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Beginner

GRE packet issue

Hi, Guys,

 

Need your precious advice.

 

GRE tunnel setup with Public IP (without NAT) is not difficult, everything is fine and GRE tunnel is running properly.

 

But after the source GRE IP is NATed :

Case1: the "GRE keepalive" can not be confgured, or the tunnel is down (traffic can not pass through the tunnel).

Case2: if no "GRE keepalive" is configured, tunnel interfaces are down, but traffic is able to pass through the tunnel.

 

 

Issued GRE packet is captured as the attached, what is the Source GEOIP: Unknown  & Destination GEOIP: Unknown ?

 

 Many thanks in advance.

 

2 REPLIES 2
Beginner

Re: GRE packet issue

Hi Benson,

 

I have this problem too, on my old c3750

 

Q1. Gre keepalive issue

refer to "keepalive" issue for Gre CLI configuration:

 

It works on router model as expected, but sometimes we have to check if we build Gre tunnel on switch model(e.g. old c3750), it does supported Gre commands, but not recommended by TAC, and performance issue is expected. 

https://community.cisco.com/t5/switching/cisco-catalyst-3750-gre-tunnel-keepalive-retry-count-cannot-be/td-p/2525258

 

There is some works tested "keepalive" feature may not work properly: 

https://community.cisco.com/t5/mpls/keepalive-brings-tunnel-in-vrf-down/td-p/1711180

 

 

 

Q2. GEOIP issue

it is refer to wireshark feature which we may not discuss in this forum in detail

 

GeoIP information is an alternating list of source and destination paramters:
[Source GeoIP Country: China]
[Destination GeoIP Country: Japan]

..

 

hope the share above may help you. [heart]

 

 

Aim

Highlighted
Hall of Fame Expert

Re: GRE packet issue

Hello Aim,

rated as it is deserved.

@bensonlei 

 

The GeoIP concept is used in security contexts with cloud based services that provides this capability to create security policies for NG firewall: many vendors Fortinet, Juniper, Palo Alto and Cisco itself provide this capabilities having each FW or FW manager to interact with a cloud based  service to get this GEOIP info.

 

Hope to help

Giuseppe

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