FWSM and ASA configurations for Internal/Externally located 6.1 CM's
We have an FWSM firewall (3.2.8) located at one location with a CM Pub on an inside subnet. In addition, we have a CM Sub located on an inside subnet of a remote ASA (8.0.4). Between the two locations are router based ipsec 3des vpn tunnels. The problem we are seeing is that database replication is not working between the two CM's.
ACL's on both FW's permit full ip between hosts, so the concern is that the FWSM and/or ASA Firewalls are reassembling fragmented packets and causing the DB connections to fail.
The MTU on the VPN routers (for the Tunnel interfaces) are set to 1420 and tcp mss set to 1300. In addition, both CM servers have the MTU adjusted down to 1400.
Packet captures on the FW's show that they are reassembling the fragmented packets (FW's are using default MTU of 1500).
Any non-intrusive configuration suggestions on the FW's to prevent the reassembly of the fragmented CM packets or to fix this DB connectivity problem? Also any other suggestions to address this problem would be helpful.
FYI the one way latency between CM's is <20ms (which is lower than the required 40ms min).
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UpdatesDocuments PurposeNAT Operation in ASA 8.3+ SectionsRule Types
Network Object NATTwice NAT / Manual NATRule Types used per SectionNAT
Types used with Twice NAT / Manual NAT and Network Obje...
Table of Contents Introduction:This document describes details on how
NAT-T works. Background: ESP encrypts all critical information,
encapsulating the entire inner TCP/UDP datagram within an ESP header.
ESP is an IP protocol in the same sense that TCP an...