04-17-2024 08:59 AM
Packets received by the router from BGP enter via a serial interface at 209.165.201.10. Each route is present within the routing table. Which interface is used to forward traffic with a destination IP of 10.10 10 24?
People are saying that the answer is F0/11. I don't understand why since F0/13 has the lowest AD.
04-17-2024 09:07 AM - edited 04-17-2024 09:10 AM
Hello @Garegin88 ,
the scenario is not real world but it is used to make you understand how the routing table choices the best path.
However, in square brackets [AD Metric] so the right answer is out of Fas0/11 because of the lowest AD and the lowest metric between the routes with the same AD 90.
out FAS0/13 you have an OSPF route with AD=110 and metric = 20 but route out Fas0/11 has AD=90 and metric= 144 and it is selected for its lower AD.
Edit:
in any case the most specific route is selected first and usually this is part of the selection. Then AD, then metric
Hope to help
Giuseppe
04-17-2024 09:13 AM
hold on. I thought in #/#, the first number is the default AD and the second one is the one specified by admin. So in this case the admin left all default ADs?
04-17-2024 09:23 AM
Hello @Garegin88 ,
in the [] we have AD / metric there is no concept of an AD defined by user. This has been this way all the time long.
if you change the AD of EIGRP it will be reflected on the left number before the /
Hope to help
Giuseppe
04-18-2024 11:23 AM
Same prefix for multi IGP/BGP?
This not real network?
MHM
04-18-2024 11:30 AM
No, it’s a practice question
04-18-2024 11:36 AM
Ok' then the
Router use belwo rules to inject prefix into RIB
1- prefix the lowest AD
If tie
2- prefer lowest metric
If tie
3- multipath is config
If Yes add all prefix
If No here the router can select old one.
MHM
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