Re: MTU Issues

Did you raise the MTU on the other links?

On Tue, Oct 6, 2009 at 12:02 PM, mike arnold <haynessmith70_at_gmail.com>wrote:

> Hello Dear's
>
> Topology:
>
> Its a Carrier Supporting Carrier Scenario.
>
> A------DS/PE---CORE/P---ISP/PE--P---ISP/PE------B
>
> AS per above topology,am not able to transfer files with MTU frame size
> above 1492 though the MTU configured on interface is 1500.The interface on
> which customer A is connected MTU is default to 1500.The link between
> DS/PE---CR/PE is mpls enabled i have configured the MTU size to 1524 to
> carry labels of MPLS as recommended by cisco.
>
> When i do extnded ping from DS/PE above MTU size of 1492 with even DF bit
> not set am not able to ping customer end (B),
>
> AND also i tried with DF bit set am not able to recieve any notifications
> ICMP destination unreacheable messages.
>
> The file transfer from customer B with packet size above 1492 are received
> by customer A but when the connection are initiated through customer A they
> are not.
>
> Within an enterprise it works with larger MTU size when tried to ping from
> Distribution loopback to core loopback.How can i troubleshoot it is a
> problem through my end or from the ISP.
>
> The link between core and ISP is back to back VRF connected via a layer 2
> trunk.The ISP is creating a sub-interfaces on his 3800 router with
> encapsulation and vlan number.AND on Core am creating a SVI with a same
> vlan
> number and ip address within the subnet.
>
> Each customer VRF for exampl:(Customer A) is associated with SVI virtual
> interface on 6500(core)and traffic is passed to customer B.On SVI the MTU
> is
> default to 1500.
>
> BGP is routing protocol between CORE nd ISP.
>
> ON 3800 router (ISP End)
> int gig0/0
> no shut
> no ip add
>
> int gig0/0.1
> no shut
> encapsulation dot1q 50
> ip vrf forwarding XX
> ip add 10.10.10.1 255.255.255.254
>
> ON MY END (CORE)
> int gig5/1
> switchport trunk encapsulation dot1q
> switch mode trunk
>
> int vlan 50
> ip vrf forwarding customer A
> ip add 10.10.10.2 255.255.255.254.
>
> Thanks
>
>
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-- 
Bryan Bartik
CCIE #23707 (R&S), CCNP
Sr. Support Engineer - IPexpert, Inc.
URL: http://www.IPexpert.com
Blogs and organic groups at http://www.ccie.net