Tag: Protocol

    What is OSPF (Open Shortest Path First) Protocol

    Open Shortest Path First Protocol

    OSPF is used inside the networks as RIP, the operation is very simple. Each router knows the nearby routers and the addresses each router has. In addition, each router (measured on routers) knows how far each router is. So when you need to send a packet, you send it the same way you have to do fewer skips.

    For example, a router with a local network with one workstation, and a router with three network connections (A) with a fast 48Mbps square relay network and a 64Kbps ISDN (B) line. Three packets from the local network to A and B to two packets go to W. The packet passes through B regardless of the saturation of the line or the bandwidth of the line.

    OSPF Types

    Undoubtedly, OSPF is a complex protocol and requires a lot of work to understand how it works, and makes many practices to master. One of the most important concepts in OSPF is the design and operation of different areas, which is quite confusing when this protocol is known.

    To explain how each works, it is necessary to know the types of LSA (Link State Ads) that the OSPF uses to communicate between neighbors and transmit routing information between them.

    Type 1 (LSA Router)

    Each router in area X sends a type 1 LSA to its neighbors. This LSA never leaves the domain to which it belongs and contains the Router ID of the sender and all connections that connect it.

    Type 2 (Network LSA)

    Sent by the DR (Private Router) within the network. Tells others the networks and masks it is connected to. This LSA never leaves the area it corresponds to. So, an ABR does not transmit to another region.

    Type 3 (Summary LSA)

    They are sent by an ABR to transfer information from one region to another. OSPF calls them a “summary”.

    Type 4 (ASBR-Summary LSA)

    Represents an ASBR (Autonomous System Border Router)

    Type 5 (External LSA)

    Represents an external route redistributed from another protocol within the OSPF (Ex: EIGRP). The ASBR takes the route from the external protocol and transmits them as type 5 to all internal areas except Stub type.

    Type 7

    OSPF rules say that redistribution is required only in a Spine zone (Area 0). In an NSSA domain, a router with a connection to another external routing protocol (eg RIP) can be connected and the ASBR sends these networks in type 7 format so that the ABR receives them and redistributes them as type 5.

    Type 1 and 2 LSAs are found in all areas and are not shipped anywhere they belong. Other LSAs are sent between fields, depending on the function they perform.

    Field Types

    • Standard
    • Backbone (Area 0)
    • Stub Area
    • Totally Stubby Area
    • Not-so-stubby Area (NSSA)
    • Totally Stubby NSSA

    Standard

    This is the default field and allows links to be updated, summary paths, and external paths.

    Backbone (Area 0)

    OSPF is the main area of ​​topology. It must be present and all others must depend on it. The field is labeled 0 and has the same properties as a standard field.

    Stub Area

    Such a field does not accept information about external routes to the autonomous system (redistribution), such as paths from non-OSPF sources. If routers need to route to networks outside the autonomous OSPF system, they use a default route (0.0.0.0/0) sent by ABR to other internal routers in the Stub area. ASBR is not allowed in this area (unless ABR is also an ASBR)

    Totally Stubby Area

    This area belongs to Cisco and does not accept routes from external autonomous systems (redistribution) or abstracts from other internal regions of the autonomous system. As with the Stub fields, ABRs send a default route for all external and SUMMARY routes (this is the difference with Stub). ASBR is not allowed in this area (unless ABR is also an ASBR)

    Not-so-stubby Area (NSSA)

    Almost the worst name in the world chose this name. There are type 7 LSAs in this field, which are similar to the Stub field because they do not accept information from external routes to the autonomous system (OSPF world) and replace them with a default route originating from ABR. However, the difference is that the NSSA accepts an ASBR directly connected to another routing protocol (eg, RIP, EIGRP, etc.). The NSSA ASBR transmits pathways within the site as LSA 7, and the corresponding ABR converts them to type 5 for normal treatment.

    Totally Stubby NSSA

    If the old is almost the worst name, make sure it is the worst. Fully Stubby Not Left-Handed Area or Fully Stubby NSSA is a proprietary Cisco area that functions in the same way as the Fully Stubby Area, does not allow external or summary routes, but permits an ASBR such as NSSA.

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    Source: https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/iproute_ospf/configuration/xe-16/iro-xe-16-book/iro-cfg.html

    What is EIGRP (Enhanced Interior Gateway Protocol)?

    What is EIGRP?

    The distance vector protocol is an elegant version of the IGRP with the sole purpose.

    It has the following features:

    • RTP Yes (Trusted Transport Protocol)
    • Maintains limited updates
    • Broadcast update algorithm (DUAL)
    • Establishing contiguities
    • Preserves topology or neighboring tables

    Data in an EIGRP message is included in a TLV-style data field (Type, Length, Value).

    EIGRP Multiprotocol

    EIGRP is capable of routing different protocols, some examples:

    • IP
    • IPX
    • Apple Talk

    This is due to the use of individual protocol modules (PDMs), which are responsible for routing tasks specific to each network layer protocol.

    For example:

    The IP-EIGRP module is responsible for sending and receiving IP-coated EIGRP packets and using DUAL to create and maintain the IP routing table. EIGRP uses different packets and provides separate neighbors, topology and routing tables for each protocol in the Network layer.

    The IPX EIGRP module is responsible for exchanging routing information about IPX networks with other IPX routes.

    RTP and EIGRP Package Types

    The Trusted Transport Protocol is the protocol used by EIGRP to deliver and receive the same packets, which is designed to operate as a routing protocol that runs outside the network layer so that services such as UDP and TCP cannot be accessed.

    Even if your name has a reliable word, even if it is possible to obtain a delivery through an unreliable ETPRP, you can identify these packages because a reliable RTP requires a confirmation of receipt that requires nothing.

    RTP can send packets with UNICAST or MULTICAST, the latter uses a reserved address: 224.0.0.10

    Routers with EIGRP can discover their neighbors through a package called “GREETING”, in most networks “greeting” packets are sent every 5 seconds and help keep the neighbors and their routes visible When the greeting is answered.

    The wait time tells the router the maximum time it will wait before receiving the next “greet” before declaring its neighbor “inaccessible”.

    As a rule, the waiting time is 3 times the salutation interval.

    Wait time before reporting a router = “dead”

    (It takes the router to send an e-mail) (3)

    When the timeout expires, the route is declared inactive and a new route is searched using queries.

    Limited updates

    EIGRP reserves some reserves as it does not send periodic updates on update packages, ONLY IN THE METRIC OF ROAD CHANGES.

    It is worth noting that these updates are PARTIAL because when this happens, the entire contents of a table are not sent, only information about route changes is sent.

    EIGRP also takes care to limit this route change information to the affected routers. The partial update is automatically updated to “Limits”, so only routers that require this information.

    Sending ONLY the necessary routing information and ONLY to the routers in need minimizes the bandwidth required to send packets.

    Administrative Distance

    The administrative distance is the “degree of reliability ın of the route.

    EIGRP has 90 administrative distances for internal routes and 170 administrative distances for routes imported from an external source (including default routes)

    Compared to other protocols, the EIGRP has less administrative distance, in other words, IT IS MORE RELIABLE.

    Authentication

    It accepts security settings and can encrypt and verify your routing information.

    It is recommended that authentication is always performed on the transmitted routing information, ensuring that routers will only accept routing information from routers configured with the same password or authentication information.

    Protocols such as:

    · RIPv2
    · OSPF
    · IS-IS
    · BGP

    They also accept encryption in routing information.

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    Source: https://www.cisco.com/c/en/us/support/docs/ip/enhanced-interior-gateway-routing-protocol-eigrp/16406-eigrp-toc.html

    What is RIP Version 2 (Routing Information Protocol – RIPv2)?

    Routing Information Protocol version 2 (RIPv2) is one of the simplest and most widely used internal routing protocols. This is especially true from version 2, which offers some important improvements that make it a necessary resource for any network administrator.

    What kind of routing protocol is RIP?

    RIP is a standard vector distance protocol based on RFCs 1388, 1723 and 2453. The main limitation is enforced by the maximum number of hops it supports: 15. The RIP assumes that everything has more than 15 hops. There is an infinite distance, and therefore there is no valid way.

    In contrast, perhaps the most applied protocol. RIP is enabled by default on most devices (for example, some routers for small offices). In addition, firewalls that support RIP but not OSPF or EIGRP may be encountered.

    Some of its features:

    • The management distance for Ripv1 and RIPv2 is 120.
    • RIPv2 sends routing updates via the multicast address 224.0.0.9.
    • On Cisco routers, version 2 is not enabled by default. You must use the version 2 command in the RIP configuration mode.
    • RIPv2 automatically summarizes routing updates.
    • The number of hops of the metric value.

    How does RIP work?

    The device sends the complete routing table to all connected neighbors every 30 seconds. Events triggered by events can occur, for example, if an interface falls before the 30-second timer expires.

    As a distance-vector protocol, it is sensitive to the appearance of orientation loops. This is a result of not recalculating neighboring relationships or network topology, as in link-state protocols. This directly affects the quality of the routing information provided by the RIP.

    What are the advantages of RIPv2?

    Main developments:

    • VLSM support.
    • Multicast routing updates.
    • Routing updates with encrypted key authentication.

    How to configure RIPv2

    Unlike other routing protocols, RIP does not use autonomous systems or field numbers that identify a type of administrative unit. Therefore, the RIP configuration is very simple:

    Router(config)# rip router
    Router(config-router)# version 2
    Router(config-router)# network 172.16.0.0

    This last parameter indicates that the protocol is present on any interface for that network address:

    • Sends routing updates.
    • You’ll be aware of getting redirect updates.
    • Any routing update it sends will contain the network address of any interface that is “on”.
    • If you do not want to send routing updates through an interface, the passive-interface command must be used.

    What are the commands that allow you to monitor RIP?

    • show ip route
    • show ip route rip
    • show ip protocols
    • show running-config
    • show running-config
    • debug ip rip

    RIPv2 is an improvement of the functions and extensions of RIPv1. Some of these advanced features include:

    • The next-hop addresses added to routing updates.
    • Using multicast addresses when sending updates.
    • Authentication option available.
    • Both RIPv1 and RIPv2 are distance vector routing protocols, but have the following functions and limitations:
    • Use wait timers and other timers to help prevent routing loops.
    • Use of split-horizon on the opposite horizon to help prevent orientation loops.
    • Use of updates triggered when there is a change in the topology to achieve faster convergence.
    • The maximum limit for a jump of 15, with a jump number of 16 representing an inaccessible network.
    • Supports VLSM.
    • Summarize the networks in the routing table.
    • Updates send the mask.
    • Loopback interface
    • It makes sense for those who don’t exist physically.
    • We simulate networks or hosts.
    • The main application is to be the identity of the router.

    RIP (Routing Information Protocol) Commands;

    Show ip protocols: Indicates whether RIP is sending and receiving version 2 updates and whether the automatic summary is valid.

    Int loopback 0: logical or virtual interfaces that interfere with router ID selection.

    Int loopback 0
    Ip address ip

    debug ip rip: Displays information about RIP routing updates when the router sends and receives them.

    no debug all: Disables all debugging that is enabled on the device.

    undebug all: Disables all debugging that is enabled on the device.

    Show version – Shows information about Cisco IOS and platform.

    debug cdp ip: Displays IP-specific CDP information.

    Using the UDP protocol and port 520, the RIP updates every 30 seconds and sends the entire routing table to its neighbors. RIPv2 makes updates triggered by events. Routes TTL (lifetime) is 180 seconds, which means that if the route does not appear active in 6 changes, it is deleted from the routing table.

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    What is Cisco RIP Protocol?

    RIP History

    The origin of the RIP was the Xerox GWINFO protocol.

    A later release was known as directed in 1982, Berkeley Standard Distribution (BSD) distributed with Unix.

    RIP has evolved as an Internet routing protocol, and other proprietary protocols use modified versions of RIP.

    For example, Apple Talk Routing Table Maintenance Protocol (RTMP) and Banyan VINES Routing Table Protocol (RTP) are based on a version of the RIP routing protocol.

    The latest development in RIP is the RIPv2 feature, which allows more information to be included in RIP packets and provides a very simple authentication mechanism.

    This is what RIPv2 needs to learn for CCNA right now and is still the version you can see on some computers.

    What is Routing Information Protocol

    RIP is a dynamic routing protocol of the vector distance type, ie the best route for a given destination for RIP is the one with the least number of hopes.

    In Router and Routing – Dynamic Routing, you can understand the concept of distance vector in detail.

    One detail to keep in mind at all times is the skip limit.

    This limit 15 hopping, for the two versions of the protocol, was something that did not develop in the new version.

    If I need to pass more than 15 routers to reach my destination, my package will be thrown on the road.

    As you can imagine, this directly affects the scalability of the protocol.

    Although at that time a protocol that meets the needs of the moment; RIP today is well below the challenges of modern data networks.

    Now you can ask me why we saw it.

    The truth is, there are still many companies that use it, for little information or for a technical decision.

    As an example, in one of the networks I met, we used RIP as a redundant network protocol because it contained a high AD (Management Distance).

    For those wondering, the RIP has an AD value of 120.

    Messages

    RIP messages can be of two types:

    Request: sent by a recently started router, requesting information from neighboring routers.

    Reply: messages containing routing tables are updated. There are three types:

    Normal messages: Sent every 30 seconds. To indicate that the link and route are still active. The full routing table is sent.
    Messages sent in response to request messages.
    Messages sent when cost changes. All routing table is sent.

    Working mode

    When the RIP starts, it sends a message to each neighbor asking for a copy of the neighbor’s routing table.

    This message is a request with “address family” in 0 and “metric” in 16.

    Neighbor routers return a copy of the routing tables.

    When the RIP is in active mode, it sends all or part of the routing table to its neighbors every 30 seconds.

    The routing table is sent in response, even if the request is not present.

    When a measurement changes, it is broadcast to other routers.

    When the RIP receives a response, the message is confirmed and the local table is updated if necessary.

    You learned one route from another, you must save it until you find a more cost-effective route.

    This prevents routers from oscillating between two or more paths at equal cost.

    The routes that the RIP learns from other routers end unless they are broadcast again in 180 seconds, ie 6 seconds and 30 seconds.

    When a route expires, its metric is set to infinity, the invalidity of the route is distributed to the neighbors, and is deleted from the table after 60 seconds.

    The information is published in the first version and in the second version by multicast (224.0.0.9).

    Advantages and disadvantages

    The main advantage of RIP is the simplicity of its configuration, which makes it very easy to implement.

    Contrary to its simplicity, there are disadvantages.

    One of the most important of these is to be a distance-vector protocol that is very limited in modern networks.

    Today we can imagine this because we show great differences in connection speed.

    Another disadvantage is the very long convergence time.

    And let’s not forget the 15-jump limit.

    Can you imagine a protocol that limits you to 15 steps in a globalized world?

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    Reference

    https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/iproute_rip/configuration/15-mt/irr-15-mt-book/irr-cfg-info-prot.html