[ovs-dev] [PATCH] bfd: Support overlay BFD

William Tu u9012063 at gmail.com
Sat Jun 27 22:06:41 UTC 2020


Thanks for the patch.

On Wed, Jun 24, 2020 at 1:58 PM Yifeng Sun <pkusunyifeng at gmail.com> wrote:
>
> Current OVS intercepts and processes all BFD packets, thus VM-2-VM
> BFD packets get lost and the recipient VM never sees them.

Can you explain in more detail the issue?
How about this below, if I understand correctly:
"
Currently we treat any packets coming into a BFD-enabled OVS interface
as BFD packets for OVS,
if they are IP, UDP, No_frag, and having BFD DEST_PORT. However, when
consider overlay network,
customers might deployment their own BFD protocol stack, and as a
result, the BFD packets should be
forwarded to the customer instead of being processed at OVS.
"

>
> This patch fixes it by only intercepting and processing BFD packets

maybe not "intercepting", but here we are adding additional check.

> destined to a configured BFD instance, and other BFD packets are made
> available to the OVS flow table for forwarding.
>
> This patch keeps BFD's backward compatibility.
>
Is there a VMware-BZ ID?

> Signed-off-by: Yifeng Sun <pkusunyifeng at gmail.com>
> ---
>  lib/bfd.c            | 16 +++++++++++++---
>  vswitchd/vswitch.xml |  7 +++++++
>  2 files changed, 20 insertions(+), 3 deletions(-)
>
> diff --git a/lib/bfd.c b/lib/bfd.c
> index cc8c6857afa4..3c965699ace3 100644
> --- a/lib/bfd.c
> +++ b/lib/bfd.c
> @@ -149,6 +149,9 @@ BUILD_ASSERT_DECL(BFD_PACKET_LEN == sizeof(struct msg));
>  #define FLAGS_MASK 0x3f
>  #define DEFAULT_MULT 3
>
> +#define BFD_DEFAULT_SRC_IP 0xA9FE0101 /* 169.254.1.1 */
> +#define BFD_DEFAULT_DST_IP 0xA9FE0100 /* 169.254.1.0 */
> +
>  struct bfd {
>      struct hmap_node node;        /* In 'all_bfds'. */
>      uint32_t disc;                /* bfd.LocalDiscr. Key in 'all_bfds' hmap. */
> @@ -457,9 +460,9 @@ bfd_configure(struct bfd *bfd, const char *name, const struct smap *cfg,
>                           &bfd->rmt_eth_dst);
>
>      bfd_lookup_ip(smap_get_def(cfg, "bfd_src_ip", ""),
> -                  htonl(0xA9FE0101) /* 169.254.1.1 */, &bfd->ip_src);
> +                  htonl(BFD_DEFAULT_SRC_IP), &bfd->ip_src);
>      bfd_lookup_ip(smap_get_def(cfg, "bfd_dst_ip", ""),
> -                  htonl(0xA9FE0100) /* 169.254.1.0 */, &bfd->ip_dst);
> +                  htonl(BFD_DEFAULT_DST_IP), &bfd->ip_dst);
>
>      forwarding_if_rx = smap_get_bool(cfg, "forwarding_if_rx", false);
>      if (bfd->forwarding_if_rx != forwarding_if_rx) {
> @@ -674,7 +677,14 @@ bfd_should_process_flow(const struct bfd *bfd_, const struct flow *flow,
>          memset(&wc->masks.nw_proto, 0xff, sizeof wc->masks.nw_proto);
>          if (flow->nw_proto == IPPROTO_UDP
>              && !(flow->nw_frag & FLOW_NW_FRAG_LATER)
> -            && tp_dst_equals(flow, BFD_DEST_PORT, wc)) {
> +            && tp_dst_equals(flow, BFD_DEST_PORT, wc)
> +            && (bfd->ip_src == htonl(BFD_DEFAULT_SRC_IP)
> +                || bfd->ip_src == flow->nw_dst)) {
> +
> +            if (bfd->ip_src == flow->nw_dst) {
> +                memset(&wc->masks.nw_dst, 0xffffffff, sizeof wc->masks.nw_dst);
Why doing the above?

btw, is it possible to add a userspace test (make check)?

Thanks,
William


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