Bug #6868
closedInterface MTU Setting not applied to all IPv6 routes
100%
Description
Running 2.3.2_1 using an HE/64 tunnel. Adjusting MTU to troubleshoot possible PMTUD problem. Found that setting for MTU in Interfaces / OPT1 only changes MTU for default route, but not for other gif0 routes. MTU of 1280 is applied to other routes.
default 2001:abc:c:1111::1 (MTU changed by OPT1 setting)
2001:abc:c:111::1 link#7 (MTU not changed)
fe80::%gif0/64 link#7 (MTU not changed)
ff01::%gif0/32 2001:abc:c:1111::2 (MTU not changed)
ff01::%gif0/32 2001:abc:c:1111::2 (MTU not changed)
Used command prompt route -6 change <route> -mtu 1480 to change MTU. After disabling OPT1 and enabling OPT1, MTU reset back to 1280.
Updated by Jim Thompson almost 8 years ago
- Assignee set to Jim Pingle
assigned to Pingle for analysis.
Updated by Jim Pingle almost 8 years ago
- Subject changed from MTU Setting in for OPT1 Interface not applied to all gif0 routes to Interface MTU Setting not applied to all IPv6 routes
- Category set to Interfaces
- Status changed from New to Confirmed
- Assignee deleted (
Jim Pingle) - Target version set to 2.4.0
- Affected Version set to All
I can reproduce the behavior on 2.3.x. If I adjust the MTU of an assigned interface, only the default and/or link route for IPv6 on the interface has its MTU adjusted, not others.
If I attempt the same thing on an IPv4 interface, the MTU for all routes is adjusted.
This does not appear to be specific to GIF, but to IPv6 in general. If I change the MTU on LAN, for example, the link route MTUs lower but none of the link-local routes do:
: netstat -rWn | grep vmx1 10.163.0.0/24 link#2 U 0 1350 vmx1 2001:470:xxxx:xxxx::/64 link#2 U 0 1350 vmx1 fe80::%vmx1/64 link#2 U 0 1500 vmx1 fe80::20c:29ff:xxxx:42f6%vmx1 link#2 UHS 0 16384 lo0 ff01::%vmx1/32 fe80::20c:29ff:xxxx:42f6%vmx1 U 0 1500 vmx1 ff02::%vmx1/32 fe80::20c:29ff:xxxx:42f6%vmx1 U 0 1500 vmx1
And the same on WAN (which doesn't have V6, but has multiple V4 routes):
default xxx.xxx.xxx.161 UGS 4 1450 vmx0 xxx.xxx.xxx.160/28 link#1 U 6 1450 vmx0 xxx.xxx.253.14 xxx.xxx.xxx.161 UGHS 13 1450 vmx0 fe80::%vmx0/64 link#1 U 0 1500 vmx0 fe80::20c:29ff:xxxx:42ec%vmx0 link#1 UHS 0 16384 lo0 ff01::%vmx0/32 fe80::20c:29ff:xxxx:42ec%vmx0 U 0 1500 vmx0 ff02::%vmx0/32 fe80::20c:29ff:xxxx:42ec%vmx0 U 0 1500 vmx0
We have had some issues setting MTU in the past (e.g. #4397, #5842, #2674), but none appear to exactly match this.
Attempting to reproduce the same issue on 2.4 has better but not perfect results. The link-local routes are updated with the correct MTU, but host and static routes are not.
If I manually set the MTU on an interface in stock FreeBSD 11, all link-local and static routes get an updated MTU.
Updated by Luiz Souza about 7 years ago
- Target version changed from 2.4.0 to 2.4.1
Updated by Jim Pingle almost 7 years ago
- Target version changed from 2.4.1 to 2.4.2
Updated by Jim Pingle almost 7 years ago
- Target version changed from 2.4.2 to 2.4.3
Updated by Luiz Souza over 6 years ago
- Target version changed from 2.4.3 to 2.4.4
Updated by Jim Pingle almost 6 years ago
- Target version changed from 2.4.4 to 48
Updated by Viktor Gurov over 4 years ago
Updated by Jim Pingle over 4 years ago
- Status changed from Confirmed to Pull Request Review
Updated by Renato Botelho over 4 years ago
- Status changed from Pull Request Review to Feedback
- % Done changed from 0 to 100
PR has been merged. Thanks!
Updated by Viktor Gurov over 4 years ago
- Status changed from Feedback to Resolved
works as expected on 2.5.0.a.20200424.1759