OSPF Sham-Link Support for MPLS VPN

Feature Overview

Figure 4 Sham-Link Example

MPLS VPN Backbone

PE-3

Sham-link 10.3.1.2

Sham-link

PE-1

10.3.1.6PE-2 10.3.1.5

Winchester

10.3.1.7Area 1

Brighton

70393

Area 1

Vienna

Stockholm

Area 1

 

 

 

10.3.1.15

10.3.1.3

 

The following example shows the forwarding that occurs between sites from the standpoint of how PE-1 views the 10.3.1.7/32 prefix, the loopback1 interface of the Winchester CE router in Figure 4.

PE-1#show ip bgp vpnv4 all 10.3.1.7

BGP routing table entry for 100:251:10.3.1.7/32, version 124 Paths: (1 available, best #1)

Local

10.3.1.2 (metric 30) from 10.3.1.2 (10.3.1.2)

Origin incomplete, metric 11, localpref 100, valid, internal, best

Extended Community: RT:1:793 OSPF DOMAIN ID:0.0.0.100 OSPF RT:1:2:0 OSPF 2

PE-1# show ip route vrf ospf 10.3.1.7 Routing entry for 10.3.1.7/32

Known via "ospf 100", distance 110, metric 13, type intra area Redistributing via bgp 215

Last update from 10.3.1.2 00:12:59 ago Routing Descriptor Blocks:

10.3.1.2 (Default-IP-Routing-Table), from 10.3.1.7, 00:12:59 ago

The next example shows forwarding information in which the next hop for the route, 10.3.1.2, is the PE-3 router rather than the PE-2 router (which is the best path according to OSPF). The reason the OSPF route is not redistributed to BGP on the PE is because the other end of the sham-link already redistributed the route to BGP and there is no need for duplication. The OSPF sham-link is used only to influence intra-area path selection. When sending traffic to a particular destination, the PE router uses the MP-BGP forwarding information.

PE-1#show ip bgp

vpnv4 all tag begin 10.3.1.7

 

10.3.1.7/32

10.3.1.2

notag/38

 

 

PE-1#show tag-switching forwarding 10.3.1.2

 

 

Local

Outgoing

Prefix

Bytes tag

Outgoing

Next Hop

tag

tag or VC

or Tunnel Id

switched

interface

 

31

42

10.3.1.2/32

0

PO3/0/0

point2point

Cisco IOS Release 12.2(8)T

6

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Cisco Systems 1400 series, 1600R manual Sham-Link Example, Vpnv4 all tag begin

1600R, 1600, 1400 series specifications

Cisco Systems 1600 series routers are well-regarded in the networking industry for their reliability, versatility, and performance. Designed to meet the needs of small to medium-sized businesses, the Cisco 1600 series is primarily oriented towards providing robust connectivity for branch offices and remote sites.

One of the most significant features of the Cisco 1600 series is its modular architecture. This allows users to customize their routers with various interface cards, enabling support for different types of WAN technologies, including serial, ISDN, and Frame Relay. The modular design not only enhances flexibility but also extends the lifespan of the equipment, as businesses can upgrade their capacity and functionalities according to evolving demands.

Another key characteristic of the Cisco 1600 routers is their advanced routing capabilities. These devices support a wide range of routing protocols, including RIP, OSPF, EIGRP, and BGP. This versatility ensures seamless integration into existing network infrastructures, facilitating the scalability and adaptability that modern networks require.

Security is also a crucial aspect of the Cisco 1600 series. Incorporating features such as access control lists (ACLs) and support for Virtual Private Networks (VPNs), these routers help businesses safeguard their sensitive data during transmission. Enhanced security features allow companies to implement secure remote access for employees, thereby maintaining productivity without compromising safety.

In addition to routing and security, the Cisco 1600 series boasts Quality of Service (QoS) capabilities. This technology enables better management of network traffic, ensuring that critical applications receive the bandwidth they need for optimal performance. By prioritizing important data flows, businesses can enhance user experience and minimize disruptions across their network.

The Cisco 1600 series routers are also equipped with user-friendly interfaces and management tools. Cisco's IOS software platform provides a command-line interface (CLI) and web-based graphical interface for straightforward configuration and monitoring. This simplifies network management tasks and reduces the learning curve for IT personnel.

In summary, the Cisco Systems 1600 series routers offer a significant combination of modularity, robust routing protocols, enhanced security measures, Quality of Service features, and user-friendly management options. These characteristics make them an excellent choice for small to medium-sized enterprises looking to establish a reliable and secure networking infrastructure. With the continued evolution of networking technologies, the Cisco 1600 series stands as a dependable solution for businesses navigating an increasingly complex digital landscape.