2008-08-05T09:13:00.005+03:00 Packing, on my way to a family vacation in Anatalya, Turkey.
Following an interesting discussion yesterday about performance metrics -- it turns out that definition of latency in event processing network is quite tricky. The reason is that an event can move in multiple paths over the network, in some it is filterred out, in some it just getting into internal state of agent since it does not complete a pattern, and in some it may complete a pattern and trigger reaction, thus there are various ways to define the metrics here. This is important since optimization has to take into account the goal function - what is being optimized. More discussion on this area -- after I'll return. I'll be out of touch for a week.
veth(4) Linux Programmer's Manual veth(4)NAME
veth - Virtual Ethernet Device
DESCRIPTION
The veth devices are virtual Ethernet devices. They can act as tunnels between network namespaces to create a bridge to a physical network
device in another namespace, but can also be used as standalone network devices.
veth devices are always created in interconnected pairs. A pair can be created using the command:
# ip link add <p1-name> type veth peer name <p2-name>
In the above, p1-name and p2-name are the names assigned to the two connected end points.
Packets transmitted on one device in the pair are immediately received on the other device. When either devices is down the link state of
the pair is down.
veth device pairs are useful for combining the network facilities of the kernel together in interesting ways. A particularly interesting
use case is to place one end of a veth pair in one network namespace and the other end in another network namespace, thus allowing communi-
cation between network namespaces. To do this, one first creates the veth device as above and then moves one side of the pair to the other
namespace:
# ip link set <p2-name> netns <p2-namespace>
ethtool(8) can be used to find the peer of a veth network interface, using commands something like:
# ip link add ve_A type veth peer name ve_B # Create veth pair
# ethtool -S ve_A # Discover interface index of peer
NIC statistics:
peer_ifindex: 16
# ip link | grep '^16:' # Look up interface
16: ve_B@ve_A: <BROADCAST,MULTICAST,M-DOWN> mtu 1500 qdisc ...
SEE ALSO clone(2), network_namespaces(7), ip(8), ip-link(8), ip-netns(8)Linux 2018-02-02 veth(4)