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Chapter 5: Advanced EIGRP (Fine-tuning EIGRP Interfaces (Hello and Hold…
Chapter 5:
Advanced EIGRP
Default Route Propagation
Configuration and Propagating Default Route Propagation
R2(config)# ip route 0.0.0.0 0.0.0.0 s0/1/0
R2(config)# router eigrp 1
R2(config)# redistribute static
• Using static route to 0.0.0.0/0 as default route is not routing protocol-independent
•The default static route is typically configured on router that has connection to network out of EIGRP routing domain,for example to an ISP.
• The redistribute static command tells EIGRP to include static routes in its EIGRP updates to other routers.
•Show ip protocols command to verify.
Verifying the Propagated Default Route
Verifying Default Routes on R1
R1#show ip route | include 0.0.0.0
Notice the routing source and administrative distance for the new default route learned using EIGRP
The entry for the EIGRP learned default route is identified by the following:
• D - indicates it was learned from an EIGRP routing update.
• * - Router is a candidate for a default route
• EX – Route is an external EIGRP route, or a static route outside of the EIGRP routing domain
• 170 – Administrative distance of an external EIGRP route
EIGRP for IPv6: Default Route
EIGRP maintains separate tables for IPv4 and IPv6, therefore an IPv6 default route must be propagated separately
The::/0 prefix and prefix-length is equivalent to the 0.0.0.0 0.0.0.0 address and subnet mask used in IPv4
The redistribute static command is used for ipv6 to redistribute the default static route into EIGRP
The propagation of the IPv6 static default route can be verified by using the Show ipv6 route command
Fine-tuning EIGRP Interfaces
EIGRP Bandwith Utilization
• EIGRP only consume half from the interface bandwidth for the information just to prevent form over-utilizing a link.
• In a configuration mode,ip bandwidth -percent eigrp is used as-number percent command to configure the percentage of the bandwidth. Add an ipv6 infront of the command for ipv6 address.
• No command is used to restore default value.
Hello and Hold Timer
-EIGRP use a Hello protocols to monitor connection status of its neighbour .
-The Hold time tells the maximum time to router to wait to receive the next Hello before declaring "neighbor unreachable" .
Use ip hello-interval eigrp to configure different Hello interval .
Use ip hold-time eigrp to configure different hold time .
Hello and Hold interval configured on per-interface basis & do not match with other EIGRP router to maintain adjacencies .
Load Balancing IPv4
Equal cost load balancing is the ability of a router to distribute outbound traffic using all interface that have the same metric from the destination. The show ip protocols command can be used to verify the number of equal-cost paths configured on the router.
Load Balancing IPv6
Output of the show ipv6 route eigrp commnd below show the eigrp netric The eigrp composite etric is the same for both eigrp ipv6 and ipv4
R3#show ipv6 route eigrp
• EIGRP for ipv4/ipv6 balance traffic across multiple routes that have different matrics (unequal-cost load balancing).
• Setting value using variance command: enable EIGRP to install multiple loop-free routes with unequal cost in local routing table.
• A route learned through EIGRP has two criteria:
Route must be loop-free
Metric of the route must be lower than the metric of the best route(successor) multiplied by the variance
Unequal –cost load balancing
• Applicable when different paths to a destination network report are of different routing metric values. The variance command determines which of these routes is used by the router.
• Variance set to 1,only routes with same metric as the successor are installed in the local routing table
• Varience set to 2, any EIGRP-learned route with a metric less than 2 times the successor metric less than 2 times the successor metric will be installed in the local routing table.