Hi Poul,
Here a small update. Like you mentioned, the issue seems to be related to SecureXL. It seems that VPN acceleration was added in R80.20. Traditional SecureXL (fwaccel on/off) and the new VPN acceleration (vpn accel on/of) can disturb each other. When investigating in my lab I've noticed that the new 'vpn accel on/of' commands, are added when installing a Jumbo HFA (I'm using Take 47). See below:
[Expert@cp-fw-01:0]# vpn accel
Usage:
vpn accel off
vpn accel off -y
vpn accel off <peer_1_main_ip>
vpn accel off <peer_1_main_ip> <peer_2_main_ip>
vpn accel off -y <peer_1_main_ip>
vpn accel off -y <peer_1_main_ip> <peer_2_main_ip>
vpn accel on
vpn accel on -y
vpn accel stat
vpn accel -h
[Expert@cp-fw-01:0]#
With the command 'vpn tu tlist' you can see if a tunnel has acceleration on or off. The acceleration flag is marked by the 'p'. See example below:
[Expert@cp-fw-01:0]# vpn tu tlist
+-----------------------------------------+-----------------------+---------------------+
| Peer: 10.23.92.25 - cp-fw-02 | MSA: ffffc20033ee0030 | i: 1 ref: 4 |
| Methods: ESP Tunnel AES-128 SHA1 | | |
| My TS: 10.23.99.0/24 | | |
| Peer TS: 10.23.93.0/24 | | |
| MSPI: 800001 (i: 1, p: 0) | Out SPI: 995c78ea | |
+-----------------------------------------+-----------------------+---------------------+
[Expert@cp-fw-01:0]# vpn accel off
You are about to disable acceleration of VPN tunnels
Note: Relevant accelerated VPN connections will be lost and IPsec SAs will be deleted.
Would you like to continue? (y/n) [n] ? y
VPN acceleration has been disabled (for all peers) and IPsec SAs deleted.
[Expert@cp-fw-01:0]# vpn tu tlist
+-----------------------------------------+-----------------------+---------------------+
| Peer: 10.23.92.25 - cp-fw-02 | MSA: ffffc20033ee0030 | i: 1 ref: 4 |
| Methods: ESP Tunnel AES-128 SHA1 | | |
| My TS: 10.23.99.0/24 | | |
| Peer TS: 10.23.93.0/24 | | |
| MSPI: 800001 (i: 1, p: - ) | Out SPI: 9b408d0b | |
+-----------------------------------------+-----------------------+---------------------+
[Expert@cp-fw-01:0]#
So to fix (workaround) the issue with the nexthop in the ESP packets set to ff:ff:ff:ff:ff:ff, make sure that SecureXL is enabled (fwaccel on) and that all tunnels are accelerated too (make sure the 'p' flag is set to 0).
Kind regards,
--Niels