2. EIGRP Flashcards
What kind of routing protocol is EIGRP?
An enhanced distance vector
What is DUAL and what does it do?
Diffusing Update Algorithm, algorithm that identifies network paths, provided fast convergence by using loop free back-up paths
Can a border router transfer routes between ASNs?
Yes, but this is turned off by default
What are PDMs and what do they do?
Protocol Dependent Modules, used by EIGRP to support multiple network protocols.
What is the successor route?
The route with the lowest path metric to reach a destination
What is the successor?
The next hop router for the successor route
What is the feasible distance?
Metric value for the the lowest metric path to reach a destination
What is the reported distance?
Distance reported by a router to reach a prefix. It is the FD of an advertising router
What is the feasibility condition?
To be considered a back-up route, the RD must be lower than the FD locally.
What is the feasible successor?
A route that satisfies the feasible condition
How does EIGRP maintain its routes?
It creates its own Topology table and installs routes from the topology table into the routing table
What is in the EIGRP topology table?
- Network prefix
- Neighbor that advertised the prefix
- Metris from each neighbor
- Values used to calculate the metric (total delay, minimum bandwith, load, reliability)
What is the command to show the EIGRP topology?
show ip eigrp topology
Does the EIGRP topology table show all links?
Not by default, with the command ‘show ip eigrp topology all links’ it can be shown
What is the IP protocol number of EIGRP?
88
Does EIGRP use unicast of multicast?
Both. Multicast if possible, unicast if necessary
What is the IP for EIGRP?
224.0.0.10
What is the MAC for EIGRP?
01:00:5e:00:00:0a
What are the type of EIGRP packets?
- Hello
- Request
- Update
- Query
- Reply
What is RTP and what does it do?
Reliable Transport Protocol, ensures that packets are delivered in order and that routers receive them
What RTP values are used?
0 for no reply needed, all others ask for an ACK
What packets do not need RTP acknowledgement?
Hello and ACK packets
With RTP, what happens if an ACK is not received before the retransmit timer expires?
The router will notify the non-ack router to stop processing the multicast packets. Will start sending unicast untill they are fully synced again.
How many times will EIGRP retry to send a packet that needs ACK?
16
What EIGRP parameters must match to become neighbors?
- ASN
- Subnet
- K values
- Authentication parameters
What are the two type of EIGRP modes?
- Classic
- Named
What are the three subsections of EIGRP named mode?
- Address family
- Interface
- Topology
How is the EIGRP router-id selected?
Highest UP loopback, if not highest IP
What is the command to apply settings on all interface in the named mode?
al-interface DEFAULT
What is the maximum EIGRP hop count?
255
What is the default maximum EIGRP hop count?
100
What is the normal formula for EIGRP?
10 tot de macht van 7 delay in micros
—————————— + ———————- x 256
bandwith 10
What is the wide metric formula for EIGRP?
10 tot de macht van 7 delay in picos
—————————— + ———————- x 65536
bandwith 10 tot de macht van 6
How is the delay displayed?
Microseconds on show interface
Tens of microseconds if configured on the interface
What type of authentication can be used on EIGPR?
MD5 for classis config or MD5 & SHA265 for named config
What is the default maximum of ECMP of UCMP?
4
What is the command to change the ECMP in EIGRP?
maximum-paths …. under classic
maximum-paths under topology in named
What is the variance multiplier?
A value that determines the value for which unequal paths can be installed in the routing table. Any feasible successors FD with a value below the variance value are installed in the RIB
How is the variance value calculated?
FD x variance multiplier
What is important to remember about the variance multiplier?
It rounds up to the whole number
What is the command to adjust the variance?
variance
What is the difference between Passive & Active state?
- Passive is a stable topology
- Active is when a new path is calculated
How can you check which EIGPR routes are installed in the RIB?
shiw ip route EIGRP
How are routers of a different ASN displayed in the routing table and what is the AD?
D EX with AD 170
