Why packets disappear on cisco?

Question

FreeBSD

Hey! Situation incomprehensible to me:
A site-to-site GRE over IPsec tunnel is configured between two ciscos.
Internal networks 192.168.0.0 and 192.168.1.0
Tunnel gateways on ciscos 10.0.0.0/29
Everything works, ping is smooth and stable, but every few minutes there is a failure of 4 - 5 packets. It's from computer to computer.
The most interesting thing is that the gateways of the 10.0.0.0 network are pinged, and moreover, a remote host that is 192.168 is pinged from cisco.
I understand that it’s almost impossible to answer, it’s interesting how to look at the tsiska why they are blocked - packets are lost, because they definitely reach the tsiska. How to see what's happening on an interface like tcpdump on freebsd?

Answer 1

View - like this - port mirror
you can also study the output of show int *

Answer 2

Ivan : If the devices are not very powerful and only Cisco is in the infrastructure, use EIGRP. Although it seems to me that in your case, dynamic routing is a nuisance that is needed solely for the sake of academic interest.
PS Read about packet capture here: www.cisco.com/c/en/us/support/docs/ios-nx-os-softw...
Of course, it will not work as convenient as tcpdump in real time, but in the future, I'm sure still come in handy.

Answer 3

Причем здесь mirror трафика, если GRE поднимается на роутерах. Если ходите dump обмена протоколов используйте debug или команды troubleshooting'a. У вас вероятно поднят DMVPN , следовательно используется протокол nhrp и есть NHS(next-hop server). В вашем случае проблема решится следующим образом:ip #nhrp map multicast [ip NHS]
То есть вам необходимо чтобы рассылка/ответ LSA отправлялись на NHS