diff --git a/ethcore/light/src/net/context.rs b/ethcore/light/src/net/context.rs
index 332d497a1..80a829962 100644
--- a/ethcore/light/src/net/context.rs
+++ b/ethcore/light/src/net/context.rs
@@ -50,13 +50,13 @@ pub trait IoContext {
 impl<'a> IoContext for NetworkContext<'a> {
 	fn send(&self, peer: PeerId, packet_id: u8, packet_body: Vec<u8>) {
 		if let Err(e) = self.send(peer, packet_id, packet_body) {
-			debug!(target: "les", "Error sending packet to peer {}: {}", peer, e);
+			debug!(target: "pip", "Error sending packet to peer {}: {}", peer, e);
 		}
 	}
 
 	fn respond(&self, packet_id: u8, packet_body: Vec<u8>) {
 		if let Err(e) = self.respond(packet_id, packet_body) {
-			debug!(target: "les", "Error responding to peer message: {}", e);
+			debug!(target: "pip", "Error responding to peer message: {}", e);
 		}
 	}
 
diff --git a/ethcore/light/src/net/error.rs b/ethcore/light/src/net/error.rs
index dda78e0b6..1c0374c7e 100644
--- a/ethcore/light/src/net/error.rs
+++ b/ethcore/light/src/net/error.rs
@@ -56,6 +56,8 @@ pub enum Error {
 	UnknownPeer,
 	/// Unsolicited response.
 	UnsolicitedResponse,
+	/// Bad back-reference in request.
+	BadBackReference,
 	/// Not a server.
 	NotServer,
 	/// Unsupported protocol version.
@@ -78,6 +80,7 @@ impl Error {
 			Error::WrongNetwork => Punishment::Disable,
 			Error::UnknownPeer => Punishment::Disconnect,
 			Error::UnsolicitedResponse => Punishment::Disable,
+			Error::BadBackReference => Punishment::Disable,
 			Error::NotServer => Punishment::Disable,
 			Error::UnsupportedProtocolVersion(_) => Punishment::Disable,
 			Error::BadProtocolVersion => Punishment::Disable,
@@ -109,6 +112,7 @@ impl fmt::Display for Error {
 			Error::WrongNetwork => write!(f, "Wrong network"),
 			Error::UnknownPeer => write!(f, "Unknown peer"),
 			Error::UnsolicitedResponse => write!(f, "Peer provided unsolicited data"),
+			Error::BadBackReference => write!(f, "Bad back-reference in request."),
 			Error::NotServer => write!(f, "Peer not a server."),
 			Error::UnsupportedProtocolVersion(pv) => write!(f, "Unsupported protocol version: {}", pv),
 			Error::BadProtocolVersion => write!(f, "Bad protocol version in handshake"),
diff --git a/ethcore/light/src/net/mod.rs b/ethcore/light/src/net/mod.rs
index 1b2433fbe..8363fcfe7 100644
--- a/ethcore/light/src/net/mod.rs
+++ b/ethcore/light/src/net/mod.rs
@@ -642,13 +642,13 @@ impl LightProtocol {
 		Ok(())
 	}
 
+	// Receive requests from a peer.
 	fn request(&self, peer: &PeerId, io: &IoContext, raw: UntrustedRlp) -> Result<(), Error> {
 		// the maximum amount of requests we'll fill in a single packet.
-		const MAX_REQUESTS: usize = 512;
-		// the maximum amount of gas we'll prove execution of in a single packet.
-		const MAX_GAS: usize = 50_000_000;
+		const MAX_REQUESTS: usize = 256;
 
 		use ::request_builder::RequestBuilder;
+		use ::request::CompleteRequest;
 
 		let peers = self.peers.read();
 		let peer = match peers.get(peer) {
@@ -661,8 +661,37 @@ impl LightProtocol {
 		let mut peer = peer.lock();
 
 		let req_id: u64 = raw.val_at(0)?;
+		let mut cumulative_cost = U256::from(0);
+		let cur_buffer = peer.local_credits.current();
 
-		unimplemented!()
+		let mut request_builder = RequestBuilder::default();
+
+		// deserialize requests, check costs and back-references.
+		for request_rlp in raw.at(1)?.iter().take(MAX_REQUESTS) {
+			let request: Request = request_rlp.as_val()?;
+			cumulative_cost = cumulative_cost + self.flow_params.compute_cost(&request);
+			if cumulative_cost > cur_buffer { return Err(Error::NoCredits) }
+			request_builder.push(request).map_err(|_| Error::BadBackReference)?;
+		}
+
+		let requests = request_builder.build();
+
+		// respond to all requests until one fails.
+		let responses = requests.respond_to_all(|complete_req| {
+			match complete_req {
+				CompleteRequest::Headers(req) => self.provider.block_headers(req).map(Response::Headers),
+				CompleteRequest::HeaderProof(req) => self.provider.header_proof(req).map(Response::HeaderProof),
+				CompleteRequest::Body(req) => self.provider.block_body(req).map(Response::Body),
+				CompleteRequest::Receipts(req) => self.provider.block_receipts(req).map(Response::Receipts),
+				CompleteRequest::Account(req) => self.provider.account_proof(req).map(Response::Account),
+				CompleteRequest::Storage(req) => self.provider.storage_proof(req).map(Response::Storage),
+				CompleteRequest::Code(req) => self.provider.contract_code(req).map(Response::Code),
+				CompleteRequest::Execution(req) => self.provider.transaction_proof(req).map(Response::Execution),
+			}
+		});
+
+		io.respond(packet::RESPONSE, ::rlp::encode(&responses).to_vec());
+		Ok(())
 	}
 
 	fn response(&self, peer: &PeerId, io: &IoContext, raw: UntrustedRlp) -> Result<(), Error> {