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| posted in Cisco Networking, Technical | |
| by roggy on September 10th, 2009 | tags: BGP, Cisco, MPLS, VPN |
Welcome to Multi Protocol Label Switching Virtual Private Networks with Multi Protocol Border Gateway Protocol. This article is designed for those who have only briefly seen MPLS and those that may already be working with an MPLS provider network and wish to have a peek into what is actually going on within the provider network.
Keep in mind however that MPLS networks almost by their definition can be deployed in a variety of ways and that is reflected by the way it is presented at the Customer Edge. Here it is presented as a L3 routed VPN.
I have put together a few videos that takes you from the very start of setting up your own MPLS lab. From dragging the router icons into the GNS workspace all the way through to testing connectivity from the customers perspective.
This is a diagram of the lab we will be setting up:
Part 1 – Basic Setup
Noteworthy:
1) Each Router is given a loopback address of the router number as its octets with a 32bit mask.
2) Remember to define the loopback before setting up configuring “mpls ip” on any interface.
3) Test connectivity as you go.
Part 2 – Setting up the IGP (OSPF) and MP-BGP on the Provider Routers
Noteworthy:
1) Although we had set-up MPLS with the “mpls ip” on each interface in the previous video, LDP does not actually bring up the adjacencies until we bring the loopback address into OSPF.
2) Check that the OSPF and LDP adjacencies comes up as you move from router to router.
3) As the provider network is not a full mesh we are using route reflectors in the core network to move the customers routes around.
4) The command “no bgp default ipv4-unicast” disables Ipv4 unicast session establishment.
i.e. BGP will not peer unless you “activate” it.
Part 3 – Setting up the Provider Edge and the Customer Edge
Noteworthy:
1) It is function of the Provider Edge routers to bring in the Customers BGP routes from the VRF into the BGP VPN.
2) Route Distinguishers “rd 1:1” are used to distinguish between two different customers that use the same prefix. e.g. Customer 1 and Customer 2 both using 192.168.0.0/24.
Part 4 – Testing The Configuration
Terminology:
- Customer Edge (CE) router – The last router with in the customer network which connects to the provider network.
- Provider Edge (PE) router – The router on the edge of the provider network which has a direct connection to the customer.
- Provider Core (Core) router – The workhorse of the provider network, generally the customer has no visibility of this router.
- VRF (Virtual Routing and Forwarding) – A virtual router within a router often used to separate the Customer and Provider routing information.
- BGP – Border Gateway Protocol
- MP-BGP (Multi Protocol BGP) – An Extension of BGP which allows customers routes to be carried across the VPN.
- OSPF – Open Shortest Path First
- VPN (Virtual Private Network) – Used here to illustrate that each network is Virtual and Private however unlike IPSec VPNs the VPNs used here have nothing to do with encryption.
References:
MPLS Configuration on Cisco IOS Software
MPLS and VPN Architectures (Vol 1)
Configuring MPLS Layer 3 VPNs
Check out roggy’s blog for more Cisco technical articles.
Sweeeeet.
Hi I have a question about the GSN3.
that has the features PC used during the practice??
I think you mean the spec of the pc?
Its a windows 7 box with a 3.8ghz quad core and 4gb of ram, however you can get away with alot less once idle pc is configured correctly. Remember for idlepc to work you have to be in exec mode.
Thanks!!
PD:sorry, I do not speak English
Good video Richard!