Anchor peer vs CORE_PEER_GOSSIP_EXTERNALENDPOINT? - hyperledger-fabric

Question

Why should one use Anchor peers when the cross org communication can be acheived by setting CORE_PEER_GOSSIP_EXTERNALENDPOINT in every peer?
Can anyone explain the correct way one should be used?

Answer 1

Let me clearly explains you
In the hyperledger fabric there are total Three Types of peers
Endorsing Peers
Committing Peers
Orderer Peer (Orderer is also a
Peer)
Something Hidden is:
Anchor Peers
Leader Peers
Anchor Peers are for cross-organization peer-to-peer communication, to setup Anchor Peers you need to setup Anchor Peers and use ENV
Step-By-Step
- &org1
Name: org1
ID: org1MSP
MSPDir: ./data/orgs/org1/msp
AnchorPeers:
- Host: org1-peer
- Port: 7051
# generate anchor peer transaction
configtxgen -profile OrgsChannel -outputAnchorPeersUpdate ./crypto-config/org1Anchors.tx -channelID publicchannel -asOrg org1
if [ "$?" -ne 0 ]; then
echo "Failed to generate anchor peer update for maersksea..."
exit 1org1 fi
Now you need to send a transaction inorder to setup Anchor Peers
Check this >> https://hyperledger-fabric.readthedocs.io/en/release-1.1/commands/peerchannel.html#peer-channel-update
If you want to make other peers in your organization known to other organizations, you need to set the
CORE_PEER_GOSSIP_EXTERNALENDPOINT
What They Do:
High-level, peer-to-peer communication happens through gossip protocol and Anchor Peers are the key to gossip communication.
Make sure peers in different organizations know about each other through gossip protocol.
One Can use Private Data Concept using Anchor Peers because gossip distributes the private data peer-to-peer across authorized organizations, it is required to set up anchor peers on the channel
Read below mentioned docs
- https://hyperledger-fabric.readthedocs.io/en/release-1.4/private-data/private-data.html
- https://hyperledger-fabric.readthedocs.io/en/release-1.4/glossary.html
LeaderPeers are the main entry point for orderer to ship blocks to peers
One can set up leader Peers or Peers can elect one by its own
Two Types
Static leader election
Dynamic leader election
Static leader election
Static leader election allows you to manually define one or more peers within an organization as leader peers. Please note, however, that having too many peers connect to the ordering service may result in inefficient use of bandwidth.
export CORE_PEER_GOSSIP_USELEADERELECTION=false
export CORE_PEER_GOSSIP_ORGLEADER=true
Dynamic leader election
Dynamic leader election enables organization peers to elect one peer which will connect to the ordering service and pull out new blocks. This leader is elected for an organization’s peers independently.
export CORE_PEER_GOSSIP_USELEADERELECTION=true
export CORE_PEER_GOSSIP_ORGLEADER=false

Answer 2

Suppose there are 2 orgs in the network A and B. Each org has 2 peers.
ORGA-peer1.orgA, peer2.orgA
ORGB-peer1.orgB, peer2.orgB
Lets say peer1 is anchor peer in both the orgs.
When org A anchor peer(peer1.orgA) communicates with orgB anchor peer(peer1.orgB), then org A anchor peer will tell the org B anchor peer about the CORE_PEER_GOSSIP_EXTERNALENDPOINT of other non anchor peer (peer2.orgA) and vice-versa.
So anchor peer shares the gossip endpoint of non anchor peers. So all the peers in the network know about all the other peers through anchor peers. And then peers can use the CORE_PEER_GOSSIP_EXTERNALENDPOINT of another peer to communicate with that peer.