On Tue, Nov 8, 2016 at 2:43 AM, Adam Moffett <[email protected]> wrote:
> Is this to say that fragmentation is simply not supported on the bearer > network? Are packets larger than the MTU simply dropped? > The PDN network, interestingly, supports large packets *even when they are being fragmented on the LTE side*; the bearer network, not so much. Try, say, pinging the WAN IP of a UE with a larger payload than its WAN MTU. Even with DNF set, you should get a response. And because we have no interface for adjusting MTUs on ENBs or EPCs, this is as much a process of trial and error as anything else — in fact I could not find any documentation of what the bearer MTUs actually are, and am simply setting my router interfaces to 1900, as that is the largest ICMP the ENB will return. We can see from the EPC behavior that ICMP is useless for determining MTU. Since the bearer network is not designed to handle fragmentation, setting bearer interfaces to at least allow the packet sizes we need appears to work. I could have been a little clearer in my previous explanation (hey, it was a long week). The bearer network will not fragment *bearer packets*. The bearer network will fragment *L3 PDN packets*. The bearer network does not appear to fragment L2 tunnel contents. -- Jeremy Austin (907) 895-2311 (907) 803-5422 [email protected] Heritage NetWorks Whitestone Power & Communications Vertical Broadband, LLC Schedule a meeting: http://doodle.com/jermudgeon
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