Cisco 10000 - Manual (Page 139)

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Cisco 10000 Series Router Software Configuration Guide
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Chapter 4 Configuring Multiprotocol Label Switching
IPv6 VPN over MPLS
Monitoring and Maintaining BGP Multipath Load Sharing for eBGP and iBGP
To display eBGP and iBGP multipath load sharing information, enter any of the following commands in
privileged EXEC mode:
IPv6 VPN over MPLS
Multiprotocol BGP is the centerpiece of the MPLS IPv6 VPN architecture in IPv4 and IPv6. It is used
to distribute IPv6 routes over the service provider backbone, with the same set of mechanisms to work
with overlapping addresses, redistribution policies, and scalability issues. The 6VPE feature is the IOS
implementation as described in RFC 4659.
IPv6 avoids overlapping address space by using either a global IPv6 Unicast prefix—RFC 3587—or
Unique IPv6 Local Addressing—RFC 4193. For redistribution, a Network Layer Reachability
Information (NLRI) 3-tuple, format—containing length, IPv6 prefix, and label—is defined to distribute
routes using multiprotocol BGP. The extended community attribute—the route target—is used to control
redistribution of routing information by tagging exported routes and filtering imported ones.
For scalability, route reflectors can be used to concentrate routing paths and avoid a full PE mesh.
Similar to IPv4, BGP features in IPv6, such as route refresh, automatic route filtering, and outbound
route filtering, help reduce the number of routes held in each PE.
Figure 4-1 illustrates the important aspects of the IPv6 VPN architecture.
Command Purpose
Router# show ip bgp all neighbors Displays information about the TCP and BGP connections to
neighbors.
Router# show ip bgp vpnv4 all ip-prefix/length Displays attributes and multipaths for a network in an MPLS
VPN.
The ip-prefix option is an IP prefix address (in dotted decimal
format) and the length option is the length of the mask (0 to 32).
You must include the slash mark when you use the length option.
Router# show ip bgp vpnv4 all labels Displays incoming and outgoing BGP labels for each NLRI
prefix.
Router# show ip bgp vpnv4 rd route-distinguisher Displays Network Layer Reachability Information (NLRI)
prefixes that have a matching route distinguisher.
Router# show ip bgp vpnv4 all summary Displays BGP neighbor status.
Router# show ip bgp vpnv4 vrf vrf-name Displays NLRI prefixes associated with the named virtual routing
and forwarding instance (VRF).
Router# show ip route vrf vrf-name ip-prefix Displays routing information for a network in an MPLS VPN.