HP 6125G HP 6125G & 6125G/XG Blade Switches Layer 3 - IP Routing Confi - Page 96

Setting the DSCP value for OSPF packets An IPv4 packet header contains an 8-bit TOS field. As defined in RFC 2474, the first six bits set the Differentiated Services Code Point (DSCP) value and the last two bits are reserved. Network devices use the DSCP value as a reference to determine the packet priority for transmission. You can set the DSCP value for OSPF packets. To set the DSCP value for OSPF packets: Step 1. Enter system view. 2. Enable an OSPF process and enter OSPF view. Command system-view ospf [ process-id | router-id router-id | vpn-instance vpn-instance-name ] * 3. Set the DSCP value for OSPF packets. dscp dscp-value Remarks N/A By default, OSPF is not enabled. Optional. By default, the DSCP value in OSPF packets is 48. Enabling OSPF ISPF When a network topology is changed, Incremental Shortest Path First (ISPF) allows the system to recomputes only the affected part of the shortest path tree (SPT), instead of the entire SPT. To enable OSPF ISPF: Step 1. Enter system view. 2. Enter OSPF view. Command system-view ospf [ process-id | router-id router-id | vpn-instance vpn-instance-name ] * 3. Enable OSPF ISPF. ispf enable Remarks N/A N/A Optional. Disabled by default. Configuring OSPF Graceful Restart OSPF GR involves the following: • IETF standard GR-Uses Opaque LSAs to implement GR. • Non IETF standard GR-Uses link local signaling (LLS) to advertise GR capability and uses out of band synchronization to synchronize the LSDB. A device can act as a GR Restarter and GR Helper at the same time. Configuring the OSPF GR Restarter You can configure the IETF standard or non IETF standard OSPF GR Restarter. Configuring the IETF standard OSPF GR Restarter 86