Advantages and disadvantages of ADSL IP VPN

There is no free lunch in the world, and adsl ip vpn is no exception. Although it is cheaper to select an adsl ip vpn than other MPLS services. But this does not mean it is suitable for anyone, because the customer's requirements are always different. In this article, I will also explain the advantages and disadvantages of ADSL IP VPN.

First, let's look at some places where adsl ip vpn is better than most wan mpls lines:

◆ Low cost.Internet service providers provide simple ADSL lines to access the Internet with a static IP address and a fast speed. 24 Mbps/1 Mbps (download/upload speed) ADSL charges are almost cheaper than any wan mpls service. This is very attractive for enterprises that strive to reduce their communication costs.

◆ Complete configuration.WAN engineers have full control over the establishment of VPN tunnels between sites. They can change the configuration at any time to fix any network problems or help solve possible problems. With the highest permissions to access the VPN, such as the router and firewall terminal equipment, engineers can find the status on the ADSL line and then take appropriate measures.

◆ The VPN must be backed up.For important sites, if the ADSL line is through ISDN, you can leave ISDN for backup. In case of a connection failure, the vro can enable ISDN dialing automatically and temporarily connect to the site through ISDN until the ADSL line returns to normal. For more complex configuration of multiple ADSL lines for each site, VPN can be automatically transferred to other ADSL paths. The response time of the standby line can be configured by the network engineer. The enterprise does not need to wait until the service provider repairs the line.

◆ Two-in-one.When configuring the site-to-site VPN, engineers can also configure remote VPN access for users traveling nationwide or around the world. In order to obtain this function from their service providers, most enterprises must pay additional fees.

◆ Functions can be upgraded.The biggest advantage of adsl ip vpn is that the site-to-site VPN function relies entirely on the support of the VPN Router/firewall. This indicates that once a new feature is added to the vro update operating system (I. e., Cisco IOS), the network engineer can deploy it immediately. For example, Cisco introduced the QoS pre-classification feature of IOS, which fixes the QoS of many services that run through the IPsec VPN tunnel. Dynamic Multi-Point VPN is another good feature that allows expansion of the IPsec VPN tunnel between multiple sites. DMVPN allows various terminals and other peers to dynamically establish a VPN tunnel to provide a low-cost mesh VPN solution.

If you think the above list about the advantages of adsl ip vpn looks very good, you would like to use it immediately. Don't worry. Please read the following disadvantages.

The following lists the disadvantages of adsl ip vpn over all wan mpls lines.

◆ Qos restrictions.To obtain the complete functional QoS model, you need to be able to access all devices and paths that pass through VPN packets. In the adsl ip vpn model, QoS always works from the LAN of each site to the ADSL interface of the router. After that, data packets enter the ISP network, but the ISP provider does not have QoS for the link. There is no doubt that although all of them are delivered as much as possible, any QoS parameter embedded in the WAN packet will be ignored by the ISP in most cases.

◆ Bottlenecks and low speeds may occur.In the structure of the adsl ip vpn, the enterprise connects to a separate digital user line to access the multiplexing DSLAM ), this is a device that uses multiplexing technology to provide high-speed Internet services over a telephone line-it establishes an ADSL connection for the ISP. When other users in the same region, including business and home users, connect to the same DSLAM, if traffic congestion occurs on the DSLAM node, you may experience extremely slow speeds during peak hours. Again, you cannot guarantee the speed of using ADSL.

◆ Asymmetric speed.ADSL provides a good download speed, but its upload speed is always limited. This is a major defect for headquarters with remote VPN terminals. It is almost impossible to connect all remote sites to an ADSL line with limited upload bandwidth, unless the traffic between the site and the headquarters is controlled. Based on the number of sites and the number of remote users and services running in the adsl ip vpn tunnel, it is necessary to split the remote site into two or more ADSL lines to the headquarters.

◆ No SLA ).Since the adsl ip vpn uses a common Internet line, you do not need to consider the service level agreement (SLA) of the service provider ). No service provider signs an SLA contract for the ADSL line.

◆VPNAnd vro/firewall security.The ADSL line is directly exposed on the Internet. This means that you are responsible for the security issues of your VPN and terminal device routers or firewalls. If Enterprise engineers do not take appropriate measures to protect device security, the Enterprise will be completely exposed to the Internet. This is not an easy topic, and the damage can be fatal. Therefore, it is very important to understand the risks. Ask the technical experts to ensure that the work is completed accurately and smoothly. Ideally, when the device configuration is correct, you do not need to worry about it because it is safe.

◆ DoS attacks.When using Internet lines, you will be vulnerable to DoS attacks at any time. All attempts can be rejected by "success". However, remember that traffic must first reach your router/firewall. This means that the maximum damage caused by a configured terminal DoS attack is a bottleneck created on ADSL, which greatly reduces the attack speed.