added op-node

Author: Bloxster

src/SUMMARY.md

@@ -40,6 +40,7 @@
     - [TxPool](advanced/txpool.md)
     - [Sentry](advanced/sentry.md)
     - [Downloader](advanced/downloader.md)
+    - [Running an Op-node](op-node.md)
     - [TLS Authentication](advanced/tls-authentication.md)
     - [Perfomance Tricks](advanced/performance.md)
 

src/op-node.md

@@ -0,0 +1,13 @@
+# Running an Op-Node Alongside Erigon
+
+To run an op-node alongside Erigon, follow these steps:
+
+1. **Start Erigon with Caplin Enabled**:
+    If Caplin is running as the consensus layer (CL), use the `--caplin.blobs-immediate-backfill` flag to ensure the last 18 days of blobs are backfilled, which is critical for proper synchronization with the op-node, assuming you start from a snapshot.
+    ```bash
+    ./build/bin/erigon --caplin.blobs-immediate-backfill
+    ```
+2. **Run the Op-Node**:
+Configure the op-node with the `--l1.trustrpc` flag to trust the Erigon RPC layer as the L1 node. This setup ensures smooth communication and synchronization.
+
+This configuration enables the op-node to function effectively with Erigon serving as both the L1 node and the CL.