Usage¶

In this section, it is assumed that Virtual Accelerator has been properly installed and configured. See Getting Started for more details.

Example¶

ICMP packets are being forwarded by the fast path:

# tcpdump -n -i eth2
# tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
 listening on eth2, link-type EN10MB (Ethernet), capture size 65535 bytes
 15:17:29.155002 00:00:00:00:00:00 > 00:02:02:00:00:21, ethertype Unknown (0x2007), length 124:
      0x0000:  6049 4000 0000 0000 6008 c1d2 0002 0200  `I@.....`.......
      0x0010:  0021 0055 0100 0021 0800 4500 0054 8047  .!.U...!..E..T.G
      0x0020:  0000 4001 245c 6e02 0201 6402 0201 0000  ..@.$\n...d.....
      0x0030:  9263 6107 0007 6810 3352 0000 0000 46f9  .ca...h.3R....F.
      0x0040:  0c00 0000 0000 0809 0a0b 0c0d 0e0f 1011  ................
      0x0050:  1213 1415 1617 1819 1a1b 1c1d 1e1f 2021  ...............!
      0x0060:  2223 2425 2627 2829 2a2b 2c2d 2e2f       "#$%&'()*+,-./
 15:17:29.155004 IP 110.2.2.1 > 100.2.2.1: ICMP echo reply, id 24839, seq 7, length 64

The copy of incoming and outgoing packets via eth2 is encapsulated in a FPTUN header (ethertype 0x2007) and delivered to the Linux stack.

Warning

Because the BPF filter is automatically synchronized, an application other than tcpdump (for example, a DHCP client), may trigger the configuration of the fast path with a copy of all incoming packets and therefore impact performance.

To disable automatic synchronization, run the cache manager with the -D option:

# cmgr -D

Then, to manually enable TAP per interface:

# fp-cli
<fp-0> tap-iface-set eth2 on

The tcpdump -i eth2 program will work the same as described in the case of automatic synchronization.

BPF management¶

Displaying BPF filters¶

Synopsis

tap-bpf [all [raw]]

all: All BPF with decoded instructions.
raw: All BPF in raw format.

Example

<fp-0> tap-bpf
BPF list (ifuid 0 is the virtual interface "any"):
8: eth1-vr0, instance 0 (# cmds: 1)
9: eth2-vr0, instance 0 (# cmds: 1)

Setting manually the interface for tapping¶

Synopsis

tap-iface-set <ifname>|any on|off

<ifname> or any: Interface name or any for select all interface.
on or off: Enable / disable TAP.

Example

Enable TAP on eth2

<fp-0> tap-iface-set eth2 on

Displaying TAP state¶

Synopsis

tap

Example

Displaying TAP:

<fp-0> tap
TAP is off

Enabling or disabling TAP¶

Synopsis

tap-set on|off

on or off: Enable / disable TAP.

Example

Enable TAP:

<fp-0> tap-set on
TAP is on (was off)