Channel Open Handshake

The tx commands can be used to establish a channel for a given connection. Only unordered channels are currently supported.

sequenceDiagram
    autonumber
    participant A as ibc-1
    participant B as ibc-0
    Note over A, B: No channel
    A->>B: ChannelOpenInit
    Note over B: channel: channel-0
    Note over B: channel: counterparty: none
    B->>A: ChannelOpenTry
    Note over A: channel: channel-1
    Note over A: channel: counterparty: channel-0
    A->>B: ChannelOpenAck
    note over B: channel: channel-0
    note over B: counterparty: channel-1
    B->>A: ChannelOpenConfirm
    Note over A, B: Channel open

Channel Open Init
Channel Open Try
Channel Open Ack
Channel Open Confirm

Channel Open Init

Use the chan-open-init command to initialize a new channel.

DESCRIPTION:
Initialize a channel (ChannelOpenInit)

USAGE:
    hermes tx chan-open-init [OPTIONS] --dst-chain <DST_CHAIN_ID> --src-chain <SRC_CHAIN_ID> --dst-connection <DST_CONNECTION_ID> --dst-port <DST_PORT_ID> --src-port <SRC_PORT_ID>

OPTIONS:
    -h, --help             Print help information
        --order <ORDER>    The channel ordering, valid options 'unordered' (default) and 'ordered'
                           [default: ORDER_UNORDERED]

REQUIRED:
        --dst-chain <DST_CHAIN_ID>
            Identifier of the destination chain

        --dst-connection <DST_CONNECTION_ID>
            Identifier of the destination connection [aliases: dst-conn]

        --dst-port <DST_PORT_ID>
            Identifier of the destination port

        --src-chain <SRC_CHAIN_ID>
            Identifier of the source chain

        --src-port <SRC_PORT_ID>
            Identifier of the source port

Example

First, let's initialize the channel on ibc-0 using an existing connection identified by connection-0:

hermes tx chan-open-init --dst-chain ibc-0 --src-chain ibc-1 --dst-connection connection-0 --dst-port transfer --src-port transfer

Success: OpenInitChannel(
    OpenInit(
        Attributes {
            height: Height {
                revision: 0,
                height: 3091
            },
            port_id: PortId(
                "transfer",
            ),
            channel_id: Some(
                ChannelId(
                    "channel-0",
                ),
            ),
            connection_id: ConnectionId(
                "connection-0",
            ),
            counterparty_port_id: PortId(
                "transfer",
            ),
            counterparty_channel_id: None,
        },
    ),
)

A new channel has been initialized on ibc-1 with identifier channel-0.

Note that the counterparty_channel_id field is currently empty.

Channel Open Try

Use the chan-open-try command to establish a counterparty to the channel on the other chain.

DESCRIPTION:
Relay the channel attempt (ChannelOpenTry)

USAGE:
    hermes tx chan-open-try [OPTIONS] --dst-chain <DST_CHAIN_ID> --src-chain <SRC_CHAIN_ID> --dst-connection <DST_CONNECTION_ID> --dst-port <DST_PORT_ID> --src-port <SRC_PORT_ID> --src-channel <SRC_CHANNEL_ID>

OPTIONS:
        --dst-channel <DST_CHANNEL_ID>
            Identifier of the destination channel (optional) [aliases: dst-chan]

    -h, --help
            Print help information

REQUIRED:
        --dst-chain <DST_CHAIN_ID>
            Identifier of the destination chain

        --dst-connection <DST_CONNECTION_ID>
            Identifier of the destination connection [aliases: dst-conn]

        --dst-port <DST_PORT_ID>
            Identifier of the destination port

        --src-chain <SRC_CHAIN_ID>
            Identifier of the source chain

        --src-channel <SRC_CHANNEL_ID>
            Identifier of the source channel (required) [aliases: src-chan]

        --src-port <SRC_PORT_ID>
            Identifier of the source port

Example

Let's now create the counterparty to channel-0 on chain ibc-1:

hermes tx chan-open-try --dst-chain ibc-1 --src-chain ibc-0 --dst-connection connection-1 --dst-port transfer --src-port transfer --src-channel channel-0

Success: OpenTryChannel(
    OpenTry(
        Attributes {
            height: Height {
                revision: 1,
                height: 3213
            },
            port_id: PortId(
                "transfer",
            ),
            channel_id: Some(
                ChannelId(
                    "channel-1",
                ),
            ),
            connection_id: ConnectionId(
                "connection-1",
            ),
            counterparty_port_id: PortId(
                "transfer",
            ),
            counterparty_channel_id: Some(
                ChannelId(
                    "channel-0",
                ),
            ),
        },
    ),
)

A new channel has been created on ibc-1 with identifier channel-1.

Note that the field counterparty_channel_id points to the channel on ibc-0.

Channel Open Ack

Use the chan-open-ack command to acknowledge the channel on the initial chain.

DESCRIPTION:
Relay acknowledgment of a channel attempt (ChannelOpenAck)

USAGE:
    hermes tx chan-open-ack --dst-chain <DST_CHAIN_ID> --src-chain <SRC_CHAIN_ID> --dst-connection <DST_CONNECTION_ID> --dst-port <DST_PORT_ID> --src-port <SRC_PORT_ID> --dst-channel <DST_CHANNEL_ID> --src-channel <SRC_CHANNEL_ID>

OPTIONS:
    -h, --help    Print help information

REQUIRED:
        --dst-chain <DST_CHAIN_ID>
            Identifier of the destination chain

        --dst-channel <DST_CHANNEL_ID>
            Identifier of the destination channel (required) [aliases: dst-chan]

        --dst-connection <DST_CONNECTION_ID>
            Identifier of the destination connection [aliases: dst-conn]

        --dst-port <DST_PORT_ID>
            Identifier of the destination port

        --src-chain <SRC_CHAIN_ID>
            Identifier of the source chain

        --src-channel <SRC_CHANNEL_ID>
            Identifier of the source channel (required) [aliases: src-chan]

        --src-port <SRC_PORT_ID>
            Identifier of the source port

Example

We can now acknowledge on ibc-0 that ibc-1 has accepted the opening of the channel:

hermes tx chan-open-ack --dst-chain ibc-0 --src-chain ibc-1 --dst-connection connection-0 --dst-port transfer --src-port transfer --dst-channel channel-0 --src-channel channel-1

Success: OpenAckChannel(
    OpenAck(
        Attributes {
            height: Height {
                revision: 0,
                height: 3301
            },
            port_id: PortId(
                "transfer",
            ),
            channel_id: Some(
                ChannelId(
                    "channel-0",
                ),
            ),
            connection_id: ConnectionId(
                "connection-0",
            ),
            counterparty_port_id: PortId(
                "transfer",
            ),
            counterparty_channel_id: Some(
                ChannelId(
                    "channel-1",
                ),
            ),
        },
    ),
)

Note that the field counterparty_channel_id now points to the channel on ibc-1.

Channel Open Confirm

Use the chan-open-confirm command to confirm that the channel has been acknowledged, and finish the handshake, after which the channel is open on both chains.

DESCRIPTION:
Confirm opening of a channel (ChannelOpenConfirm)

USAGE:
    hermes tx chan-open-confirm --dst-chain <DST_CHAIN_ID> --src-chain <SRC_CHAIN_ID> --dst-connection <DST_CONNECTION_ID> --dst-port <DST_PORT_ID> --src-port <SRC_PORT_ID> --dst-channel <DST_CHANNEL_ID> --src-channel <SRC_CHANNEL_ID>

OPTIONS:
    -h, --help    Print help information

REQUIRED:
        --dst-chain <DST_CHAIN_ID>
            Identifier of the destination chain

        --dst-channel <DST_CHANNEL_ID>
            Identifier of the destination channel (required) [aliases: dst-chan]

        --dst-connection <DST_CONNECTION_ID>
            Identifier of the destination connection [aliases: dst-conn]

        --dst-port <DST_PORT_ID>
            Identifier of the destination port

        --src-chain <SRC_CHAIN_ID>
            Identifier of the source chain

        --src-channel <SRC_CHANNEL_ID>
            Identifier of the source channel (required) [aliases: src-chan]

        --src-port <SRC_PORT_ID>
            Identifier of the source port

Example

Confirm on ibc-1 that ibc-0 has accepted the opening of the channel, after which the channel is open on both chains.

hermes tx chan-open-confirm --dst-chain ibc-1 --src-chain ibc-0 --dst-connection connection-1 --dst-port transfer --src-port transfer --dst-channel channel-1 --src-channel channel-0

    OpenConfirm(
        Attributes {
            height: Height {
                revision: 1,
                height: 3483
            },
            port_id: PortId(
                "transfer",
            ),
            channel_id: Some(
                ChannelId(
                    "channel-1",
                ),
            ),
            connection_id: ConnectionId(
                "connection-1",
            ),
            counterparty_port_id: PortId(
                "transfer",
            ),
            counterparty_channel_id: Some(
                ChannelId(
                    "channel-0",
                ),
            ),
        },
    ),
)

We have now successfully opened a channel over an existing connection between the two chains.

Hermes (IBC Relayer CLI) Documentation

Channel Open Handshake

Table of Contents

Channel Open Init

Channel Open Try

Channel Open Ack

Channel Open Confirm