What are the common routing protocols?—Vecloud

Common routing protocols can be classified as follows:
1.
Interior Gateway
Protocol Interior Gateway Protocol (IGP: Interior Gateway Protocol), which is suitable for the operation of a single ISP's unified routing protocol. Generally, the network operated by an ISP is located in an AS (Autonomous System). ), there is a unified AS
number (autonomous system number), used to process internal routing.
RIP, IGRP (Cisco Proprietary Protocol), EIGRP (Cisco Proprietary Protocol), OSPF, IS-IS, etc. are all internal gateway protocols.
RIP, IGRP, EIGRP, OSPF, IS-IS are internal gateway protocols (IGP), which are suitable for the operation of a single ISP's unified routing protocol. Generally, a network operated by an ISP is located in an AS (autonomous system), with a unified AS
number (autonomous system number). BGP is a routing protocol between autonomous systems and an external gateway protocol. It is mostly used to exchange routing information between different ISPs, as well as large-scale private networks such as large enterprises and governments.
1. RIP
RIP is
the abbreviation of " Route Information Protocol (Route Information Protocol)". It mainly transmits routing information. It maintains the location relationship of neighboring routers by broadcasting the routing table every 30 seconds, and calculates itself based on the received routing table information. Routing table information. RIP is a distance vector routing protocol. The maximum number of hops is 16 hops. Networks with 16 hops and more than 16 hops are considered unreachable. This protocol is usually used in small-scale network environments with relatively simple network architecture. It is now divided into two versions, RIPv1 and RIPv2, the latter supports VLSM technology and a series of technical improvements. RIP has a slower convergence speed.
2. IGRP
IGRP protocol is the abbreviation of "Interior Gateway Routing Protool".
Independently developed in the 1980s, it is a Cisco proprietary agreement. IGRP and RIP, like, belong to distance vector routing protocol, and therefore has similarities in many aspects, such as IGRP also periodic wide
multicast routing table, there is also the maximum number of hops (the default is 100 jumps, 100 or more is considered a target network hop Unreachable). The biggest feature of IGRP is the use of mixed metric values, and the
five aspects of link bandwidth, delay, load, MTU, and reliability are considered to calculate routing metric values, unlike other IGP protocols that simply consider one aspect. Calculate the metric value. At present, IGRP has been replaced by the EIGRP protocol independently developed by Cisco. Cisco
IOS (Internetwork Operating System) with version numbers of 12.3 and above does not support this protocol. Nowadays, there are rare networks running IGRP protocol.
3. OSPF
OSPF protocol is
the abbreviation of " Open Shortest Path First", which belongs to the link state routing protocol. OSPF proposes the concept of "area". All routers in each area maintain the same link state database
(LSDB). Areas are divided into backbone areas (the backbone area must be numbered 0) and non-backbone areas (non-zero numbered areas). If there is only a single area in a network running OSPF, the area can be a
backbone area or a non-backbone area. If the network has multiple areas, there must be a backbone area, and all non-backbone areas must be directly connected to the backbone area. OSPF uses the maintained link state
database to calculate the routing table through the shortest spanning tree algorithm (SPF algorithm). The convergence speed of OSPF is faster. Due to its unique openness and good scalability, the OSPF protocol is currently widely deployed in various networks.
4. IS-IS
IS-IS agreement is Intermediate system to intermediate
System (Intermediate System to Intermediate System) is an abbreviation of link state routing protocol. The standard IS-IS protocol is defined by ISO/IEC 10589:2002 formulated by the International Organization for Standardization
. The standard IS-IS is not suitable for use in IP networks. Therefore, the IETF has developed an integrated IS-IS protocol (Integrated
IS-IS). Like OSPF, IS-IS also uses the concept of "area" and also maintains a link state database to calculate the best path through the shortest spanning tree algorithm (SPF).
The convergence speed of IS-IS is faster. The integrated IS-IS protocol is the most commonly used IGP protocol on the ISP backbone network.
2. Inter-domain routing protocol
1. BGP
In order to maintain the independent interests of each ISP, the standardization organization has formulated the routing protocol BGP between ISPs. BGP is
the abbreviation of " Border Gateway Protocol", which handles routing between ISPs. However, BGP runs in a relatively core position and requires users to have a considerable understanding of the network structure, otherwise it may cause greater losses.
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