Differences

This shows you the differences between two versions of the page.

--- hardware:erspan [2018/05/01 21:37] – [Configuring] veera
+++ hardware:erspan [2018/05/01 21:38] (current) – [On MTU and packet sizes] veera
@@ Line 55: / Line 55: @@
-<note important>Note about MTU for ERSPAN </note>
+<note important>Make sure you increase the MTU of the ERSPAN session and the IP path to accommodate the extra 42 bytes of tunnel header </note>
-  - **mtu 1900**  -- ERSPAN adds about 48 bytes of extra header bytes by way of Ethernet/IP/GRE header. The default ERSPAN MTU is 1500 bytes, so when you mirror full length packets they can be truncated. Make sure you increase the MTU of the ERSPAN to 1700 or 1900 or even the maximum size of 9000 bytes.
+  - **mtu 1900**  -- ERSPAN adds about 42 bytes of extra header bytes by way of Ethernet/IP/GRE header. The default ERSPAN MTU is 1500 bytes, so when you mirror full length packets they can be truncated. Make sure you increase the MTU of the ERSPAN to 1700 or 1900 or even the maximum size of 9000 bytes.
   - You also need to set the MTU on any bridges you create on the VM infrastructure.
   - If you dont set the MTU to a higher numbers, then packets will be truncated as per the ERSPAN documentation. Some implementations may fragment the IP packets, which will they place a load on the NSM tool to reassemble the packets.