Cisco Cisco IOS Software Release 12.4(9)T
Access List-Based RBSCP
Information About Access List-Based RBSCP
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Cisco IOS Release 12.4(9)T
Rate-Based Satellite Control Protocol
Rate-Based Satellite Control Protocol (RBSCP) was designed for wireless or long-distance delay links
with high error rates, such as satellite links. RBSCP can improve the performance of certain IP protocols,
such as TCP and IP Security (IPsec), over satellite links without breaking the end-to-end model. For
instructions on how to implement RBSCP over a tunnel, see the “Implementing Tunnels” chapter of the
Interface and Hardware Component Configuration Guide.
with high error rates, such as satellite links. RBSCP can improve the performance of certain IP protocols,
such as TCP and IP Security (IPsec), over satellite links without breaking the end-to-end model. For
instructions on how to implement RBSCP over a tunnel, see the “Implementing Tunnels” chapter of the
Interface and Hardware Component Configuration Guide.
The TCP ACK splitting capability of RBSCP can be implemented without a tunnel, by using an IP access
list, as shown in
list, as shown in
. The TCP ACK splitting occurs at the outgoing interface between the router
and the internal network or Internet. It does not occur over the link to the satellite.
Figure 1
ACL-Based RBSCP on Outgoing Interfaces
TCP ACK Splitting
TCP ACK splitting is a software technique to improve performance for clear-text TCP traffic using
acknowledgment (ACK) splitting, in which a number of additional TCP ACKs are generated for each
TCP ACK received. TCP ACK splitting causes TCP to open the congestion window more quickly than
usual, thus decreasing the effect of long latencies. TCP will generally open the congestion window by
one maximum transmission unit (MTU) for each TCP ACK received. Opening the congestion window
results in increased bandwidth becoming available. Configure this feature only when the satellite link is
not using all the available bandwidth. Encrypted traffic cannot use TCP ACK splitting.
acknowledgment (ACK) splitting, in which a number of additional TCP ACKs are generated for each
TCP ACK received. TCP ACK splitting causes TCP to open the congestion window more quickly than
usual, thus decreasing the effect of long latencies. TCP will generally open the congestion window by
one maximum transmission unit (MTU) for each TCP ACK received. Opening the congestion window
results in increased bandwidth becoming available. Configure this feature only when the satellite link is
not using all the available bandwidth. Encrypted traffic cannot use TCP ACK splitting.
The size argument in the ip rbscp ack-split command determines how many TCP ACKs are generated
from the incoming TCP ACK, as shown in
from the incoming TCP ACK, as shown in
.
155880
Internet
Satellite network
Remote station
Router
TCP ACK
TCP ACK
TCP ACKs
TCP ACKs
ACL on outgoing IF
ACL on outgoing IFs
Host
Host
Host
Router
Hub station
Rate Based Satellite Control Protocol
TCP/UDP/SCTP user data
Host
Host