LCP plug-in creates peer-to-peer physical interface

Create a physical interface as follows GigabitEthernet7/0/0 Peer to peer interface of e7.

vpp# show interface GigabitEthernet7/0/0
              Name               Idx    State  MTU (L3/IP4/IP6/MPLS)     Counter          Count
GigabitEthernet7/0/0              10    down         9000/0/0/0
vpp#
vpp# lcp create GigabitEthernet7/0/0 host-if e7
vpp#
vpp# show tap
Interface: tap10 (ifindex 17)
  name "e7"
  host-mtu-size "9000"
  host-mac-addr: 00:60:e0:6f:5a:f0

Create physical interfaces GigabitEthernet8/0/0 Peer to peer interface of e8, And the interface status is set to UP,MTU Set to 1500（ The default is 9000）. Peer interface MAC Address and actual physical interface MAC The address is the same .

vpp# show interface GigabitEthernet8/0/0
              Name               Idx    State  MTU (L3/IP4/IP6/MPLS)     Counter          Count
GigabitEthernet8/0/0              11    down         9000/0/0/0
vpp#
vpp#
vpp# set interface state GigabitEthernet8/0/0 up
vpp# set interface mtu packet 1500 GigabitEthernet8/0/0
vpp#
vpp# lcp create GigabitEthernet8/0/0 host-if e8
vpp#
vpp# show tap
Interface: tap11 (ifindex 18)
  name "e8"
  host-mtu-size "1500"
  host-mac-addr: 00:60:e0:6f:5a:f1

LCP Command to view interface pairs .

vpp# show lcp
lcp default netns '<unset>'
lcp lcp-auto-subint off
lcp lcp-sync off
itf-pair: [0] GigabitEthernet7/0/0 tap10 e7 18 type tap
itf-pair: [1] GigabitEthernet8/0/0 tap11 e8 19 type tap

sign out VPP Command line , stay Linux shell View the two created tap Interface ,e7 Of mtu by 9000, Status as down. Interface e8 Of mtu by 1500, Status as up. also , Interface e7 and e8 Of MAC Address and VPP The interface GigabitEthernet7/0/0 and GigabitEthernet8/0/0 Of MAC The address is the same .

$ ip link show type tun
18: e7: <BROADCAST,MULTICAST> mtu 9000 qdisc mq state DOWN mode DEFAULT group default qlen 1000
    link/ether 00:60:e0:6f:5a:f0 brd ff:ff:ff:ff:ff:ff
19: e8: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UNKNOWN mode DEFAULT group default qlen 1000
    link/ether 00:60:e0:6f:5a:f1 brd ff:ff:ff:ff:ff:ff

Manage state synchronization

LCP Interface management status synchronization switch .

vpp# lcp lcp-sync on
vpp#
vpp# show lcp
lcp lcp-sync on

Here is VPP Lieutenant general GigabitEthernet7/0/0 The interface status is set to UP,linux Peer interface in e7 The status is also synchronized to UP.

vpp# set interface state GigabitEthernet7/0/0 up
vpp# quit
#
#
# ip link show type tun
18: e7: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 9000 qdisc mq state DOWN mode DEFAULT group default qlen 1000
    link/ether 00:60:e0:6f:5a:f0 brd ff:ff:ff:ff:ff:ff

The interface link status is not limited by the above switches . Disconnect the physical interface GigabitEthernet8/0/0 The Internet cable ,VPP and linux Medium e8 The link state of the interface is DOWN.

# ip link show type tun
19: e8: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UNKNOWN mode DEFAULT group default qlen 1000
    link/ether 00:60:e0:6f:5a:f1 brd ff:ff:ff:ff:ff:ff
#
#
# vppctl
vpp#
vpp# show hardware-interfaces GigabitEthernet8/0/0
              Name                Idx   Link  Hardware
GigabitEthernet8/0/0              11    down  GigabitEthernet8/0/0

vpp#
vpp# quit
#
# ip link show type tun
19: e8: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc mq state DOWN mode DEFAULT group default qlen 1000
    link/ether 00:60:e0:6f:5a:f1 brd ff:ff:ff:ff:ff:ff

Set interface IP Address

VPP Physical interface and linux Medium peer interface e8 Set exactly the same IP Address .

vpp# set interface ip address GigabitEthernet8/0/0 10.0.1.1/24
vpp# quit
vpp#
#
# ip addr add dev e8 10.0.1.1/24

stay linux in ping External host 10.0.1.2.

# ping 10.0.1.2
PING 10.0.1.2 (10.0.1.2) 56(84) bytes of data.
64 bytes from 10.0.1.2: icmp_seq=1 ttl=64 time=0.290 ms

stay VPP in trace reply ICMP message , as follows ：

vpp# trace add dpdk-input 100
vpp#
vpp# show trace

Packet 3

00:40:13:066975: dpdk-input
  GigabitEthernet7/0/0 rx queue 0
  buffer 0x82ca6: current data 0, length 98, buffer-pool 0, ref-count 1, trace handle 0x2000002
                  ext-hdr-valid
  PKT MBUF: port 9, nb_segs 1, pkt_len 98
    buf_len 2176, data_len 98, ol_flags 0x180, data_off 128, phys_addr 0x92cb2a00
    packet_type 0x11 l2_len 0 l3_len 0 outer_l2_len 0 outer_l3_len 0
    rss 0x0 fdir.hi 0x0 fdir.lo 0x0
    Packet Offload Flags
      PKT_RX_IP_CKSUM_GOOD (0x0080) IP cksum of RX pkt. is valid
      PKT_RX_IP_CKSUM_NONE (0x0090) no IP cksum of RX pkt.
      PKT_RX_L4_CKSUM_GOOD (0x0100) L4 cksum of RX pkt. is valid
      PKT_RX_L4_CKSUM_NONE (0x0108) no L4 cksum of RX pkt.
    Packet Types
      RTE_PTYPE_L2_ETHER (0x0001) Ethernet packet
      RTE_PTYPE_L3_IPV4 (0x0010) IPv4 packet without extension headers
  IP4: 54:e1:ad:3f:11:f4 -> 00:60:e0:6f:5a:f0
  ICMP: 10.0.1.2 -> 10.0.1.1
    tos 0x00, ttl 128, length 84, checksum 0xd71b dscp CS0 ecn NON_ECN
    fragment id 0x4d8b
  ICMP echo_reply checksum 0xecf9 id 3
00:40:13:066978: ethernet-input
  frame: flags 0x3, hw-if-index 10, sw-if-index 10
  IP4: 54:e1:ad:3f:11:f4 -> 00:60:e0:6f:5a:f0
00:40:13:066980: ip4-input-no-checksum
  ICMP: 10.0.1.2 -> 10.0.1.1
    tos 0x00, ttl 128, length 84, checksum 0xd71b dscp CS0 ecn NON_ECN
    fragment id 0x4d8b
  ICMP echo_reply checksum 0xecf9 id 3
00:40:13:066980: ip4-lookup
  fib 0 dpo-idx 7 flow hash: 0x00000000
  ICMP: 10.0.1.2 -> 10.0.1.1
    tos 0x00, ttl 128, length 84, checksum 0xd71b dscp CS0 ecn NON_ECN
    fragment id 0x4d8b
  ICMP echo_reply checksum 0xecf9 id 3
00:40:13:066984: ip4-receive
    ICMP: 10.0.1.2 -> 10.0.1.1
      tos 0x00, ttl 128, length 84, checksum 0xd71b dscp CS0 ecn NON_ECN
      fragment id 0x4d8b
    ICMP echo_reply checksum 0xecf9 id 3
00:40:13:066985: ip4-icmp-input
  ICMP: 10.0.1.2 -> 10.0.1.1
    tos 0x00, ttl 128, length 84, checksum 0xd71b dscp CS0 ecn NON_ECN
    fragment id 0x4d8b
  ICMP echo_reply checksum 0xecf9 id 3
00:40:13:066985: ip4-icmp-echo-reply
  ICMP4 echo id 3 seq 1 (unknown)
00:40:13:066988: ip4-punt
    ICMP: 10.0.1.2 -> 10.0.1.1
      tos 0x00, ttl 128, length 84, checksum 0xd71b dscp CS0 ecn NON_ECN
      fragment id 0x4d8b
    ICMP echo_reply checksum 0xecf9 id 3
00:40:13:066988: ip4-punt-redirect
  via redirect:0
00:40:13:066989: ip4-dvr-dpo 
     sw_if_index:17
00:40:13:066990: ip4-dvr-reinject
     sw_if_index:17
00:40:13:066992: tap11-output
  tap11
  IP4: 54:e1:ad:3f:11:f4 -> 00:60:e0:6f:5a:f0
  ICMP: 10.0.1.2 -> 10.0.1.1
    tos 0x00, ttl 128, length 84, checksum 0xd71b dscp CS0 ecn NON_ECN
    fragment id 0x4d8b
  ICMP echo_reply checksum 0xecf9 id 3
00:40:13:066993: tap11-tx
    buffer 0x82ca6: current data 0, length 98, buffer-pool 0, ref-count 1, trace handle 0x2000002
                    ext-hdr-valid
                    local dvr l2-hdr-offset 0 l3-hdr-offset 14
  hdr-sz 0 l2-hdr-offset 0 l3-hdr-offset 14 l4-hdr-offset 0 l4-hdr-sz 0
  IP4: 54:e1:ad:3f:11:f4 -> 00:60:e0:6f:5a:f0
  ICMP: 10.0.1.2 -> 10.0.1.1
    tos 0x00, ttl 128, length 84, checksum 0xd71b dscp CS0 ecn NON_ECN
    fragment id 0x4d8b
  ICMP echo_reply checksum 0xecf9 id 3

On receiving ICMP After replying to the message , Go through the following node node ：

ip4-icmp-echo-reply -> ip4-punt -> ip4-punt-redirect -> ip4-dvr-dpo -> ip4-dvr-reinject ->tap11-output -> tap11-tx

adopt tap11-tx Send message to linux Peer interface in .