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slugman
Asked: 2012-04-22 22:33:52 +0800 CST

Are Link-Local routes necessary (IPv4)?

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I noticed in my routes output in RHEL6 (and most 2.6.x series Linux), for every interface I see the creation of the following route in my kernel routing table:

169.254.0.0     0.0.0.0         255.255.0.0     U     1018   0        0 bond0
169.254.0.0     0.0.0.0         255.255.0.0     U     1019   0        0 bond1
169.254.0.0     0.0.0.0         255.255.0.0     U     1020   0        0 bond2

My understanding is that the link-local addresses are used when auto address configuration fails (when dhcp breaks). When dhcp fails the system will assign itself an available link-local address (more or less).

In your guy's experience, are these necessary? I'm utilizing manual/static IP assignment in my network, so there is no auto-address configuration. Therefore, there is no chance that auto-address configuration would fail. Can I safely remove these routes?

Or is there some other hack/reason I should keep these guys?

Diego

routing local-area-network rhel6

1 Answers

  1. Best Answer

    Link Local address space (RFC 3927) is a nice idea for client addressing, but in practice is rarely used for anything except catching an administrator's eye when reading ipconfig/ifconfig output to learn why someone's PC isn't on the network.

    In fact, on my servers, I don't want link local addressing. I don't want servers to have a chance at being assigned a different address space. I don't even like link local address space on client PCs, but that's another post.

    There is no kernel level wonkery going on with link local addressing that I am aware of. In fact, link local tables should simply be predefined in /etc/sysconfig/static-routes. Yank 'em, I say.

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