1) IS-IS only defines two network topology types: broadcast and general topology. In Cisco routers, links are divided into point-to-point
and broadcast.
OPSF defines four network topology types: point-to-point, point-to-multipoint, broadcast and nonbroadcast.
2) Both protocols maintain a link state database (Link State Database)
IS-IS uses LSP (Link State PDU), and LSP itself is a datagram;
OSPF uses LSA (Link State Advertisements), which must be encapsulated (encapsulated) in the OSPF header and IP header.
3) Both protocols use SPF algorithm to calculate routing
IS-IS runs Level 1 SPF compute routes within the domain (intra-area) and Level 2 SPF compute routes within the domain (inter-area);
OSPF runs SPF computation routes within the domain (intra-area), and runs distance vector algorithms between domains (inter-area) to calculate routes.
4) Both protocols use areas to establish a two-layer hierarchical network topology
The backbone of IS-IS is not a specific domain, but consists of continuous Level 2 routers;
The backbone of OSPF must have and must be area 0;
The domain boundary of IS-IS is on the link between routers (link);
The domain boundary of OSPF is on the router;
The two-layer hierarchical network topology of IS-IS is not necessary, and the network can be composed entirely of Level 1 routers or entirely of Level 2 routers.
OSPF must have area 0, there can be only one area, but it must be area 0.
5) One of the characteristics of IS-IS is that the IS-IS router can have up to 3 domain addresses, which is very useful in inter-domain transmission.
6) Both protocols are classless routing protocols, and are summarized between areas (summary)
7) The two protocols have different methods of handling errors (corrupted) LSP/LSA:
Any router in IS-IS can purge corrupted LSP;
In OSPF, only the originator of the corrupted LSA can be discarded (purged).
8) Both protocols must establish adjacency relationships in the broadcast network
In IS-IS, as long as your identity is included in the Hello datagram of neighbor, the adjacency relationship will be successfully established. This stage goes through a three-way handshake: Down→Init→Up.
In OSPF, the process experienced before establishing an adjacency relationship: Download → Init → Two-way → Exstart → Exchange → Uploading → Full.
9) IS-IS neighbors will establish adjacency relationships, even if Hello-intervals or Hello multipliers are different;
OSPF neighbors do not establish adjacency relationships if Hello-intervals or Dead-intervals are different.
10) In the broadcast network, both protocols must choose a DIS/DR
DIS in IS-IS is dynamically selected, that is, if a router with a higher priority or larger address joins the network, the newly added router becomes DIS;
DR is relatively stable in OSPF, that is, as long as DR is not down, DR maintains its status;
In IS-IS, routers in the broadcast network establish adjacency relationships with all neighbors;
In OSPF, routers in the broadcast network only establish adjacency relationships with DR and BDR neighbors;
In IS-IS, DIS does not synchronize with its neighbors (synchronize). DIS generates the pseudonode for the LAN and sends PSNPs (partial sequence number PDUs) every 3 seconds or CSNPs (complete sequence number PDUs) every 10 seconds. Other routers can also use PSNPs to apply for lost LSPs to DIS or send a new LSP to DIS. Because DIS can flood PDUs, DIS does not need to be synchronized with its neighbors; because it does not need to be synchronized with its neighbors, BDIS is not required.
In OSPF, DR/BDR uses unicast to transmit DDP synchronization with other routers respectively.
11) Both protocols have authentication (authentication)
IS-IS only supports simple authentication;
OSPF supports simple authentication and MD5 authentication.
12) The L1/L2 router of IS-IS does not publish L2 routes to the L1 router. The L1 router is like the totally stubby area in OSPF. Article entry: csh Editor in charge: csh
and broadcast.
OPSF defines four network topology types: point-to-point, point-to-multipoint, broadcast and nonbroadcast.
2) Both protocols maintain a link state database (Link State Database)
IS-IS uses LSP (Link State PDU), and LSP itself is a datagram;
OSPF uses LSA (Link State Advertisements), which must be encapsulated (encapsulated) in the OSPF header and IP header.
3) Both protocols use SPF algorithm to calculate routing
IS-IS runs Level 1 SPF compute routes within the domain (intra-area) and Level 2 SPF compute routes within the domain (inter-area);
OSPF runs SPF computation routes within the domain (intra-area), and runs distance vector algorithms between domains (inter-area) to calculate routes.
4) Both protocols use areas to establish a two-layer hierarchical network topology
The backbone of IS-IS is not a specific domain, but consists of continuous Level 2 routers;
The backbone of OSPF must have and must be area 0;
The domain boundary of IS-IS is on the link between routers (link);
The domain boundary of OSPF is on the router;
The two-layer hierarchical network topology of IS-IS is not necessary, and the network can be composed entirely of Level 1 routers or entirely of Level 2 routers.
OSPF must have area 0, there can be only one area, but it must be area 0.
5) One of the characteristics of IS-IS is that the IS-IS router can have up to 3 domain addresses, which is very useful in inter-domain transmission.
6) Both protocols are classless routing protocols, and are summarized between areas (summary)
7) The two protocols have different methods of handling errors (corrupted) LSP/LSA:
Any router in IS-IS can purge corrupted LSP;
In OSPF, only the originator of the corrupted LSA can be discarded (purged).
8) Both protocols must establish adjacency relationships in the broadcast network
In IS-IS, as long as your identity is included in the Hello datagram of neighbor, the adjacency relationship will be successfully established. This stage goes through a three-way handshake: Down→Init→Up.
In OSPF, the process experienced before establishing an adjacency relationship: Download → Init → Two-way → Exstart → Exchange → Uploading → Full.
9) IS-IS neighbors will establish adjacency relationships, even if Hello-intervals or Hello multipliers are different;
OSPF neighbors do not establish adjacency relationships if Hello-intervals or Dead-intervals are different.
10) In the broadcast network, both protocols must choose a DIS/DR
DIS in IS-IS is dynamically selected, that is, if a router with a higher priority or larger address joins the network, the newly added router becomes DIS;
DR is relatively stable in OSPF, that is, as long as DR is not down, DR maintains its status;
In IS-IS, routers in the broadcast network establish adjacency relationships with all neighbors;
In OSPF, routers in the broadcast network only establish adjacency relationships with DR and BDR neighbors;
In IS-IS, DIS does not synchronize with its neighbors (synchronize). DIS generates the pseudonode for the LAN and sends PSNPs (partial sequence number PDUs) every 3 seconds or CSNPs (complete sequence number PDUs) every 10 seconds. Other routers can also use PSNPs to apply for lost LSPs to DIS or send a new LSP to DIS. Because DIS can flood PDUs, DIS does not need to be synchronized with its neighbors; because it does not need to be synchronized with its neighbors, BDIS is not required.
In OSPF, DR/BDR uses unicast to transmit DDP synchronization with other routers respectively.
11) Both protocols have authentication (authentication)
IS-IS only supports simple authentication;
OSPF supports simple authentication and MD5 authentication.
12) The L1/L2 router of IS-IS does not publish L2 routes to the L1 router. The L1 router is like the totally stubby area in OSPF. Article entry: csh Editor in charge: csh