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    Packet loss when connected to L2TP/IPsec VPn

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    edgerouter lite l2tp vpn
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    • RomoR
      Romo
      last edited by Romo

      Had a working remote access vpn setup on an edge router lite, but this weekend we changed our main ISP from Comcast to ATT. The only change made to the working config was the outside-address setting which now points to the new ATT ip everything else is exactly the same.

      Today users where reporting that the VPN was really slow, windows shares wouldn't open for them and web browsing was also not working. When I remoted into one of the machines, it was indeed barely working when connected to the vpn, the remote session was having lots of trouble being open.

      I set up the vpn on a test vm and starting pinging the file share:

      Ping

      Ping statistics for 10.10.10.1:
    Packets: Sent = 195, Received = 109, Lost = 86 (44% loss),
Approximate round trip times in milli-seconds:
    Minimum = 87ms, Maximum = 238ms, Average = 103ms

      Tracert

      Tracing route to 10.10.10.1
over a maximum of 30 hops:

  1     *       98 ms   102 ms  10.255.255.0
  2    96 ms     *        *     10.10.10.1
  3    93 ms    96 ms     *     10.10.10.1
  4     *        *      106 ms  10.10.10.1

      Any idea what could be causing this issue? Also seems strange the tracert reaches the server 3 times for some reason.

      Could this be the provider? this only started after the change to ATT, with comcast everything was working properly.

      scottalanmillerS 1 Reply Last reply Reply Quote 2
      • scottalanmillerS
        scottalanmiller @Romo
        last edited by

        @Romo said in Packet loss when connected to L2TP/IPsec VPn:

        Also seems strange the tracert reaches the server 3 times for some reason.

        that is super weird

        1 Reply Last reply Reply Quote 0
        • dafyreD
          dafyre
          last edited by

          @Romo said in Packet loss when connected to L2TP/IPsec VPn:

          Also seems strange the tracert reaches the server 3 times for some reason.

          Maybe some kind of routing issue?

          1 Reply Last reply Reply Quote 2
          • dafyreD
            dafyre
            last edited by

            Also, could this be an MTU settings issue? I know they're rare... but that was the first thing that popped into my mind.

            RomoR 1 Reply Last reply Reply Quote 1
            • S
              Skratch08
              last edited by

              We had a similar problem with one of our warehouse locations after switching to AT&T Business Fiber. IPsec site to site VPN to our head office would randomly stop passing traffic, traffic outside the tunnel was fine. For us, the issue was fixed by disabling ESP ALG on the AT&T gateway.

              1 Reply Last reply Reply Quote 2
              • wrx7mW
                wrx7m
                last edited by

                That is weird. Have you disabled and re-enabled the tunnel?

                1 Reply Last reply Reply Quote 0
                • RomoR
                  Romo
                  last edited by

                  This is remote access not site to site by the way. I have indeed restarted the vpn and packet loss still is there.

                  1 Reply Last reply Reply Quote 0
                  • RomoR
                    Romo @dafyre
                    last edited by

                    @dafyre said in Packet loss when connected to L2TP/IPsec VPn:

                    Also, could this be an MTU settings issue? I know they're rare... but that was the first thing that popped into my mind.

                    Was inded thinking about playing with the MTU, just now sure why it wouldn't on ATT. It is currently set for 1492

                    JaredBuschJ 1 Reply Last reply Reply Quote 0
                    • JaredBuschJ
                      JaredBusch @Romo
                      last edited by

                      @Romo said in Packet loss when connected to L2TP/IPsec VPn:

                      @dafyre said in Packet loss when connected to L2TP/IPsec VPn:

                      Also, could this be an MTU settings issue? I know they're rare... but that was the first thing that popped into my mind.

                      Was inded thinking about playing with the MTU, just now sure why it wouldn't on ATT. It is currently set for 1492

                      UVerse? Then your service is PPPoE. You likely need to lower the MTU to account for it.

                      Also If UVerse, you are screwed in your router options.

                      wrx7mW RomoR scottalanmillerS 3 Replies Last reply Reply Quote 0
                      • wrx7mW
                        wrx7m
                        last edited by

                        I'm assuming that the performance outside the VPN connection is fine, right?

                        1 Reply Last reply Reply Quote 0
                        • wrx7mW
                          wrx7m @JaredBusch
                          last edited by wrx7m

                          @JaredBusch said in Packet loss when connected to L2TP/IPsec VPn:

                          @Romo said in Packet loss when connected to L2TP/IPsec VPn:

                          @dafyre said in Packet loss when connected to L2TP/IPsec VPn:

                          Also, could this be an MTU settings issue? I know they're rare... but that was the first thing that popped into my mind.

                          Was inded thinking about playing with the MTU, just now sure why it wouldn't on ATT. It is currently set for 1492

                          UVerse? Then your service is PPPoE. You likely need to lower the MTU to account for it.

                          Also If UVerse, you are screwed in your router options.

                          I haven't dealt with PPPoE since I stopped using DSL 12 years ago.

                          JaredBuschJ 1 Reply Last reply Reply Quote 0
                          • JaredBuschJ
                            JaredBusch @wrx7m
                            last edited by

                            @wrx7m said in Packet loss when connected to L2TP/IPsec VPn:

                            @JaredBusch said in Packet loss when connected to L2TP/IPsec VPn:

                            @Romo said in Packet loss when connected to L2TP/IPsec VPn:

                            @dafyre said in Packet loss when connected to L2TP/IPsec VPn:

                            Also, could this be an MTU settings issue? I know they're rare... but that was the first thing that popped into my mind.

                            Was inded thinking about playing with the MTU, just now sure why it wouldn't on ATT. It is currently set for 1492

                            UVerse? Then your service is PPPoE. You likely need to lower the MTU to account for it.

                            Also If UVerse, you are screwed in your router options.

                            I haven't dealt with PPPoE since I stopped using DSL 12 years ago.

                            U-Verse is just DSL2 or some variant there of.

                            1 Reply Last reply Reply Quote 1
                            • RomoR
                              Romo @JaredBusch
                              last edited by

                              @JaredBusch said in Packet loss when connected to L2TP/IPsec VPn:

                              @Romo said in Packet loss when connected to L2TP/IPsec VPn:

                              @dafyre said in Packet loss when connected to L2TP/IPsec VPn:

                              Also, could this be an MTU settings issue? I know they're rare... but that was the first thing that popped into my mind.

                              Was inded thinking about playing with the MTU, just now sure why it wouldn't on ATT. It is currently set for 1492

                              UVerse? Then your service is PPPoE. You likely need to lower the MTU to account for it.

                              Also If UVerse, you are screwed in your router options.

                              How low should I go, or is it just a matter of testing? Currently at 1400, web browsing is still not working properly.

                              Tracing route to 10.10.10.1
over a maximum of 30 hops:

  1     *      105 ms   102 ms  10.255.255.0
  2   118 ms   104 ms   102 ms  10.10.10.1

Trace complete.
PS C:\WINDOWS\system32> tracert 10.10.10.1

Tracing route to 10.10.10.1
over a maximum of 30 hops:

  1   106 ms   106 ms     *     10.255.255.0
  2   116 ms     *        *     10.10.10.1
  3   103 ms   109 ms   121 ms  10.10.10.1
                              JaredBuschJ 1 Reply Last reply Reply Quote 0
                              • JaredBuschJ
                                JaredBusch @Romo
                                last edited by

                                @Romo I do not recall what the TCP overhead is on PPPoE without looking it up.

                                1 Reply Last reply Reply Quote 0
                                • scottalanmillerS
                                  scottalanmiller @JaredBusch
                                  last edited by

                                  @JaredBusch said in Packet loss when connected to L2TP/IPsec VPn:

                                  @Romo said in Packet loss when connected to L2TP/IPsec VPn:

                                  @dafyre said in Packet loss when connected to L2TP/IPsec VPn:

                                  Also, could this be an MTU settings issue? I know they're rare... but that was the first thing that popped into my mind.

                                  Was inded thinking about playing with the MTU, just now sure why it wouldn't on ATT. It is currently set for 1492

                                  UVerse? Then your service is PPPoE. You likely need to lower the MTU to account for it.

                                  Also If UVerse, you are screwed in your router options.

                                  Not Uverse, it's their enterprise leased line.

                                  1 Reply Last reply Reply Quote 0
                                  • RomoR
                                    Romo
                                    last edited by

                                    Been playing for the value for a while and still no luck. I am still seeing packet loss.

                                    Edge router logs have been showing:

                                    May  7 18:00:48 office pppd[24483]: pppd 2.4.7 started by root, uid 0
May  7 18:00:48 office pppd[24483]: Connect: ppp0 <-->
May  7 18:00:48 office pppd[24483]: Overriding mtu 1500 to 1474
May  7 18:00:48 office pppd[24483]: Overriding mru 1500 to mtu value 1474
May  7 18:00:50 office pppd[24483]: Unsupported protocol 'IPv6 Control Protocol' (0x8057) received
May  7 18:00:50 office pppd[24483]: Unsupported protocol 'Compression Control Protocol' (0x80fd) received
May  7 18:00:51 office pppd[24483]: Cannot determine ethernet address for proxy ARP
May  7 18:00:51 office pppd[24483]: local  IP address 10.255.255.0
May  7 18:00:51 office pppd[24483]: remote IP address 192.168.4.10
May  7 18:03:45 office pppd[24483]: Overriding mtu 1500 to 1474
May  7 18:03:45 office pppd[24483]: Overriding mru 1500 to mtu value 1474

                                    Any other ideas?

                                    JaredBuschJ 1 Reply Last reply Reply Quote 0
                                    • JaredBuschJ
                                      JaredBusch @Romo
                                      last edited by

                                      @Romo said in Packet loss when connected to L2TP/IPsec VPn:

                                      Been playing for the value for a while and still no luck. I am still seeing packet loss.

                                      Based on what @scottalanmiller said, I would not expect MTU to be involved.

                                      RomoR 1 Reply Last reply Reply Quote 0
                                      • RomoR
                                        Romo @JaredBusch
                                        last edited by

                                        Ok even weirder behavior now, currently I am getting steady pings for a very short period of time and then the connections just seems to die.

                                        MTU is currently set to 1472

                                        Pinging 10.10.10.1 with 32 bytes of data:
Reply from 10.10.10.1: bytes=32 time=87ms TTL=127
Reply from 10.10.10.1: bytes=32 time=89ms TTL=127
Reply from 10.10.10.1: bytes=32 time=87ms TTL=127
Reply from 10.10.10.1: bytes=32 time=89ms TTL=127
Reply from 10.10.10.1: bytes=32 time=90ms TTL=127
Reply from 10.10.10.1: bytes=32 time=88ms TTL=127
Reply from 10.10.10.1: bytes=32 time=87ms TTL=127
Reply from 10.10.10.1: bytes=32 time=88ms TTL=127
Reply from 10.10.10.1: bytes=32 time=93ms TTL=127
Reply from 10.10.10.1: bytes=32 time=93ms TTL=127
Reply from 10.10.10.1: bytes=32 time=94ms TTL=127
Reply from 10.10.10.1: bytes=32 time=91ms TTL=127
Reply from 10.10.10.1: bytes=32 time=88ms TTL=127
Reply from 10.10.10.1: bytes=32 time=87ms TTL=127
Reply from 10.10.10.1: bytes=32 time=93ms TTL=127
Reply from 10.10.10.1: bytes=32 time=95ms TTL=127
Reply from 10.10.10.1: bytes=32 time=91ms TTL=127
Reply from 10.10.10.1: bytes=32 time=90ms TTL=127
Reply from 10.10.10.1: bytes=32 time=101ms TTL=127
Reply from 10.10.10.1: bytes=32 time=89ms TTL=127
Reply from 10.10.10.1: bytes=32 time=88ms TTL=127
Reply from 10.10.10.1: bytes=32 time=88ms TTL=127
Reply from 10.10.10.1: bytes=32 time=89ms TTL=127
Reply from 10.10.10.1: bytes=32 time=106ms TTL=127
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Request timed out.

                                        During that initial time, when the connection has just established web browsing also works close to normal speeds I would say. Really strange behavior.

                                        1 Reply Last reply Reply Quote 0
                                        • JaredBuschJ
                                          JaredBusch
                                          last edited by JaredBusch

                                          I never have a problem with my VPN on my iPhone.

                                          May  7 19:42:34 bna-jared xl2tpd[4722]: Connection established to 172.58.142.195, 50961.  Local: 48550, Remote: 4 (ref=0/0).  LNS session is 'default'
May  7 19:42:34 bna-jared xl2tpd[4722]: Call established with 172.58.142.195, Local: 3582, Remote: 2938, Serial: 1
May  7 19:42:34 bna-jared pppd[8432]: pppd 2.4.7 started by root, uid 0
May  7 19:42:34 bna-jared pppd[8432]: Connect: ppp0 <-->
May  7 19:42:34 bna-jared pppd[8432]: Overriding mtu 1500 to 1492
May  7 19:42:34 bna-jared pppd[8432]: Overriding mru 1500 to mtu value 1492
May  7 19:42:34 bna-jared pppd[8432]: Overriding mtu 1500 to 1492
May  7 19:42:35 bna-jared pppd[8432]: Warning - secret file /etc/ppp/chap-secrets has world and/or group access
May  7 19:42:35 bna-jared pppd[8432]: Unsupported protocol 'IPv6 Control Protocol' (0x8057) received
May  7 19:42:35 bna-jared pppd[8432]: local  IP address 10.255.255.0
May  7 19:42:35 bna-jared pppd[8432]: remote IP address 10.254.203.2
May  7 19:43:05 bna-jared pppd[8432]: Connection terminated: no multilink.
May  7 19:43:05 bna-jared pppd[8432]: Modem hangup

                                          Here is my config.

                                          set vpn l2tp remote-access authentication local-users username jbusch password 'SmegOff'
set vpn l2tp remote-access authentication mode local
set vpn l2tp remote-access authentication require mschap-v2
set vpn l2tp remote-access client-ip-pool start 10.254.203.2
set vpn l2tp remote-access client-ip-pool stop 10.254.203.10
set vpn l2tp remote-access dhcp-interface eth0
set vpn l2tp remote-access dns-servers server-1 8.8.8.8
set vpn l2tp remote-access dns-servers server-2 8.8.4.4
set vpn l2tp remote-access idle 1800
set vpn l2tp remote-access ipsec-settings authentication mode pre-shared-secret
set vpn l2tp remote-access ipsec-settings authentication pre-shared-secret SmegOff
set vpn l2tp remote-access ipsec-settings ike-lifetime 3600
set vpn l2tp remote-access ipsec-settings lifetime 3600
set vpn l2tp remote-access mtu 1492

                                          The IP range is not used elsewhere in my router at all.

                                          1 Reply Last reply Reply Quote 1
                                          • RomoR
                                            Romo
                                            last edited by

                                            This was working properly until we switched to ATT. It is still properly reaching the router and also authenticating correctly to the radius server. It's just after connecting it completely craps out.

                                            1 Reply Last reply Reply Quote 0
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