MTU SIZE Issue with JUNIPER Router In MPLS

[moorthy1977]

Hi,

I have Juniper router & Next Hop router is Connetd Via Metro Ethernet switch Atrica & then It is given L2 MPLS Connectivity.Issue is when, i am not able to use more than 1472 packet size in Juniper.How to go ahead with MTU Issue.My Metro Atrica Switch is set 1500 MTU Size & I do not know about MPLS since it is through provider & Provider is saying no issue from there side.Find the Ping Respnse From Juniper.

ping do-not-fragment 172.16.8.10 size 1472

PING 172.16.8.10 (172.16.8.10): 1472 data bytes

1480 bytes from v: icmp_seq=0 ttl=251 time=7.704 ms

--- 172.16.8.10 ping statistics ---

1 packets transmitted, 1 packets received, 0% packet loss

round-trip min/avg/max/stddev = 7.329/7.719/8.125/0.325 ms

------------------------------------------------------------------------

ping do-not-fragment 172.16.8.10 size 1473

PING 172.16.8.10 (172.16.8.10): 1473 data bytes

ping: sendto: Message too long

ping: sendto: Message too long

ping: sendto: Message too long

^C

--- 172.16.8.10 ping statistics ---

3 packets transmitted, 0 packets received, 100% packet loss

Regards,

Moorthy

[AnandJalawadi]

sorry,its IP header not tcp

[Jim.Mills]

I am assuming you are pinging from the CE router? If it is connected to the PE router via standard ethernet, you need to make sure both CE and PE agree on Jumbo frame sizes, otherwise you won't be able to get the ICMP out the CE router without fragmenting.