zs
!
controller T1 3/4
 framing esf
 linecode b8zs
!
controller T1 3/5
 framing esf
 linecode b8zs
!
controller T1 3/6
 framing esf
 linecode b8zs
!
controller T1 3/7
 framing esf
 linecode b8zs
!
interface Loopback0
 ip vrf forwarding yellow
 ip address 70.0.0.1 255.0.0.0
!
interface FastEthernet1/0
 no ip address
 shutdown
 duplex half
!
interface Ethernet2/0
 ip address 10.0.58.3 255.255.255.0
 duplex full
!
interface Ethernet2/1
 ip vrf forwarding yellow
 ip address 50.0.0.1 255.0.0.0
 duplex half
!
interface Ethernet2/2
 no ip address
 shutdown
 duplex half
!
interface Ethernet2/3
 no ip address
 shutdown
 duplex half
!
interface Serial3/0:23
 description phone# 555-3123
 no ip address
 encapsulation ppp
 dialer rotary-group 0
 dialer-group 1
 isdn switch-type primary-5ess
 ppp authentication chap
!
interface Serial4/0
 no ip address
 shutdown
 no fair-queue
!
interface Dialer0
 ip address negotiated
 encapsulation ppp
 dialer in-band
 dialer map ip 60.0.0.12 vrf yellow name rubbertree02 5552171
 dialer map ip 60.0.0.2 5552172
 dialer-group 1
 ppp authentication chap
!
ip classless
ip route 0.0.0.0 0.0.0.0 10.0.58.1
ip route 60.0.0.2 255.255.255.255 Dialer0
ip route vrf yellow 60.0.0.0 255.0.0.0 Dialer0 permanent
no ip http server
ip pim bidir-enable
!
ip director cache time 60
dialer-list 1 protocol ip permit
!
radius-server host 172.19.192.89 auth-port 1645 acct-port 1646 key rad123
radius-server retransmit 3
call rsvp-sync
!
no mgcp timer receive-rtcp
!
mgcp profile default
!
dial-peer cor custom
!
gatekeeper
 shutdown
!
banner motd ^C   F/A-18    PINETREE ^C
!
line con 0
 exec-timeout 0 0
 login authentication con-log
line aux 0
line vty 5 15
!
end
Peer Router
hostname rubbertree02
!
logging buffered 32000 debugging
enable secret 5 $1$RCKC$scgtdlaDzjSyUVAi7KK5Q.
enable password Windy
!
username pinetree02 password 0 Hello
!
ip subnet-zero
no ip domain-lookup
!
isdn switch-type basic-5ess
!
interface Ethernet0
 ip address 10.0.58.9 255.255.255.0
 no ip route-cache
!
interface BRI0
 description phone# 555-2171
 ip address 60.0.0.12 255.0.0.0
 encapsulation ppp
 no ip route-cache
 dialer map ip 60.0.0.11 5553123
 dialer map ip 60.0.0.2 5552172
 dialer-group 1
 isdn switch-type basic-5ess
 isdn fast-rollover-delay 45
!
ip default-gateway 10.0.58.1
ip classless
ip route 0.0.0.0 0.0.0.0 10.0.58.1
ip route 50.0.0.0 255.0.0.0 70.0.0.1
no ip http server
!
dialer-list 1 protocol ip permit
no cdp run
banner motd ^C   F-4B   RUBBERTREE^C
!
line con 0
 exec-timeout 0 0
line vty 0 4
 password Windy
 login
!
end
AAA Server User File
[aaa-serv]/usr/testing/bin> ./radiusd_1.16 -d . -a . -x
greentree-16        Password = "Hello", Expiration = "Dec 31 2005"
        Service-Type = Framed-User,
        Framed-Protocol = PPP
        cisco-avpair = "lcp:interface-config=ip vrf forwarding yellow \nip 
unnumbered Loopback0"
Additional References

Related Documents

Related Topic

Document Title

MPLS

MPLS Product Literature

Standards

Standard

Title

No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature.

—

MIBs

MIB

MIBs Link

No new or modified MIBs are supported by this feature, and support for existing MIBs has not been modified by this feature.

To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL:

http://www.cisco.com/go/mibs

RFCs

RFC

Title

RFC 1164

Application of the Border Gateway Protocol in the Internet

RFC 1171

A Border Gateway Protocol 4

RFC 1700

Assigned Numbers

RFC 1966

BGP Route Reflection: An Alternative to Full Mesh IBGP

RFC 2283

Multiprotocol Extensions for BGP-4

RFC 2547

BGP/MPLS VPNs

RFC 2842

Capabilities Advertisement with BGP-4

RFC 2858

Multiprotocol Extensions for BGP-4

Technical Assistance

Description

Link

The Cisco Technical Support website contains thousands of pages of searchable technical content, including links to products, technologies, solutions, technical tips, and tools. Registered Cisco.com users can log in from this page to access even more content.

http://www.cisco.com/techsupport

Feature Information for Dialing to Destinations with the Same IP Address

Table 1 lists the features in this module and provides links to specific configuration information.

Not all commands may be available in your Cisco IOS software release. For details on when support for specific commands was introduced, see the command reference documents.

Cisco IOS software images are specific to a Cisco IOS software release, a feature set, and a platform. Use Cisco Feature Navigator to find information about platform support and Cisco IOS software image support. Access Cisco Feature Navigator at http://www.cisco.com/go/fn. You must have an account on Cisco.com. If you do not have an account or have forgotten your username or password, click Cancel at the login dialog box and follow the instructions that appear.

Note Table 1 lists only the Cisco IOS software release that introduced support for a given feature in a given Cisco IOS software release train. Unless noted otherwise, subsequent releases of that Cisco IOS software release train also support that feature.

Table 1 Feature Information for Dialing to Destinations with the Same IP Address

Feature Name

Releases

Feature Configuration Information

Dialer Map VRF-Aware for MPLS VPNs

12.2(8)T

The Cisco IOS dialer software is "VRF-aware for an MPLS VPN," which means that it can distinguish between two destinations with the same IP address using information stored in the VRF.

The following sections provide information about this feature:

•Introduction to Dialing to Destinations with the Same IP Address

•How to Enable Dialing to Destinations with the Same IP Address

Any Internet Protocol (IP) addresses used in this document are not intended to be actual addresses. Any examples, command display output, and figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses in illustrative content is unintentional and coincidental.

© 2007 Cisco Systems, Inc. All rights reserved.