I missed the details. Not clear if using vlan tagging for example. Here is a stab.
IIRC, for l2vpn you have: 1. 4 bytes control word (can be disabled, on by default) 2. 12 bytes SA/DA MAC 3. 2 bytes type code/length Subtracting the 16 above from 1528 leaves 1512. IIRC, family mpls subtracts 12 bytes from the device mtu by default to accommodate a 3 level label stack, which would then yield a payload length of 1500. Either that or perhaps vlan tagging also in effect. HTHs Regards -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Eric Van Tol Sent: Wednesday, September 29, 2010 11:57 AM To: juniper-nsp Subject: Re: [j-nsp] L2VPN MTU Issue > -----Original Message----- > From: Dermot Williams [mailto:[email protected]] > Sent: Wednesday, September 29, 2010 10:43 AM > To: Eric Van Tol; juniper-nsp > Subject: RE: [j-nsp] L2VPN MTU Issue > > Hi Eric, > > Unless it's sensitive, would you mind sharing how you arrived at that > number please? > > Thanks, > > Dermot Well, primary credit goes to JTAC, but doing some packet captures, I found that the packets entering the customer interface were not leaving the router. JTAC suggested 1520, but that only allowed 1498-bytes through. I bumped it up to 1524, which still did not work, so then I bumped it up to 1528. I am still not too keen on the math, but JTAC hasn't broken it down for me yet. If anyone out there knows, please point me to a reference. I googled like mad yesterday, but either overlooked the obvious, or wasn't searching for the right info. -evt _______________________________________________ juniper-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/juniper-nsp _______________________________________________ juniper-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/juniper-nsp
