Tag Archives: 3.5b

3.5.b Implement and troubleshoot neighbor relationship

3.5.b [i] Multicast, unicast EIGRP peering

To create an EIGRP routing process, use the following commands from within global configuration mode:

Router( config)# router eigrp autonomous-system

Router( config-router)# network network-number

EIGRP sends updates to the interfaces in the specified networks. If you do not specify the network of an interface , the interface will not be advertised in any EIGRP update.

IPv6 equivalent of (group address that is used to send routing information to all EIGRP routers on a network segment) is FF02:: A.

Adam, Paul (2014-07-12). All-in-One CCIE V5 Written Exam Guide (Kindle Locations 3054-3060).  . Kindle Edition.


3.5.b Implement and troubleshoot neighbor relationship

3.5.b [ii] OTP point-to-point peering

EIGRP Over-the-Top (OTP) is focused on simplifying the deployment of branch networks utilizing an end- to-end EIGRP solution over public and private networks. This simplicity is further enhanced with EIGRP use of OTP to support multiple service provider IP networks.

EIGRP Over the ToP allows the customer to establish EIGRP adjacencies across the MPLS/ VPN provider cloud. An EIGRP targeted adjacency between CPEs is created. This EIGRP neighborship is done via unicast packets , using the CPE ‘WAN’ IP address. This “over the top” peering allows EIGRP to exchange customer prefixes directly between CPEs. Customer prefixes are NOT injected in the providers VRF routing table. In order to allow for proper forwarding of user traffic across the

MPLS/ VPN cloud, user packets are encapsulated on the CPE. The encapsulation header uses the WAN IP address of the CEs, which are known in the MPLS/ VPN cloud.

OTP control plane consists in an EIGRP targeted adjacency between CPEs. Neighborship is established using the CPE WAN address , i.e. address of CPE on the PE/ CPE link, so there is no need for any dynamic routing protocol between the PE/ CPE. The PE just needs to redistribute the connected routes.

This adjacency is using unicast packets and the CPE needs to know the IP of the remote CPE. In the first phase of OTP, only static neighbors are allowed. With manual neighbor configuration, it wouldn’t scale to establish full mesh peering between all CEs. Instead, the concept of Route Reflector, i.e. CPEs peer with RRs only is used and RRs reflect the routes they receive to other CPEs. Each CPE is configured with the RRs WAN address and each RR is configured in EIGRP promiscuous mode, i.e. to accept incoming ‘connections’ (similar to BGP listen feature).

Adam, Paul (2014-07-12). All-in-One CCIE V5 Written Exam Guide (Kindle Locations 3069-3077).  . Kindle Edition.


3.5.b Implement and troubleshoot neighbor relationship

3.5.b [iii] OTP route-reflector peering

OTP offers Route Reflectors (RRs) to form a half-mesh topology and ensure connectivity among all sites in the network. A Route Reflector is an EIGRP peer that receives route updates from remote sites and “reflects” the routes to other sites. Route Reflectors are configured using the keyword “unicast-listen”. This option enables the Route Reflectors to listen for unicast Hello messages from other sites, and upon receiving the first Hello message, automatically forms a peering relationship. OTP supports the use of dual or multiple Route Reflectors for redundancy.

OTP RRs should have split horizon disabled in addition to next-hop-self.

Adam, Paul (2014-07-12). All-in-One CCIE V5 Written Exam Guide (Kindle Locations 3078-3083).  . Kindle Edition.


3.5.b Implement and troubleshoot neighbor relationship

3.5.b [iv] OTP multiple service providers scenario

The EIGRP OTP solution simplifies multi-provider IP WAN network designs. It simplifies the interface with the WAN providers and facilitates an end-to-end EIGRP network, which is easier to troubleshoot.

EIGRP OTP is configured in the Customer Edge (CE) routers. They include CE, CE1 and CE2. CE1 and CE2 establish an EIGRP neighbor association with CE, which maintains a database of all the Customer Edge routers and their associated prefixes. Essentially, the router CE is supporting a route reflector type functionality for EIGRP. This is accomplished with a single line of configuration on the each router. Once the EIGRP neighbor association is established the customer’s traffic or data forwarding can start.

Adam, Paul (2014-07-12). All-in-One CCIE V5 Written Exam Guide (Kindle Locations 3085-3091).  . Kindle Edition.