On Fri, Nov 4, 2016 at 6:30 PM, Nathan Anderson <[email protected]> wrote:
> I'd still love to know how you end up making out on this. Please keep us > updated. > > > After several extensive sessions wrangling MTUs, and a good deal of help from Nick, I have gotten at least halfway to the bottom of my initial issues. 0.) It is possible to have multiple HSS records for the same IMSI, but not advised. ;] 1.) Disregard the EPC VLAN MTUs. Weird, I know. 2.) Configure all router bearer interfaces, vlans, switch ports, &c per numbers passed around previously on the list. In my case, I wished to provide a L2 MTU of 1500, so something in the ~1570 range would be expected. For testing, I ran all the way up to 1900, which may (or may not!) be the maximum bearer packet size 3.) It is pointless to try to troubleshoot MTU to/from the EPC bearer network itself, as outbound packet size (for ICMP) *is* dictated by the underlying VLAN MTU (1496-28=1468) as Nathan showed previously. 4.) The bearer network is capable of passing larger packets than 1500 (and must!) without fragmentation, and *will not fragment*, even if we knew what the router interfaces MTUs ought to be 5.) At release 729, I am unable to use (on a 7000) a WAN MTU larger than 1556 with a resulting L2 tunnel MTU of 1500. However, at least I have a working 1500! (Maybe.) Nick was unable to replicate this; on R729 he can pass (I am guessing) somewhere between 1524 and 1544. (1600-76 or 56) The reason I am not yet to the bottom of the rabbit hole… is that the tunnel still appears a bit odd. I'm testing Mikrotik CCR to Mikrotik RB2011, running 6.37.1 and 6.36.3. Also tested directly between two CCR1009s running the same revision, 6.37.1 If I set MRRU=1500, I get MTU of 1496 (auto, both clients) and MRU of 1500. Max packet size 1496. Whatever I set MRRU to, I get 4 bytes fewer. Perhaps this is normal. If I *don't* set MRRU, I get NOTHING, regardless of whether I set MTU/MRU. For instance, if I leave MTU/MRU blank, I get a server-side of 1480/1492, and client-side of 1480/1480. Weird. [This is with local router interfaces at 1500, so 1492 would imply an MTU of 1512?) And with 1480/1480, I get zero packets of any size (after the initial tunnel-up) Rx on the client side. If I set the MTU/MRU to something sane, like 1460, I get the same behavior — zero packets Rx! So something about MRRU (multilink) makes it work, but it doesn't explain how it's failing in the absence of MRRU. To clients without MRRU, no packets Rx. Tx direction works fine up to the expected/allowed MTU. -- 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
_______________________________________________ Telrad mailing list [email protected] http://lists.wispa.org/mailman/listinfo/telrad
