Comparison of four dynamic routes: Rip, OSPF, Isis, BGP

RIP

RIP(Routing Information Protocol, Routing information protocol ） Is one of the oldest protocols .RIP It is a distributed routing protocol based on distance vector ,RIP The agreement is Xerox 20 century 80 Introduced in the s , It is mainly applicable to small-scale network environment .RIP The protocol is mainly used for one AS( Autonomous systems ) The transmission of routing information within , Every time 30s Send a routing information update .

OSPF

OSPF(Open Shortest Path First Open shortest paths take precedence ） It's an internal gateway protocol (Interior Gateway Protocol, abbreviation IGP）, Used in a single autonomous system （autonomous system,AS） Internal decision routing . It is an implementation of link state routing protocol , It belongs to the internal gateway protocol （IGP）, Therefore, it operates within the autonomous system . The famous dixcher （Dijkstra） The algorithm is used to calculate the shortest path tree .OSPF Support load balancing and routing based on service type , It also supports multiple routing forms , Such as specific host routing and subnet routing .

ISIS

Intermediate system to intermediate system （ISIS-Intermediate system to intermediate system） Is a hierarchical link state routing protocol , be based on DECnet PhaseV Routing algorithm , Actually with OSPF Very similar , It also uses Hello The protocol looks for adjacent nodes , Use a propagation protocol to send link information .ISIS You can operate on different subnets , Including broadcast type LAN、WAN And point-to-point links .

BGP

Border gateway protocol （BGP） Is running on TCP A routing protocol for autonomous systems . BGP It's the only protocol used to handle networks the size of the Internet , The only inter domain connection protocol that can be handled properly is also the only one . BGP Builds on the EGP On the experience of . BGP The main function of the system is with other BGP System exchange network reachable information . Network accessibility information includes listed autonomous systems （AS） Information about . This information effectively constructs AS The topology of the interconnection and thus the routing loop is cleared , At the same time AS Strategic decisions can be implemented at a level .

Comparison of route update methods

Distance vector routing protocol	RIP（ Periodically flood your routing table 30s）、BGP （ Delivery route entry ）
Link state routing protocol	OSPF（ Periodic flooding link status information 1800s）、ISIS （ Periodicity is determined by DIS Pseudo node flooding LSP）

Path cost calculation （ By default , Generally, you can manually specify ）

RIP	Calculate by hops ,16 Can't jump , Beckmann algorithm
OSPF	According to the interface bandwidth , Compare numerator and denominator ,SPF Algorithm
ISIS	According to the interface , The default is 10,SPF Algorithm
BGP	11 Path optimization algorithm , Path attribute routing principle

Message type

RIP	request、response
OSPF	hello、dd、LSR、LSU、LSACK
ISIS	level-1、level-2、level-1-2
BGP	open、keepalive、update、notification、router-refresh

Route update cycle comparison

RIP	Send routing table periodically
OSPF	hello、dd、LSR、LSU、LSACK（ Triggered updates ）
ISIS	level-1、level-2（ Triggered updates ）
BGP	Will not send periodically , Triggered updates , Incremental updating

Anti ring mechanism

RIP	Define the maximum hops , Horizontal segmentation , Poison Reverse , Trigger update , Toxic routing
BGP	AS_PATH attribute ,IBGP Horizontal segmentation , Reflector Originator_ID and Cluster_List
OSPF	In the area SPF Algorithm anti loop , Interregional Type3 LSA,Area0 Direct connection , Route introduction anti ring
ISIS	Level-1 LSP And Level-2 LSP The principle of transmission

reliability

RIP	30s Primary flood routing table , unreliable
ISIS	DIS Every time 10s Send it once CSNP, unreliable
BGP	TCP Protocol transfer
OSPF	LSACK confirm