R2511-HP MSR Router Series Layer 2 - WAN Command Reference(V5)

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FRF.9 compression configuration varies by the interface type.
• For a point-to-point frame relay subinterface, you can use the fr compression frf9 command on the
subinterface to enable FRF.9 compression.
• For a point-to-multipoint frame relay interface or subinterface, you should configure FRF.9
compression by configuring static address mapping. For more information, see the fr map ip
command.
This command applies to only data messages and InARP messages, and does not apply to LMI
messages.
Frame relay compression takes effect only when the frame relay packet type of the interface is IETF. When
this command is configured, the system automatically changes the packet type of the interface into IETF
if the frame relay packet type of an interface is not IETF.
Examples
# Enable frame relay compression on the point-to-point frame relay subinterface Serial 2/1.1.
<Sysname> system-view
[Sysname] interface serial 2/1.1 p2p
[Sysname-Serial2/1.1] fr compression frf9
fr compression iphc
Use fr compression iphc to enable FRF.20 (FRF.20 IPHC) compression.
Use undo fr compression iphc to disable FRF.20 (FRF.20 IPHC) compression.
Syntax
fr compression iphc
undo fr compression iphc
Default
FRF.20 (FRF.20 IPHC) compression is disabled.
Views
Frame relay interface view
Default command level
2: System level
Usage guidelines
The system supports the frame relay FRF.20 IPHC function. By compressing the IP headers carried in
frame relay frames, the technology saves bandwidth and improves data transmission efficiency over
frame relay. The technology is mainly applied to voice traffic.
FRF.20 categorized messages into control messages and data messages. Control messages are used for
state negotiation. The two sides of a connection can exchange FRF.20 data messages only after the
negotiation succeeds. If FRF.20 fails to negotiate the state after sending a specific number of FRF.20
control messages, FRF.20 stops the negotiation and the negotiation fails. As a result, the compression
configuration does not take effect.
FRF.20 compression applies to only RTP and TCP ACK messages.