Cisco IOS Family

Below Diagram show the Cisco ISO Tree

EIGRP CE-PE Routing Protocol with MPLS Domain

EIGRP PE-CE routing protocol is used by service providers for customers who use EIGRP as their IGP routing protocol and, hence, prefer to use EIGRP to exchange routing information between the customer sites across an MPLS VPN backbone. In an MPLS VPN environment, to achieve this, the original EIGRP metrics must be carried inside MP-BGP updates. This is achieved by using BGP extended community attributes to carry and preserve EIGRP metrics when crossing the MP-iBGP domain. These communities define the intrinsic characteristics associated with EIGRP, such as the AS number or EIGRP cost metric like bandwidth, delay, load, reliability, and MTU.

BGP Extended Communities for EIGRP PE-CE Routing

Loop Prevention : OSPF Down Bit and Domain Tag

Loop Prevention in MPLS VPN Domain using OSPF

Down Bit


Routing loops can occur in the MPLS VPN environment when customer edge routers are dual-homed to the service provider network. MPLS VPN network implementing OSPF PE-CE routing for Customer A VPN-A sites, Site 1 and Site 2. Site 2 is in OSPF Area 2 and has multiple connections to the provider backbone.

The routing loop can be prevented by the use of the OSPF down bit, which is part of the options field in the OSPF header. The LSA header with the option field

Tag

The down bit helps prevent routing loops between MP-BGP and OSPF, but not when external routes are announced, such as when redistribution between multiple OSPF domains or when external routes are injected in an area that is dual-homed to the provider network. The PE router redistributes an OSPF route from a different OSPF domain into an OSPF domain as an external route. The down bit is not set because LSA Type 5 does not support the down bit. The redistributed route is propagated across the OSPF domain.


The routing loops introduced by route redistribution between OSPF domains can be solved with the help of the tag field, using standard BGP-OSPF redistribution rules. A non-OSPF route is redistributed as an external OSPF route by a PE router. By default, the tag field is set to the BGP-AS number. The redistributed route is propagated across the OSPF domain without the down bit but with the tag field set. When the route is redistributed into another OSPF domain, the tag field is propagated. Another PE router receives the external OSPF route and filters the route based on the tag field. The tag field matches the AS number so the route is not redistributed into MP-BGP

MPLS TE with OSPF Sham-link

When OSPF sites have a backdoor connection, they will by default prefer that link over the MPLS VPN link. Because of the redistribution that occurs, the VPN routes will be seen as inter-area (if OSPF process numbers match on PEs), E1 or E2 routes. As you probably know by now, inter-area and external routes are less preferred than intra-area routes in OSPF. No amount of administrative distance-altering or interface cost- changing can affect this decision making. Here we look briefly at a feature designed to allow VPN routes to look like intra-area routes, giving us the ability to prefer them over the VPN connection by adjusting interface costs.

Above topology show the how OSPF Sham-Link configured .

Below Link give you complete Document for same .

MPLS Traffic Engineering with OSPF Sham-link

Regards
Chetan Kumar

MPLS TE VPN with OSPF Process ID vs Domain ID

The below scenario shows the different flavours of OSPF between CE-PE.

 OSPF with unique process = O IA (OSPF Route)

 OSPF with different process = O E2 (OSPF Route)

 OSPF with unique Process ID but different domain ID = O E2 (OSPF Route)

OSPF with different process ID but unique domain ID = O IA (OSPF Route)

Below link is the complete document for same.

MPLS Traffic engineering VPN with OSPF Process ID vs Domain ID

Regards
Chetan Kumar Ress

MPLS TE VPN with Extranet

MPLS provides the flexibility to link VPN sites in a number of ways. When several VPNs get access to a shared part of network infrastructure, this is called an extranet .

Below Topology show the example of MPLS Traffic Engineering VPN with Extranet.

Attach link is the complete document for same.

MPLS Traffic Engineering VPN with Extranet


Regards
Chetan Kumar Ress

MPLS TEVPN with Export-Map

The Document show that how to configure MPLS VPN with Export - Map feature .
Using Export Map feature we can advertise the route that customer had requested .

We can restrict that advertisement of HUB VPN to other Spoke VPN .
Above topology show thta how to configure MPLS VPN with Export - Map Feature.

The attach link will give you complete document.

MPLS Traffic Engineering VPN with Export-Map

Regards
Chetan Kumar Ress

MPLS TE with Per VRF / VPN

Always we can see that in service provider network there will be primary link & Secondary link but only one link will be utilize. Implementing Policy base routing somehow we manipulate the route,



But still it required man force to monitor the link & manipulate the route as per requirement. It becomes very chaotic to do route manipulation every time in service provider network. So the solution is to have a technology where we can use un-equal load balancing or path manipulation as per requirement. So it give us scalability to use or chose any path that we required, may be it can primary path, backup path or both path i.e. un-equal circuit load balancing . So the solution is MPLS- Traffic Engineering , using MPLS traffic engineering we can manipulate the route as per our requirement where you can use each circuit or you can have route path on-demand.


MPLS Traffic Engineering (MPLS TE) is a growing implementation in today's service provider networks. MPLS adoption in service provider networks has increased manifold due to its inherent TE capabilities. MPLS TE allows the MPLS-enabled network to replicate and expand upon the TE capabilities of Layer 2 ATM and Frame Relay networks. MPLS uses the reachability information provided by Layer 3 routing protocols and operates like a Layer 2 ATM network. With MPLS, TE capabilities are integrated into Layer 3, which can be implemented for efficient bandwidth utilization between routers in the SP network.

Below link is an example where we have redundant link in service provider network, Without MPLS Traffic engineering we can see that we can only one link will be utilized . But after implementing MPLS Traffic engineering we can use both circuit as per our requirement or on-demand path manipulation per VRF.

MPLS Traffic Engineering with Per VRF / VPN

Regards
Chetan Kumar

MPLS Central VPN with Route Reflector

In certain circumstances, it may be desirable to use a hub-and-spoke topology so that all spoke sites send all their traffic toward a central site location. This may be because certain central site services for a particular VPN, such as Internet access, firewalls, server farms, and so on, are housed within the hub site. Or it may be because this particular VPN customer requires that all connectivity between its sites be via the central site

Above Topology & Attach Link show how to configure MPLS Central VPN with Route Reflector ( RR is used for more scalability in SP network )

https://learningnetwork.cisco.com/docs/DOC-8644

Regards
Chetan Kumar Ress

SDH / SONET Mapping Abbreviation

In my previous post ( SDH Mapping )  i had shared all SDH mapping & here are the terms & there abbreviation that used in configuration of STM or STS .

1] STM: Synchronise Transport Module

2] STS : Synchronise Transport Signal

3] AUG: Administrative Unit Group

4] AU: Administrative Unit

5] VC: Virtual Container

6] TUG: Tributary Unit Group

7] TU: Tributary Unit Group

8] VT: Virtual Tributary

9] C: Container