Per Vrf And Per Ce Label For Ipv6 Provider Edge; Ipv6 Unicast Routing - Cisco NCS 5500 Series Configuration Manual

Bgp configuration ios xr
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Implementing BGP
A backbone carrier offers Border Gateway Protocol and Multiprotocol Label Switching (BGP/MPLS) VPN
services. The customer carrier can be either:
• An Internet service provider (ISP) (By definition, an ISP does not provide VPN service.)
• A BGP/MPLS VPN service provider
You can configure a CSC network to enable BGP to transport routes and MPLS labels between the backbone
carrier provider edge (PE) routers and the customer carrier customer edge (CE) routers using multiple paths.
The benefits of using BGP to distribute IPv4 routes and MPLS label routes are:
• BGP takes the place of an Interior Gateway Protocol (IGP) and Label Distribution Protocol (LDP) in a
VPN routing and forwarding (VRF) table. You can use BGP to distribute routes and MPLS labels. Using
a single protocol instead of two simplifies the configuration and troubleshooting.
• BGP is the preferred routing protocol for connecting two ISPs, mainly because of its routing policies
and ability to scale. ISPs commonly use BGP between two providers. This feature enables those ISPs
to use BGP.
For detailed information on configuring MPLS VPN CSC with BGP, see the Implementing MPLS Layer 3
VPNs on module of the MPLS Configuration Guide.

Per VRF and Per CE Label for IPv6 Provider Edge

The per VRF and per CE label for IPv6 feature makes it possible to save label space by allocating labels per
default VRF or per CE nexthop.
All IPv6 Provider Edge (6PE) labels are allocated per prefix by default. Each prefix that belongs to a VRF
instance is advertised with a single label, causing an additional lookup to be performed in the VRF forwarding
table to determine the customer edge (CE) next hop for the packet.
However, use the label-allocation-mode command with the per-ce keyword or the per-vrf keyword to avoid
the additional lookup on the PE router and conserve label space.
Use per-ce keyword to specify that the same label be used for all the routes advertised from a unique customer
edge (CE) peer router. Use the per-vrf keyword to specify that the same label be used for all the routes
advertised from a unique VRF.

IPv6 Unicast Routing

Cisco provides complete Internet Protocol Version 6 (IPv6) unicast capability.
An IPv6 unicast address is an identifier for a single interface, on a single node. A packet that is sent to a unicast
address is delivered to the interface identified by that address. Cisco IOS XR software supports the following
IPv6 unicast address types:
• Global aggregatable address
• Site-local address
• Link-local address
• IPv4-compatible IPv6 address
For more information on IPv6 unicast addressing, refer the IP Addresses and Services Configuration Guide.
BGP Configuration Guide for Cisco NCS 5500 Series Routers, IOS XR Release 6.2.x
Information about Implementing BGP
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