On 7/3/2015 1:12 AM, Saumya Dikshit (sadikshi) wrote:
> 
> 
> On 7/2/15, 11:00 PM, "Joe Touch" <[email protected]> wrote:
> 
>>
>>
>> On 7/1/2015 8:45 PM, Saumya Dikshit (sadikshi) wrote:
>>> <Saumya> The encapsulation and reassembly mention in 3.1.1 is with
>>> respect
>>> to the outer header encapsulation  (for Vxlan tunnel encap).
>>> Frag/reassembly in underlay is performed in context of outer encap which
>>> is L3 based. That¹s one of the reason Vxlan scores over other
>>> L2-tunneling
>>> schema.
>>
>> That's good, but then the PTB needs to be interpreted correctly.
>>
>> PTB is TB. It isn't "packet larger than I'd like, but I can deal with
>> it". There is no such signal for the latter.
> 
> Sure, That¹s what is being conveyed here; for underlay indeed its a PTB
> (without frag). 

That's not what PTB means. It doesn't mean "I can't get there optimally"
- it means "I can't get there at all".

When an ingress sends PTB rather than doing frag and reassembly, it
makes the network more fragile. If the PTB indicates a transit payload
smaller than the required smallest size, then the link is effectively no
longer supporting that protocol (e.g., 1280 for IPv6).

> I believe that it will serve good, if this TB which is
> generated by any node in the path (overlay or underlay), is not
> black-holed.=

It is only helping relieve a problem you're creating by forcing the
ingress to be more limited. Yes, it helps fix a problem you create, but
that's not a good thing. Stop creating the problem.

Joe

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