diff --git a/swarm/CHANGELOG.md b/swarm/CHANGELOG.md
index 281f6ca3bc7..2afa04c91b7 100644
--- a/swarm/CHANGELOG.md
+++ b/swarm/CHANGELOG.md
@@ -13,9 +13,13 @@
 - Require `ProtocolsHandler::{InEvent,OutEvent,Error}` to implement `Debug` (see
   [PR 2183]).
 
-[PR 2150]: https://github.com/libp2p/rust-libp2p/pull/2150/
+- Implement `ProtocolsHandler` on `either::Either`representing either of two
+  `ProtocolsHandler` implementations (see [PR 2192]).
+
+[PR 2150]: https://github.com/libp2p/rust-libp2p/pull/2150
 [PR 2182]: https://github.com/libp2p/rust-libp2p/pull/2182
 [PR 2183]: https://github.com/libp2p/rust-libp2p/pull/2183
+[PR 2192]: https://github.com/libp2p/rust-libp2p/pull/2192
 
 # 0.30.0 [2021-07-12]
 
diff --git a/swarm/src/protocols_handler.rs b/swarm/src/protocols_handler.rs
index 911693f32af..208d3ce6e13 100644
--- a/swarm/src/protocols_handler.rs
+++ b/swarm/src/protocols_handler.rs
@@ -38,6 +38,7 @@
 //! >           the network as a whole, see the `NetworkBehaviour` trait.
 
 mod dummy;
+pub mod either;
 mod map_in;
 mod map_out;
 pub mod multi;
@@ -45,7 +46,7 @@ mod node_handler;
 mod one_shot;
 mod select;
 
-pub use crate::upgrade::{InboundUpgradeSend, OutboundUpgradeSend, UpgradeInfoSend};
+pub use crate::upgrade::{InboundUpgradeSend, OutboundUpgradeSend, SendWrapper, UpgradeInfoSend};
 
 use libp2p_core::{upgrade::UpgradeError, ConnectedPoint, Multiaddr, PeerId};
 use std::{cmp::Ordering, error, fmt, task::Context, task::Poll, time::Duration};
diff --git a/swarm/src/protocols_handler/either.rs b/swarm/src/protocols_handler/either.rs
new file mode 100644
index 00000000000..c51baadd2d7
--- /dev/null
+++ b/swarm/src/protocols_handler/either.rs
@@ -0,0 +1,305 @@
+// Copyright 2021 Protocol Labs.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the "Software"),
+// to deal in the Software without restriction, including without limitation
+// the rights to use, copy, modify, merge, publish, distribute, sublicense,
+// and/or sell copies of the Software, and to permit persons to whom the
+// Software is furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+
+use crate::protocols_handler::{
+    IntoProtocolsHandler, KeepAlive, ProtocolsHandler, ProtocolsHandlerEvent,
+    ProtocolsHandlerUpgrErr, SubstreamProtocol,
+};
+use crate::upgrade::{InboundUpgradeSend, OutboundUpgradeSend, SendWrapper};
+use either::Either;
+use libp2p_core::either::{EitherError, EitherOutput};
+use libp2p_core::upgrade::{EitherUpgrade, UpgradeError};
+use libp2p_core::{ConnectedPoint, Multiaddr, PeerId};
+use std::task::{Context, Poll};
+
+pub enum IntoEitherHandler<L, R> {
+    Left(L),
+    Right(R),
+}
+
+/// Implementation of a [`IntoProtocolsHandler`] that represents either of two [`IntoProtocolsHandler`]
+/// implementations.
+impl<L, R> IntoProtocolsHandler for IntoEitherHandler<L, R>
+where
+    L: IntoProtocolsHandler,
+    R: IntoProtocolsHandler,
+{
+    type Handler = Either<L::Handler, R::Handler>;
+
+    fn into_handler(self, p: &PeerId, c: &ConnectedPoint) -> Self::Handler {
+        match self {
+            IntoEitherHandler::Left(into_handler) => Either::Left(into_handler.into_handler(p, c)),
+            IntoEitherHandler::Right(into_handler) => {
+                Either::Right(into_handler.into_handler(p, c))
+            }
+        }
+    }
+
+    fn inbound_protocol(&self) -> <Self::Handler as ProtocolsHandler>::InboundProtocol {
+        match self {
+            IntoEitherHandler::Left(into_handler) => {
+                EitherUpgrade::A(SendWrapper(into_handler.inbound_protocol()))
+            }
+            IntoEitherHandler::Right(into_handler) => {
+                EitherUpgrade::B(SendWrapper(into_handler.inbound_protocol()))
+            }
+        }
+    }
+}
+
+/// Implementation of a [`ProtocolsHandler`] that represents either of two [`ProtocolsHandler`]
+/// implementations.
+impl<L, R> ProtocolsHandler for Either<L, R>
+where
+    L: ProtocolsHandler,
+    R: ProtocolsHandler,
+{
+    type InEvent = Either<L::InEvent, R::InEvent>;
+    type OutEvent = Either<L::OutEvent, R::OutEvent>;
+    type Error = Either<L::Error, R::Error>;
+    type InboundProtocol =
+        EitherUpgrade<SendWrapper<L::InboundProtocol>, SendWrapper<R::InboundProtocol>>;
+    type OutboundProtocol =
+        EitherUpgrade<SendWrapper<L::OutboundProtocol>, SendWrapper<R::OutboundProtocol>>;
+    type InboundOpenInfo = Either<L::InboundOpenInfo, R::InboundOpenInfo>;
+    type OutboundOpenInfo = Either<L::OutboundOpenInfo, R::OutboundOpenInfo>;
+
+    fn listen_protocol(&self) -> SubstreamProtocol<Self::InboundProtocol, Self::InboundOpenInfo> {
+        match self {
+            Either::Left(a) => a
+                .listen_protocol()
+                .map_upgrade(|u| EitherUpgrade::A(SendWrapper(u)))
+                .map_info(Either::Left),
+            Either::Right(b) => b
+                .listen_protocol()
+                .map_upgrade(|u| EitherUpgrade::B(SendWrapper(u)))
+                .map_info(Either::Right),
+        }
+    }
+
+    fn inject_fully_negotiated_outbound(
+        &mut self,
+        output: <Self::OutboundProtocol as OutboundUpgradeSend>::Output,
+        info: Self::OutboundOpenInfo,
+    ) {
+        match (self, output, info) {
+            (Either::Left(handler), EitherOutput::First(output), Either::Left(info)) => {
+                handler.inject_fully_negotiated_outbound(output, info)
+            }
+            (Either::Right(handler), EitherOutput::Second(output), Either::Right(info)) => {
+                handler.inject_fully_negotiated_outbound(output, info)
+            }
+            _ => unreachable!(),
+        }
+    }
+
+    fn inject_fully_negotiated_inbound(
+        &mut self,
+        output: <Self::InboundProtocol as InboundUpgradeSend>::Output,
+        info: Self::InboundOpenInfo,
+    ) {
+        match (self, output, info) {
+            (Either::Left(handler), EitherOutput::First(output), Either::Left(info)) => {
+                handler.inject_fully_negotiated_inbound(output, info)
+            }
+            (Either::Right(handler), EitherOutput::Second(output), Either::Right(info)) => {
+                handler.inject_fully_negotiated_inbound(output, info)
+            }
+            _ => unreachable!(),
+        }
+    }
+
+    fn inject_event(&mut self, event: Self::InEvent) {
+        match (self, event) {
+            (Either::Left(handler), Either::Left(event)) => handler.inject_event(event),
+            (Either::Right(handler), Either::Right(event)) => handler.inject_event(event),
+            _ => unreachable!(),
+        }
+    }
+
+    fn inject_address_change(&mut self, addr: &Multiaddr) {
+        match self {
+            Either::Left(handler) => handler.inject_address_change(addr),
+            Either::Right(handler) => handler.inject_address_change(addr),
+        }
+    }
+
+    fn inject_dial_upgrade_error(
+        &mut self,
+        info: Self::OutboundOpenInfo,
+        error: ProtocolsHandlerUpgrErr<<Self::OutboundProtocol as OutboundUpgradeSend>::Error>,
+    ) {
+        match error {
+            ProtocolsHandlerUpgrErr::Timer => match (self, info) {
+                (Either::Left(handler), Either::Left(info)) => {
+                    handler.inject_dial_upgrade_error(info, ProtocolsHandlerUpgrErr::Timer);
+                }
+                (Either::Right(handler), Either::Right(info)) => {
+                    handler.inject_dial_upgrade_error(info, ProtocolsHandlerUpgrErr::Timer);
+                }
+                _ => unreachable!(),
+            },
+            ProtocolsHandlerUpgrErr::Timeout => match (self, info) {
+                (Either::Left(handler), Either::Left(info)) => {
+                    handler.inject_dial_upgrade_error(info, ProtocolsHandlerUpgrErr::Timeout);
+                }
+                (Either::Right(handler), Either::Right(info)) => {
+                    handler.inject_dial_upgrade_error(info, ProtocolsHandlerUpgrErr::Timeout);
+                }
+                _ => unreachable!(),
+            },
+            ProtocolsHandlerUpgrErr::Upgrade(UpgradeError::Select(error)) => match (self, info) {
+                (Either::Left(handler), Either::Left(info)) => {
+                    handler.inject_dial_upgrade_error(
+                        info,
+                        ProtocolsHandlerUpgrErr::Upgrade(UpgradeError::Select(error)),
+                    );
+                }
+                (Either::Right(handler), Either::Right(info)) => {
+                    handler.inject_dial_upgrade_error(
+                        info,
+                        ProtocolsHandlerUpgrErr::Upgrade(UpgradeError::Select(error)),
+                    );
+                }
+                _ => unreachable!(),
+            },
+            ProtocolsHandlerUpgrErr::Upgrade(UpgradeError::Apply(EitherError::A(e))) => {
+                match (self, info) {
+                    (Either::Left(handler), Either::Left(info)) => {
+                        handler.inject_dial_upgrade_error(
+                            info,
+                            ProtocolsHandlerUpgrErr::Upgrade(UpgradeError::Apply(e)),
+                        );
+                    }
+                    _ => unreachable!(),
+                }
+            }
+            ProtocolsHandlerUpgrErr::Upgrade(UpgradeError::Apply(EitherError::B(e))) => {
+                match (self, info) {
+                    (Either::Right(handler), Either::Right(info)) => {
+                        handler.inject_dial_upgrade_error(
+                            info,
+                            ProtocolsHandlerUpgrErr::Upgrade(UpgradeError::Apply(e)),
+                        );
+                    }
+                    _ => unreachable!(),
+                }
+            }
+        }
+    }
+
+    fn inject_listen_upgrade_error(
+        &mut self,
+        info: Self::InboundOpenInfo,
+        error: ProtocolsHandlerUpgrErr<<Self::InboundProtocol as InboundUpgradeSend>::Error>,
+    ) {
+        match error {
+            ProtocolsHandlerUpgrErr::Timer => match (self, info) {
+                (Either::Left(handler), Either::Left(info)) => {
+                    handler.inject_listen_upgrade_error(info, ProtocolsHandlerUpgrErr::Timer);
+                }
+                (Either::Right(handler), Either::Right(info)) => {
+                    handler.inject_listen_upgrade_error(info, ProtocolsHandlerUpgrErr::Timer);
+                }
+                _ => unreachable!(),
+            },
+            ProtocolsHandlerUpgrErr::Timeout => match (self, info) {
+                (Either::Left(handler), Either::Left(info)) => {
+                    handler.inject_listen_upgrade_error(info, ProtocolsHandlerUpgrErr::Timeout);
+                }
+                (Either::Right(handler), Either::Right(info)) => {
+                    handler.inject_listen_upgrade_error(info, ProtocolsHandlerUpgrErr::Timeout);
+                }
+                _ => unreachable!(),
+            },
+            ProtocolsHandlerUpgrErr::Upgrade(UpgradeError::Select(error)) => match (self, info) {
+                (Either::Left(handler), Either::Left(info)) => {
+                    handler.inject_listen_upgrade_error(
+                        info,
+                        ProtocolsHandlerUpgrErr::Upgrade(UpgradeError::Select(error)),
+                    );
+                }
+                (Either::Right(handler), Either::Right(info)) => {
+                    handler.inject_listen_upgrade_error(
+                        info,
+                        ProtocolsHandlerUpgrErr::Upgrade(UpgradeError::Select(error)),
+                    );
+                }
+                _ => unreachable!(),
+            },
+            ProtocolsHandlerUpgrErr::Upgrade(UpgradeError::Apply(EitherError::A(e))) => {
+                match (self, info) {
+                    (Either::Left(handler), Either::Left(info)) => {
+                        handler.inject_listen_upgrade_error(
+                            info,
+                            ProtocolsHandlerUpgrErr::Upgrade(UpgradeError::Apply(e)),
+                        );
+                    }
+                    _ => unreachable!(),
+                }
+            }
+            ProtocolsHandlerUpgrErr::Upgrade(UpgradeError::Apply(EitherError::B(e))) => {
+                match (self, info) {
+                    (Either::Right(handler), Either::Right(info)) => {
+                        handler.inject_listen_upgrade_error(
+                            info,
+                            ProtocolsHandlerUpgrErr::Upgrade(UpgradeError::Apply(e)),
+                        );
+                    }
+                    _ => unreachable!(),
+                }
+            }
+        }
+    }
+
+    fn connection_keep_alive(&self) -> KeepAlive {
+        match self {
+            Either::Left(handler) => handler.connection_keep_alive(),
+            Either::Right(handler) => handler.connection_keep_alive(),
+        }
+    }
+
+    fn poll(
+        &mut self,
+        cx: &mut Context<'_>,
+    ) -> Poll<
+        ProtocolsHandlerEvent<
+            Self::OutboundProtocol,
+            Self::OutboundOpenInfo,
+            Self::OutEvent,
+            Self::Error,
+        >,
+    > {
+        let event = match self {
+            Either::Left(handler) => futures::ready!(handler.poll(cx))
+                .map_custom(Either::Left)
+                .map_close(Either::Left)
+                .map_protocol(|p| EitherUpgrade::A(SendWrapper(p)))
+                .map_outbound_open_info(Either::Left),
+            Either::Right(handler) => futures::ready!(handler.poll(cx))
+                .map_custom(Either::Right)
+                .map_close(Either::Right)
+                .map_protocol(|p| EitherUpgrade::B(SendWrapper(p)))
+                .map_outbound_open_info(Either::Right),
+        };
+
+        Poll::Ready(event)
+    }
+}