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Packet Creation Delay
Table 3: Packet Creation Delay for Serial Interfaces
Serial Interface Delay (msec)
Packet Size (bytes)
Interface Rate
(Kbps)
128
64
16.0
128
8.0
256
4.0
1024
1.0
1544
0.7
2048
.5
Performance of the IP Network
Copyright © 2018, Juniper Networks, Inc.
encapsulation overhead varies, but is typically either 6 or 8 bytes on serial links. This
overhead causes smaller packets to be less efficient and result in serial data requiring
more bandwidth.
Calculate the bandwidth required for a serial bit stream as follows:
IP Bandwidth = [Packet Size (bytes) + 20 (bytes) + 2 (bytes) + Encapsulation
Overhead (bytes) x [Packet Rate (pps)] x 8
Serial data received at the CTP interface must be buffered long enough to allow a packet
to be created. The delay to create the packet increases as either the size of the packet
increases or as the rate of the serial interface decreases. Generally, this delay is minimal
except when the rate of the serial interface is low and the packet size is large. We
recommend that you set the packet size to a smaller value for lower-speed serial
interfaces.
Table 3 on page 9
in milliseconds.
256
512
32.0
64.0
16.0
32.0
8.0
16.0
2.0
4.0
1.3
2.7
1.0
2.0
The number of packets created (packet rate) is inversely related to the packet size
configured. For example, smaller packets result in a greater packet rate. When you
configure the packet size, consider the packet-forwarding performance of the attached
router and network.
Table 4 on page 10
packet sizes and serial interface rates.
provides examples of serial interface packet creation delay
768
96.0
48.0
24.0
6.0
4.0
3.0
provides examples of packet rates for various
Chapter 1: Overview of CTP Bundles
1024
1400
128.0
175.0
64.0
87/5
32.0
43.8
8.0
10.9
5.3
7.3
4.0
5.5
9
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