> For the complete documentation index, see [llms.txt](https://archive-docs.klaytn.foundation/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://archive-docs.klaytn.foundation/content/klaytn/design/multiport.md).
# Multi-Channel
A Klaytn node can be run with **Multi-channel**.
If a node is executed with multi-channel configuration, 2 ports are set up for communication. On the otherhand, if a node is executed with single channel configuration, 1 port is set up. If 2 multi-channel nodes are trying to connect, a connection is established using 2 ports. Otherwise, they will use 1 port for communication.
A multi-channel node can be enabled through the flag `--multichannel`. If you use [`kend`](/content/installation-guide/deployment/endpoint-node/installation-guide/startup-the-en.md), multi-channel is enabled by default due to the statement `MULTICHANNEL=1` in [`kend.conf`](/content/installation-guide/deployment/endpoint-node/installation-guide/configuration.md). To disable multi-channel, please replace the statement with `MULTICHANNEL=0`. If you want to run a node with specific ports, flags `port` and `subport` can be used. If you want to specify ports values of a connecting peer, check out [KNI](/content/klaytn/design/kni.md).
## Architecture
The picture above shows a connection between two multi-channel nodes. Two ports, mainport (A) and subport (B), transfer different messages.
* **Mainport**(A) is used to transfer messages related to blocks and consensus protocols.
* Block messages include requests and responses of the hash, header, body and receipt of a block.
* Consensus messages include Request, Preprepare, Prepare, Commit and RoundChange. The meaning of the messages can be found in [PBFT](/content/klaytn/design/consensus-mechanism.md#pbft-practical-byzantine-fault-tolerance).
* **Subport**(B) is for transferring transaction messages.
The picture shows a connection between two single channel nodes or between a single channel node and a multi-channel node. In this case, all messages related to blocks, transactions, and consensus protocols are transported via the same port.
## Ports
To set port numbers in KNI, please refer to [the KNI scheme](/content/klaytn/design/kni.md).
* Single Channel : A single channel node uses one port (default is 32323).
* Multi-Channel: A multi-channel node uses two ports. The ports can be specified in `port` and `subport`. In Klaytn, the default values of `port` and `subport` are 32323 and 32324, respectively.
* You might not set `subport` when connecting to multi-channel node. In this case, at first, a Klaytn node tries to connect using a single-channel. In handshake process, the actual peer's port numbers are revealed. If the peer is a multi-channel node, the ongoing connection will be canceled and a reconnection will be made with the updated ports.