Xen devel - Oct 2012 - Question about antispoofing and sys-flood protection on xen bridges

I''m in doubt about antispoofing and sys-flood protection on dom0 and 
their effect on xen bridges.
Added these parameters on /etc/sysctl.conf:
net.ipv4.conf.default.rp_filter=1
net.ipv4.conf.all.rp_filter=1
net.ipv4.tcp_syncookies=1
Can they give problem on xen bridges and/or its performance?
Thanks for any reply