On 01/01/2018 03:09 AM, Roberto Ragusa wrote: > On 12/24/2017 10:00 PM, Chris Adams wrote: >> Once upon a time, Sam Varshavchik <mrsam@xxxxxxxxxxxxxxx> said: >>> I defy anyone to identify a tangible benefit that comes from >>> removing a static IP address from a port when it loses carrier, and >>> installing one only once a carrier is present. >> >> It is useful for systems with multiple interfaces, for example a desktop >> with wired and wifi, and different preference default routes out both >> (so if the wired goes down, traffic can still go out over the wifi). >> Anything acting like a router also needs this behavior, typically in >> conjuction with dynamic routing protocols. >> > > Routing fail over is not a good reason to totally unconfigure an interface, > especially on machines where there is nowhere else to send packets. > You should just change the default gw, maybe. As a network admin, I can see no reason to remove a fixed IP address from a NIC based on whether or not there's a carrier present. Even in the case of DHCP, unless the address lease expires between a disconnect and reconnect or there's pressure on the DHCP pool, most DHCP servers will try to give a client NIC the same IP address it had when it disconnected. Thus, even in those cases, the address "sticks". Route failover is a common thing to do. We have multiple uplinks on our routers, a primary and at least one backup with each uplink on a different ISP. If the primary goes down the router fails over to (one of) the secondary uplink(s) based on cost factors. However the primary is NOT deconfigured and its IP address remains assigned. If the primary uplink comes back up, then the routes fail back to it. This is standard practice. There's no need to remove its fixed IP address while it's down (and, in fact, would be a "bad idea"). Now, if we want one of the uplinks to remain unavailable, it is marked "administratively down" (in Cisco IOS-speak). For Linux, this would essentially be "ip link dev <devname> down". This takes the link down, but doesn't change the IP address for it. To remove the address, you'd "ip addr del <addr> dev <devname>". Utterly unnecessary (and sort of stupid) if you do the "ip link" command. That's my stubborn, curmudgeon-y opinion. ---------------------------------------------------------------------- - Rick Stevens, Systems Engineer, AllDigital ricks@xxxxxxxxxxxxxx - - AIM/Skype: therps2 ICQ: 226437340 Yahoo: origrps2 - - - - Never put off 'til tommorrow what you can forget altogether! - ---------------------------------------------------------------------- _______________________________________________ users mailing list -- users@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe send an email to users-leave@xxxxxxxxxxxxxxxxxxxxxxx
