Where is OSPF reference bandwidth?
Open Shortest Path First (OSPF) uses “Cost” as the value of metric and uses a Reference Bandwidth of 100 Mbps for cost calculation. The formula to calculate the cost is Reference Bandwidth divided by interface bandwidth. For example, in the case of 10 Mbps Ethernet , OSPF Metric Cost value is 100 Mbps / 10 Mbps = 10.
What is reference bandwidth and interface bandwidth?
The reference bandwidth is a value in Mbps that we can set ourselves. By default this is 100Mbps on Cisco IOS routers. The interface bandwidth is something we can lookup.
Does OSPF use bandwidth?
Like EIGRP, OSPF bases its metric by default on link bandwidth, so that OSPF makes a better choice than simply relying on the router hop-count metric used by RIP.
What does the bandwidth command do in Cisco?
The Cisco bandwidth command is used to communicate the bandwidth value of an interface to higher-level protocols (Ex. routing protocols). Set the inherited and received bandwidth values for an interface using the bandwidth statement in interface configuration mode.
What is OSPF bandwidth?
OSPF uses a reference bandwidth of 100 Mb/s for any links that are equal to or faster than a fast Ethernet connection. Therefore, the cost assigned to a fast Ethernet interface with an interface bandwidth of 100 Mb/s would equal 1.
What is reference bandwidth in OSPF?
The reference bandwidth defines the link speed that has an OSPF cost of 1. By default, the reference bandwidth is 100 Mbps. However, if you have faster links in your network, such as gigabit Ethernet or OC-3 connections, OSPF can’t give these links a better cost than 1.
What is OSPF reference bandwidth?
What is the default OSPF reference bandwidth?
The reference bandwidth defines the link speed that has an OSPF cost of 1. By default, the reference bandwidth is 100 Mbps.
How do I change bandwidth in OSPF?
To adjust the reference bandwidth, use the auto-cost reference-bandwidth Mb/s router configuration command. This command must be configured on every router in the OSPF domain. Notice that the value is expressed in Mb/s; therefore, to adjust the costs for: Gigabit Ethernet – auto-cost reference-bandwidth 1000.
What is the bandwidth command?
The bandwidth command sets an informational parameter to communicate the current bandwidth to the higher-level protocols. IGRP uses the minimum path bandwidth to determine a routing metric. The TCP protocol adjusts initial retransmission parameters based on the apparent bandwidth of the outgoing interface.
What is OSPF auto cost reference bandwidth?
OSPF calculates the cost of a route as the ratio of the reference bandwidth to the bandwidth of the egress interface. An increase in the reference bandwidth results in an increased cost. If the resulting cost is less than 1, the software rounds the cost up to 1.
What will an OSPF router prefer to use?
The first preference for an OSPF router ID is an explicitly configured 32-bit address. This address is not included in the routing table and is not defined by the network command.