| 1 | |
| 2 |
|
| 3 | ============
|
| 4 | Devlink Trap
|
| 5 | ============
|
| 6 |
|
| 7 | Background
|
| 8 | ==========
|
| 9 |
|
| 10 | Devices capable of offloading the kernel's datapath and perform functions such
|
| 11 | as bridging and routing must also be able to send specific packets to the
|
| 12 | kernel (i.e., the CPU) for processing.
|
| 13 |
|
| 14 | For example, a device acting as a multicast-aware bridge must be able to send
|
| 15 | IGMP membership reports to the kernel for processing by the bridge module.
|
| 16 | Without processing such packets, the bridge module could never populate its
|
| 17 | MDB.
|
| 18 |
|
| 19 | As another example, consider a device acting as router which has received an IP
|
| 20 | packet with a TTL of 1. Upon routing the packet the device must send it to the
|
| 21 | kernel so that it will route it as well and generate an ICMP Time Exceeded
|
| 22 | error datagram. Without letting the kernel route such packets itself, utilities
|
| 23 | such as ``traceroute`` could never work.
|
| 24 |
|
| 25 | The fundamental ability of sending certain packets to the kernel for processing
|
| 26 | is called "packet trapping".
|
| 27 |
|
| 28 | Overview
|
| 29 | ========
|
| 30 |
|
| 31 | The ``devlink-trap`` mechanism allows capable device drivers to register their
|
| 32 | supported packet traps with ``devlink`` and report trapped packets to
|
| 33 | ``devlink`` for further analysis.
|
| 34 |
|
| 35 | Upon receiving trapped packets, ``devlink`` will perform a per-trap packets and
|
| 36 | bytes accounting and potentially report the packet to user space via a netlink
|
| 37 | event along with all the provided metadata (e.g., trap reason, timestamp, input
|
| 38 | port). This is especially useful for drop traps (see :ref:`Trap-Types`)
|
| 39 | as it allows users to obtain further visibility into packet drops that would
|
| 40 | otherwise be invisible.
|
| 41 |
|
| 42 | The following diagram provides a general overview of ``devlink-trap``::
|
| 43 |
|
| 44 | Netlink event: Packet w/ metadata
|
| 45 | Or a summary of recent drops
|
| 46 | ^
|
| 47 | |
|
| 48 | Userspace |
|
| 49 | +---------------------------------------------------+
|
| 50 | Kernel |
|
| 51 | |
|
| 52 | +-------+--------+
|
| 53 | | |
|
| 54 | | drop_monitor |
|
| 55 | | |
|
| 56 | +-------^--------+
|
| 57 | |
|
| 58 | | Non-control traps
|
| 59 | |
|
| 60 | +----+----+
|
| 61 | | | Kernel's Rx path
|
| 62 | | devlink | (non-drop traps)
|
| 63 | | |
|
| 64 | +----^----+ ^
|
| 65 | | |
|
| 66 | +-----------+
|
| 67 | |
|
| 68 | +-------+-------+
|
| 69 | | |
|
| 70 | | Device driver |
|
| 71 | | |
|
| 72 | +-------^-------+
|
| 73 | Kernel |
|
| 74 | +---------------------------------------------------+
|
| 75 | Hardware |
|
| 76 | | Trapped packet
|
| 77 | |
|
| 78 | +--+---+
|
| 79 | | |
|
| 80 | | ASIC |
|
| 81 | | |
|
| 82 | +------+
|
| 83 |
|
| 84 | |
| 85 |
|
| 86 | Trap Types
|
| 87 | ==========
|
| 88 |
|
| 89 | The ``devlink-trap`` mechanism supports the following packet trap types:
|
| 90 |
|
| 91 | * ``drop``: Trapped packets were dropped by the underlying device. Packets
|
| 92 | are only processed by ``devlink`` and not injected to the kernel's Rx path.
|
| 93 | The trap action (see :ref:`Trap-Actions`) can be changed.
|
| 94 | * ``exception``: Trapped packets were not forwarded as intended by the
|
| 95 | underlying device due to an exception (e.g., TTL error, missing neighbour
|
| 96 | entry) and trapped to the control plane for resolution. Packets are
|
| 97 | processed by ``devlink`` and injected to the kernel's Rx path. Changing the
|
| 98 | action of such traps is not allowed, as it can easily break the control
|
| 99 | plane.
|
| 100 | * ``control``: Trapped packets were trapped by the device because these are
|
| 101 | control packets required for the correct functioning of the control plane.
|
| 102 | For example, ARP request and IGMP query packets. Packets are injected to
|
| 103 | the kernel's Rx path, but not reported to the kernel's drop monitor.
|
| 104 | Changing the action of such traps is not allowed, as it can easily break
|
| 105 | the control plane.
|
| 106 |
|
| 107 | |
| 108 |
|
| 109 | Trap Actions
|
| 110 | ============
|
| 111 |
|
| 112 | The ``devlink-trap`` mechanism supports the following packet trap actions:
|
| 113 |
|
| 114 | * ``trap``: The sole copy of the packet is sent to the CPU.
|
| 115 | * ``drop``: The packet is dropped by the underlying device and a copy is not
|
| 116 | sent to the CPU.
|
| 117 | * ``mirror``: The packet is forwarded by the underlying device and a copy is
|
| 118 | sent to the CPU.
|
| 119 |
|
| 120 | Generic Packet Traps
|
| 121 | ====================
|
| 122 |
|
| 123 | Generic packet traps are used to describe traps that trap well-defined packets
|
| 124 | or packets that are trapped due to well-defined conditions (e.g., TTL error).
|
| 125 | Such traps can be shared by multiple device drivers and their description must
|
| 126 | be added to the following table:
|
| 127 |
|
| 128 | .. list-table:: List of Generic Packet Traps
|
| 129 | :widths: 5 5 90
|
| 130 |
|
| 131 | * - Name
|
| 132 | - Type
|
| 133 | - Description
|
| 134 | * - ``source_mac_is_multicast``
|
| 135 | - ``drop``
|
| 136 | - Traps incoming packets that the device decided to drop because of a
|
| 137 | multicast source MAC
|
| 138 | * - ``vlan_tag_mismatch``
|
| 139 | - ``drop``
|
| 140 | - Traps incoming packets that the device decided to drop in case of VLAN
|
| 141 | tag mismatch: The ingress bridge port is not configured with a PVID and
|
| 142 | the packet is untagged or prio-tagged
|
| 143 | * - ``ingress_vlan_filter``
|
| 144 | - ``drop``
|
| 145 | - Traps incoming packets that the device decided to drop in case they are
|
| 146 | tagged with a VLAN that is not configured on the ingress bridge port
|
| 147 | * - ``ingress_spanning_tree_filter``
|
| 148 | - ``drop``
|
| 149 | - Traps incoming packets that the device decided to drop in case the STP
|
| 150 | state of the ingress bridge port is not "forwarding"
|
| 151 | * - ``port_list_is_empty``
|
| 152 | - ``drop``
|
| 153 | - Traps packets that the device decided to drop in case they need to be
|
| 154 | flooded (e.g., unknown unicast, unregistered multicast) and there are
|
| 155 | no ports the packets should be flooded to
|
| 156 | * - ``port_loopback_filter``
|
| 157 | - ``drop``
|
| 158 | - Traps packets that the device decided to drop in case after layer 2
|
| 159 | forwarding the only port from which they should be transmitted through
|
| 160 | is the port from which they were received
|
| 161 | * - ``blackhole_route``
|
| 162 | - ``drop``
|
| 163 | - Traps packets that the device decided to drop in case they hit a
|
| 164 | blackhole route
|
| 165 | * - ``ttl_value_is_too_small``
|
| 166 | - ``exception``
|
| 167 | - Traps unicast packets that should be forwarded by the device whose TTL
|
| 168 | was decremented to 0 or less
|
| 169 | * - ``tail_drop``
|
| 170 | - ``drop``
|
| 171 | - Traps packets that the device decided to drop because they could not be
|
| 172 | enqueued to a transmission queue which is full
|
| 173 | * - ``non_ip``
|
| 174 | - ``drop``
|
| 175 | - Traps packets that the device decided to drop because they need to
|
| 176 | undergo a layer 3 lookup, but are not IP or MPLS packets
|
| 177 | * - ``uc_dip_over_mc_dmac``
|
| 178 | - ``drop``
|
| 179 | - Traps packets that the device decided to drop because they need to be
|
| 180 | routed and they have a unicast destination IP and a multicast destination
|
| 181 | MAC
|
| 182 | * - ``dip_is_loopback_address``
|
| 183 | - ``drop``
|
| 184 | - Traps packets that the device decided to drop because they need to be
|
| 185 | routed and their destination IP is the loopback address (i.e., 127.0.0.0/8
|
| 186 | and ::1/128)
|
| 187 | * - ``sip_is_mc``
|
| 188 | - ``drop``
|
| 189 | - Traps packets that the device decided to drop because they need to be
|
| 190 | routed and their source IP is multicast (i.e., 224.0.0.0/8 and ff::/8)
|
| 191 | * - ``sip_is_loopback_address``
|
| 192 | - ``drop``
|
| 193 | - Traps packets that the device decided to drop because they need to be
|
| 194 | routed and their source IP is the loopback address (i.e., 127.0.0.0/8 and ::1/128)
|
| 195 | * - ``ip_header_corrupted``
|
| 196 | - ``drop``
|
| 197 | - Traps packets that the device decided to drop because they need to be
|
| 198 | routed and their IP header is corrupted: wrong checksum, wrong IP version
|
| 199 | or too short Internet Header Length (IHL)
|
| 200 | * - ``ipv4_sip_is_limited_bc``
|
| 201 | - ``drop``
|
| 202 | - Traps packets that the device decided to drop because they need to be
|
| 203 | routed and their source IP is limited broadcast (i.e., 255.255.255.255/32)
|
| 204 | * - ``ipv6_mc_dip_reserved_scope``
|
| 205 | - ``drop``
|
| 206 | - Traps IPv6 packets that the device decided to drop because they need to
|
| 207 | be routed and their IPv6 multicast destination IP has a reserved scope
|
| 208 | (i.e., ffx0::/16)
|
| 209 | * - ``ipv6_mc_dip_interface_local_scope``
|
| 210 | - ``drop``
|
| 211 | - Traps IPv6 packets that the device decided to drop because they need to
|
| 212 | be routed and their IPv6 multicast destination IP has an interface-local scope
|
| 213 | (i.e., ffx1::/16)
|
| 214 | * - ``mtu_value_is_too_small``
|
| 215 | - ``exception``
|
| 216 | - Traps packets that should have been routed by the device, but were bigger
|
| 217 | than the MTU of the egress interface
|
| 218 | * - ``unresolved_neigh``
|
| 219 | - ``exception``
|
| 220 | - Traps packets that did not have a matching IP neighbour after routing
|
| 221 | * - ``mc_reverse_path_forwarding``
|
| 222 | - ``exception``
|
| 223 | - Traps multicast IP packets that failed reverse-path forwarding (RPF)
|
| 224 | check during multicast routing
|
| 225 | * - ``reject_route``
|
| 226 | - ``exception``
|
| 227 | - Traps packets that hit reject routes (i.e., "unreachable", "prohibit")
|
| 228 | * - ``ipv4_lpm_miss``
|
| 229 | - ``exception``
|
| 230 | - Traps unicast IPv4 packets that did not match any route
|
| 231 | * - ``ipv6_lpm_miss``
|
| 232 | - ``exception``
|
| 233 | - Traps unicast IPv6 packets that did not match any route
|
| 234 | * - ``non_routable_packet``
|
| 235 | - ``drop``
|
| 236 | - Traps packets that the device decided to drop because they are not
|
| 237 | supposed to be routed. For example, IGMP queries can be flooded by the
|
| 238 | device in layer 2 and reach the router. Such packets should not be
|
| 239 | routed and instead dropped
|
| 240 | * - ``decap_error``
|
| 241 | - ``exception``
|
| 242 | - Traps NVE and IPinIP packets that the device decided to drop because of
|
| 243 | failure during decapsulation (e.g., packet being too short, reserved
|
| 244 | bits set in VXLAN header)
|
| 245 | * - ``overlay_smac_is_mc``
|
| 246 | - ``drop``
|
| 247 | - Traps NVE packets that the device decided to drop because their overlay
|
| 248 | source MAC is multicast
|
| 249 | * - ``ingress_flow_action_drop``
|
| 250 | - ``drop``
|
| 251 | - Traps packets dropped during processing of ingress flow action drop
|
| 252 | * - ``egress_flow_action_drop``
|
| 253 | - ``drop``
|
| 254 | - Traps packets dropped during processing of egress flow action drop
|
| 255 | * - ``stp``
|
| 256 | - ``control``
|
| 257 | - Traps STP packets
|
| 258 | * - ``lacp``
|
| 259 | - ``control``
|
| 260 | - Traps LACP packets
|
| 261 | * - ``lldp``
|
| 262 | - ``control``
|
| 263 | - Traps LLDP packets
|
| 264 | * - ``igmp_query``
|
| 265 | - ``control``
|
| 266 | - Traps IGMP Membership Query packets
|
| 267 | * - ``igmp_v1_report``
|
| 268 | - ``control``
|
| 269 | - Traps IGMP Version 1 Membership Report packets
|
| 270 | * - ``igmp_v2_report``
|
| 271 | - ``control``
|
| 272 | - Traps IGMP Version 2 Membership Report packets
|
| 273 | * - ``igmp_v3_report``
|
| 274 | - ``control``
|
| 275 | - Traps IGMP Version 3 Membership Report packets
|
| 276 | * - ``igmp_v2_leave``
|
| 277 | - ``control``
|
| 278 | - Traps IGMP Version 2 Leave Group packets
|
| 279 | * - ``mld_query``
|
| 280 | - ``control``
|
| 281 | - Traps MLD Multicast Listener Query packets
|
| 282 | * - ``mld_v1_report``
|
| 283 | - ``control``
|
| 284 | - Traps MLD Version 1 Multicast Listener Report packets
|
| 285 | * - ``mld_v2_report``
|
| 286 | - ``control``
|
| 287 | - Traps MLD Version 2 Multicast Listener Report packets
|
| 288 | * - ``mld_v1_done``
|
| 289 | - ``control``
|
| 290 | - Traps MLD Version 1 Multicast Listener Done packets
|
| 291 | * - ``ipv4_dhcp``
|
| 292 | - ``control``
|
| 293 | - Traps IPv4 DHCP packets
|
| 294 | * - ``ipv6_dhcp``
|
| 295 | - ``control``
|
| 296 | - Traps IPv6 DHCP packets
|
| 297 | * - ``arp_request``
|
| 298 | - ``control``
|
| 299 | - Traps ARP request packets
|
| 300 | * - ``arp_response``
|
| 301 | - ``control``
|
| 302 | - Traps ARP response packets
|
| 303 | * - ``arp_overlay``
|
| 304 | - ``control``
|
| 305 | - Traps NVE-decapsulated ARP packets that reached the overlay network.
|
| 306 | This is required, for example, when the address that needs to be
|
| 307 | resolved is a local address
|
| 308 | * - ``ipv6_neigh_solicit``
|
| 309 | - ``control``
|
| 310 | - Traps IPv6 Neighbour Solicitation packets
|
| 311 | * - ``ipv6_neigh_advert``
|
| 312 | - ``control``
|
| 313 | - Traps IPv6 Neighbour Advertisement packets
|
| 314 | * - ``ipv4_bfd``
|
| 315 | - ``control``
|
| 316 | - Traps IPv4 BFD packets
|
| 317 | * - ``ipv6_bfd``
|
| 318 | - ``control``
|
| 319 | - Traps IPv6 BFD packets
|
| 320 | * - ``ipv4_ospf``
|
| 321 | - ``control``
|
| 322 | - Traps IPv4 OSPF packets
|
| 323 | * - ``ipv6_ospf``
|
| 324 | - ``control``
|
| 325 | - Traps IPv6 OSPF packets
|
| 326 | * - ``ipv4_bgp``
|
| 327 | - ``control``
|
| 328 | - Traps IPv4 BGP packets
|
| 329 | * - ``ipv6_bgp``
|
| 330 | - ``control``
|
| 331 | - Traps IPv6 BGP packets
|
| 332 | * - ``ipv4_vrrp``
|
| 333 | - ``control``
|
| 334 | - Traps IPv4 VRRP packets
|
| 335 | * - ``ipv6_vrrp``
|
| 336 | - ``control``
|
| 337 | - Traps IPv6 VRRP packets
|
| 338 | * - ``ipv4_pim``
|
| 339 | - ``control``
|
| 340 | - Traps IPv4 PIM packets
|
| 341 | * - ``ipv6_pim``
|
| 342 | - ``control``
|
| 343 | - Traps IPv6 PIM packets
|
| 344 | * - ``uc_loopback``
|
| 345 | - ``control``
|
| 346 | - Traps unicast packets that need to be routed through the same layer 3
|
| 347 | interface from which they were received. Such packets are routed by the
|
| 348 | kernel, but also cause it to potentially generate ICMP redirect packets
|
| 349 | * - ``local_route``
|
| 350 | - ``control``
|
| 351 | - Traps unicast packets that hit a local route and need to be locally
|
| 352 | delivered
|
| 353 | * - ``external_route``
|
| 354 | - ``control``
|
| 355 | - Traps packets that should be routed through an external interface (e.g.,
|
| 356 | management interface) that does not belong to the same device (e.g.,
|
| 357 | switch ASIC) as the ingress interface
|
| 358 | * - ``ipv6_uc_dip_link_local_scope``
|
| 359 | - ``control``
|
| 360 | - Traps unicast IPv6 packets that need to be routed and have a destination
|
| 361 | IP address with a link-local scope (i.e., fe80::/10). The trap allows
|
| 362 | device drivers to avoid programming link-local routes, but still receive
|
| 363 | packets for local delivery
|
| 364 | * - ``ipv6_dip_all_nodes``
|
| 365 | - ``control``
|
| 366 | - Traps IPv6 packets that their destination IP address is the "All Nodes
|
| 367 | Address" (i.e., ff02::1)
|
| 368 | * - ``ipv6_dip_all_routers``
|
| 369 | - ``control``
|
| 370 | - Traps IPv6 packets that their destination IP address is the "All Routers
|
| 371 | Address" (i.e., ff02::2)
|
| 372 | * - ``ipv6_router_solicit``
|
| 373 | - ``control``
|
| 374 | - Traps IPv6 Router Solicitation packets
|
| 375 | * - ``ipv6_router_advert``
|
| 376 | - ``control``
|
| 377 | - Traps IPv6 Router Advertisement packets
|
| 378 | * - ``ipv6_redirect``
|
| 379 | - ``control``
|
| 380 | - Traps IPv6 Redirect Message packets
|
| 381 | * - ``ipv4_router_alert``
|
| 382 | - ``control``
|
| 383 | - Traps IPv4 packets that need to be routed and include the Router Alert
|
| 384 | option. Such packets need to be locally delivered to raw sockets that
|
| 385 | have the IP_ROUTER_ALERT socket option set
|
| 386 | * - ``ipv6_router_alert``
|
| 387 | - ``control``
|
| 388 | - Traps IPv6 packets that need to be routed and include the Router Alert
|
| 389 | option in their Hop-by-Hop extension header. Such packets need to be
|
| 390 | locally delivered to raw sockets that have the IPV6_ROUTER_ALERT socket
|
| 391 | option set
|
| 392 | * - ``ptp_event``
|
| 393 | - ``control``
|
| 394 | - Traps PTP time-critical event messages (Sync, Delay_req, Pdelay_Req and
|
| 395 | Pdelay_Resp)
|
| 396 | * - ``ptp_general``
|
| 397 | - ``control``
|
| 398 | - Traps PTP general messages (Announce, Follow_Up, Delay_Resp,
|
| 399 | Pdelay_Resp_Follow_Up, management and signaling)
|
| 400 | * - ``flow_action_sample``
|
| 401 | - ``control``
|
| 402 | - Traps packets sampled during processing of flow action sample (e.g., via
|
| 403 | tc's sample action)
|
| 404 | * - ``flow_action_trap``
|
| 405 | - ``control``
|
| 406 | - Traps packets logged during processing of flow action trap (e.g., via
|
| 407 | tc's trap action)
|
| 408 | * - ``early_drop``
|
| 409 | - ``drop``
|
| 410 | - Traps packets dropped due to the RED (Random Early Detection) algorithm
|
| 411 | (i.e., early drops)
|
| 412 | * - ``vxlan_parsing``
|
| 413 | - ``drop``
|
| 414 | - Traps packets dropped due to an error in the VXLAN header parsing which
|
| 415 | might be because of packet truncation or the I flag is not set.
|
| 416 | * - ``llc_snap_parsing``
|
| 417 | - ``drop``
|
| 418 | - Traps packets dropped due to an error in the LLC+SNAP header parsing
|
| 419 | * - ``vlan_parsing``
|
| 420 | - ``drop``
|
| 421 | - Traps packets dropped due to an error in the VLAN header parsing. Could
|
| 422 | include unexpected packet truncation.
|
| 423 | * - ``pppoe_ppp_parsing``
|
| 424 | - ``drop``
|
| 425 | - Traps packets dropped due to an error in the PPPoE+PPP header parsing.
|
| 426 | This could include finding a session ID of 0xFFFF (which is reserved and
|
| 427 | not for use), a PPPoE length which is larger than the frame received or
|
| 428 | any common error on this type of header
|
| 429 | * - ``mpls_parsing``
|
| 430 | - ``drop``
|
| 431 | - Traps packets dropped due to an error in the MPLS header parsing which
|
| 432 | could include unexpected header truncation
|
| 433 | * - ``arp_parsing``
|
| 434 | - ``drop``
|
| 435 | - Traps packets dropped due to an error in the ARP header parsing
|
| 436 | * - ``ip_1_parsing``
|
| 437 | - ``drop``
|
| 438 | - Traps packets dropped due to an error in the first IP header parsing.
|
| 439 | This packet trap could include packets which do not pass an IP checksum
|
| 440 | check, a header length check (a minimum of 20 bytes), which might suffer
|
| 441 | from packet truncation thus the total length field exceeds the received
|
| 442 | packet length etc
|
| 443 | * - ``ip_n_parsing``
|
| 444 | - ``drop``
|
| 445 | - Traps packets dropped due to an error in the parsing of the last IP
|
| 446 | header (the inner one in case of an IP over IP tunnel). The same common
|
| 447 | error checking is performed here as for the ip_1_parsing trap
|
| 448 | * - ``gre_parsing``
|
| 449 | - ``drop``
|
| 450 | - Traps packets dropped due to an error in the GRE header parsing
|
| 451 | * - ``udp_parsing``
|
| 452 | - ``drop``
|
| 453 | - Traps packets dropped due to an error in the UDP header parsing.
|
| 454 | This packet trap could include checksum errors, an improper UDP
|
| 455 | length detected (smaller than 8 bytes) or detection of header
|
| 456 | truncation.
|
| 457 | * - ``tcp_parsing``
|
| 458 | - ``drop``
|
| 459 | - Traps packets dropped due to an error in the TCP header parsing.
|
| 460 | This could include TCP checksum errors, improper combination of SYN, FIN
|
| 461 | and/or RESET etc.
|
| 462 | * - ``ipsec_parsing``
|
| 463 | - ``drop``
|
| 464 | - Traps packets dropped due to an error in the IPSEC header parsing
|
| 465 | * - ``sctp_parsing``
|
| 466 | - ``drop``
|
| 467 | - Traps packets dropped due to an error in the SCTP header parsing.
|
| 468 | This would mean that port number 0 was used or that the header is
|
| 469 | truncated.
|
| 470 | * - ``dccp_parsing``
|
| 471 | - ``drop``
|
| 472 | - Traps packets dropped due to an error in the DCCP header parsing
|
| 473 | * - ``gtp_parsing``
|
| 474 | - ``drop``
|
| 475 | - Traps packets dropped due to an error in the GTP header parsing
|
| 476 | * - ``esp_parsing``
|
| 477 | - ``drop``
|
| 478 | - Traps packets dropped due to an error in the ESP header parsing
|
| 479 | * - ``blackhole_nexthop``
|
| 480 | - ``drop``
|
| 481 | - Traps packets that the device decided to drop in case they hit a
|
| 482 | blackhole nexthop
|
| 483 | * - ``dmac_filter``
|
| 484 | - ``drop``
|
| 485 | - Traps incoming packets that the device decided to drop because
|
| 486 | the destination MAC is not configured in the MAC table and
|
| 487 | the interface is not in promiscuous mode
|
| 488 | * - ``eapol``
|
| 489 | - ``control``
|
| 490 | - Traps "Extensible Authentication Protocol over LAN" (EAPOL) packets
|
| 491 | specified in IEEE 802.1X
|
| 492 | * - ``locked_port``
|
| 493 | - ``drop``
|
| 494 | - Traps packets that the device decided to drop because they failed the
|
| 495 | locked bridge port check. That is, packets that were received via a
|
| 496 | locked port and whose {SMAC, VID} does not correspond to an FDB entry
|
| 497 | pointing to the port
|
| 498 |
|
| 499 | Driver-specific Packet Traps
|
| 500 | ============================
|
| 501 |
|
| 502 | Device drivers can register driver-specific packet traps, but these must be
|
| 503 | clearly documented. Such traps can correspond to device-specific exceptions and
|
| 504 | help debug packet drops caused by these exceptions. The following list includes
|
| 505 | links to the description of driver-specific traps registered by various device
|
| 506 | drivers:
|
| 507 |
|
| 508 | * Documentation/networking/devlink/netdevsim.rst
|
| 509 | * Documentation/networking/devlink/mlxsw.rst
|
| 510 | * Documentation/networking/devlink/prestera.rst
|
| 511 |
|
| 512 | |
| 513 |
|
| 514 | Generic Packet Trap Groups
|
| 515 | ==========================
|
| 516 |
|
| 517 | Generic packet trap groups are used to aggregate logically related packet
|
| 518 | traps. These groups allow the user to batch operations such as setting the trap
|
| 519 | action of all member drop traps whose action may legally change. Exception and
|
| 520 | control traps remain unchanged. In addition, ``devlink-trap`` can report
|
| 521 | aggregated per-group packets and bytes statistics, in case per-trap statistics
|
| 522 | are too narrow. The description of these groups must be added to the following
|
| 523 | table:
|
| 524 |
|
| 525 | .. list-table:: List of Generic Packet Trap Groups
|
| 526 | :widths: 10 90
|
| 527 |
|
| 528 | * - Name
|
| 529 | - Description
|
| 530 | * - ``l2_drops``
|
| 531 | - Contains packet traps for packets that were dropped by the device during
|
| 532 | layer 2 forwarding (i.e., bridge)
|
| 533 | * - ``l3_drops``
|
| 534 | - Contains packet traps for packets that were dropped by the device during
|
| 535 | layer 3 forwarding
|
| 536 | * - ``l3_exceptions``
|
| 537 | - Contains packet traps for packets that hit an exception (e.g., TTL
|
| 538 | error) during layer 3 forwarding
|
| 539 | * - ``buffer_drops``
|
| 540 | - Contains packet traps for packets that were dropped by the device due to
|
| 541 | an enqueue decision
|
| 542 | * - ``tunnel_drops``
|
| 543 | - Contains packet traps for packets that were dropped by the device during
|
| 544 | tunnel encapsulation / decapsulation
|
| 545 | * - ``acl_drops``
|
| 546 | - Contains packet traps for packets that were dropped by the device during
|
| 547 | ACL processing
|
| 548 | * - ``stp``
|
| 549 | - Contains packet traps for STP packets
|
| 550 | * - ``lacp``
|
| 551 | - Contains packet traps for LACP packets
|
| 552 | * - ``lldp``
|
| 553 | - Contains packet traps for LLDP packets
|
| 554 | * - ``mc_snooping``
|
| 555 | - Contains packet traps for IGMP and MLD packets required for multicast
|
| 556 | snooping
|
| 557 | * - ``dhcp``
|
| 558 | - Contains packet traps for DHCP packets
|
| 559 | * - ``neigh_discovery``
|
| 560 | - Contains packet traps for neighbour discovery packets (e.g., ARP, IPv6
|
| 561 | ND)
|
| 562 | * - ``bfd``
|
| 563 | - Contains packet traps for BFD packets
|
| 564 | * - ``ospf``
|
| 565 | - Contains packet traps for OSPF packets
|
| 566 | * - ``bgp``
|
| 567 | - Contains packet traps for BGP packets
|
| 568 | * - ``vrrp``
|
| 569 | - Contains packet traps for VRRP packets
|
| 570 | * - ``pim``
|
| 571 | - Contains packet traps for PIM packets
|
| 572 | * - ``uc_loopback``
|
| 573 | - Contains a packet trap for unicast loopback packets (i.e.,
|
| 574 | ``uc_loopback``). This trap is singled-out because in cases such as
|
| 575 | one-armed router it will be constantly triggered. To limit the impact on
|
| 576 | the CPU usage, a packet trap policer with a low rate can be bound to the
|
| 577 | group without affecting other traps
|
| 578 | * - ``local_delivery``
|
| 579 | - Contains packet traps for packets that should be locally delivered after
|
| 580 | routing, but do not match more specific packet traps (e.g.,
|
| 581 | ``ipv4_bgp``)
|
| 582 | * - ``external_delivery``
|
| 583 | - Contains packet traps for packets that should be routed through an
|
| 584 | external interface (e.g., management interface) that does not belong to
|
| 585 | the same device (e.g., switch ASIC) as the ingress interface
|
| 586 | * - ``ipv6``
|
| 587 | - Contains packet traps for various IPv6 control packets (e.g., Router
|
| 588 | Advertisements)
|
| 589 | * - ``ptp_event``
|
| 590 | - Contains packet traps for PTP time-critical event messages (Sync,
|
| 591 | Delay_req, Pdelay_Req and Pdelay_Resp)
|
| 592 | * - ``ptp_general``
|
| 593 | - Contains packet traps for PTP general messages (Announce, Follow_Up,
|
| 594 | Delay_Resp, Pdelay_Resp_Follow_Up, management and signaling)
|
| 595 | * - ``acl_sample``
|
| 596 | - Contains packet traps for packets that were sampled by the device during
|
| 597 | ACL processing
|
| 598 | * - ``acl_trap``
|
| 599 | - Contains packet traps for packets that were trapped (logged) by the
|
| 600 | device during ACL processing
|
| 601 | * - ``parser_error_drops``
|
| 602 | - Contains packet traps for packets that were marked by the device during
|
| 603 | parsing as erroneous
|
| 604 | * - ``eapol``
|
| 605 | - Contains packet traps for "Extensible Authentication Protocol over LAN"
|
| 606 | (EAPOL) packets specified in IEEE 802.1X
|
| 607 |
|
| 608 | Packet Trap Policers
|
| 609 | ====================
|
| 610 |
|
| 611 | As previously explained, the underlying device can trap certain packets to the
|
| 612 | CPU for processing. In most cases, the underlying device is capable of handling
|
| 613 | packet rates that are several orders of magnitude higher compared to those that
|
| 614 | can be handled by the CPU.
|
| 615 |
|
| 616 | Therefore, in order to prevent the underlying device from overwhelming the CPU,
|
| 617 | devices usually include packet trap policers that are able to police the
|
| 618 | trapped packets to rates that can be handled by the CPU.
|
| 619 |
|
| 620 | The ``devlink-trap`` mechanism allows capable device drivers to register their
|
| 621 | supported packet trap policers with ``devlink``. The device driver can choose
|
| 622 | to associate these policers with supported packet trap groups (see
|
| 623 | :ref:`Generic-Packet-Trap-Groups`) during its initialization, thereby exposing
|
| 624 | its default control plane policy to user space.
|
| 625 |
|
| 626 | Device drivers should allow user space to change the parameters of the policers
|
| 627 | (e.g., rate, burst size) as well as the association between the policers and
|
| 628 | trap groups by implementing the relevant callbacks.
|
| 629 |
|
| 630 | If possible, device drivers should implement a callback that allows user space
|
| 631 | to retrieve the number of packets that were dropped by the policer because its
|
| 632 | configured policy was violated.
|
| 633 |
|
| 634 | Testing
|
| 635 | =======
|
| 636 |
|
| 637 | See ``tools/testing/selftests/drivers/net/netdevsim/devlink_trap.sh`` for a
|
| 638 | test covering the core infrastructure. Test cases should be added for any new
|
| 639 | functionality.
|
| 640 |
|
| 641 | Device drivers should focus their tests on device-specific functionality, such
|
| 642 | as the triggering of supported packet traps.
|