Hi, I was doing a PoC to simulate label swap operation on Service Provider Router(non PE Routers) by creating a mpls tunnel interface and using that tunnel interface as a target in mpls route entry.
Reference:https://wiki.fd.io/view/VPP/MPLS_FIB Please find below the set of configs that I tried and the corresponding observation with VPP 21.01 *Config 1:* Configured MPLS FIB entry without eos bit set. mpls table add 0 set interface mpls GigabitEthernet0/6/0 enable--------------->Incoming Interface is GigabitEthernet0/6/0 set interface mpls GigabitEthernet0/7/0 enable--------------->Outgoing Interface is GigabitEthernet0/7/0 mpls tunnel add via 10.10.10.10 GigabitEthernet0/7/0 out-labels 44 set interface state *mpls-tunnel0* up *mpls local-label add 33 via mpls-tunnel0* *Expectation:-* On receiving an MPLS encapsulated label with in-label as 33 and without "eos" bit set, it should swap the label 33 with label 44 and send to it's neighbor i.e. 10.10.10.10 via GigabitEthernet0/7/0 interface. *Observation:-* I am seeing the forwarding action as dpo-drop in mpls fib table. Please find the output of mplf-fib tables below 33:neos/21 fib:0 index:18 locks:2 CLI refs:1 entry-flags:attached, src-flags:added,contributing,active, path-list:[25] locks:2 flags:shared, uPRF-list:21 len:1 itfs:[96, ] path:[27] pl-index:25 mpls weight=1 pref=0 attached-nexthop: oper-flags:resolved, cfg-flags:attached, 2100::200:0:0:0 mpls-tunnel0 (p2p) [@0]: mpls via 0.0.0.0 mpls-tunnel0: mtu:9000 next:2 stacked-on: [@2]: dpo-load-balance: [proto:mpls index:20 buckets:1 uRPF:-1 to:[0:0]] [0] [@6]: mpls-label[@0]:[44:64:0:neos] [@1]: arp-mpls: via 10.10.10.10 GigabitEthernet0/7/0 forwarding: mpls-neos-chain [@0]: dpo-load-balance: [proto:mpls index:21 buckets:1 uRPF:21 to:[0:0]] [0] [@0]: dpo-drop mpls On receiving an MPLS packet, it is getting dropped in mpls-lookup node. Please find the vpp trace output below. 00:13:33:711978: *dpdk-input* GigabitEthernet0/6/0 rx queue 0 buffer 0x5e3cc: current data 0, length 60, buffer-pool 0, ref-count 1, totlen-nifb 0, trace handle 0x1000000 ext-hdr-valid l4-cksum-computed l4-cksum-correct PKT MBUF: port 0, nb_segs 1, pkt_len 60 buf_len 2176, data_len 60, ol_flags 0x0, data_off 128, phys_addr 0xbd8f380 packet_type 0x0 l2_len 0 l3_len 0 outer_l2_len 0 outer_l3_len 0 rss 0x0 fdir.hi 0x0 fdir.lo 0x0 MPLS: 52:54:00:06:61:da -> 52:54:00:00:00:1a label 33 exp 0, s 0, ttl 64 00:13:33:712035: *ethernet-input* frame: flags 0x1, hw-if-index 1, sw-if-index 1 MPLS: 52:54:00:06:61:da -> 52:54:00:00:00:1a 00:13:33:712089: *mpls-input* MPLS: next mpls-lookup[1] label 33 ttl 64 exp 0 00:13:33:712100: *mpls-lookup* MPLS: next [0], lookup fib index 0, LB index 21 hash 0 label 33 eos 0 00:13:33:712103: *mpls-drop* drop 00:13:33:712105: *error-drop* rx:GigabitEthernet0/6/0 00:13:33:712106: drop mpls-input: MPLS DROP DPO *Config 2:-* Configured MPLS FIB entry with eos bit set. mpls table add 0 set interface mpls GigabitEthernet0/6/0 enable--------------->Incoming Interface is GigabitEthernet0/6/0 set interface mpls GigabitEthernet0/7/0 enable--------------->Outgoing Interface is GigabitEthernet0/7/0 mpls tunnel add via 10.10.10.10 GigabitEthernet0/7/0 out-labels 44 set interface state mpls-tunnel0 up mpls local-label add 33 *eos* via mpls-tunnel0 *Expectation:-* On receiving an MPLS encapsulated label with in-label as 33 and with "eos" bit set, it should swap the label 33 with label 44 and send to it's neighbor i.e. 10.10.10.10 via GigabitEthernet0/7/0 interface. *Observation:* - Observing a crash in vpp on issuing the CLI "mpls local-label add 33 eos via mpls-tunnel0". Is this some known issue? The following is the stack trace #0 __GI_raise (sig=sig@entry=6) at /usr/src/debug/glibc/2.31+gitAUTOINC+f84949f1c4-r0/git/sysdeps/unix/sysv/linux/raise.c:50 #1 0x00000038bb625528 in __GI_abort () at /usr/src/debug/glibc/2.31+gitAUTOINC+f84949f1c4-r0/git/stdlib/abort.c:79 #2 0x000000000040857a in os_exit () at /usr/src/debug/vpp/21.01+gitAUTOINC+18aaa0b698-r0/git/src/vpp/vnet/main.c:433 #3 0x00007f05d7fa6540 in unix_signal_handler (signum=11, si=<optimized out>, uc=<optimized out>) at /usr/src/debug/vpp/21.01+gitAUTOINC+18aaa0b698-r0/git/src/vlib/unix/main.c:187 #4 <signal handler called> #5 0x00007f05d8e813f0 in dpo_get_next_node (parent_dpo=parent_dpo@entry=0x7f05952468e8, child_proto=<optimized out>, child_proto@entry=16, child_type=<optimized out>, child_type@entry=DPO_IP_NULL) at /usr/src/debug/vpp/21.01+gitAUTOINC+18aaa0b698-r0/git/src/vnet/dpo/dpo.c:441 #6 dpo_stack (child_type=child_type@entry=DPO_MPLS_DISPOSITION_PIPE, child_proto=child_proto@entry=DPO_PROTO_MPLS, dpo=dpo@entry=0x7f059861dbc0, parent=parent@entry=0x7f05952468e8) at /usr/src/debug/vpp/21.01+gitAUTOINC+18aaa0b698-r0/git/src/vnet/dpo/dpo.c:526 #7 0x00007f05d8ea0019 in mpls_disp_dpo_create (payload_proto=payload_proto@entry=DPO_PROTO_MPLS, rpf_id=rpf_id@entry=4294967295, mode=mode@entry=FIB_MPLS_LSP_MODE_PIPE, parent=parent@entry=0x7f05952468e8, dpo=dpo@entry=0x7f059861d540) at /usr/src/debug/vpp/21.01+gitAUTOINC+18aaa0b698-r0/git/src/vnet/dpo/mpls_disposition.c:68 #8 0x00007f05d8e67f0e in fib_path_stack_mpls_disp (path_index=<optimized out>, payload_proto=<optimized out>, mode=<optimized out>, dpo=0x7f059861d540) at /usr/src/debug/vpp/21.01+gitAUTOINC+18aaa0b698-r0/git/src/vnet/fib/fib_path.c:2364 #9 0x00007f05d8e5d665 in fib_entry_src_collect_forwarding (pl_index=<optimized out>, path_index=28, arg=0x7f05952469a0) at /usr/src/debug/vpp/21.01+gitAUTOINC+18aaa0b698-r0/git/src/vnet/fib/fib_entry_src.c:483 #10 0x00007f05d8e658a6 in fib_path_list_walk (path_list_index=26, func=func@entry=0x7f05d8e5d530 <fib_entry_src_collect_forwarding>, ctx=ctx@entry=0x7f05952469a0) at /usr/src/debug/vpp/21.01+gitAUTOINC+18aaa0b698-r0/git/src/vnet/fib/fib_path_list.c:1398 #11 0x00007f05d8e5dd94 in fib_entry_src_mk_lb (fib_entry=fib_entry@entry=0x7f059dbde7b0, esrc=esrc@entry=0x7f059861cc70, fct=<optimized out>, dpo_lb=dpo_lb@entry=0x7f059dbde7d8) at /usr/src/debug/vpp/21.01+gitAUTOINC+18aaa0b698-r0/git/src/vnet/fib/fib_entry_src.c:575 #12 0x00007f05d8e5e0f0 in fib_entry_src_action_install (fib_entry=fib_entry@entry=0x7f059dbde7b0, source=source@entry=FIB_SOURCE_CLI) at /usr/src/debug/vpp/21.01+gitAUTOINC+18aaa0b698-r0/git/src/vnet/fib/fib_entry_src.c:705 #13 0x00007f05d8e5e3dc in fib_entry_src_action_activate (fib_entry=fib_entry@entry=0x7f059dbde7b0, source=source@entry=FIB_SOURCE_CLI) at /usr/src/debug/vpp/21.01+gitAUTOINC+18aaa0b698-r0/git/src/vnet/fib/fib_entry_src.c:1078 #14 0x00007f05d8e5b917 in fib_entry_create (fib_index=fib_index@entry=0, prefix=prefix@entry=0x7f0595246b40, source=source@entry=FIB_SOURCE_CLI, flags=<optimized out>, paths=paths@entry=0x7f059861cc00) at /usr/src/debug/vpp/21.01+gitAUTOINC+18aaa0b698-r0/git/src/vnet/fib/fib_entry.c:746 #15 0x00007f05d8e51eda in fib_table_entry_path_add2 (fib_index=0, prefix=prefix@entry=0x7f0595246b40, source=source@entry=FIB_SOURCE_CLI, flags=<optimized out>, flags@entry=FIB_ENTRY_FLAG_NONE, rpaths=rpaths@entry=0x7f059861cc00) at /usr/src/debug/vpp/21.01+gitAUTOINC+18aaa0b698-r0/git/src/vnet/fib/fib_table.c:625 ---Type <return> to continue, or q <return> to quit--- #16 0x00007f05d8c7273f in vnet_mpls_local_label (vm=<optimized out>, input=<optimized out>, cmd=<optimized out>) at /usr/src/debug/vpp/21.01+gitAUTOINC+18aaa0b698-r0/git/src/vnet/mpls/mpls.c:347 #17 0x00007f05d7f41521 in vlib_cli_dispatch_sub_commands (vm=vm@entry=0x7f05d7fc4680 <vlib_global_main>, cm=cm@entry=0x7f05d7fc48e0 <vlib_global_main+608>, input=input@entry=0x7f0595246db0, parent_command_index=<optimized out>) at /usr/src/debug/vpp/21.01+gitAUTOINC+18aaa0b698-r0/git/src/vlib/cli.c:572 #18 0x00007f05d7f4165b in vlib_cli_dispatch_sub_commands (vm=vm@entry=0x7f05d7fc4680 <vlib_global_main>, cm=cm@entry=0x7f05d7fc48e0 <vlib_global_main+608>, input=input@entry=0x7f0595246db0, parent_command_index=parent_command_index@entry=0) at /usr/src/debug/vpp/21.01+gitAUTOINC+18aaa0b698-r0/git/src/vlib/cli.c:529 #19 0x00007f05d7f41a51 in vlib_cli_input () at /usr/src/debug/vpp/21.01+gitAUTOINC+18aaa0b698-r0/git/src/vlib/cli.c:674 #20 0x0000000000410aad in vl_api_cli_inband_t_handler (mp=0x1300b90c8) at /usr/src/debug/vpp/21.01+gitAUTOINC+18aaa0b698-r0/git/src/vpp/api/api.c:227 #21 0x00007f05d9060bf9 in vl_msg_api_handler_with_vm_node (am=am@entry=0x7f05d9073f60 <api_global_main>, vlib_rp=vlib_rp@entry=0x13002b000, the_msg=<optimized out>, vm=vm@entry=0x7f05d7fc4680 <vlib_global_main>, node=node@entry=0x7f0598209100, is_private=is_private@entry=0 '\000') at /usr/src/debug/vpp/21.01+gitAUTOINC+18aaa0b698-r0/git/src/vlibapi/api_shared.c:635 #22 0x00007f05d9047591 in void_mem_api_handle_msg_i (is_private=0 '\000', node=0x7f0598209100, vm=0x7f05d7fc4680 <vlib_global_main>, vlib_rp=0x13002b000, am=0x7f05d9073f60 <api_global_main>) at /usr/src/debug/vpp/21.01+gitAUTOINC+18aaa0b698-r0/git/src/vlibmemory/memory_api.c:696 The only difference between config 1 and config 2 was that of "eos" bit i.e. bit was set in the latter. *Config 3:-* Also, I tried configuring PE Router by creating tunnel interface and used that interface as a target in IP Route. Following is the config used. mpls table add 0 set interface mpls GigabitEthernet0/6/0 enable--------------->Incoming Interface is GigabitEthernet0/6/0 set interface mpls GigabitEthernet0/7/0 enable--------------->Outgoing Interface is GigabitEthernet0/7/0 mpls tunnel add via 20.20.20.20 GigabitEthernet0/7/0 out-labels 44 set interface state mpls-tunnel0 up ip route add 10.10.10.10/32 via mpls-tunnel0------------------>It seems to be working as expected *Expectation:-* On receiving IP packet, it should be able to encapsulate an MPLS header with label 44 and send the packet out via GigabitEthernet0/7/0 *Observation:-* It was able to encapsulate an MPLS header with label 44 and sent the packet out via GigabitEthernet0/7/0. The stats corresponding to mpls-tunnel0 interface were also incremented in vpp “show int“ CLI command Based on the above observations, I have the following set of queries around vpp tunnel interface usage:- - Are mpls tunnel interface creation meant only for PE(Provider Edge Routers)? - Can we create and use tunnel interface as a target in mpls routes on Provider Routers for achieving label swap operation i.e. label pop followed by label push i.e. something like this “mpls local-label add 33 [ *eos]* via mpls-tunnel0”? - Usage of mpls tunnel interface? Any documentation? Regards Amit
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