Date: Wed, 26 Feb 2014 20:01:14 GMT From: Robert Blayzor <rblayzor@inoc.net> To: freebsd-gnats-submit@FreeBSD.org Subject: misc/187094: FreeBSD DHCP ignores dhcp option interface-mtu Message-ID: <201402262001.s1QK1E8L040866@cgiserv.freebsd.org> Resent-Message-ID: <201402262010.s1QKA0xO068990@freefall.freebsd.org>
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>Number: 187094 >Category: misc >Synopsis: FreeBSD DHCP ignores dhcp option interface-mtu >Confidential: no >Severity: non-critical >Priority: low >Responsible: freebsd-bugs >State: open >Quarter: >Keywords: >Date-Required: >Class: sw-bug >Submitter-Id: current-users >Arrival-Date: Wed Feb 26 20:10:00 UTC 2014 >Closed-Date: >Last-Modified: >Originator: Robert Blayzor >Release: 10.0 >Organization: INOC, LLC >Environment: FreeBSD rootbsd.ops.inoc.net 10.0-RELEASE FreeBSD 10.0-RELEASE #0 r261846: Tue Feb 25 13:50:12 UTC 2014 root@rootbsd.ops.inoc.net:/usr/obj/.amd_mnt/juno/pub/FreeBSD/10.0-RELEASE/sys/ESXBSD amd64 >Description: Upon PXE booting FreeBSD kernel trying to set a higher MTU via DHCP. Using "option interface-mtu ...." in ISC-DHCP, MTU never properly gets set to anything higher than 1500. Attempting to change the MTU in rc startup scripts only appears to cosmetically change.. dev@rns0 [~] cat /etc/rc.conf | grep vmx ifconfig_vmx0="mtu 9000" dev@rns0 [~] ifconfig vmx0 vmx0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 9000 options=60039b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM,TSO4,TSO6,RXCSUM_IPV6,TXCSUM_IPV6> ether 00:50:56:a7:03:22 inet6 fe80::250:56ff:fea7:322%vmx0 prefixlen 64 scopeid 0x1 inet 10.0.0.20 netmask 0xffff0000 broadcast 10.0.255.255 nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL> media: Ethernet autoselect status: active dev@rns0 [~] sudo ping -D -c 1 -s 1600 10.0.0.200 PING 10.0.0.200 (10.0.0.200): 1600 data bytes ping: sendto: Message too long dev@rns0 [~] sudo ping -D -c 1 -s 1472 10.0.0.200 PING 10.0.0.200 (10.0.0.200): 1472 data bytes 1480 bytes from 10.0.0.200: icmp_seq=0 ttl=64 time=0.064 ms --- 10.0.0.200 ping statistics --- 1 packets transmitted, 1 packets received, 0.0% packet loss >How-To-Repeat: Using dhclient or PXE boot configure DHCP server to use MTU > 1500. ie: option interface-mtu 9000; System boots and gets IP address properly but MTU cannot be set. >Fix: None. Attempting to set MTU via rc.conf startup does not work. >Release-Note: >Audit-Trail: >Unformatted:
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