Enabling Fragmentation on GRE Tunnels

[ Contents] [ Prev] [ Next] [ Index] [ Report an Error]

To enable fragmentation of IPv4 packets in generic routing encapsulation (GRE) tunnels, include the clear-dont-fragment-bit statement and a maximum transmission unit (MTU) setting for the tunnel as part of an existing GRE configuration at the [edit interfaces] hierarchy level:


            
               [edit interfaces]
               gr-fpc/pic/port {
               
               
                  
                     unit logical-unit-number {
                     
                     clear-dont-fragment-bit;
                     
                     ...
                     
                        
                           family inet {
                           
                           mtu 1000;
                           ...
                           }
                        
                     
                     }
                  
               
               }

This statement clears the Don’t Fragment (DF) bit in the packet header, regardless of the packet size. If the packet size exceeds the tunnel MTU value, the packet is fragmented before encapsulation. The maximum MTU size configurable on the AS or MultiServices PIC is 9192 bytes.

Fragmentation is enabled only on IPv4 packets being encapsulated in IPv4-based GRE tunnels.

Note: This configuration is supported only on GRE tunnels on AS or MultiServices interfaces. If you commit gre-fragmentation as the encapsulation type on a standard Tunnel PIC interface, the following console log message appears when the PIC comes online:


                           
                              gr-fpc/pic/port: does not support this encapsulation

[ Contents] [ Prev] [ Next] [ Index] [ Report an Error]