No relevant resource is found in the selected language.

This site uses cookies. By continuing to browse the site you are agreeing to our use of cookies. Read our privacy policy>

Reminder

To have a better experience, please upgrade your IE browser.

upgrade

MPLS network - Fragmentation issue

Publication Date:  2018-04-30 Views:  133 Downloads:  0
Issue Description
if we configure "ipv4 fragmentation enable" on S5720-32C-HI-24S-AC,what's the behavior in the below situations:
1. the IP packets exceed the MTU and DF bit is not set in the IP header.
2. the IP packets exceed the MTU and DF bit is set in the IP header.
Solution

1. if the network is just a IP network, not MPLS network:

 the IP packets exceed the MTU and DF bit is not set in the IP header. --- the packets will be fragmented and forwarded.

 the IP packets exceed the MTU and DF bit is set in the IP header. ---- the packets will be dropped.

2. if the network is MPLS network:

 the IP packets exceed the MTU and DF bit is not set in the IP header. --- for PE node,the packets will be fragmented and forwarded. for P node, the packets will be forwarded directly without fragmentation.

 the IP packets exceed the MTU and DF bit is set in the IP header. ---- for PE node, the packet will be dropped, for P node, the packets will be forwarded directly since P node don't check the MTU.


finally, the command "ipv4 fragmentation enable" just take effect for IP packets for not MPLS packets, so for P node in the MPLS network,the packets will be forwarded directly. 

END