Which of the following is not a valid reason for a packet to be punted?
A. The TCAM has reached capacity
B. An unknown destination MAC address
C. A packet being discarded due to a security violation
D. A Telnet packet from a session being initiated with the switch
E. Routing protocols sending broadcast traffic
F. A packet belonging to a GRE tunnel
by process of elimination 🙂 c is correct that we know, b we are not sure, so C is the winner. as a result, also
Broadcast = punted 🙂 🙂
A
If a switch’s TCAM has reached capacity, additional packets are punted to the CPU. A TCAM might reach capacity if it has too many installed routes or configured access control lists. This is usually the case when you attempt to use a lower-end switch in place of a higher-end switch to save money. This is not generally a good practice.
A packet being discarded due to a security violation – it’s a classic discart so not a valid reason for a packet to be punted.
B ok
tipical punt reason:
lack of hw or config: A
local L2 process: ARP req, CDP.
node L3 process: E, D.
encription or encapsulation: F
very uncommon packets: long mtu, ip option headers.
nor B, C are there. But at B state is CEF is “glean” that is processed as a broadcast.
cisco says that it is not processed by CEF, but no so clear about if they are really punted
https://www.cisco.com/c/en/us/support/docs/ios-nx-os-software/ios-software-releases-120-mainline/47205-cef-whichpath.html
there say “packets that match a glean adjacency are punted” maybe one to be happy with these explanation.