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Table Of Contents
Hardware and Software Requirements
MPLS-VPN Hardware configuration
MPLS-VPN Software Configuration
Further Reading Recommendations
Reference Guide
IGX MPLS & MPLS-VPN
Introduction
The purpose of this guide is to help reduce the time needed to deploy IGX-based Multiprotocol Label Switching (MPLS) and MPLS-Virtual Private Network (VPN) networks.It is an implementation helper and the emphasis is put on setup and configuration, additional reading is highly recommended to gain in-depth knowledge (see last section).
Basic knowledge of MPLS technology, IGX and router operation is assumed.
Manuals are to be consulted for an exhaustive equipment and command reference.
Hardware and Software Requirements
Following a typical MPLS architecture, we will build a network made up of Label Switch Routers (LSR), Label Switch Controllers (LSC) and Edge-Label Switch Routers (E-LSR).MPLS-VPNs are then composed of Customer Edge (CE) and Provider Edge (PE) equipment.
These architectures are illustrated below:
Figure 1
While many platforms could be used as LSRs, we will focus on the IGX 8400 in this document.
With this assumption, the following table outlines the different options that are available for each network component:
MPLS Hardware Setup
As mentioned earlier, all MPLS-enabled IGX nodes must be equipped with NPM-64B processor modules.Connectivity from the IGX to the LSC and E-LSR is established with UXM or UXM-E modules.
Asynchronous Transfer Mode (ATM) DS-3/E-3 or OC-3 is recommended between the IGX (LSR) and the 7200(LSC), so as to ensure fast transport of the Tag signalling protocol.
Connectivity between the IGX (LSR) and the E-LSRs can be accomplished with almost any ATM physical medium.
The diagram below illustrates these principles:
Figure 2
MPLS Software configuration
This section features Configuration samples for each part of the network.Almost any IP routing protocol can be used between the MPLS nodes, we have tested successfully in our lab OSPF and EIGRP.
The examples below will focus on OSPF.
What's more, a hierarchical OSPF implementation has been chosen here, as it is commonly found in Service Provider Networks.
The diagram below outlines the lab setup:
Figure 3
Notes on Figure 3:
•
lb stands for Loopback interface
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IGX (LSR) Software Config
Setup sequence:1.
- Upln- Cnfln (optional)- Upport- cnfrsrc- Cnfport (optional)2.
- addctrlr3.
Important Note: VSI-controlled virtual trunks cannot carry Autoroute traffic, which results in the inability to add the trunk after enabling VSI, or the inability to enable VSI on a trunk that's been added. This only applies to virtual trunks and not to regular trunks.
Let's do this configuration on our sanjose IGX lab node:
1.
upln 6.6
Upport 6.6
(Maximum PVC Bandwidth: BW reserved for non-vsi pvcs)
(Reserved BW : BW reserved for vsi controller traffic)2.
Addctrlr
3.
4.
Configuring the LSC (7200):
tahiti lab router config:
The "ip route-cache cef" command should be issued on all Xtag interfaces!!! (not displayed here as it is the default setting)
The bombay lab router config is similar to tahiti, and is provided below for your convenience:
Configuring the E-LSR
london lab router config:
The paris lab router config is provided below for your convenience:
MPLS Debug commands
Before doing extensive debugging, we have found the following problems to occur frequently:•
•
•
While there are many debug commands available for MPLS, we have found the following to be most useful:
On the IGX side:
Dspvsich:
Dspvsipartinfo:
On the IOS side (LSC):
Show controllers vsi descriptor:
This command is extremely useful to verify that the Xtag interfaces created manually on the router did bind with the advertised interfaces from the IGX...
This is also a great command to find out which interfaces have been MPLS-enabled on the IGX from a router's perspective.
IF status should be up, except for the LSC control port, which should be n/a.
Show controllers vsi session:
Some sessions should be established, if not, there is a problem. (thank you, Sherlock).
MPLS-VPN Hardware configuration
There is no limitation to the physical medium that can be used to connect the CE and PE routers.MPLS-VPN Software Configuration
No specific changes are required on the IGX to add VPNs to the MPLS network. The LSC(7200) configuration can also remain untouched.The following diagram illustrates the lab MPLS-VPN setup:
Figure 4
The following IP routing scheme has been implemented in this setup:
Figure 5
Revised E-LSR 3640 (PE) configs:
Customer Edge (CE) 3810 Configs:
MPLS QoS
This lab test does not cover MPLS multi-VC mode.Multi-VC mode requires the use of PA-A1 port adapters on the 7200 routers (as opposed to PA-A3).
The IGX supports multi-vc mode by way of its user-configurable qbins (cnfqbin,...), which can be left at their default settings for most networks.
Multi-vc mode needs only to be enabled on the E-LSR (no special configuration required on IGX or LSC).
When Multi-VC mode is enabled, IP packets are differentiated in the E-LSR by the IP Type of Service (TOS) bits, and then sent on different parallel permanent virtual circuits (PVCs). These PVCs will use different user-configurable queues end-to-end (qbins), which helps maintain different Quality of Service (QoS) levels for each of them.
Further Reading Recommendations
Update to the Cisco IGX 8400 Series Reference Guide (MPLS related IGX documentation):
http://www.cisco.com/en/US/products/hw/switches/ps988/tsd_products_support_reference_guides.html
Your feedback is welcome, let us know how useful this document has been for you, e-mail Frederic Laruelle at flaruell@cisco.com.
