mpls auto-template mtu 17916??

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Aug 12th, 2010
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Hi There,

Anyone know where the mtu 17916 comes from when setting up an mpls auto-tunnel template?

Im running mpls auto-tunnels and when i setup the auto-template, it seems to give me a default mpls mtu of 17916.  Any idea where this mtu value comes from? is it a cisco default?  This only popped in after the ios upgrade to 12.2(33)SRE1 on a 7609S router.


interface Auto-Template1
ip unnumbered Loopback0
mpls ip
mpls label protocol ldp
mpls mtu 17916
tunnel mode mpls traffic-eng
tunnel destination access-list 1
tunnel mpls traffic-eng autoroute announce
tunnel mpls traffic-eng path-option 1 dynamic
tunnel mpls traffic-eng fast-reroute

Is this the default behaviour? should i be reducing this? seems a tag high.

Best Regards,


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Chetan Kumar Ress Fri, 08/13/2010 - 12:41
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For MTU 17916 there is not document , As per my you should take it as default behaviour or if you are facing any issue the you can configure statically.

With tunnel interface some time it take default MTU 17916.


Chetan Kumar


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