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Unable to establish GRE tunnel between linux-based instance and Cisco Router [Resolved]

I would like to establish a GRE Tunnel connection between a Cisco CSR1000v and an EC2 instance that runs Ubuntu 18.04.02 LTS Linux 4.15.

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In R1 CSR1000v the configuration is the following:

interface Tunnel99
 ip address
 keepalive 2 3 
 tunnel mode gre ip
 tunnel source GigabitEthernet1
 tunnel destination
 tunnel path-mtu-discovery

The Tunnel interface description is the following

Interface          IP-Address      OK? Method Status                Protocol
GigabitEthernet1       YES DHCP   up                    up
Tunnel99       YES manual up                    down

In the EC2 instance, I got the following configuration

modprobe ip_gre
lsmod | grep gr
sudo ip tunnel add gre0 mode gre remote local ttl 255
sudo ip link set gre0 up
ip addr add dev gre0

The problem is I couldn't ping the tunnel's interface from both sides. And the GRE0 interface shows a destination address as same as the tunnel's IP address.

gre0: flags=209  mtu 8977
        inet  netmask  destination
        inet6 fe80::200:5efe:ac00:106  prefixlen 64  scopeid 0x20
        unspec AC-00-01-06-00-00-00-00-00-00-00-00-00-00-00-00  txqueuelen 1000  (UNSPEC)
        RX packets 171  bytes 4104 (4.1 KB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 7  bytes 392 (392.0 B)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

Question Credit: Khalil Mebarkia
Question Reference
Asked June 14, 2019
Posted Under: Network
1 Answers

It turns out that MPLS is not running the Linux kernel 4.15 in AWS. In order to install Quagga with LDP daemon that runs SR MPLS from a VM to another, the kernel must be updated or you need Linux 4.5 or latest.

credit: Khalil Mebarkia
Answered June 14, 2019
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