SMB and ICMP protocols

These two protocols are more common than you think. microsoft's SMB protocol has two implementation styles: one is the TCP version on NetBIOS and the other is the direct hosting version. the NetBIOS over TCP version uses ports 137,138 and 139 for SMB communication. the direct Hosted version uses port 445.

 

In addition to these ports, both versions of SMB send an initial ICMP echo request to the target server. if the request succeeds, but the request cannot use port 137,137,139 or 445, the SMB protocol will undergo multiple retries. The result is that the SharePoint explorer view will be slow. delay is inevitable because these SMB connection ports fail, and the interaction sent to other Protocols may be successful.

For this reason, if you have blocked port 137,138,139 or port 445 on your server, you should block ICMP to Improve the Performance of Explorer view.

The usage of the SMB protocol for ICMP is recorded in the section "service overview and network port requirements for the Windows Server System" in KB article 832017.

Translated from:

Understanding and troubleshooting the SharePoint explorer View

 

KB Information link:

Service overview and network port requirements for the Windows Server System

Http://support.microsoft.com/kb/832017