RoutingOSPF · EIGRP · BGP
OSPFCost Calculator
Reference Bandwidth
Interface Speed
Cost at common interface speeds with current reference bandwidth:
| Interface | Speed | Cost | Status |
|---|
Formula: Cost = Reference_BW / Interface_BW (minimum 1, always rounded up).
Default reference is 100 Mbps — meaning FastEthernet=1, GigE=1, 10GbE=1 (all the same!). Always set reference to at least 100 Gbps in modern networks so different speeds have differentiated costs.
Default reference is 100 Mbps — meaning FastEthernet=1, GigE=1, 10GbE=1 (all the same!). Always set reference to at least 100 Gbps in modern networks so different speeds have differentiated costs.
EIGRPComposite Metric Calculator
Add one row per hop. EIGRP uses the minimum bandwidth along the path and sum of delays.
Default K values: K1=1, K2=0, K3=1, K4=0, K5=0 → Metric = (10⁷/BW_min + Delay_sum) × 256
Default K values: K1=1, K2=0, K3=1, K4=0, K5=0 → Metric = (10⁷/BW_min + Delay_sum) × 256
K Values (default Cisco IOS)
K1
K2
K3
K4
K5
#
Bandwidth (kbps)
Delay (µs)
Common IOS defaults: GigE BW=1,000,000 kbps delay=10µs · FastEthernet BW=100,000 kbps delay=100µs · Serial T1 BW=1,544 kbps delay=20,000µs
Delay unit: EIGRP uses delay in tens of microseconds internally. The µs value shown in
FD vs AD: Feasible Distance = cost to destination. Advertised Distance = neighbor's cost. AD must be < current FD to be a feasible successor (loop-free backup).
Delay unit: EIGRP uses delay in tens of microseconds internally. The µs value shown in
show interface is divided by 10 in the formula.FD vs AD: Feasible Distance = cost to destination. Advertised Distance = neighbor's cost. AD must be < current FD to be a feasible successor (loop-free backup).
BGPPath Selection Comparator
Add candidate paths. The tool walks the BGP decision process step-by-step and identifies which path wins and why.
BGP Decision Order (Cisco IOS):
1. Highest Weight (Cisco-proprietary, local to router) · 2. Highest Local Preference · 3. Locally originated routes · 4. Shortest AS-Path · 5. Lowest Origin (IGP < EGP < Incomplete) · 6. Lowest MED (same AS only, by default) · 7. eBGP over iBGP · 8. Lowest IGP metric to next-hop · 9. Lowest Router ID / oldest eBGP route
1. Highest Weight (Cisco-proprietary, local to router) · 2. Highest Local Preference · 3. Locally originated routes · 4. Shortest AS-Path · 5. Lowest Origin (IGP < EGP < Incomplete) · 6. Lowest MED (same AS only, by default) · 7. eBGP over iBGP · 8. Lowest IGP metric to next-hop · 9. Lowest Router ID / oldest eBGP route