DHCP 서버가 MTU를 설정할 때 링크 플래핑

Ubuntu 18.04 시스템에서 고유한 네트워크 문제가 발생했습니다. 내 이더넷 인터페이스 중 하나는 특정 브랜드의 라우터(Sierra Wireless MP70)를 사용할 때와 DHCP가 활성화된 경우에만 링크 플래핑을 경험합니다. 나는 다른 요인을 완전히 배제했습니다. 고정 IP 설정을 사용하면 링크가 제대로 작동하고 다른 문제도 발견되지 않습니다(예: 패킷 손실 없음).

관찰된 동작은 링크가 잠시 온라인 상태가 되어 DHCP 임대를 얻은 것처럼 보이고 즉시 전환된 NO-CARRIER다음 반복된다는 것입니다.

이전에는 이것이 물리 계층 문제라고 생각했지만 링크를 아래에서 위로 전환한 후 잠시 나타나는 것을 보았으므로 NO-CARRIER현재 가설은 일부 시스템 프로세스가 단순히 네트워크의 순환을 위아래로 유발한다는 것입니다.

이 장치에 대한 내 네트워크 계획은 간단합니다.

    eth1:
      dhcp4: true
      dhcp4-overrides:
        use-routes: false

이것은 순환 로그 부분입니다 systemd-networkd.

eth1: Flags change: +LOWER_UP +RUNNING
Sent message type=signal sender=n/a destination=n/a path=/org/freedesktop/network1/link/_34 interface=org.freedesktop.DBus.Properties member=PropertiesChanged cookie=12 reply_cookie=0 signature=sa{sv}as error-name=n/a error-message=n/a
eth1: Gained carrier
eth1: Acquiring DHCPv4 lease
DHCP CLIENT (0xe616919c): STARTED on ifindex 4
Sent message type=signal sender=n/a destination=n/a path=/org/freedesktop/network1 interface=org.freedesktop.DBus.Properties member=PropertiesChanged cookie=13 reply_cookie=0 signature=sa{sv}as error-name=n/a error-message=n/a
DHCP CLIENT (0xe616919c): DISCOVER
DHCP CLIENT (0xe616919c): OFFER
DHCP CLIENT (0xe616919c): REQUEST (requesting)
DHCP CLIENT (0xe616919c): ACK
DHCP CLIENT (0xe616919c): lease expires in 1d 23h 59min 59s
DHCP CLIENT (0xe616919c): T2 expires in 1d 18h
DHCP CLIENT (0xe616919c): T1 expires in 1d
eth1: DHCPv4 address 192.168.13.110/24 via 192.168.13.31
eth1: Setting MTU: 1430
Setting transient hostname: 'ifcb000'
Sent message type=method_call sender=n/a destination=org.freedesktop.hostname1 path=/org/freedesktop/hostname1 interface=org.freedesktop.hostname1 member=SetHostname cookie=14 reply_cookie=0 signature=sb error-name=n/a error-message=n/a
eth1: Flags change: -LOWER_UP
eth1: Setting MTU done.
eth1: Updating address: 192.168.13.110/24 (valid for 2d)
Sent message type=signal sender=n/a destination=n/a path=/org/freedesktop/network1/link/_34 interface=org.freedesktop.DBus.Properties member=PropertiesChanged cookie=15 reply_cookie=0 signature=sa{sv}as error-name=n/a error-message=n/a
Sent message type=signal sender=n/a destination=n/a path=/org/freedesktop/network1 interface=org.freedesktop.DBus.Properties member=PropertiesChanged cookie=16 reply_cookie=0 signature=sa{sv}as error-name=n/a error-message=n/a
eth1: DHCP error: could not get routes: No data available
Got message type=method_return sender=:1.6 destination=:1.2 path=n/a interface=n/a member=n/a cookie=3 reply_cookie=14 signature=n/a error-name=n/a error-message=n/a
eth1: Flags change: -RUNNING
Sent message type=signal sender=n/a destination=n/a path=/org/freedesktop/network1/link/_34 interface=org.freedesktop.DBus.Properties member=PropertiesChanged cookie=17 reply_cookie=0 signature=sa{sv}as error-name=n/a error-message=n/a
eth1: Lost carrier
DHCP CLIENT (0xe616919c): STOPPED
eth1: DHCP lease lost
eth1: Removing address 192.168.13.110
eth1: Setting MTU: 1500
Setting transient hostname: 'n/a'
Sent message type=method_call sender=n/a destination=org.freedesktop.hostname1 path=/org/freedesktop/hostname1 interface=org.freedesktop.hostname1 member=SetHostname cookie=18 reply_cookie=0 signature=sb error-name=n/a error-message=n/a
eth1: Removing address 192.168.13.110
eth1: State is configuring, dropping config
Sent message type=signal sender=n/a destination=n/a path=/org/freedesktop/network1 interface=org.freedesktop.DBus.Properties member=PropertiesChanged cookie=19 reply_cookie=0 signature=sa{sv}as error-name=n/a error-message=n/a
eth1: Removing address: 192.168.13.110/24 (valid for 2d)
Got message type=method_return sender=:1.6 destination=:1.2 path=n/a interface=n/a member=n/a cookie=4 reply_cookie=18 signature=n/a error-name=n/a error-message=n/a
eth1: Setting MTU done.
eth1: Adding address: fe80::206:d5ff:fe2f:60c2/64 (valid forever)
eth1: Gained IPv6LL
eth1: Discovering IPv6 routers
NDISC: Started IPv6 Router Solicitation client
NDISC: Sent Router Solicitation, next solicitation in 4s
eth1: Flags change: +LOWER_UP +RUNNING