Iphc Overview - Cisco ASR 9000 Series Configuration Manual

Information About Configuring Serial Interfaces
If a subinterface and PVC are configured under the serial interface, then the router includes the
subinterface number at the end of the serial interface address. In this case, the naming notation is
rack/slot/module/port[/channel-num:channel-group-number].subinterface, as shown in the following
examples:
interface serial 0/0/1/2.1
interface serial 0/0/1/2/4:3.1
A slash between values is required as part of the notation.
Note
The naming notation syntax for serial interfaces is as follows:
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Use the question mark (?) online help function following the serial keyword to view a list of all valid
interface choices.

IPHC Overview

IP header compression (IPHC) is based on the premise that most of the headers in the packets of a
particular transmission remain constant throughout the flow. Only a few fields in the headers of related
packets change during a flow.
IPHC compresses these headers so that the compressed header contains only the fields that change from
packet to packet. All fields that remain the same from packet to packet are eliminated in the compressed
headers. Full headers are sent between compressed headers.
Full headers are uncompressed headers that contain all the original header fields along with additional
information (context ID) to identify the flow. The interval at which full headers are sent between
compressed packets is configurable using the refresh max-period and refresh max-time commands.
IPHC contexts are used by the compressor (sender) and decompressor (receiver) of compressed packets
to encode and decode the packets in a flow. A context is stored on the compressor and decompressor and
is used in the delta calculation at both ends. The number of contexts allowed on a particular interface is
configurable. The maximum size of the header that can be compressed is also configurable.
IPHC supports the compression and decompression of RTP and UDP traffic and the decompression of
CN on TCP and CTCP traffic.
Users may choose one of the following types of compression formats:
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Cisco ASR 9000 Aggregation Services Router Interfaces and Hardware Component Configuration Guide
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rack: Chassis number of the rack.
slot: Physical slot number of the modular services card or line card.
module: Module number. Shared port adapters (SPAs) are referenced by their subslot number.
port: Physical port number of the controller.
channel-num: T1 or E1 channel number. T1 channels range from 0 to 23; E1 channels range from 0
to 31.
channel-group-number: Time slot number. T1 time slots range from 1 to 24; E1 time slots range
from 1 to 31. The channel-group-number is preceded by a colon and not a slash.
subinterface: Subinterface number.
Internet Engineering Task Force (IETF) standard format.
Uses RFC2507 and RFC2508 compression schemes.
IPHC format.
Provides options similar to IETF.
Configuring Serial Interfaces on the Cisco ASR 9000 Series Router
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