Hi! Old topic:
http://puck.nether.net/pipermail/juniper-nsp/2007-June/008349.html On Tue, Dec 2, 2008 at 6:05 PM, Andreas Friedrich <[EMAIL PROTECTED]> wrote: > That sounds as we have interpreted it. But it does not seam to work for us. > We have following setup > CPE - PE (E-Series) - P (Cisco CRS-1) > We send from the CPE ipv4 ping with 1500 byte DF set > We get at the PE 2 labels on top. Only difference for E-Series is 18 bytes > for Ethernet. > PE int to P config: > mtu 1534 > ip mtu 1500 > > Calculation: 1534 - Ethernet header 18 byte - 4 byte .1q - 12 byte labels = > 1500 > > We use only 2 labels. > > If we configure mtu 1542 it works. If I calculate back I get > > 1500 IP packet > 4 .1q > 8 2 MPLS labels > 18 Ethernet > ------ > 1530 byte used > > So I need to configure 12 byte more. And that sounds for the 12 byte (3 > labels). > > What do you think? > > Thanks, > Andreas > > > Am 02.12.2008 um 20:47 schrieb Cyn D.: > > Juniper default physical layer MTU 1514, family inet (IP) MTU 1500, family >> MPLS 1488 (=1514-14-3X4) counted most tags possible (3). >> >> To pass big IP packet (1460+20+20), make MPLS MTU 1500, therefore >> interface physical MTU is set to 1500+3x4+14=1526. this also makes family >> inet mtu=1526-14=1512. >> >> >> >> C. >> >> ----- Original Message ----- From: "Andreas Friedrich" <[EMAIL PROTECTED] >> > >> To: "Phil Bedard" <[EMAIL PROTECTED]> >> Cc: <juniper-nsp@puck.nether.net> >> Sent: Tuesday, December 02, 2008 2:04 PM >> Subject: Re: [j-nsp] juniper mpls mtu >> >> >> >> One more question regarding this MPLS MTU. >> Are the 12 byte (3 labels) reserved by Juniper for there purpose and I >> have to calculate my labels additional? So is MPLS MTU than 1512 if I >> want to use also 3 labels? >> >> Thanks, >> Andreas >> >> Am 04.06.2008 um 01:54 schrieb Phil Bedard: >> >> I think with most of the forwarding engines, the maximum number of >>> labels that can be pushed at one time is 3, hence the 12 bytes. >>> >>> Phil >>> >>> On Jun 3, 2008, at 9:15 AM, cp wrote: >>> >>> I hoping someone can provide insight into why by default juniper >>>> calculates mpls mtu at 12 bytes less than the ip mtu? I've been >>>> testing >>>> using l3vpn and it seems that mpls mtu pads 8 bytes to its mpls mtu >>>> reducing the ip mtu the inside packet by 8 bytes. Quick example. So if >>>> mpls mtu is 1508 the ip mtu of the packet inside is 1500. That means >>>> the >>>> ip mtu of the mpls interface is 1520. The only reason I can see >>>> additional bytes needed on top of the l3vpn two is for fast reroute >>>> bypass. I assume it's for the safety factor although I am probably >>>> missing something. Any information is appreciated. >>>> >>>> >>>> >>>> -Chip >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> _______________________________________________ >>>> juniper-nsp mailing list juniper-nsp@puck.nether.net >>>> https://puck.nether.net/mailman/listinfo/juniper-nsp >>>> >>> >>> _______________________________________________ >>> juniper-nsp mailing list juniper-nsp@puck.nether.net >>> https://puck.nether.net/mailman/listinfo/juniper-nsp >>> >> >> Andreas Friedrich >> Network Engineer >> >> COLT Telecom GmbH >> Herriotstr. 4 >> 60528 Frankfurt >> >> >> Tel: + 49 (0)69 56606 6005 Internal: 8 491 6005 >> Fax: + 49 (0)69 56606 6350 >> Email: [EMAIL PROTECTED] >> >> >> >> www.colt.net >> >> >> >> >> >> Data | Voice | Managed Services >> >> Schütze Deine Umwelt | Erst denken, dann drucken >> >> ***************************************** >> COLT Telecom GmbH, Herriotstraße 4, 60528 Frankfurt/Main, Deutschland >> • Tel +49 (0)69 56606 0 • Fax +49 (0)69 56606 2222 • >> >> Geschäftsführer: Albertus Marinus Oosterom (Vors.), Rita Thies • >> Amtsgericht Frankfurt/Main HRB 46123 • USt.-IdNr. DE 197 498 400 >> >> >> _______________________________________________ >> juniper-nsp mailing list juniper-nsp@puck.nether.net >> https://puck.nether.net/mailman/listinfo/juniper-nsp >> > > Andreas Friedrich > Network Engineer > > COLT Telecom GmbH > Herriotstr. 4 > 60528 Frankfurt > > > Tel: + 49 (0)69 56606 6005 Internal: 8 491 6005 > Fax: + 49 (0)69 56606 6350 > Email: [EMAIL PROTECTED] > > > > www.colt.net > > > > > > Data | Voice | Managed Services > > Schütze Deine Umwelt | Erst denken, dann drucken > > ***************************************** > COLT Telecom GmbH, Herriotstraße 4, 60528 Frankfurt/Main, Deutschland • Tel > +49 (0)69 56606 0 • Fax +49 (0)69 56606 2222 • > > Geschäftsführer: Albertus Marinus Oosterom (Vors.), Rita Thies • > Amtsgericht Frankfurt/Main HRB 46123 • USt.-IdNr. DE 197 498 400 > > > _______________________________________________ > juniper-nsp mailing list juniper-nsp@puck.nether.net > https://puck.nether.net/mailman/listinfo/juniper-nsp > -- __________________________________________ Vai Encarar? http://www.vaiencarar.com.br _______________________________________________ juniper-nsp mailing list juniper-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/juniper-nsp