5 Differences Between Static and Dynamic Crypto Map

What are the differences between static and dynamic crypto map? Static and dynamic crypto maps are two completely different things that together enhance the efficacy and security of a network while making a transaction.

Both these terms being a bit technical may seem difficult to understand their significance, working process and the differences. In this article you will come to know about the differences explained in the simplest way possible.

A crypto map, whether it is static or dynamic, is basically a feature that binds all the information together. A crypto map can be applied to one particular interface or to multiple interfaces.

Specific crypto map entries are used to put up several tunnels and one single crypto map may have several entries. All these entries are identified by a particular number.

It is all about the creation, application, configuration, and verification of the design to use both static and dynamic crypto maps that enhance the efficiency, security and usefulness of the network.

Therefore, in spite of the differences between the two, it is the combined effort and functionality of them that facilitates a better, more productive and secure transaction.

5 Differences Between Static and Dynamic Crypto Map

Differences Between Static and Dynamic Crypto Map

Just as the nomenclature signifies, one is dynamic and the other is static and therefore their working process is quite dissimilar.

However, both serve the same purpose which is to make the VPN or Virtual Private Network more proactive.

These facilitate in initiating negotiations between the endpoints and discover the unknown and remote IPSec peers.

Here are some significant differences between static crypto maps and dynamic crypto maps for you to know.

The list includes everything from the purpose to the configuration of the two. Check out Differences Between Crypto Staking and Crypto Mining.

1. Purpose

A static crypto map can be used as a reference for a dynamic crypto map. It all depends on the purpose of the two types of crypto maps. As is in the case of a static crypto map, it typically identifies the traffic that needs to be encrypted as well as the peer explicitly.

Its primary purpose is to accommodate a number of tunnels with diverse characteristics and profiles such as sites, partners, and locations.

Therefore, in simple words, a static VPN or Virtual Private Network is used only when all information regarding both the peers is available and the policies to be used are known.

When you compare the dynamic crypto maps, on the other hand, these are actually the ways in which the peers with similar characteristics are shared such as several branches that have the same configuration.

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It also helps in sharing of the peers that follow dynamic IP addressing processes such as the DHCP or Dynamic Host Configuration Protocol.

2. Usage

In specific scenarios, the use of static and dynamic crypto maps can vary notably. For example, in a Hub-and-Spoke VPN, there is one dynamic and two static crypto maps used in the routers.

The central HQ site of the Hub of the VPN network will comprise a dynamic crypto map. This type of setting enables the remote branch sites to have a dynamic public IP address due to the dynamic crypto map.

On the other hand, in the same given scenario, the two branch sites that work as the spokes in the VPN network will comprise a static crypto map. This crypto map will allow the central HQ or the remote site to contain a static public IP address.

3. Configuration

Depending on the particular scenario, there are some key differences in the configuration of a static crypto map and a dynamic crypto map that you should also take note of.

In the case of a static crypto map all the existing peers on the terminator or the Hub of the Virtual Private Network need to be configured manually. In such situations, the particular static public IP address is used.

On the other hand, in the case of a dynamic crypto map, there is no need to configure the peers manually and individually.

Instead of doing it one by one on the VPN Hub, the configuration can be done all together and automatically and there is also no need to make any changes in the spoke sites. This means that the static crypto map is left as it was.

4. Initiator Session

In the case of the dynamic crypto map, the initiator session of the VPN is restricted to the spoke site only. This means that the dynamic VPN tunnel will not be created if the traffic does not come in the VPN tunnel from the spoke.

However, when the traffic is initiated from the branch or spoke site then automatically the VPN tunnel will be created. In this particular case, the connection between the HQ and the branch or spoke will be ideally bidirectional.

In comparison, for the static crypto maps, it is all about making a simple arrangement on the HUB site. When more spokes are added to it, there will be no need to make any changes on the HUB since the entire configuration will be done on the spoke site only.

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5. Peer Specification

In reality, the traffic that is in between the path of the crypto protected dynamic crypto map with no TED is automatically dropped provided the remote peer does not initiate or negotiate an IPSec tunnel with the IPSec endpoint already by using that particular dynamic crypto map.

Therefore, if you want to start a negotiation between the ISAKMP and IPSec SA with remote peers that are unknown, you must certainly use the dynamic crypto maps in combination with the TED.

However, with the static crypto maps, the IPSec peer is statically specified much unlike the dynamic crypto maps. This means that the static crypto maps will not respond to the attempts made for an ISAKMP and IPSec SA negotiation since the peer will be unknown to it.

This typically limits the static crypto maps from changing the diverse concepts related to the ISAKMP and IPSec design, administration and deployment.

Which is Needed More – Static and Dynamic Crypto Map?

As said earlier, both dynamic crypto map and static crypto map work differently but their primary purpose is the same: to ensure safety and security to the network. Therefore, that answers your question reasonably well.

However, if you want to have a more comprehensive knowledge, then here are a few other important facts to know.

The dynamic crypto map is used typically for establishing a connection with the IPSec clients and for this the remote end does not need to have any static IP address.

This is because these peers are considered to be dynamic due to the absence of a static peer IP address in these scenarios.

In order to configure these dynamic crypto maps, these are usually done separately and it is typically done by using the crypto dynamic map command.

This prevents applying it directly on the interface because it is nested inside the crypto map which is typically applied to the interface.

The entire process of making entries in the crypto maps is made in order. Therefore, the best practice to follow here is to put the entries that refer to the dynamic crypto map at the end of it.

This will prevent any of the static peers from potentially negotiating a VPN tunnel connection with that specific dynamic crypto map and fail in the attempt.

The use of dynamic crypto maps facilitates the negotiation between IPSec and ISAKMP as well as the IPSec Security Associations or SA.

All these happen from the remote endpoints and for this the addresses are not required to be known.

However, these dynamic crypto maps do not enable the VPN endpoints by themselves to discover the unknown and remote IPSec peers proactively.

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They also do not help the VPN endpoints to set off the IPSec SA and ISAKMP negotiation with the undiscovered peers.

Using dynamic crypto maps by altering their design and configuration can help in discovering static IPSec peers more dynamically along with some specific components.

These include the dynamic configuration and acceptance of remote IP addresses of the peers in the IPSec SA that are negotiated and the address space in the IPSec SA that is crypto protected.

Also, in the case of deploying remote access VPN, the use of the dynamic crypto maps is commonly seen.

This enhances the functionality with additional dynamics such as assigning the IP addresses of the VPN clients, assigning IP domain names with the use of IKE mode configuration, and assigning DNS/WINS servers.

When it comes to the static crypto maps, all of these should be done manually, as said before, at both the ends, local as well as remote peers.

In comparison, in a dynamic crypto map solution, it is only the remote endpoint that needs to be configured statically.

On the other end, the local endpoint can discover the IP address of the remote peer by using its dynamic crypto map retroactively.

Whether an existing or a new dynamic crypto map is used, it is the command configuration that enables negotiations with IPSec SA from the dynamically addressed IPSec peers.

Also, when the dynamic crypto map is well defined, this map can be optionally associated with the default global map. For this, the crypto-map-global-map command is used.

Therefore, considering all the facts and figures it can be safely said that it is due to the diverse nature and utility of both dynamic and static crypto maps that affect the operation of the IPSec and ISAKMP on the whole.

Conclusion

A dynamic crypto map and a static crypto map both are needed today to ensure safety and security while making an online transaction. Now that you know the differences between the two, you know how exactly each of them works.