The Cisco IOS and IOS XE qos pre-classify command allows which kind of packet classification
on IP packets that are encapsulated with GRE and IPsec?
A.
allows for packets to be classified based on the ToS byte values before packet encryption
B.
allows for packets to be classified based on the ToS byte values after packet encryption
C.
allows for packets to be classified based on the packet payload before packet encryption
D.
allows for packets to be classified based on the packet payload after packet encryption
E.
allows for packets to be classified based on the packet header parameters other than the ToS
byte values after packet encryption
Explanation:
qos pre-classify command
If you want to classify traffic based on something other than ip prec/dscp markings, then you must:
o apply the service policy to the tunnel interface w/o qos pre-classify command, in order to use the pre-tunnel header – qos policy is applied only for that tunnel
o apply the service policy on the physical int w/o using the qos pre-classify command, in order to classify traffic on the post-tunnel header
o apply the service policy on the physical interface with the qos pre-classify command, in order to use the pre-tunnel header
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If QoS markings are applied BEFORE they enter the router, these markings will be auto reflected into the GRE or IPSec header.
If QoS markings are applied on the router itself, WITHOUT the qos pre-classify command, these markings will NOT be reflected into the GRE or IPSec header.
If QoS markings are applied on the router itself, WITH the qos pre-classify command, these markings WILL be reflected into the GRE or IPSec header.
When configuring an IPSec encrypted IP GRE tunnel, apply the qos pre-classify command to BOTH the tunnel interface and the crypto map.
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