Specifications

Implementing EIGRP on Cisco IOS XR Software
Information About Implementing EIGRP on Cisco IOS XR Software
RC-145
Cisco IOS XR Routing Configuration Guide
EIGRP Layer 3 VPN PE-CE Site-of-Origin
The EIGRP MPLS and IP VPN PE-CE Site-of-Origin (SoO) feature introduces the capability to filter
Multiprotocol Label Switching (MPLS) and IP Virtual Private Network (VPN) traffic on a per-site basis
for EIGRP networks. SoO filtering is configured at the interface level and is used to manage MPLS and
IP VPN traffic and to prevent transient routing loops from occurring in complex and mixed network
topologies.
Router Interoperation with the Site-of-Origin Extended Community
The configuration of the SoO extended community allows routers that support this feature to identify the
site from which each route originated. When this feature is enabled, the EIGRP routing process on the
PE or CE router checks each received route for the SoO extended community and filters based on the
following conditions:
• A received route from BGP or a CE router contains a SoO value that matches the SoO value on the
receiving interface:
– If a route is received with an associated SoO value that matches the SoO value that is configured
on the receiving interface, the route is filtered out because it was learned from another PE router
or from a backdoor link. This behavior is designed to prevent routing loops.
• A received route from a CE router is configured with a SoO value that does not match:
– If a route is received with an associated SoO value that does not match the SoO value that is
configured on the receiving interface, the route is accepted into the EIGRP topology table so
that it can be redistributed into BGP.
– If the route is already installed in the EIGRP topology table but is associated with a different
SoO value, the SoO value from the topology table is used when the route is redistributed into
BGP.
• A received route from a CE router does not contain a SoO value:
– If a route is received without a SoO value, the route is accepted into the EIGRP topology table,
and the SoO value from the interface that is used to reach the next-hop CE router is appended
to the route before it is redistributed into BGP.
When BGP and EIGRP peers that support the SoO extended community receive these routes, they also
receive the associated SoO values and pass them to other BGP and EIGRP peers that support the SoO
extended community. This filtering is designed to prevent transient routes from being relearned from the
originating site, which prevents transient routing loops from occurring.
In conjunction with BGP cost community, EIGRP, BGP, and the RIB ensure that paths over the MPLS
VPN core are preferred over backdoor links.
For MPLS and IP VPN and SoO configuration information, see Implementing MPLS Layer 3 VPNs in
Cisco IOS XR Multiprotocol Label Switching Configuration Guide.
IPv6 and IPv6 VPN Provider Edge Support over MPLS and IP
IPv6 Provider Edge (6PE) and IPv6 VPN Provider Edge (6VPE) uses the existing IP and Multiprotocol
Label Switching (MPLS) IPv4 core infrastructure for IPv6 transport. 6PE and 6VPE enable IPv6 sites
to communicate with each other over an IP and MPLS IPv4 core network using MPLS label switched
paths (LSPs).