Date: Wed, 20 Feb 2002 10:40:02 -0800 (PST) From: "."@babolo.ru To: freebsd-bugs@FreeBSD.org Subject: Re: kern/35136: VLAN & bridging & MTU Message-ID: <200202201840.g1KIe2t17630@freefall.freebsd.org>
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The following reply was made to PR kern/35136; it has been noted by GNATS. From: "."@babolo.ru To: algr@rocc.ru (Alexander Grebennikov) Cc: freebsd-gnats-submit@FreeBSD.ORG Subject: Re: kern/35136: VLAN & bridging & MTU Date: Wed, 20 Feb 2002 21:44:53 +0300 (MSK) Alexander Grebennikov writes: > > >Number: 35136 > >Category: kern > >Synopsis: VLAN & bridging & MTU > >Confidential: no > >Severity: serious > >Priority: medium > >Responsible: freebsd-bugs > >State: open > >Quarter: > >Keywords: > >Date-Required: > >Class: sw-bug > >Submitter-Id: current-users > >Arrival-Date: Wed Feb 20 00:20:01 PST 2002 > >Closed-Date: > >Last-Modified: > >Originator: Alexander Grebennikov > >Release: tried many up to 4.4-RELEASE > >Organization: > RCC > >Environment: > FreeBSD x2.rocc.ru 4.4-RELEASE FreeBSD 4.4-RELEASE #0: Thu Dec 20 11:11:47 MSK 2001 > > >Description: > I'm trying to bridge traffic between 2 VLANs using FreeBSD in BRIDGE mode. > Channel between 2 VLANS going through G.703. > There are 2 G.703<-->Ethernet converters at both sides. > Converters are modems. These modems cannot pass VLAN packets because VLAN packets are 4 bytes large then usual. > What i did: setting up 1-st interface on FreeBSD with MTU=1500 , second interface ( to converter) with MTU=1400. Started BRIDGE mode. > Packets not fragmented passing FreeBSD. :( > And still getting out to converter with MTU=1500 via ethernet interface with MTU=1400 !! I think it's a bug ?? > > >How-To-Repeat: > Need 3 computers: > 2 of them - usual PCs with 1 Ethernet card each. > 3-rd = FreeBSD in Bridge mode with 2 ethernet cards. 1 card must be setted MTU=1500. Second card - MTU=1400 > E.g. > PC1 <--(MTU_1500)-->FreeBSD_BRIDGE<--(MTU_1400)--> PC2 > Ping PC2 from PC1 with packet size=4000 byes (for example) > Start to sniff packets from PC1 on PC2. They should have maximum size=1400 bytes ! But they will have size =1500 ! That is bug. As far as I remember ;-0 level 3 only can fragment packets. So use routing, not bridging (level 2) to fragment packets -- @BABOLO http://links.ru/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-bugs" in the body of the message
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