I have a site to site VPN over a DSL. My DSL line terminates on an 877 router on the one end and a pix 506 on the other end. I have a site-to-site VPN from an ASA on the other side of the 877 and the 506. I have having problems running certain application across this VPN and I believe it is related to the MTU permitted over DSL. I know on the 877 you can use the ip tcp adjust mss to change the MTU to the required size, but I have done this and it doesn't appear to have helped. Is it possible to adjust the MTU on the ASA or on the site-to-site VPN config to get this to work?
Thanks for your assistance