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Enabling packet information pre-extraction on the IPsec tunnel
interface
Because packets that an IPsec tunnel interface passes to a physical interface are encapsulated, the QoS
module cannot obtain the 5-tuple (source IP, destination IP, source port, destination port, and protocol) of
the original packets. To address this problem, enable packet information pre-extraction on the tunnel
interface.
With packet information pre-extraction enabled, an IPsec tunnel interface buffers the IP 5-tuple data in
the original packets, so that the corresponding physical interface can perform QoS processing such as
traffic classification, IP precedence setting, rate limit, and congestion avoidance.
To implement QoS for IPsec packets, however, you must also apply a QoS policy to the physical
outbound interface. For more information, see
ACL and
QoS Configuration Guide
.
CAUTION:
When the QoS policy applied to the physical outbound interface provides congestion management,
IPsec packets arriving at the destination may be out of order. This may cause IPsec out of order to be
dropped by the IPsec anti-replay function. For more information, see "
Configuring the IPsec anti-replay
To enable packet information pre-extraction on an IPsec tunnel interface:
To do…
Command…
Remarks
1.
Enter system view.
system-view
—
2.
Enter tunnel interface view.
interface tunnel
number
—
3.
Enable packet information
pre-extraction.
qos pre-classify
Required.
Disabled by default.
For more information, see
ACL and
QoS
Command Reference
.
Applying a QoS policy to an IPsec tunnel interface
The router allows you to apply a QoS policy to the IPsec tunnel interface. In this case, QoS is performed
before IPsec encapsulation, and the priority of a resulting packet is the same as that of the original
packet. In addition, the QoS congestion management is done to the packets before encapsulation,
avoiding the disorder of IPsec packets.
This method is much more explicit and flexible than the QoS implementation method of enabling packet
information pre-extraction on the IPsec tunnel interface, which requires applying a QoS policy to the
physical outbound interface.