Enhanced Interior Gateway Routing Protocol (EIGRP)
Contents
- Enhanced Interior Gateway Routing Protocol (EIGRP)
About
Wiki EN Interior Gateway Protocol (IGP)
- Runs within an autonomous system (AS)
- Needs an ASN (unlike OSPF)
- Needs to match on a neighbor (IGP)
- Fast convergence
- Incremental updates
- Scalable
- Load-balance over unequal cost links
- Classless (Variable Length Subnet Mask (VLSM) support)
- Communicates over multicast
- Addresses
IPv4: 224.0.0.10
IPv6: ff02::a ip6-alleigrprouters (link-local)
Protocol number: 88
- Dynamically neighbor discovery
- Neighbors do not need to be configured explicitly
- Addresses
- Uses Cisco's Reliable Transport Protocol (RTP) to ensure router updates are delivered to all neighbors completely
- Operates on layer 3 (no ports like in TCP/UDP)
- Optimized for efficiency and multicast
- Router updates are acknowledged
- Originally proprietary protocol of Cisco
- Opened up but probably not well featured by other vendors
- Probably sufficient for migrations
- "DUAL", a Diffusing Update Algorithm as referenced in "Loop-Free Routing Using Diffusing Computations" (Garcia-Luna-Aceves 1993).
Based on Bellman-Ford algorithm
- Protocol independence
- with protocol-dependent modules
- EIGRP data tables
- interface table
- neighbor table
- topology table
- EIGRP replaced the Interior Gateway Routing Protocol (IGRP) in 1993. One of the major reasons for this was the change to classless IPv4 addresses in the Internet Protocol, which IGRP could not support.
IETF RFC7868 - Cisco's Enhanced Interior Gateway Routing Protocol (EIGRP)
- Cisco remains in control of the protocol development.
Implementations
Abbreviations
Include: Nothing found for "^End of abbreviations$"!
- ACL
- Access Control List
- AF
- Address Family
- AFI
- Address Family Identifier
- AIGP
- Accumulated Interior Gateway Protocol
- AS
- Autonomous System
- ASN
- Autonomous System Number
- BGP
- Border Gateway Protocol
- CE
- Customer Edge
- DD
- Database Description packages
- DUAL
- Diffusing Update ALgorithm
- eBGP
- External BGP
- EGP
- Exterior Gateway Protocol
- EIGRP
- Enhanced Interior Gateway Routing Protocol
- EOR
- End Of RIB
- EVPN
- Ethernet Virtual Private Network
- FIB
- Forwarding Information Base
- GR
- Graceful Restart
- HA
- High Availability
- iBGP
- Internal BGP
- IGP
- Interior Gateway Protocol
- IGRP
- Interior Gateway Routing Protocol
- IRR
- Internet Routing Registry
- IXP
- Internet Exchange Point
- L2VPN
- Layer 2 Virtual Private Network
- LIR
- Local Internet Registry
- LSA
- Link State Advertisments
- LSDB
- Link State Database
- LSR
- Link State Request
- LSU
- Link State Update
- Packet that may contain multiple LSAs
- MBGP
- Multicast BGP
- MP-BGP
- Multi-Protocol BGP
- NBMA
- Non-Broadcast Multi Access [network type]
- NLRI
- Network Layer Reachability Information
- NSF
- Non Stop Forwarding
- NSR
- Non Stop Routing
- NSSA
- Not So Stubby area
- OSPF
- Open Shortest Path First
- PA
- Path Attribute
- PE
- Provider Edge
- PMTUD
- Path MTU Discovery
- POP
- Point Of Presence
- RIB
- Routing Information Base
- RIR
- Regional Internet Registry
- RR
- Route Reflector
- RS
- Route-Server
- RTP
- Reliable Transport Protocol
- SAFI
- Subsequent Address Family Identifier
- SIA
- Stuck In Action
- SNM
SubNet Mask
- Tier 1 transit provider
- An IP transit provider that can reach any network on the Internet without purchasing transit services.
- SSO
- Stateful Switchover
- TNSSA
- Totally Not So Stubby area
- uRPF
- Unicast Reverse Path Forwarding
- VXLAN
- Virtual eXtensible LAN
- EoR
- End of RIB
- VTEP
- Virtual Tunnel Endpoint
- VLSM
- Variable Length Subnet Mask
EoI
Administrative distance
Wiki EN Administrative distance
Administrative distance (AD) or route preference is a number of arbitrary unit assigned to dynamic routes, static routes and directly-connected routes. The value is used in routers to rank routes from most preferred (low AD value) to least preferred (high AD value). When multiple paths to the same destination are available in its routing table, the router uses the route with the lowest administrative distance.FRR Docs - Zebra #Administrative distance
Administrative distance allows FRR to make decisions about what routes should be installed in the rib based upon the originating protocol. The lowest Admin Distance is the route selected.
Autonomous system (AS)
IETF RFC1930 - Guidelines for creation, selection, and registration of an Autonomous System (AS)<<BR>
- Autonomous System (AS)
- An autonomous system (AS) is a collection of connected Internet Protocol (IP) routing prefixes under the control of one or more network operators on behalf of a single administrative entity or domain, that presents a common and clearly defined routing policy to the Internet.
- Each AS is assigned an autonomous system number (ASN),
for use in Border Gateway Protocol (BGP) routing.
- Autonomous System Numbers are assigned to Local Internet Registries (LIRs) and end-user organizations by their respective Regional Internet Registries (RIRs), which in turn receive blocks of ASNs for reassignment from the Internet Assigned Numbers Authority (IANA).
- The IANA also maintains a registry of ASNs which are reserved for private use (and should therefore not be announced to the global Internet).
Autonomous system numbers (AS)
- 16 bit
- Completely allocated
Number (Hex)
Number (Dec)
Description
Reference
Registration Date
0x0
0
Reserved
0xFBF0-0xFBFF
64496-64511
Reserved for use in documentation and sample code
[RFC5398]
2008-12-03
0xFC00-0xFFFE
64512-65534
Reserved for Private Use
[RFC6996]
0xFFFF
65535
Reserved
[RFC7300]
- Completely allocated
- 32 bit
- 16 bit ASNs are contained
- Lots of free unallocated address space
Number (Hex)
Number (Dec)
Number (Dec Dotted)
Description
Reference
Registration Date
0x00000000-0x0000FFFF
0-65535
0:0-0:65535
16 bit ASNs
0x00010000-0x0001000F
65536-65551
1:0-1:15
Reserved for use in documentation and sample code
[RFC5398]
2008-12-03
0x00010010-0x0001FFFF
65552-131071
1:16-1:65535
Reserved
0xFA56EA00-0xFFFFFFFE
4200000000-4294967294
64086:59904-65535:65534
Reserved for Private Use
[RFC6996]
0xFFFFFFFF
4294967295
65535:65535
Reserved
[RFC7300]
Router ID
Looks like an IP address, but is just a name.
- Router ID should be configured.
- Can be configured for multiple routing protocols differently.
- If there is no configured router-ID, the highest IP address on a loopback-address is assigned as the Router ID
- If there is no loopback-interface, the highest IP address on an interface is assigned as the Router ID.
- If addresses cannot be determined (e.g. if FRR has no connection to zebra)
the router id is set to 0.0.0.0
Number of adjacencies in a full mesh
A = n * (n -1) / 2
Wildcard mask
WILDCARD_MASK = 255.255.255.255 - SUBNET_MASK
Network command
- Defines just address space not network to be advertised
- If an interface address falls into this address space, the network belonging to the interface is advertised
- In IPv6 interface commands are used.
EoI
Advanced routing
Route aggregation
- Reduces the size of the routing table
- Makes routing tables more readable
- Increases the efficiency routing table
- Saves cycles and memory
- Works best if summarization is already considered when assigning subnet addressing
- Plan your networks
- Algorithm
- Binary AND of network prefixes to determine common bits.
- Appending bits with value 0 of the resulting network address are counted, subtracted from the maximum length of the SNM (32/128) and converted to decimal to calculate the subnet mask.
- Summarized network address and SNM are concatenated to the summarized network prefix.
- Summarized address
- Be careful, because summarization may also span holes, which may cause issues.
- Should work, because advertisements of network falling into that route are more specific.
- Network with the least cost (OSPF) or highest metric (EIGRP) is picked for the summarized route.
Determine if automatic summarization is configured Automatic summarization
1 show ip protocols
EoI
Route redistribution
- Use cases
- If there is more than one IGPs or IGP instances
- e.g. after a merge of companies
- different departments under different administrative control
- Connection to partner networks
- IPG routes need to be advertised into BGP
- BPG routes need to be advertised into IGP
- If there is more than one IGPs or IGP instances
- Seed/Default metric
- Metrics are very different between RPs and but need to be meaning full
- assigned, by default, to redistributed routes, when no metric is manually configured, if a route is imported into a routing protocol
Target Routing Protocol
Default Seed Metric
RIP
infinity
EIGRP
infinity
OSPF
20 (1 for BGP)
BGP
Uses IGP metric value
in multi-exit descriminator (MED)
redistribute command and default metrics
Meaning of the command:
- "Redistribute routes from a specified routing source into this routing protocol."
- Options:
- Set a default metric for all routing protocols being injected into a specific routing protocol.
Set a metric as part of the redistribute command.
- Set a matrix via route-map
Redistribute into OSPF process 1
(updates the area using OSPF external type 2 LSAs)
Redistribute into OSPF process 1
(updates the area using OSPF external type 1 LSAs)
Set the metric-type to 1 changes the metric calculation. With type 2 the cost value was constant throughout the entire area. With type 1 the cost of the path is added (to the default metric), which is much more accurate in larger topologies.
Redistribute into EIGRP ASN 1
(routes will not be injected into rib because the default metric is infinity)
Assign default-metric in eigrp for all routing protocols
1 conf term
2 router eigrp 1
3 ! Bandwidth BW … uINT32 [kbps]
4 ! Delay D … uINT32 [units of 10 µs]
5 ! Reliability R … BYTE ([low] 0-255 [high])
6 ! Load L … BYTE ([low] 0-255 [high])
7 ! Maximum Transmission Unit MTU … uINT16 (1-65535)
8 ! default-metric BW D R L MTU
9 default-metric 1000000 1 255 1 1500
Assign default-metric in ospf
Assign default-metric in eigrp
1 conf term
2 router eigrp 1
3 ! DEFAULT METRIC MAY BE REMOVED BEFOREHAND
4 ! no default-metric
5 ! REMOVE OLD REDISTRIBUTION COMMAND
6 ! no redistribute ospf 1
7 ! Bandwidth BW … uINT32 [kbps]
8 ! Delay D … uINT32 [units of 10 µs]
9 ! Reliability R … BYTE ([low] 0-255 [high])
10 ! Load L … BYTE ([low] 0-255 [high])
11 ! Maximum Transmission Unit MTU … uINT16 (1-65535)
12 ! redistribute ospf 1 metric BW D R L MTU
13 redistribute ospf 1 metric 1000000 1 255 1 1500
Assign default-metric in eigrp using a route-map
Redistribution Loops
Issue:
- Area/AS A publishes a route to another Area/AS B.
- Area/AS Bs secondary router publishes the route back to Area/AS A with a lower metric.
- A sub-optimal path is selected.
Solutions:
- Higher-Metric of redistributed routes
- Adjust Administrative distance
- eBGP is more believable than EIGRP
- OSPF is more believable than RIP
- Filter routes (e.g. on ABR, ASBR or during injection to the RIB)
- Tag the routes
Set tag on redistribution (from Area/AS A to Area/AS
- Deny tag on redistribution (from Area/AS B to Area/AS A)
IP SLA
Use cases
- Measure network performance (like jitter)
- RTR Response Time Reporter/RealTime Responder
- Influence routing decisions
Response Time Reporter (RTR)
- Configure a router to be a RTR
- Configure a router to be a RTR
Track IP SLA operation to switch static routes
1 conf term 2 ! DEFINE OPERATION ENTRY 3 ip sla 1 4 ! PING INGRESS IFACE ON TARGET ROUTER 5 icmp-echo IP-ADDRESS_NEXTHOP1 source-ip SRC-IP 6 frequency 30 7 ! 100ms THRESHOLD 8 threshold 100 9 exit 10 ! SCHEDULE OPERATION ENTRY 11 ip sla schedule 1 life forever start-time now 12 ! CREATE A TRACKER THAT FOLLOWS OPERATION 1 13 track 1 ip sla 1 14 ! COUNTER ROUTE FLAPPING (HYSTERIS) 15 delay down 10 up 10 16 exit 17 ! CREATE A ROUTE THAT IS TRIGGERED ON TRACKER 1 18 ip route PREFIX SNM NEXT-HOP1 track 1 19 ! CREATE A ROUTE WHOSE ADMINISTRATIVE DISTANCE 20 ! (LAST POS ARG, DEFAULT FOR STATIC ROUTES 1) 21 ! IS HIGHER (LESS PREFERABLE) THAN THE PREVIOUS ROUTE 22 ip route PREFIX SNM NEXT-HOP2 2 23 ! CHECK WITH 24 show track 1
Policy-based routing (PBR)
- Routing decisions based on a policy
Configure an alternative route only for a single host
== Configuration ===
Timers
- Default Hello Interval: 5 s
- Default Hold Timer: 15 s
- Meaning opposite of OSPF Deadtime
- Holdtime is advertised to neighbor and defines how long the neighbor should wait before tearing down the neighborship
Composite and vector metrics
Attribute |
Mnemonic |
Description |
Bandwidth |
Big |
Minimum Bandwidth (in kilobits per second) |
Total Delay |
Dogs |
Delay, in 10s of microseconds, |
Reliability |
Really |
Number in range 1 to 255; |
Load |
Like |
Number in range 1 to 255; |
MTU |
ME |
Minimum path Maximum Transmission Unit (MTU) |
Hop Count |
|
Number of routers a packet passes through when routing to a remote network, used to limit the EIGRP AS. EIGRP maintains a hop count for every route, however, the hop count is not used in metric calculation. It is only verified against a predefined maximum on an EIGRP router (by default it is set to 100 and can be changed to any value between 1 and 255). Routes having a hop count higher than the maximum will be advertised as unreachable by an EIGRP router. |
Routing metric calculation
![$\left[\left(
K_1 \cdot \mbox{Bandwidth}_{min}
+ \frac{K_2 \cdot {\mbox{Bandwidth}}_{min}}{256-\mbox{Load}}
+ K_3 \cdot \mbox{Delay}_{E}
\right)
\cdot \frac {K_5}{K_4 + \mbox{Reliability}}
\right] \cdot 256$
\vspace{1em}
where:
$\mbox{Bandwidth}_{min} = \frac{10^7}{\mbox{least-Bandwidth}}$
\vspace{1em}
So the reference bandwidth in EIGRP is
$\SI{10}{\giga\bit/s} = \SI{10000000}{\kilo\bit/s} = 10^7 \si{\kilo\bit/s}$.
\vspace{1em}
$\mbox{Delay}_{E} = \frac
{\mbox{Delay-Along-Path}}
{\SI{10}{\micro s}}$
\vspace{1em}
where the units are:
$[Bandwidth] = \SI{1}{\kilo\bit/s}$
$[Delay] = \SI{10}{\micro s}$](/networking/DynamicRouting/EIGRP?action=AttachFile&do=get&target=latex_af27426c6c38f4f58628bb04174eb00c857457ed_p1.png "$\left[\left(
K_1 \cdot \mbox{Bandwidth}_{min}
+ \frac{K_2 \cdot {\mbox{Bandwidth}}_{min}}{256-\mbox{Load}}
+ K_3 \cdot \mbox{Delay}_{E}
\right)
\cdot \frac {K_5}{K_4 + \mbox{Reliability}}
\right] \cdot 256$
\vspace{1em}
where:
$\mbox{Bandwidth}_{min} = \frac{10^7}{\mbox{least-Bandwidth}}$
\vspace{1em}
So the reference bandwidth in EIGRP is
$\SI{10}{\giga\bit/s} = \SI{10000000}{\kilo\bit/s} = 10^7 \si{\kilo\bit/s}$.
\vspace{1em}
$\mbox{Delay}_{E} = \frac
{\mbox{Delay-Along-Path}}
{\SI{10}{\micro s}}$
\vspace{1em}
where the units are:
$[Bandwidth] = \SI{1}{\kilo\bit/s}$
$[Delay] = \SI{10}{\micro s}$")
- By default only bandwidth and delay are considered, the default values of the metric weights are
If
, then by definition 
- Named EIGRP introduces K6 with wide metrics
- Line-Speeds above 10G are not supported by older EIGRP
So respecting the default weights and thus removing the terms, which add zero or multiply by one, the following "default formula" results
Example calculation with the following parameters
least bandwidth = 1 Gbit/s = 1000000 kbit/s = 106 kbit/s
- 2 hops each introducing a delay of 10 µs
IGRP Routing metric calculation
IGRP uses the same basic formula for computing the overall metric, the only difference is that in IGRP, the formula does not contain the scaling factor of 256. In fact, this scaling factor was introduced as a simple means to facilitate backward compatility between EIGRP and IGRP: In IGRP, the overall metric is a 24-bit value while EIGRP uses a 32-bit value to express this metric. By multiplying a 24-bit value with the factor of 256 (effectively bit-shifting it 8 bits to the left), the value is extended into 32 bits, and vice versa. This way, redistributing information between EIGRP and IGRP involves simply dividing or multiplying the metric value by a factor of 256, which is done automatically.
Path selection
- Reported Distance (RD)
- An EIGRP neighbor advertises a network with its metric.
- Feasible Distance (FD)
- Reported Distance plus the local metric to get to this neighbor.
- Successor route
- Local route that incorporates the lowest metric
- Feasible successor route
- Route with the next metric, which meets the feasible successor condition
Feasible successor condition
- An EIGRP route is a feasible successor route if the Reported Distance (RD) from our neighbor is less than the Feasible Distance of the successor route.
- This condition is introduced as a heuristic to find out if the feasible successor depends on the successor.
- Possible topology
- R3 depends on R2, therefor its reported distance must be higher than R2s …
- In some scenarios a valid candidate fails the condition.
- Possible topology
- Path selection
Neighbor
RD
FD
(Feasible)
SuccessorR2
4000
6000
Successor
R3
4000
7000
Feasible
SuccessorR4
7000
8000
Fails condition
Query for route
- Even routes that don't fulfill the feasibility condition may be used, if nothing else exists.
- If successor route and feasible successor routes have failed
EIGRP goes in state active
- EIGRP floods out (MC) queries for a new route to the lost network through its interfaces
- A timer is started and (Default: 180s) waiting for the reply
- If the timer expires the neighbor is taken down and routes from neighbors are pruned from EIGRP and thus eventually from the routing table
- A timer is started and (Default: 180s) waiting for the reply
- Receiving adjacent routers receive the query and do the same, if they do not have a route to the queried network
- If a router no longer has adjacent routers to query (no hellos or already received a query on an interface), it sends a reply to the adjacent routers.
- A router waits for all replies from its neighbors before replying itself.
- Router by router, these replies then propagate back to the origin.
- When a reply gets dropped
- Older EIGRP versions tended to get into a state called "stuck in active" (SIA)
- Some partition of the network is waiting for replies that got dropped
- The timers expire and the routes are pruned
- Recent EIGRP versions fixed this behaviour
- After 90s a SIA-Query is send to the neighbor that did not respond.
- If a SIA-Reply is received the process continues otherwise the neighbor is taken down and routes are pruned.
- SIA is dissolved
- Older EIGRP versions tended to get into a state called "stuck in active" (SIA)
- EIGRP floods out (MC) queries for a new route to the lost network through its interfaces
Basic configuration
Cisco
Stub routers
- Idea is different from OSPFs
- Optimizes performance (e.g. convergence time, load, …)
- Don't advertise routes from on EIGRP neighbor to another EIGRP neighbor
- The configured router will announce to be a stub router to its neighbors.
- During configuration adjacencies are reset
- Queries not send from non-stub routers to stub routers
- Because stub routers cannot have an alternative path
Combine it with #Passive interfaces
Configure stub router
Configure router as stub router (resets adjacencies)
where OPTIONS are
connected: The stub router advertises routes matched with a network command
summary: The stub router advertises summarized routes, (either automatically or statically summarized).
static: The stub router advertises statically configured routes, if the redistribute static command has been configured.
leak-map name: The stub router's dynamic prefixes are based on a leak-map.
redistribute: The stub router advertises any redistributed routes.
receive-only: The stub router does not advertise any routes.
Check neighbor info on adjacent router
1 show ip eigrp neighbor detail
Load Balancing
- By default only the best path is selected
- EIGRP variance FACTOR
- Define a FACTOR to multiply with the feasible distance (e.g. 2)
- Creates a range from FD to FD * FACTOR
- Routes whose metrics fall into that range are load-balanced
- Variance feature accounts for different throughput using the metrics
- Only puts a share of the traffic to the lower speed route
Configure variance
Route aggregation
- Reduces the size of the routing table
- Makes routing tables more readable
- Increases the efficiency routing table
- Saves cycles and memory
- Works best if summarization is already considered when assigning subnet addressing
- Plan your networks
- Algorithm
- Binary AND of network prefixes to determine common bits.
- Appending bits with value 0 of the resulting network address are counted, subtracted from the maximum length of the SNM (32/128) and converted to decimal to calculate the subnet mask.
- Summarized network address and SNM are concatenated to the summarized network prefix.
- Summarized address
- Be careful, because summarization may also span holes, which may cause issues.
- Should work, because advertisements of network falling into that route are more specific.
- Network with the least cost (OSPF) or highest metric (EIGRP) is picked for the summarized route.
Determine if automatic summarization is configured Automatic summarization
1 show ip protocols
- Summarization can be performed on any router (unlike OSPF)
- Reduces EIGRP query scope
Enable automatic summarization
Configure summarization
IPv6
Updates are send via ff02::a
- Next-hop is neighbors's link local address
- Neighbors don't need to be on the same subnet
- No auto summarization
- On Cisco IPv6 routing is disabled by default
Enable it with ipv6 unicast-routing
- No network statements
- Interfaces are now used
Show information about IPv6 in EIGRP
Classical configuration
Named EIGRP configuration
Creates a Virtual Router Instance containing
- Address-family configuration
- Router ID
- Stub router
- Address-family-interface configuration
- Passive interfaces
- Timers
- Address-family-topology configuration
- Variance
- Redistribution
- Introduces K6 in the metric calculation
Configure named EIGRP
1 conf term
2 ipv6 unicast-routing
3 ! PRIVATE ASN MAY BE 64512
4 router eigrp INSTANCE_NAME
5 address-family ipv4 unicast autonomous-system ASN
6 !SET DEFAULT CONFIGURATION
7 !TO BE INHERITED BY THE INTERFACES IN THE ADDRESS-FAMILY
8 af-interface default
9 !PLACE IFGACE CONFIG HERE
10 exit
11 af-topology
12 topology base
13 variance 2
14 exit
15 exit
16 exit
17 network 0.0.0.0 255.255.255.255
18 !AFTER CREATING THE AF FOR IPV6 ADJACENCIES WILL INSTANTLY COME UP
19 !INTERFACES ARE PARTICIPATING AUTOMATICALLY
20 address-family ipv6 unicast autonomous-system ASN
21 topology base
22 variance 2
23 exit
Security
Authentication
Auth methods
- Plain text
- Discouraged
- Supported by: RIPv2, OSPFv2, IS-IS
- Pre Shared Key (PSK)
- Vulnerable to MITM-attacks
- MAC-Address-Table-Overflow attacks on a switch
- dis-ARP
- Steal PSK and introduce Rogue-Router
- Hash based
- Supported hash algorithms: MD5 and SHA
- Supported for MD5: RIPv2, EIGRP for IPv4/6, Named EIGRP, OSPFv2/3, IS-IS, BGP
- Supported for SHA: RIPng, Named EIGRP, OSPFv2/3, IS-IS
HashDigest = hash(Routing update + PSK) can be calculated by sender and receiver
- Integrity and authenticity can be proofed
- Supported hash algorithms: MD5 and SHA
- Side note:
- RIPng and OSPFv3 rely on IPsec for authentication (because ipsec is part of IPv6 protocoll protection)
Time-based key chain
Configure key chain
1 conf term
2 key chain KC_NAME
3 key 1
4 key-string PRIMARY_KEY_SECRET
5 !INBOUND
6 !accept-lifetime HH:MM:SS Month DayOfMonth YYYY
7 !accept-lifetime 00:00:00 January 1 2024
8 !OUTBOUND
9 !send-lifetime 00:00:00 January 1 2024
10 key 2
11 key-string SECONDARY_KEY_SECRET
12 !accept-lifetime 00:00:00 January 31 2024 infinite
13 !send-lifetime 00:00:00 January 31 2024 infinite
14 end
Configure EIGRP to use key chain during authentication on an interface
1 conf term
2 ipv6 unicast-routing
3 ! PRIVATE ASN MAY BE 64512
4 router eigrp INSTANCE_NAME
5 ! PRIVATE ASN MAY BE 64512
6 address-family ipv4 unicast autonomous-system ASN
7 !SET DEFAULT CONFIGURATION
8 !TO BE INHERITED BY THE INTERFACES IN THE ADDRESS-FAMILY
9 af-interface INTERFACE_ID
10 !authentication mode hmac-sha-256
11 authentication key-chain KC_NAME
Passive interfaces
- Don't send EIGRP messages through this interface.
- Increase security
Configure interface as passive-interface