Questions tagged [eigrp]

Use this tag for questions about Cisco's EIGRP - Enhanced Interior Gateway Routing Protocol.

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22 votes
3 answers
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Protocols: EIGRP vs OSPF [closed]

EIGRP and OSPF are both IGP protocols, the former is a mostly Cisco protocol and the latter is a well established open standard. What are the benefits of one over the other? Put another way, when ...
12 votes
2 answers
11k views

Error: `EIGRP is restricted to stub configurations only on this platform`

We just bought some new Cat4507R+E distribution switches. When we bought the switches, we asked for an Advanced Services K9 image, but our reseller told us they only come with a Universal K9 image. ...
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10 votes
2 answers
6k views

Why does the MTU need to match on interior link state routing protocols like EIGRP and OSPF?

If one tries to configure the neighbor adjacencys without matching MTU, The routers fail to become neighbors. I assume this is to protect the routing protocol from it self but I don't understand ...
  • 203
9 votes
2 answers
2k views

Why do summary routes get a low Administrative Distance?

Why do summary routes get a lower AD than other routing protocols? For example: The AD of EIGRP is 90, whereas the AD of a summary route is 5.
  • 489
9 votes
4 answers
6k views

Delay or Offset-List for EIGRP tuning?

Studying for CCNP-ROUTE - everything I read says it's preferable to use delay and offset-lists for metric tuning vs. say bandwidth in EIGRP. In practice what is more commonly used out of those two ...
  • 3,300
9 votes
2 answers
2k views

Can one configure several static EIGRP Neighbors on one interface?

Can one configure several static EIGRP Neighbors on one interface and are there any considerations apart from disabling split-horizon that one should consider?
  • 827
9 votes
5 answers
5k views

Static redistribution into EIGRP as internal failure

I am redistributing a static route into EIGRP on a 6500. I had read here if you enter a network statement matching a static route that it would be redistributed as an internal route by EIGRP. However, ...
  • 799
9 votes
1 answer
166 views

EIGRP FD not the same in topology table

In EIGRP when showing topology table, i notice in some entries are like below: P 10.1.6.0/24, 1 successors, FD is 793600 via 10.1.2.2 (2195456/281600), Serial0/0/0 via 10.1.3.2 ...
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6 votes
1 answer
917 views

Does EIGRP use AS number/process number as it's PORT NUMBER between routers in the same AS/group?

Does EIGRP use AS number/process number as it's PORT NUMBER between routers in the same AS/group? I know that EIGRP does NOT use TCP/UDP; I know that that EIGRP uses RTP as a mechanism to establish a ...
  • 475
6 votes
2 answers
893 views

Connect one router to layer 3 3750-X stack for redundancy

I'm connecting a Cisco 2851 router to a Layer 3 3750-X stack (2 switches). The Gi0/0 interface connects to an access port on the stack master. How can I achieve redundancy from the 2851 to the ...
6 votes
1 answer
223 views

Keep EIGRP up even through an interface flaps

Does EIGRP have a feature similar to disabling fast fallover in BGP, where we can allow a link to flap for a (hopefully definable) period of time and still leave the EIGRP neighborship up? My ...
  • 3,300
5 votes
2 answers
2k views

Summarized route not being shared in EIGRP

Working through a lab for CCNP prep. Task is simple - create 4 loopback addresses on R3 - all 172.16.X.0/24 addresses, and share the routes to neighboring routers so that they appear as /22's instead....
  • 3,300
5 votes
2 answers
2k views

EIGRP topology table - unexpected behavior

Prepping for CCNP - In my topology the path R1 takes to a Loopback Ip is via R2 by default. My goal is to have a feasible successor route through R3. I've attached a diagram of topology. http://...
  • 3,300
5 votes
1 answer
2k views

Controlling route-map distribution with 'match interface' in EIGRP

I have a "Tun0" interface over which I speak EIGRP. On this same router I have a "Vlan1" interface. What i'd like to do is speak only of the interfaces that pass a route-map, e.g. route-map foo ...
  • 599
5 votes
3 answers
4k views

DMVPN EIGRP Config Error - No EIGRP Hello packets sent out interface

I've been tasked with helping to troubleshoot a DMVPN Phase 3 connection over the internet. Unfortunately, I'm not experienced with DMVPN configs and setups. We have two test devices right now that ...
4 votes
2 answers
450 views

Why does EIGRP aim to be loop free?

As far as I understand: EIGRP is a routing protocol and handles IP packets. IP packets are outfitted with the TTL field and thus, do not loop indefinitely like layer 2 frames do. Why does EIGRP try ...
  • 264
4 votes
5 answers
2k views

Choosing a routing protocol

I have always wondered what causes an network engineer to pick EIGRP or OSPF over the other. Obviously OSPF is opened standard so can be used in a multi-vendor environment. If all equipment was cisco, ...
  • 63
4 votes
3 answers
794 views

Why I cant Ping An Address across my a routed link

I have two layer 3 switches (Main And back up) and a palo alto firewall main switch connects to the firewall with a routed link port(gi1/1 ip add 10.1.70.2)- firewall (10.1.70.1). All connectivity is ...
4 votes
3 answers
2k views

Role of MTU in EIGRP metric calculation!

From what I have found on the internet, there is confusion about the role of MTU in EIGRP metric calculation. I performed an experiment in GNS with few routers. I was not able to find any change in ...
  • 253
4 votes
2 answers
3k views

Cisco ASA Dynamic Routing - Originating a NAT Block

Network guy working on Security problems -- hoping for some guidance! I have a subnet that I am using as a NAT block for one of my inside subnets. NAT from inside->outside : Convert source 10.0.0....
  • 1,589
4 votes
1 answer
2k views

What is the purpose of EIGRP stubs?

I have a strong background in OSPF and am now learning EIGRP so everything I read gets compared to my existing knowledge of OSPF. Because of this, I don't see the purpose of EIGRP stubs. In OSPF, you ...
  • 1,005
4 votes
1 answer
569 views

EIGRP to iBGP metric calculation

Consider the following output: router#show ip bgp vpnv4 rd 300:1 5.5.5.5/26 BGP routing table entry for 300:1:5.5.5.5/26, version 538213 Paths: (2 available, best #2, no table) Advertised to ...
  • 2,527
4 votes
1 answer
16k views

RIP V2 multicasting looks as broadcasting at IP add 224.0.0.9

In RIPv1 the packets are broadcasted out all ports with dest. IP 255.255.255.255. In v2 they are multicasted with dest. IP 224.0.0.9. In Packet Tracer, this v2 packet is transmitted over all ...
  • 253
4 votes
1 answer
68 views

Filter routes based on interface

In EIGRP is there a way to filter routes entering from a specific interface? The intent is to protect the network core's routing table from receiving misconfigured or maliciously-inserted routes from ...
4 votes
1 answer
714 views

EIGRP MD5 authentication

I would like to know more about EIGRP MD5 authentication in the following situation: an attacker captured the MD5 hashed key and send to the target router to fake the authentication, is it possible? ...
4 votes
3 answers
1k views

Why does EIGRP have lower Administrative distance than OSPF?

I have given the following network diagram and been told that, Since EIGRP has a better (lower) administrative distance than OSPF, the router on the far left will use the EIGRP path and publish ...
  • 583
4 votes
1 answer
4k views

eigrp configuration problem over frame-relay

I have a set up with back to back connection with EIGRP over frame-relay, mention below the device connection setup using GNS3. Problem is: I am configuring EIGRP over frame-relay, but its not ...
4 votes
1 answer
2k views

eigrp load balacing - per packet or per destination

Assume i have no cef enabled and there are 2 paths with the same cost ( both traffic share count = 1) Router#show ip route 20.20.20.1 Routing entry for 20.20.20.0/24 Known via "eigrp 10", distance ...
  • 529
4 votes
0 answers
460 views

Dual-Hub DMVPN Outage

Our backup links have always utilized a GRE tunnel based VPN to a hub. Recently we installed a second hub and migrated the primary links to GRE tunnel based VPN with EIGRP to handle routing between ...
3 votes
2 answers
1k views

No passive-interface error

I'm trying to nest some EIGRP configurations on a router in GNS3. I'm trying to connect the EIGRP 2801 in SW01 to RTR-01 and EIGRP 2864 to RTR-02 when I do. When I put no passive-interface ...
  • 133
3 votes
2 answers
614 views

EIGRP failover - how do i verify it happened?

I have 2 links to a destination and EIGRP was setup. The faster link is the successor and the slower link is the feasible successor. Switch1#show ip eigrp topology 192.168.1.0 EIGRP-IPv4 Topology ...
  • 529
3 votes
2 answers
417 views

Cannot see the differende between distance-vector and link-state

At link-state routing protocols each router advertises every link he knows about to the next router, which again advertises his links and so on until every router knows all links in his area. So every ...
  • 772
3 votes
1 answer
910 views

Why can't I ping in this situation?

This is the topology As you can see routers and switches are all named out, so I will use those names to explain the issue. First of all this network consists of VLANs, WANs running on EIGRP and ...
3 votes
2 answers
110 views

EIGRP neighbors discovering process

Quick question regarding EIGRP, as far I know, EIGRP has two tables: neighbors, and topology, and the router has its routing table obtained with DUAL algorithm applied to the topology table. ...
  • 1,075
3 votes
1 answer
108 views

EIGRP Auto-summary

One more question about EIGRP, EIGRP auto-summary what is the impact on the network ? i was reading about but it was not clear for me. And why is it a good Cisco practice to be disabled ? I am ...
  • 328
3 votes
1 answer
834 views

"Debug ip eigrp" command, output interpretation?

"Debug ip eigrp" command, output interpretation? as you see in this output, it's a line from "Show ip eigrp" command, output IP-EIGRP(Default-IP-Routing-Table:90): Int 172.30.7.0/24 M 2297856 - ...
  • 475
3 votes
2 answers
510 views

EIGRP unequal load balancing, variance command

Is correct to say that the value inserted in the variance command, lets say the value of "2" on a route that has a cost of, lets say "100", will unequally load balance all routes up to a cost of 200 ? ...
  • 328
3 votes
1 answer
76 views

EIGRP Adjacency Table

From Cisco IP Routing by Alex Zinin According to this figure Adjacency Table gets messages from DUAL module also.As far as I know, Adjacency Table is populated only because of Hello packets exchanged ...
  • 536
2 votes
2 answers
4k views

How to stop a connected network from being advertised in eigrp?

How to stop a connected network (gig2/1) from being advertised in eigrp? I was thinking to use passive interface but the connected subnet would still be advertised because of "network 10.0.0.0" under ...
  • 21
2 votes
3 answers
5k views

EIGRP metric explanation

I'm looking for an understanding of how the metrics are structured within EIGRP, this includes the routing table, and also the topology table. I'm sure I'm not the only one that finds the concepts of ...
2 votes
3 answers
4k views

How do OSPF and EIGRP deal with 2 exactly same routes?

If you refer this diagram, Will ospf and eigrp share the 10 network on the right to their neighbors? I am asking the question in two separate scenarios using a single protocol at a time and not ...
2 votes
2 answers
1k views

Preventing Load balancing in EIGRP

In a recent project, I have been told to consider four Hubs (two in HQ, and two in DR), where each branch will have EIGRP neighborships with all four, as part of a DMVPN based WAN. I have tested this ...
  • 400
2 votes
2 answers
358 views

How does EIGRP determine the path to far away destinations?

10.0.10.0/24 10.0.11.0/24 192.168.178.0/24 R1 ╚════════════╝ R2 ╚════════════╝ R3 ╚════ R3 LAN ════╝ In OSPF each router knows the full topology, so it uses the Dijkstra algorithm to ...
2 votes
1 answer
3k views

How exactly does "bandwidth" in the Cisco IOS affect network performance?

While troubleshooting a problem that a client reported I came across the IOS interface setting bandwidth. For whatever reason their interface was set to bandwidth 20. I understand that it doesn't ...
2 votes
2 answers
257 views

EIGRP advertising of routes for other networks behind us

Continuing my expedition in to trying to learn EIGRP and other routing techniques in GNS3, I now have another theoretical network, depicted below: Everything in the red area is a mystery. We do not ...
2 votes
2 answers
373 views

How to ping from PC on EIGRP area to PC on OSPF area without middle router?

This is my topology. And I can send a package to every router and PC within the colored area, how can I ping from a PC on EIGRP area to a PC on the OSPF area? I heard about default route but I saw it ...
2 votes
1 answer
496 views

EIGRP authentication on GRE tunnel interface?

I want to implement authentication on EIGRP updates. Can I enable EIGRP authentication on a GRE tunnel interface instead of physical interface?
  • 311
2 votes
1 answer
99 views

Why Static route (AD=150) and EIGRP route coexist under "show ip route"?

pic1 is topology pic2 is routing table. EIGRP is enabled with auto summary, why there is a static router (AD=150)?
  • 179
2 votes
1 answer
165 views

This is an EIGRP Topology with frame relay. I'm not able to figure out why R1's topology table doesn't a show feasible successor for 192.168.2.0/24

P 192.168.1.0/24, 1 successors, FD is 2730496 via 172.16.124.2 (2730496/2218496), Serial3/0 via 172.16.124.3 (3193856/2681856), Serial3/0 P 192.168.2.0/24, 1 successors, FD is 2681856 ...
2 votes
1 answer
398 views

EIGRP advertisement suppressed with static entry

I am trying to understand this behavior. I have an EIGRP router that receives eigrp external route (redistributed from BGP). Lets says 192.168.100.0/24. This route gets advertised further to other ...
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