On Tue, Feb 05, 2013 at 01:31:14PM +0400, Alexandre Snarskii wrote: > PHP router: > > 604050 *[LDP/9] 4d 00:37:22, metric 1 > > to AA.BBB.233.13 via ae4.9, Pop > 604050(S=0) *[LDP/9] 4d 00:37:22, metric 1 > > to AA.BBB.233.13 via ae4.9, Pop > > (BA-classification is most possibly done on ip-prec after Pop is done, > but that's the point where I'm not sure....
BA classification is done on EXP bits, if you have defined a MPLS classifier (there is a default classifier with DPCs, but non for MPCs). It's a common strategy to enforce UHP via explicit-null label signalling, in order to pass L3VPN traffic with unmodified IPP/DSCP end-to-end between CEs. The egress PE BA-classifies the L3VPN packet according to EXP/TC, and and forwards the packet to the CE with the explicit null label popped, without rewriting IPP/DSCP on egress. > Classification on EXP may be more accurate: as there are no "payload > type" field in MPLS header, this router just can't know that packet's > content is IPv4). MPCs (Trio) uses a heuristic to determine MPLS payload for load-balancing purposes. If the first payload octet is 0x04, IPv4 is assumed, for 0x06, IPv6 is assumed. Otherwise, it will be treated as ethernet frame, IIRC. Best regards, Daniel _______________________________________________ juniper-nsp mailing list juniper-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/juniper-nsp
