Current network architecture was primarily built for point to point communication. IP address forms the backbone of internet’s hourglass architecture. Every host in the network is assigned an unique ID ( IP address ) with which it can be reached. Internet packets carry the source and destination IP addresses (communication endpoints)
But networks have evolved over time from being host-centric to data-centric. An internet user is interested primarily in obtaining the data and doesn’t really care which host delivers it. For e.g. when you login to youtube and you search for a particular video, you want youtube to stream that video to you. However it doesn’t really matter if the host is in India, US, UK or anywhere else in the world. It doesn’t matter from which IP address you receive the streaming data.
The current internet architecture has its share of issues. There is no guaranteed quality of service and supports only best effort delivery. Security is mostly limited to the end devices with network mostly exposed to the threats.
Information Centric Networks or ICN, caters to this changing user and network behaviour.
How ICN works
ICN attempts to do away with the IP address and instead adopts a Consumer-Producer model.
IP addresses are no longer used in ICN. Instead, a request is made by the consumer using the content path. A likely video path in youtube could be /com/google/youtube/videos/myvideo. The ue request would be transferred to the nearest ICN router. The router will then send it to “com” ICN router to fetch the data. The com ICN router will send the request to google and the google ICN to youtube and so on till the data is received. Every intermediate ICN router will cache the data to enable quick access of data for later requests. So the next time user2 requests for /com/google/youtube/videos/myvideo, the video can be retrieved directly from the closes ICN router. Thereby considerably reducing the round trip time.
As you can see, the above approach requires a complete new set of routers with a different routing mechanism. It’s not easy or practical to dismantle the entire existing to replace with a different technology. The change has to come gradually.
One of the proposals is to introduce ICN with the existing routers. To access a youtube video, “myvideo”, UE will send a request to one of the youtube servers i.e. UE will send a request with source ip as it’s ip and destination ip as the server’s ip. The router at the next hop will replace UE source ip to it’s ip and send the request to the next router. Every router in the path will replace the source ip to its own ip and forward the request onwards. Every router will cache the data it receives and forward it downwards to the UE. Eventually, all routers would have cached the data before the UE receives. Any request that comes thereafter can be services directly from the cache of the first router and needn’t go all the way to the youtube servers.
ICN also employs concepts such as named content , name-based routing , security mechanisms applied directly to content and in-network content caching as mentioned above.
Offline Access: As we discussed before, the fundamental advantage of an ICN network is to remove the dependency for both the UE and Server to be online to transfer the data. UE can access the latest data from the data cached in various routers.
Mobile Edge Access: ICN enables mobile edge computing. All routers at the edge can easily cache frequently requested data, lowering the time taken for data access and removing congestion at the core network.
5G and ICN
5G can act as a launchpad for ICN. But what are changes in mobility to support ICN?
First of all, the 5G core has to have the support to detect a new PDP-Type – ICN. An ICN capable UE on an attach will request for a ICN PDN. All traffic from the ICN capable UE has to be forwarded to ICN router. The APN configurations should have an additional capability to distinguish Ipv4, Ipv6 and ICN UEs. Needless to say built in support for ICN PDU sessions within access and 5G core network nodes have to be ensured.
The ICN based traffic can also be handled on a entirely different network slice.
Another aspect of mobility that ICN addresses is the Mobility itself ! This is done through anchor-less mobility. In the present day scenario, when the UE moves from one location to another, it depends on the PGW to act as an anchor to maintain the IP continuity and on the MME for all the signalling information. With ICN, when the UE moves to a different location, it just needs to rebroadcast its request to the nearby ICN router.
ICN Use cases
With content caching being one of the main points of discussion in ICN, one of the earliest use cases showing interest in ICN were the Content Distribution Networks (CDN). However if ICN does become a reality, internet itself can become a use case.