hello
just for reference i'm asking MT support to answer me about this things:
in RB winbox interface:
L2MTU is full L2 ethernet frame with data accepted from upper layers ? It is unchangeable option in interface menu. Is it active by default and is accepting this maximum frames on interface?
MTU is maximum packet size accepted from upper layers to be inserted in L2 Ethernet frame ? by default it's 1500 everywhere. MPLS/VPLS is not included in this option but in L2MTU size, is it?
BT packet size - is it generating full frame L2 frame (ip data)+(ethernet frame) or it is only L3 ip packet ?
how can you describe me next thing:
(493ah) <-> (450g) <-> (3550) <-> (450g) <-> (493ah)
I ran BT from 493ah to other one on other side (both connected with eth1, which has max 1526 L2MTU).
1. changed MTU to 1524 on those 493ah's eth1 interfaces, for traffic not to be fragmented.
2. ran UDP BT from 493ah to other one, with 1524 packet size. but didn't changed anything on 450Gs
Result: no fragmentation occured on 450gs. max L2mtu is 1524 on them. MTU remained 1500.
So how 450g transported this frames which have size 1524 and is maximum L2MTU for 450g ? where ethernet header is placed ? after 1524 ? I dont think so. So, from this example i can say that BT generates packets with already included standard ethernet header ?
3. finally when i rised MTU on 493ahs up to 1526. and ran test with packet size of 1526.......nothing worked ....450g didn't receive traffic...because it's L2mtu max can receive 1524.......again how did 493 transported packet with size of 1526 when it's L2MTU is max of 1526..so out of here i can say that BT generates full L2 data frames with included standard ethernet headers...am i right ?
sorry for such annoying request. but it's very important ...
BTW: change list of max L2MTUs for RBs on wiki page................. 450G doesn't has 1526 on eth1 !!!!!!!!!! all interfaces have max l2mtu of 1524 !!!!!!!!!!!!! this thing very upsets !!!!!!! why 450g shouldn't have at least one interface with 1526.....
other thing which upsets and frustrates me too much is that Mikrotik can't deal with MPLS+VPLS without fragmentation ((((