Security Services Operations Center-Restricted Created on: 2/22/2009 Page 1 of 1

1 GRE Tunnel Configuration Guide

The GRE tunnel is setup between TATA Communications and customer for providing clean pipe to customer as part of mDDoS detection & mitigation service. The following steps are to be followed for successful GRE tunnel creation & establishment in Cisco router or Cisco 3750 switch at customer end.

1.1 Step 1: Loopback Interface configuration

A loopback interfaces should be created to act as the source of the tunnel at customer site. To

create and configure the loopback interface with an IP address that does not conflict with any

other IP Addresses in network, configure Cisco router or Cisco 3750 switch with following entries.

Interface loopback [number-1]

ip address [unique interface IP Address-1] 255.255.255.255

1.2 Step 2: GRE Tunnel Configuration

Preferably more than one GRE tunnel should be configured between customer router and TATA Communications’s mitigation centers to provide redundancy. The following are the instructions to configure GRE tunnels on Cisco routers.

1.3 Commands for Configuring GRE Tunnels

Interface Tunnel [number-1] ip unnumbered <interface connected to Tata Communicationsend> description mDDoS-GRE-Tunnel-for-mumbai-farm tunnel source loopback[number-1] tunnel destination 121.240.24.198 end