Which two statements about IS-IS are true? (Choose two.)
A.
The default hello interval is 10 seconds and the default hold timer is 30 seconds.
B.
The hello interval can be changed on a per-interface basis with the command isis hello-multiplier.
C.
Both routers need to have the same hello intervals and hold timers in order to form IS-IS
neighbors.
D.
Both IS-IS routers need to have the same capabilities in the hello packet in order to form
neighbors.
To specify the length of time between hello packets that the Cisco IOS software sends, use the
isis hello-interval command in interface configuration mode.
By default, a value three times the hello interval seconds is advertised as the hold time in the hello
packets sent. (Change the multiplier of 3 by specifying the isis hello-multiplier command.) With
smaller hello intervals, topological changes are detected faster, but there is more routing traffic.
The default is 10 seconds.
Reference.
http://www.cisco.com/c/en/us/td/docs/ios/12_2/iproute/command/reference/fiprrp_r/1rfisis.html
It seems to me the hold timer is changed with the hello-multiplier.
At http://www.cisco.com/c/en/us/support/docs/ip/integrated-intermediate-system-to-intermediate-system-is-is/200293-IS-IS-Adjacency-and-Area-Types.html it says that:
“If an IS-IS Router does not support the Capability TLV from the other IS-IS Router it silently ignores the TLV. However, there might be events due to capability mismatch when one router reaches INIT state whereas the other one discards the packets and doesn’t form adjacency. So as a general recommendation Capability TLV must match for successful adjacency formation.”
So maybe A and D are correct?
couldn’t agree more, must be A and D.
B is wrong. the hello multiplier is to do with how many hello packets can be missed before declaring an adjacency is down.
http://www.cisco.com/c/en/us/td/docs/ios/12_2/ip/configuration/guide/1cfisis.html#wp1001111
Setting the Hello Multiplier
To specify the number of IS-IS hello packets a neighbor must miss before the router should declare the adjacency as down, use the following command in interface configuration command. The default value is 3.
A and D.
A and D 100%