protocols ospf area <area-id> virtual-link <ipv4> transmit-delay <delay>
Sets the transmission delay for a virtual link in an OSPF area.
Link-state transmissions occur at one-second intervals.
- process pid
- Specifies the PID of an IPv4 OSPF process.
- area-id
- The ID of the OSPF area being configured, expressed as an IP address or a decimal value.
- ipv4
- The area ID of the virtual link, expressed as an IPv4 address.
- delay
- The delay, in seconds, between link-state transmissions. This delay must be the same for all nodes on the network. The delay ranges from 1 through 65535. The default delay is 1 second.
Configuration mode
protocols {
ospf {
area area-id {
virtual-link ipv4 {
transmit-delay delay
}
}
}
}Use this command to set the transmission delay for a virtual link in an OSPF area. This delay is the estimated time that is required to send a link-state update (LSU) packet.
This timer accommodates transmission and propagation delays on the network, particularly on low-speed networks in which delays may be significant. The router increments the age of link-state advertisements (LSAs) in LSU packets to account for these delays.
The transmission delay includes both the transmission time and propagation delay across the network. The delay is added to the age of the LSA packet before the LSA is transmitted. The LSA age helps the network sequence LSAs, so that it can determine which of competing LSAs is the most recent and trustworthy.
LSAs are numbered in sequence, but the sequence numbers are finite, and so cannot be used as the sole determinant of the most recent LSA. Instead, OSPF also tracks the age of LSAs. Each time the LSA is forwarded to another router, its current age is incremented by the transmission delay. The age of the LSA packet, together with its sequence number, helps the receiving router to determine which version of a received LSA is more recent and, therefore, to be used.
Use the set form of this command to set the transmission delay for a virtual link in an OSPF area.
Use the delete form of this command to restore the default transmission delay, which is 1 second, for a virtual link in an OSPF area.
Use the show form of this command to display the transmission delay for a virtual link in an OSPF area.