Delay field in EIGRP wide metrics

[cags2]

Hey y'all,

I'm trying to figure out the calculation process for EIGRP wide metrics, but I can't seem to find a straightforward answer. Since the delay for composite EIGRP metrics is calculated in 10s of microseconds, is the wide metric the same? In the CCNP ENCOR Official Cert Guide, it says, "The total interface delay is measured in picoseconds (10^-12) instead of measuring in microseconds (10^-6)." The cert guide also mentions "Default EIGRP Interface Metrics for Classic Metrics" and shows a table of interfaces associated with delay, like FastEthernet delay = 100 microseconds, GigabitEthernet delay = 10 microseconds, 10 GigabitEthernet delay = 10 microseconds, and so on. Do wide metrics also have these default values in picoseconds?

[paul driver]

Hello

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@cags2 wrote:
Do wide metrics also have these default values in picoseconds?

First of all If you look at a successor route calculated values

sh ip eigrp topology x.x.x.0/24
EIGRP-IPv4 VR(STAN) Topology Entry for AS(1)/ID(78.1.1.7) for x.xx.0/24
State is Passive, Query origin flag is 1, 1 Successor(s), FD is 340787200, RIB is 2662400
Descriptor Blocks:
78.1.1.8 (GigabitEthernet0/0), from 78.1.1.8, Send flag is 0x0
Composite metric is (340787200/327745536), route is Internal
Vector metric:
Minimum bandwidth is 100000 Kbit
Total delay is 5100000000 picoseconds


1) Rib scale
router eigrp stan
address-family ipv4 unicast autonomous-system 1
metric rib-scale xx (default 128)

sh ip eigrp topology x.x.x.0/24 | sec FD
FD is 340787200, RIB is 2662400

The RIB is calculated with the default wide metric rib scale value of 128  which is used to divide the calculated FD  so the riib value isn't to large to fit in the route table (rib)

340787200 / 128 = 2662400

Note -This value will be seen in the GRT  against the installed route (see below)

2) Feasible distance
FD is 340787200, RIB is 2662400

The FD is calculated by Throughput + Latency metrics which are themselves calculated with eigrp constants and additional Min Bw and total delay values:

eigrp constants
EIGRP_BANDWIDTH  =10,000,000
EIGRP_DELAY_PICO = 1,000,000
Multiplier = 65536

Now with these constants, the formula for calculating the FD metric is:
Feasible distance= (Throughput + Latency)

Throughput = (EIGRP_ BANDWIDTH * 65536 / Min Bandwidth) 
10,000,000 *65536/100000 = 6553600
+
Latency = (TOTAL DELAY ( picoseconds) * 65536 / EIGRP_DELAY_PICO)
5100000000 *65536/1,000,000 = 334233600

result is= 6553600 + 334233600 = FD =340787200




End result 
sh ip route x.x.x.x 
D x.x.x.x/24 [90/2662400} via 78.1.1.8  01:21:09, GigabitEthernet0/0

sh ip eigrp topology x.x.x.0/24
EIGRP-IPv4 VR(STAN) Topology Entry for AS(100)/ID(78.1.1.7) for x.xx.0/24
State is Passive, Query origin flag is 1, 1 Successor(s), FD is 340787200, RIB is 2662400