Information Technology Reference
In-Depth Information
RFC 2598 defines the EF PHB for low loss, loss latency, and assured bandwidth types of
traffic. This is considered a premium service. Traffic such as VoIP is classified as EF. The
codepoint for EF is 101110, which corresponds to a DSCP value of 46.
When you are configuring Cisco routers, the following options are preconfigured and
summarize the defined values for DSCP. Table 8-8 shows the IP DSCP values predefined in
Cisco values.
Ta b l e 8 - 8
IP DSCP Values
DSCP Class
Codepoint Value
Default
000000
CS1
001000
AF11
001010
AF12
001100
AF13
001110
CS2
010000
AF21
010010
AF22
010100
AF23
010110
CS3
011000
AF31
011010
AF32
011100
AF33
011110
CS4
100000
AF41
100010
AF42
100100
AF43
100110
CS5
101000
EF
101110
CS6
110000
CS7
111000
IPv4 Fragmentation
One key characteristic of IPv4 is fragmentation and reassembly. Although the
length of an IP packet is 65,535 bytes, most of the common lower-layer protocols
not
