IPSec and packet loss

For those of you which configuring IPSec and have packet loss in transit… Perhaps this configuration could help :

crypto ipsec client ezvpn REGISBTP
 connect auto
 group VPN-CLIENT2 key jsdfxkqwpoe
 local-address FastEthernet0
 mode network-extension
 username ipsec1@client2.vpn password jsdfxkqwpoe
 xauth userid mode local

interface FastEthernet0
 ip address
 ip mtu 1460
 no ip route-cache cef
 ip tcp adjust-mss 1420
 duplex auto
 speed auto
 crypto ipsec client ezvpn CLIENT2

interface Vlan1
 ip address
 ip mtu 1460
 ip virtual-reassembly
 ip tcp adjust-mss 1420
 crypto ipsec client ezvpn CLIENT2 inside
ip forward-protocol nd
ip route

The really interesting command (which resolves packet loss) is :

no ip route-cache cef

Ok, now you use FastSwitching and use more CPU, but the service is now OK agains 50% packet loss…

You could read :

2 comments on “IPSec and packet loss

  • The router I use is Cisco 881 and this does not accept ” ip-route cache ” command.
    could you please let me know an appropriate solution.


    • I think a same command must exist on this plateform to use fast switching instead of cef. Doccd is your friend 🙂 i will search too …

      Best regards,


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