sonic-buildimage/src/isc-dhcp
Saikrishna Arcot d9517c77f1
dhcrelay: Don't look up the ifindex for the fallback interface (#17797)
Currently, whenever isc-dhcp-relay forwards a packet upstream,
internally, it will try to send it on a "fallback" interface. My
understanding is that this isn't meant to be a real interface, but
instead is basically saying to use Linux's regular routing stack to
route the packet appropriately (rather than having isc-dhcp-relay
specify specifically which interface to use).

The problem is that on systems with a weak CPU, a large number of
interfaces, and many upstream servers specified, this can introduce a
noticeable delay in packets getting sent. The delay comes from trying to
get the ifindex of the fallback interface. In one test case, it got to
the point that only 2 packets could be processed per second. Because of
this, dhcrelay will easily get backlogged and likely get to a point
where packets get dropped in the kernel.

Fix this by adding a check saying if we're using the fallback interface,
then don't try to get the ifindex of this interface. We're never going
to have an interface named this in SONiC.

Signed-off-by: Saikrishna Arcot <sarcot@microsoft.com>
2024-01-18 10:50:22 +08:00
..
patch dhcrelay: Don't look up the ifindex for the fallback interface (#17797) 2024-01-18 10:50:22 +08:00
.gitignore Reorganize .gitignore files (#4707) 2020-06-09 21:04:55 -07:00
Makefile [build] update isc-dhcp to 4.4.1-2.3+deb11u2 to fix build failure (#15002) 2023-05-11 22:14:20 +08:00