D-Link DGS-1520 User Manual - Page 266

DGS-1520 Series Gigabit Ethernet Smart Managed Switch Web UI Reference Guide Parameter Network Type Authentication Password MD5 Key ID MD5 Description become the DR, the router with the higher router priority will be elected the DR. If the routers have the same priority, the router with the higher router ID takes precedence. Only routers with non-zero router priority values are eligible to become the DR or Backup Designated Router (BDR). By default, this value is 1. Select the Default option to use the default value. Select the OSPF network type here. Options to choose from are: • Broadcast - Specifies the network type as broadcast. On a broadcast network, only the designated router and backup designated router become adjacent neighbors of all other routers attached. • Point-to-Point - Specifies the network type as point-to-point. On point-topoint network, only two routers become adjacent if they can communicate. Select the authentication type that will be used here. Options to choose from are None, Simple Password, and MD5. After selecting the Simple Password option, enter the simple password here. This password can be up to 8 characters long. The syntax is general string that does not allow spaces. This creates a password (key) that is inserted into the OSPF header when the router originates routing protocol packets. Assign a separate password to each network for different interfaces. Routers on the same network must use the same password to be able to exchange OSPF routing data. Configure the routers in the same routing domain with the same password. After selecting the MD5 option, enter the MD5 key ID for the password here. The range is from 1 to 255. After selecting the MD5 option, enter the MD5 key here. This key must be 16 characters long. The syntax is an alphanumeric string that does not allow spaces. In the MD5 mode, the OSPF message sender will compute a message digest based on the message digest key for the TX message. The message digest and the key ID will be encoded in the packet. The receiver of the packet will verify the digest in the message against the digest computed based on the locally defined message digest key corresponding to the same key ID. The same key ID on the neighboring router should be defined with the same key string. All the neighboring routers on the same interface must use the same key to exchange the OSPF packet with each other. Normally, all neighboring routers on the interface use the same key. With the MD5 digest mode, the user can roll over to a new key without disrupting the current message exchange using the new key. Supposing that a router is currently using an old key to exchange OSPF packets with the neighbor router, as the user configures a new key, the router will start the roll over process by sending duplicated packets for both of the old and the new key. The router will stop sending duplicated packets until it finds that all routers on the network have learned the new key. After the rollover process completed, the user should delete the old key to prevent the router from communicating with the router using the old key. Click the Apply button to accept the changes made. OSPFv2 Redistribute Settings This window is used to display and configure the OSPFv2 redistribution settings. External routes can be redistributed to normal areas as Type-5 external routes and redistributed to NSSA stub areas as Type-7 external routes by the ASBR. If the redistributed external route is of Type-1, the metric represents the internal metric. If the redistributed external route is of Type-2, the metric represents the external metric. An internal metric will consider the cost of the route from itself to the redistributing router plus the advertised cost to reach the destination. An external metric only considers the advertised metric to reach the destination. If no metric value is specified by the default metric, routes redistributed from other protocols will get a metric value of 20. 256