STM SatLink VSAT - TCP Performance Enhancing Proxy (PEP-TCP)

SatLink VSAT User Guide
Publication no. 101557
Rev 14.1.1-2
Copyright 2006-2012 – STM Group, Inc.
Page 97 (182)
# ip show
Interfaces
If IPAddress SubnetMask BroadCastAddr MTU Alias
AdminStatus
1 10.20.42.1 255.255.255.0 10.20.42.255 1500 eth0 1
2 N/A N/A N/A 4074 air0 1
3 10.42.0.42 255.255.255.255 10.42.0.42 4074 dvb0 1
DNS Client Configuration
Primary DNS Server: 213.42.20.20, Secondary DNS Server:
Interface Statistics
------------- Input ----------------- ------------- Output ---------------
If UCast NUCast Disc Octets UCast NUCast Disc Octets
1 4867 8265 7091 936333 108 115 0 19901
2 0 0 0 0 0 0 0 0
3 768 0 0 72982 5622 0 0 422960
IP Receive Deliver Errors Discards Forward Request NoRoute Discards
6386 1456 0 0 4930 894 0 4
Interface Directed Routing Table
In If Out If
Routing Table
DestMask RouteMask NextHop If
0.0.0.0 0.0.0.0 0.0.0.0 3
10.20.42.0 255.255.255.0 0.0.0.0 1
10.42.0.42 255.255.255.255 0.0.0.0 3
To route unicast/multicast addresses specifically into a GRE tunnel, use the CLI command ip addroute.
Example
# ip addroute 225.0.0.2 255.255.255.255 4
The above configuration will forward multicast datagrams with IP address 225.0.0.2 from the VSAT
LAN interface to the GRE tunnel identified by the specific GRE interface ID.
Forwarding of multicast IP traffic from a DVB interface to a GRE interface is not
supported in the current release.
This is shown by the CLI command ip show –mcast:
# ip show -mcast
IP Multicast Routing Table
RouteAddress AddressMask IfIndex
225.0.0.2 255.255.255.255 4
239.255.255.250 255.255.255.255 1
18.2 TCP Performance Enhancing Proxy (PEP)
Conditions particular to satellite communication severely constrict the performance of TCP and reduce
the end user‘s experience of accessing the Internet over satellite. Large latency, elevated bit error rates,
and asymmetric bandwidth are all characteristics of satellite networks that result in degraded TCP
performance. Various TCP Performance Enhancing techniques are used to improve the performance of
the TCP protocol over satellite links. The TCP PEP implementation in the SatLink System makes use of a
TCP Performance Enhancing Server installed in the SatLink Hub and a PEP software client embedded in
the VSAT.