OSPF and IS-IS comparison - Basic Features
The same point
1. are the IGP, and widely used.
2. support IP environment.
3. The hierarchical design and are designed with the subregion.
Different points
1.OSPF support IP only; IS-IS supports both IP, and support CLNP.
2.OSPF supported network types have rich P2P network, P2MP networks, NBMA networks and broadcast networks; IS-IS supports only two network types, P2P networks and broadcast networks.
3.OSPF support virtual connection; Although IS-IS has a similar function, but most manufacturers are not supported.
4.OSPF works over IP, protocol No. 89; IS-IS operates above the data link layer.
5.OSPF divided areas based on the interface; IS-IS area division based device.
OSPF and IS-IS comparison - Characteristics adjacencies
The same point
1. Hello are to establish and maintain neighbor relationship.
2. The multi-access networks are elections DR / DIS.
Different
1.OSPF neighbor relationship relatively harsh conditions, it is necessary to check the mask Hello packets, authentication, hello / dead time interval, information fields and the like;. IS-IS is relatively relaxed requirements.
2.OSPF point link neighbor relationship requires more reliable three-way handshake; IS-IS reliability is relatively weak, and the three-way handshake with a two-way handshake.
3.OSPF neighbor relationship not hierarchical; IS-IS Neighbor Relationship between two levels, layers 1 and 2.
4.OSPF processing DR / BDR and IS-IS process DIS different ways.
OSPF and IS-IS comparison - database synchronization features
Same point
- Required to form a unified LSDB.
Different
1.OSPF LSA wide range; less IS-IS LSP types.
2.OSPF and IS-IS database synchronization process is different.
3.OSPF LSA survival time increment from zero; IS-IS LSP survival time decreases from a maximum value.
Less 4.IS-IS LSP type, but the strong expansion, primarily by extensions carried LSP TLV field.
OSPF and IS-IS comparison - Other Features
The same point
1. routes are calculated using the SPF algorithm.
2. loop-free, fast convergence, support large-scale network deployment.
Different
1.OSPF simple overhead type, is based on the bandwidth; IS-IS cost type is relatively complex, the cost is theoretically divided into four types, including default cost, delay overhead, the cost of overhead, the overhead of error, but in the using only the default cost on implementation.
2.OSPF support on-demand dial-up networking; IS-IS no such characteristic.