[Openswan Users] compression on gre-traffic fails

[Jordan Paschalidis]

Hello all,

i have following setup:
Multicast Source -> Router -> openswan GW --- >
freeswan GW -> Router -> Multicast client

The two Routers are useing a GRE-Tunnel to transport the Multicast-Traffic.

The GRE-Tunnel is working, the VPN-connection is working fine.
I recently enabled compression for the VPN-connection, this is working for 
normal traffic, e.g. http, for pc's which are connected also to the 
vpn-gw's beside the router.

But the GRE-traffic is not beeing compressed.
If i use a 'ipsec look | grep comp' the 'ratio' shows that nearly no 
compression took place.

Could someone please explain why the GRE-traffic is not beeing compressed?
Is GRE-Traffic not compressable, or does 'Protocol 47' play a role?


Statistic after 5 Days of Multicast-Traffic:

ipsec look | grep comp
comp0x2397 at 10.63.20.6 COMP_DEFLATE: dir=out src=10.10.204.149 
life(c,s,h)=bytes(596824830,0,0)addtime(6010,0,0)usetime(6010,0,0)packets(1159362,0,0) 
idle=0 ratio=596824830:595809233 natencap=none natsport=0 natdport=0 
refcount=5 ref=6674

comp0x2e50 at 10.10.204.149 COMP_DEFLATE: dir=in  src=10.63.20.6 
life(c,s,h)=bytes(103812,0,0)addtime(6010,0,0)usetime(5972,0,0)packets(223,0,0) 
idle=2 ratio=320752:300988 natencap=none natsport=0 natdport=0 refcount=228 
ref=6666



thanks
jordan