Cisco router nat
Cisco routers contain the Cisco Networking Management Technology (CNP) feature wherein it enables organizations to define and manage their internal and external network resources. The internal network resources are those resources that are within the organization and not to external users. They include the inside source routes, inside destination routes, and the subnet inside source and destination addresses. There is also the use of the private label networking (PLN) within private local area networks (PBANs) as well as public IP networks. An IP packet has the private network label attached to it as an indication that it originated from a particular internal resource rather than an external one.
The Cisco routers have the ability to manage and secure all the IP addresses assigned to an organization. With this feature, the organization can block certain external resources and restricted or allow access to only specific and selected IP addresses from an outside global region. For organizations that aim at reducing the risk of security threats, internal IP addresses are often blocked from being advertised on the Internet. With the CNP feature, only the trusted externally accessible addresses will be advertised on the Internet to prevent unauthorized access from the outside world.
The primary use of the Cisco router for managing the inside traffic within a private LAN is for VOIP or voice over IP services. With this capability, the internet bandwidth usage can be managed and controlled, which is very helpful for business enterprises. However, when the internal network resources become full, the routing table in the router automatically generates more nat overload response packets that cause the system to slow down or even crash. It can cause major damage to the business enterprise and may lead to loss of revenues.
Cisco router nat
To avoid such problems, companies should make sure that they do not overload the internal network resource with too many external IP addresses. They should also keep monitoring the route whenever the nat overload response packets exceed the average number of expected packets sent and received by the router. They should also keep a record of the packets that are being dropped. Sometimes, the DNS servers or other filtering systems may respond with warnings saying that the given IP addresses are already in use or no longer available. Hence, the company should be aware of such occurrences and take remedial measures to limit or stop the usage of the IP addresses that are already in use.
If a router’s CPU gets slower due to the excessive NAT service, the process of answering and forwarding the requests will be greatly affected. The performance of the routers will get affected as well as the general connectivity of the enterprise. To resolve the issue, the company should remove the unnecessary hardware and should reduce the number of connections or switches used for the HSRP functions.
For controlling the rate at which the packets are delivered and received by the Cisco router, the software used in the routers must have the capability of translating the TCP Sequence and LPR header fields. The translation table contains the IP addresses, types of data, and port numbers along with the control port addresses. The inside global inside local, outside global (IGLG) and internal global inside local, outside global (IGLH) translations are performed by the Cisco routers. The IGLG is for local area network and the IGLG is for interconnecting the GREs within the same LAN or LANs.
There might be some problems associated with the inside global translation table. In such cases, the only solution is to remove or change the address on the IGR and restart the device. For the purpose of understanding the above mentioned problem better, it is advisable to check whether there is a connection of the GRE inside the Ethernet network before considering a solution to the above mentioned problem. If the problem is not resolved then it might be due to a security vulnerability or some other minor glitch.
When the IP nat inside source static nat firewalls or the reverse network filters are used for the purpose of filtering the outside network traffic, then this might affect the forwarding process. The nat configuration of the Cisco routers must be done in a manner so as to protect the legitimate network users from the unauthorized users. For this purpose, the nat rules have to be modified accordingly. Some of the common modifications include the use of the source port number instead of the Destination port number, use of static IP addresses instead of the static IP addresses, use of BGP neighbor finding for the purpose of forwarding the inside network traffic to the outside network destination and others. All the aforementioned modifications can be done manually, but in most of the cases it is better to automate the process.
<