What is EIGRP protocol dependent module?
Protocol-dependent module. Protocol-dependent modules (PDMs) are used by the routing protocol EIGRP to make decisions about adding routes learned from other sources; for example other routers or routing protocols to the routing table.
What is the PDM responsible for encapsulating EIGRP messages?
The PDM is also responsible for encapsulating EIGRP messages in IP packets. EIGRP packets are encapsulated directly in IP with the protocol field set to 88.
Can EIGRP add PDMs for IPv6?
"In theory, EIGRP can add PDMs to easily adapt to new or revised routed protocols such as IPv6. Each PDM is responsible for all functions related to its specific routed protocol. The IP-EIGRP module is responsible for the following functions: Send and receive EIGRP packets that bear IP data.
Does EIGRP require a database?
EIGRP is not a link-state routing protocol, but rather it is a distance-vector routing protocol. The topology table must be used for the correct operation of Diffuse Update Algorithm (DUAL), not because the EIGRP is a link-state routing protocol; hence, it requires a database.
What are the primary functions of the PDM in EIGRP?
EIGRP uses protocol-dependent modules (PDMs) to support multiple network protocols, such as IPv4, IPv6, AppleTalk, and IPX. EIGRP is written so that the PDM is responsible for the functions to handle the route selection criteria for each communication protocol.
What is autonomous system in EIGRP?
The links between the routers within an independent network, or autonomous system (AS), are referred to as Interior Gateway Protocol (IGP) links. The links between routers in different autonomous systems are referred to as Exterior Gateway Protocol (EGP) links. EIGRP is an IGP. AS. Autonomous system.
What is the routing algorithm used by EIGRP?
diffusing update algorithm (DUAL)EIGRP is a distance vector & Link State routing protocol that uses the diffusing update algorithm (DUAL) (based on work from SRI International) to improve the efficiency of the protocol and to help prevent calculation errors when attempting to determine the best path to a remote network.
Which is better EIGRP or OSPF?
The network convergence time is faster than OSPF networks, because EIGRP network can learn the topology information and updates more rapidly. The performance of packet delay variation for EIGRP is better than for OSPF.
What is FD and RD in EIGRP?
Feasible distance (FD) – the metric of the best route to reach a network. That route will be listed in the routing table. Reported distance (RD) – the metric advertised by a neighboring router for a specific route. It other words, it is the metric of the route used by the neighboring router to reach the network.
What is autonomous system in routing protocol?
An Autonomous System (AS) is a set of Internet routable IP prefixes belonging to a network or a collection of networks that are all managed, controlled and supervised by a single entity or organization. An AS utilizes a common routing policy controlled by the entity.
Why does EIGRP use RTP?
How does EIGRP use RTP? EIGRP uses RTP to communicate with other EIGRP speaking routers on the network. In EIGRP implementation, RTP is responsible for guaranteed and ordered delivery of EIGRP packets with the use of sequence and acknowledge numbers. Each EIGRP router knows who its neighbors are.
Why EIGRP is called hybrid protocol?
EIGRP is called a hybrid protocol because is uses metrics from both distance vector protocols and link state protocols. Configuration of EIGRP on a Cisco router is similar to enabling other routing processes. All that needs to be done to start EIGRP on a Cisco router is to define an EIGRP routing process.
What is the difference between BGP and EIGRP?
In BGP, Transmission control protocol is used. It is type of mesh topology or design.It works by two independent networks (Autonomous Systems or AS) exchanging routing information....Difference between EIGRP and BGP :SR.NOEIGRPBGP7.In EIGRP, Internet protocol is used.In BGP, Transmission control protocol is used.7 more rows•Jun 22, 2020
Which is the fastest routing protocol?
Many network engineers believe that EIGRP is the best choice for a routing protocol on private networks because it offers the best balance between speed, scalability and ease of management.
Why we use BGP instead of OSPF?
BGP and OSPF are two of the most common routing protocols. While BGP excels with dynamic routing for large networks, OSPF offers more efficient path choice and convergence speed.
What are LSA types?
OSPF LSA Types ExplainedLSA Type 1: Router LSA.LSA Type 2: Network LSA.LSA Type 3: Summary LSA.LSA Type 4: Summary ASBR LSA.LSA Type 5: Autonomous system external LSA.LSA Type 6: Multicast OSPF LSA.LSA Type 7: Not-so-stubby area LSA.LSA Type 8: External attribute LSA for BGP.
What is the purpose of the autonomous system autonomous system number command?
The autonomous system number used for EIGRP configuration is only significant to the EIGRP routing domain. It functions as a process ID to help routers keep track of multiple, running instances of EIGRP. This is required because it is possible to have more than one instance of EIGRP running on a network.
What is an autonomous system Cisco?
An Autonomous System (AS) is a group of networks under a single administrative control which could be an Internet Service Provider (ISP) or a large Enterprise Organization. An Interior Gateway Protocol (IGP) refers to a routing protocol that handles routing within a single autonomous system.
How do I change my EIGRP autonomous number?
To configure EIGRP on the router, use the global configuration command. Router eigrp autonomous-system number - It is used to enable the EIGRP process. This AS-number is a 16-bit value between 1 and 65,535. The value chosen must be the same for all routers within a given EIGRP routing domain.
What are the different types of EIGRP packets?
EIGRP sends out five different types of packets—hello, update, query, reply, and acknowledge (ACK)—that are used to establish the initial adjacency between neighbors and to keep the topology and routing tables current.
What is EIGRP protocol?
It is a technologically, more advanced distance vector-based routing protocol. To exchange information using EIGRP, first and foremost, the routers need to become neighbors to EIGRP, then EIGRP uses the multicast address to share the information. Start Your Free Software Development Course. Web development, programming languages, Software testing & ...
What is EIGRP in Cisco routers?
Enhanced Interior Gateway Routing Protocol or EIGRP automates the routing decisions and configurations in computer networking. Cisco designed the protocol and is available only on Cisco routers. Minimum bandwidth is used from the source to destination, and the delay is measured using metrics of the network. This is an advanced protocol to measure the distance and uses both link servicing and distance routing. Hence it is called a hybrid protocol. It transitions well with IPv6 and has the support of IPv4 as well. This is a classless routing technique. Two routers are connected, and the network is shared in EIGRP.
What is EIGRP load balancing?
EIGRP performs load balancing over the equal-cost path and un-equal cost path. To perform the functions of EIGRP, it creates three tables which are: Following represents the ideology and concepts behind the three major tables: 1.
What does hello mean in router?
Hello: It determines the neighbors’ router and also serves as a keep-alive mechanism between the routers. If Router X is connected with Router Y and the Router X is not receiving the hello packets from Router Y, then it assumes that Router Y is not reachable and the network is down.
What is the ip summary address for EIGRP?
A. Do this under the outbound interface on the hub router with the ip summary-address eigrp X 0.0.0.0 0.0.0.0 command. This command suppresses all the more specific routes and only sends the summary route. In the case of the 0.0.0.0 0.0.0.0, it means it suppresses everything, and the only route that is in the outbound update is 0.0.0.0/0. One drawback to this method is that EIGRP installs a 0.0.0.0/0 route to Null0 is the local routing table with an admin distance of 5.
What is neighbor command?
A. The neighbor command is used in EIGRP in order to define a neighboring router with which to exchange routing information. Due to the current behavior of this command, EIGRP exchanges routing information with the neighbors in the form of unicast packets whenever the neighbor command is configured for an interface. EIGRP stops processing all multicast packets that come inbound on that interface. Also, EIGRP stops sending multicast packets on that interface.
Why is EIGRP preferring VLAN interface?
If there are two paths to reach a network either through a VLAN interface or tunnel interface, EIGRP prefers the Virtual-Access Interface (VAI) VLAN interface because the VLAN interface has greater bandwidth than the tunnel interface.
How to find the EIGRP metric?
The EIGRP metric is obtained when you multiply the IGRP metric by 256. The IGRP uses only 24 bits in its update packet for the metric field, but EIGRP uses 32 bits in its update packet for the metric field. For example, the IGRP metric to a destination network is 8586, but the EIGRP metric is 8586 x 256 = 2,198,016.
What is EIGRP version 1?
EIGRP version 1 introduced a feature that prevents any single EIGRP process from using more than fifty percent of the configured bandwidth on any link during periods of network convergence. Each AS or protocol (for instance, IP, IPX, or Appletalk) serviced by EIGRP is a separate process. You can use the ip bandwidth-percent eigrp interface configuration command in order to properly configure the bandwidth percentage on each WAN interface. Refer to the EIGRP White Paper for more information on how this feature works.
Why does EIGRP send hello packets?
Unlike IGRP or RIP, EIGRP sends hello packets in order to form and sustain neighbor adjacencies. Without a neighbor adjacency, EIGRP cannot exchange routes with a neighbor. Therefore, the passive-interface command prevents the exchange of routes on the interface.
What is split horizon?
A. The split horizon rule prohibits a router from advertising a route through an interface that the router itself uses to reach the destination. In order to disable the split horizon behavior, use the no ip split-horizon eigrp as-number interface command. Some important points to remember about EIGRP split horizon are:
How does EIGRP work?
How EIGRP Works. Unlike traditional DV protocols such as RIP and IGRP, EIGRP does not rely on periodic updates: routing updates are sent only when there is a change. Remember that RIP and IGRP reset the invalid and flush timers upon receiving a route update. When a route is lost, the updates stop; the invalid and flush timers grow and grow ...
What is a successor in a dual topology table?
The successors in the DUAL topology table are eligible for installation in the routing table. Successors represent the best path to the destination known to DUAL. However, whether the successor is copied into the routing table is another matter. The router may be aware of a route to the same destination from another source (such as another routing protocol or via a static route) with a lower distance. The IP protocol-dependent module (PDM) handles this task. The PDM may also carry information in the reverse direction -- from the routing table to the topology table. This will occur if routes are being redistributed into EIGRP from another protocol.
What is the IP address of EIGRP?
All transmissions use IP with the protocol type field set to 88. The IP multicast address used is 224.0.0.10.
What is the dual task in EIGRP?
All route computations in EIGRP are handled by DUAL. One of DUAL’s tasks is maintaining a table of loop-free paths to every destination. This table is referred to as the topology table . Unlike traditional DV protocols that save only the best (least-cost) path for every destination, DUAL saves all paths in the topology table. The least-cost path (s) is copied from the topology table to the routing table. In the event of a failure, the topology table allows for very quick convergence if another loop-free path is available. If a loop-free path is not found in the topology table, a route recomputation must occur, during which DUAL queries its neighbors, who, in turn, may query their neighbors, and so on... hence the name “Diffusing” Update Algorithm.
What is feasibility condition?
The feasibility condition is a test for loop freedom : if the FC is met, the router advertising the RD must have a path to the destination not through the router checking the FC -- if it did, the RD would have been higher than the FD.
Does a hello interval change the hold time?
If the hello-interval is changed, the hold-time should also be modified.
What is EIGRP configuration?
The EIGRP supports configurations with one or more static neighbors on the same interface. As soon as you configure one static EIGRP neighbor on the interface, the router no longer sends the EIGRP packets as multicast on that interface or processes the received multicasted EIGRP packets. This means that the Hello, Update, and Query packets are now unicasted. No additional neighborships can be formed unless the static neighbor command is explicitly configured for those neighbors on that interface.
What is EIGRP routing?
The EIGRP is a distance-vector routing protocol. You can use a distribute-list on any router in order to block prefixes. You can use it on an interface in order to stop the prefixes from being sent out or being received, or you can configure the distribute-list globally under the router EIGRP process in order to apply the routing filter on all of the EIGRP-enabled interfaces.
What does SIA mean in EIGRP?
The SIA state means that an EIGRP router has not received a reply to a query from one or more neighbors within the allotted time (approximately three minutes). When this occurs, the EIGRP clears the neighbors that do not send a reply and logs a DUAL-3-SIA error message for the route that went active.
How long does an EIGRP hold time?
However, if the EIGRP hold time is larger than 80 seconds, the neighborship does not go down until the hold time has expired.
What does an expired holding timer mean?
An expired holding timer indicates that the router did not receive any EIGRP packet (that is, an EIGRP Hello or any other EIGRP packet) during the hold-time interval. There is more than likely a problem on the link in this case.
Why does EIGRP go down?
Authentication can be misconfigured or missing. This can cause the EIGRP neighborship to go down because of the exceeded retry-limit. Enable the debug eigrp packets command in order to confirm that it is the Message Digest 5 (MD5) authentication that causes the issue:
What is EIGRP used for?
The EIGRP used to perform summarization at the major network (networks A, B, and C) boundaries by default. This means that more specific routes than the /8 prefixes for the major network type A, more specific routes than the /16 prefixes for major network type B, and more specific routes than the /24 prefixes for major networks type C, are lost when they cross their boundaries. Here is an example where auto-summary causes a problem:
EIGRP Fundamentals
EIGRP Characteristics
- Let’s being our EIGRP review by reminding ourselves of a few basic EIGRP characteristics: 1. Fast Convergence:If a link goes down in a network, in many cases EIGRP can rapidly reroute around the link failure. This typically happens in no more than 3 seconds. This fast convergence is made possible by EIGRP having a standby route to a network, and that standby route is ready to take o…
Configuration Review
- A basic EIGRP configuration is very easy to configure. In fact, it only requires two commands: router eigrp asn network net-id wildcard-mask The router eigrp asn command starts the EIGRP routing process on a router for an autonomous system (AS) specified by the asn variable. This command also brings you into router configuration mode. From there, y...
Verification Review
- The process of EIGRP verification is more than just making sure neighborships have formed between all routers and that all routers have learned all the routes in the network. The verification process needs to help us verify our design requirements were met. For example, we need to look for appropriate routes to appear in the EIGRP topology table, desired interfaces to appear in the …