内核VRF
Linux内核的Virtual Routing and Forwarding (VRF) 是由路由表和一组网络设备组成的路由实例。
VRF安装
Ubuntu默认不包括vrf内核模块，需要额外安装:
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apt-get install linux-headers-4.10.0-14-generic linux-image-extra-4.10.0-14-generic
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reboot
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apt-get install linux-image-extra-$(uname -r)
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modprobe vrf
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VRF示例
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# create vrf device
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ip link add vrf-blue type vrf table 10
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ip link set dev vrf-blue up
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# An l3mdev FIB rule directs lookups to the table associated with the device.
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# A single l3mdev rule is sufficient for all VRFs.
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# Prior to the v4.8 kernel iif and oif rules are needed for each VRF device:
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ip ru add oif vrf-blue table 10
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ip ru add iif vrf-blue table 10
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#Set the default route for the table (and hence default route for the VRF).
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ip route add table 10 unreachable default
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# Enslave L3 interfaces to a VRF device.
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# Local and connected routes for enslaved devices are automatically moved to
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# the table associated with VRF device. Any additional routes depending on
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# the enslaved device are dropped and will need to be reinserted to the VRF
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# FIB table following the enslavement.
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ip link set dev eth1 master vrf-blue
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# The IPv6 sysctl option keep_addr_on_down can be enabled to keep IPv6 global
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# addresses as VRF enslavement changes.
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sysctl -w net.ipv6.conf.all.keep_addr_on_down=1
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# Additional VRF routes are added to associated table.
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ip route add table 10 ...
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进程绑定VRF
Linux进程可以通过在VRF设备上监听socket来绑定VRF：
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setsockopt(sd, SOL_SOCKET, SO_BINDTODEVICE, dev, strlen(dev)+1);
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TCP & UDP services running in the default VRF context (ie., not bound to any VRF device) can work across all VRF domains by enabling the
tcp_l3mdev_accept and udp_l3mdev_accept sysctl options:1
sysctl -w net.ipv4.tcp_l3mdev_accept=1
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sysctl -w net.ipv4.udp_l3mdev_accept=1
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VRF操作
创建VRF
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ip link add dev NAME type vrf table ID
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查询VRF列表
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# ip -d link show type vrf
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16: vrf-blue: <NOARP,MASTER,UP,LOWER_UP> mtu 65536 qdisc noqueue state UP mode DEFAULT group default qlen 1000
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link/ether 9e:9c:8e:7b:32:a4 brd ff:ff:ff:ff:ff:ff promiscuity 0
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vrf table 10 addrgenmode eui64
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添加网卡到VRF
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ip link set dev eth0 master vrf-blue
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查询VRF邻接表和路由
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ip neigh show vrf vrf-blue
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ip addr show vrf vrf-blue
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ip -br addr show vrf vrf-blue
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ip route show vrf vrf-blue
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从VRF中删除网卡
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ip link set dev eth0 nomaster
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参考文档