How do you set auto-cost reference bandwidth?
How do you set auto-cost reference bandwidth?
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 function of auto-cost reference bandwidth command?
Overview: Auto-cost Reference Bandwidth is the command used to modify the OSPF metric.
How is reference bandwidth calculated?
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 the default reference 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.
Why would you want to change the OSPF default reference bandwidth?
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. So you should set the reference bandwidth to at least as high as the fastest link in your network.
What is point to OSPF?
A point-to-point connection is a serial link that connects two routers, making them Open Shortest Path First (OSPF) neighbors.
What does the bandwidth command do in Cisco?
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 the reference bandwidth in OSPF?
100 Mbps
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 bandwidth command in Cisco router?
What does Nbma stand for?
Non-broadcast multiple access
Non-broadcast multiple access (NBMA) is one of four network types in the Open Shortest Path First (OSPF) communications protocol. In an NBMA network all hosts are connected on a single network, but data is sent from one host directly to the next host and is not broadcast across to all hosts.
What is the cost of the auto-cost reference-bandwidth commands?
cost= 100000000/bandwith in bps The auto-cost reference-bandwidth commands changes the first value in the above formula, but uses Mbits per second as the argument, so the formula will now be cost= 52428800000/bandwith in bps
What is OSPF auto-cost reference bandwidth?
Auto-cost reference bandwidth is used to modify the OSPF metric. The OSPF metric is cost. Cost is calculated by dividing 100 by the bandwidth in Mbps. Cost = 100/ (bw in Mbps) Any result less than 0 will use a cost of 1. Default OSPF costs using the default reference bandwidth. Interface Bandwidth. Cost. 10 Gigabit Ethernet 10Gbps.
Do I need to change the reference bandwidth on all routers?
02-16-200903:28 AM 02-16-200903:28 AM Hello Alman, if you change the reference bandwidth you need to do it on all your routers or possible routing problems can occur.
Can I change the reference bandwidth of a GE interface?
Hello Alman, if you change the reference bandwidth you need to do it on all your routers or possible routing problems can occur. With your change for example the OSPF cost of a GE interface becomes 50 (from 1 using the original reference BW) so it is important to be consistent in this parameter.