R2511-HP MSR Router Series ACL and QoS Configuration Guide(V5)

Configuring DAR

Overview

The Deeper Application Recognition (DAR) feature identifies packets of dynamic protocols like BitTorrent,

HTTP, FTP, and RTP by examining Layer 4 to Layer 7 content other than the IP header. The feature helps

service providers and businesses limit aggressive bandwidth use by applications like BitTorrent to ensure

fairness and network performance.

BitTorrent is a P2P file sharing communications protocol, which enables personal computers to directly

exchange data or services. P2P has been widely used for content (such as audio and video) file sharing.

It represents a large amount of bandwidth on the Internet.

DAR can limit, block, or manipulate identified application traffic depending on your configuration.

The DAR feature is applicable to IP packets.

Introduction to packet types

IP packet

IP packet format

The IP packet format is shown in Figure 25. An IP header without the option field is 20 bytes in length.

Figure 25 The format and fields of an IP datagram

The protocol field in the header is 8-bit long. The protocol field value indicates the protocol type of the

data.

Table 7 li

sts the recognizable protocol field values and protocols.

Table 4 Protocols corresponding to the protocol field values

Protocol field value Protocol

1 ICMP

2 IGMP

015

Data

Version HLEN Type of service (TOS) Total length (in bytes)

3137

Identification Flag Fragmentation offset

Time to live (TTL) Protocol Header checksum

Source IP address

Destination IP address

Option (if any)