Network statement does not control what networks are being advertised but instead what interfaces are running EIGRP process Uses protocol number 88 Multicast to 224.0.0.10 (TTL=0) Receiving neighbour unicasts are acknowledged Unequal cost load sharing of up to 16 links EIGRP does not form neighbours over secondary networks/IPs Using the wildcard address 0.0.0.0 in the EIGRP network statement this means that only the interface with that particular IP address will have the EIGRP process enabled. By using all zeros in the wildcard there is no question as to which interfaces are running the EIGRP process. IGRP did not allow the advertisement of the network 0.0.0.0/0 so the ‘ip default-network’ was used as a work around. EIGRP supports both. By default EIGRP uses 50% of the interface bandwidth Hellos are sent using unicast every 60 seconds on links of speed T1 or less and 5 seconds on all other links The ‘hold down’ time internal is 180 seconds on low-speed NBMA networks or 15 seconds on all others To advertise summary and default routes out of interface using EIGRP process
interface se0/0/0
ip summary-address eigrp 100 0.0.0.0 0.0.0.0 5 #OR
ip summary-address eigrp 100 31.0.0.0 255.252.0.0 5
The EIGRP ‘leak-map’ feature of the ‘summary-address’ allows the advertisement of specific subnets encompassed by the interface level summary (similar to BGPs unsppress-map feature). Routes in the leak-map router map will be advertised in addition to the summary. If the route-map matches all routes, all subnets of the aggregate will be advertised in addition to the aggregate. This is useful in cases where you want to originate a default route with the interface summary-address but don’t want to stop the advertisements of any subnet. The metric formula (which is also well explained in Cisco’s EIGRP Whitepaper is EIGRP Metric = 256*((K1Bw) + (K2Bw)/(256-Load) + K3Delay)(K5/(Reliability + K4)))
- K1 = Bandwidth
- K2 = Load
- K3 = Delay
- K4 = Reliability
- K5 = MTU
To configure EIGRP from the ‘router’ context;
router eigrp
no auto-summary
network 0.0.0.0 #advertises the existing and future directly connected networks in the AS
network 10.1.1.1 0.0.0.0
network 10.1.1.1 0.0.0.255
neighbor
metric wight 0 1 0 0 0 0 #EIGRP only uses BW to calculate metric (tos, k1, k2, k3, k4, k5)
metric wight 0 0 0 1 0 0 #EIGRP only uses delay to calculate metric
variance #enable unequal cost load balance
timers active-time
metric maximum-hops #Changes the default hop-count limit of 100. Values 1-225
distance
eigrp stub recieve-olny
eigrp stub connected leak-map
redistribute connected route-map
redistribute static
default metric
eigrp stub connected static
no eigrp log-nieghbor-changes
eigrp log-neighbor-warning #log neighbour warning message every no. seconds
offset-list <0|acl> in #if the offset list references 0 rather than an ACL it ill apply to ALL routes received
redistribute eigrp #redistribution between AS
traffic-share balanced #(default)
traffic-share min across-interfaces #only use the best metric path even if multiple in routing table
passive-interface #disables the interface from sending updates
no default-information allowed [out|in]
To configure EIGRP from the ‘interface’ context;
interface fa0/0
ip hello-interval eigrp
ip hold-time eigrp
ip summary-address eigrp 10.1.0.0 255.255.252.0 #advertises only summary route out the interface
ip summary-address eigrp 10.1.0.0 255.255.252.0 leak-map #summary address as well as entries in leak map. Leak map cant be used on sub-interface, you could use a virtual-template if required
timers active-time [minutes|disabled] #changes the SIA timer (default=180 sec)
ip authentication key-chain eigrp
ip authentication mode eigrp md5
ip bandwidth-percent eirgp #percentage of the link to be used for exchanging updates
delay
no ip split-horizon eigrp #disables split horizon
To help with troubleshooting;
show ip route eigrp
show ip route eigrp
show ip eigrp topology
show ip eigrp interface detail
show ip protocols
show ip eigrp neighbours
show ip eigrp traffic
debug eigrp packet hello
debug eigrp packet upadte query reply
debug eigrp neighbors