udp fragmentation

[Hugo Koji Kobayashi]

On Thu, Jun 28, 2007 at 09:34:18PM +0200, Max Laier wrote:
> On Thursday 28 June 2007, Hugo Koji Kobayashi wrote:
> > On Thu, Jun 28, 2007 at 07:19:25PM +0200, Max Laier wrote:
> >   dig @a.ns.se se dnskey +dnssec +bufsize=4500
> >
> > This query is supposed to receive a DNS answer of more than 4KB.
> 
> See the attached script I did just now.
> 
> The only thing common about your setup seems to be the bge(4) NIC.  Can 
> you try disabling hardware checksumming (ifconfig -txcsum -rxcsum)?  My 
> test is over a hardware checksumming fxp(4) card, though.

It worked when disabling hardware checksumming:

fbsd7# ifconfig bge0
bge0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
        options=9b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM>
        ether 00:12:3f:15:36:7d
        inet 200.160.3.113 netmask 0xffffffc0 broadcast 200.160.3.127
        media: Ethernet autoselect (1000baseTX <full-duplex>)
        status: active

fbsd7# dig @a.ns.se se dnskey +dnssec +bufsize=4500

; <<>> DiG 9.4.1 <<>> @a.ns.se se dnskey +dnssec +bufsize=4500
; (2 servers found)
;; global options:  printcmd
;; connection timed out; no servers could be reached


fbsd7# ifconfig bge0 -txcsum
fbsd7# ifconfig bge0 
bge0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
        options=98<VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM>
        ether 00:12:3f:15:36:7d
        inet 200.160.3.113 netmask 0xffffffc0 broadcast 200.160.3.127
        media: Ethernet autoselect (1000baseTX <full-duplex>)
        status: active

fbsd7# dig @a.ns.se se dnskey +dnssec +bufsize=4500 | tail -5
;; Query time: 243 msec
;; SERVER: 192.36.144.107#53(192.36.144.107)
;; WHEN: Thu Jun 28 16:46:49 2007
;; MSG SIZE  rcvd: 4088