What occurs when a router running IS-IS receives an LSP with the overload bit set?
What occurs when a router running IS-IS receives an LSP with the overload bit set?
When a router running IS-IS receives an LSP with the overload bit set, the LSP is ignored during the Shortest Path First (SPF) calculation. This mechanism helps to prevent the router from being used as a transit node, as it indicates that the router is overloaded and should not be considered in the optimal path calculation.
A. The LSP is ignored during SPF calculation.
Correct In overload mode, the routing device advertisement is originated with all the transit routing device links (except stub) set to a metric of 0xFFFF. https://www.juniper.net/documentation/us/en/software/junos/is-is/topics/ref/statement/overload-edit-protocols-isis.html
0xFFFF = 65535
well, then it's C :) 0xFFFF = 65535 https://www.juniper.net/documentation/us/en/software/junos/is-is/topics/ref/statement/overload-edit-protocols-isis.html
Yep you are right
The correct answer should be A. This depends on how you read the question. It's not asking what the advertising router will do, rather what a receiving router does with the LSP. It will not take it into account when doing an SPF run.
SPF will set the metric to 65535; the result is the LSA's routes will be ignored because of the SPF calculation
overload bit in isis results in ignoring in spf. In ospf max metric is set to the link. My answer on the question would be A.
Clearly mentioned in the official Juniper book, overload bit will cause other routers to ignore the LSP during SPF calculation. Correct Answer: A
Answer is A.
The LSP is ignored during SPF calculation, BECAUSE the metric is set to 0xFFFF (=65535). So C is the most specific answer.
Referred to link shared by mikkamilla. Cheers
In overload mode, the routing device advertisement is originated with all the transit routing device links (except stub) set to a metric of 0xFFFF = 65535
C metric is set to 65535
I think A too. The question is "when a router running IS-IS receives an LSP with the overload bit set" The answer C is about the metric already being set in the LSP, not what happens when a router receives LSP.
It’s C look at my comment
When advertise-high-metric is configured, IS-IS does not set the overload bit. Rather, it sets the metric to 63 or 16,777,214, depending whether wide metrics are enabled. This allows the overloaded routing device to be used for transit as a last resort.
In overload mode, the routing device advertisement is originated with all the transit routing device links (except stub) set to a metric of 0xFFFF. The stub routing device links are advertised with the actual cost of the interfaces corresponding to the stub. This causes the transit traffic to avoid the overloaded routing device and take paths around the routing device. 65535 = 0xFFFF
D is correct: In overload mode, the routing device advertisement is originated with all the transit routing device links (except stub) set to a metric of 0xFFFF
C is correct: In overload mode, the routing device advertisement is originated with all the transit routing device links (except stub) set to a metric of 0xFFFF = 65535.
A is correct. Overload bit will cause other routers to ignore the LSP during SPF calculation.