Example of IOS-XE SD-WAN Issues Troubleshoot With Help of EPC and Packet-Trace
Available Languages
Contents
Introduction
This document describes the example of intermittent connectivity failures troubleshoot approach on a router running Cisco IOS-XE SD-WAN using Embedded Packet Capture (EPC) and Packet Trace utilities.
Problem
Your users of a Branch site report that some Internet applications that use Direct Internet Access (DIA) like SAP®, SSH, some FTP clients and set of others applications are timing out if a user is idle longer than about 2-3 minutes. If they perform any active actions within the applications requiring network communication, applications work well and no problems are observed.
For instance, if you execute show version and leave the session for more than 2 minutes idle without any activity and after that press any key on the keyboard as in the output here:
router#Connection reset by 100.64.2.9 port 22
IDLE timeout on the terminal line of the router was checked and found that exec-timeout is set to 10 minutes and is not responsible for the described behavior (keep in mind that other applications are also affected):
router#show user
Line User Host(s) Idle Location
* 1 vty 0 ekhabaro idle 00:00:00 10.149.4.41
Interface User Mode Idle Peer Address
unknown (ONEP) csrmgmt_infr 00:00:14
router#show line vty 0 | s Timeout
Timeouts: Idle EXEC Idle Session Modem Answer Session Dispatch
00:10:00 never none not set
Idle Session Disconnect Warning
never
Login-sequence User Response
00:00:30
Autoselect Initial Wait
not set
Another way to experience the problem live is to connect to some public FTP. Then, If you try to refresh directory listing, change folder or download something after 2-3 minutes of inactivity, the message is seen (in red):
Solution
Such issues are complex to troubleshoot sometimes, but great help can provide IOS-XE Datapath Packet Trace feature and Embedded Packet Capture (EPC) IOS-XE utilities. Here an example of usage and approach to troubleshoot.
Troubleshoot with EPC
Configure and start Embedded Packet Capture (EPC) on the router. Since this site is using DIA, you need to capture traffic on external and internal interfaces separately. Here 198.51.100.7 is the IP-address of FTP server and 10.5.40.14 is the IP-address of the client:
Branch#config-transaction admin connected from 127.0.0.1 using console on Branch Branch(config)# ip access-list extended CAP_ACL Branch(config-ext-nacl)# 10 permit ip any host 10.5.40.14 Branch(config-ext-nacl)# 20 permit ip host 10.5.40.14 any Branch(config-ext-nacl)# 30 permit ip any host 198.51.100.7 Branch(config-ext-nacl)# 40 permit ip host 198.51.100.7 any Branch(config-ext-nacl)# commit Commit complete. Branch(config-ext-nacl)# end Branch# Branch#monitor capture CAP_EXT interface GigabitEthernet 2 both Branch#monitor capture CAP_EXT interface GigabitEthernet 3 both Branch#monitor capture CAP_INT interface GigabitEthernet 7 both Branch#monitor capture CAP_EXT access-list CAP_ACL Branch#monitor capture CAP_INT access-list CAP_ACL Branch#monitor capture CAP_EXT start Started capture point : CAP_EXT Branch#monitor capture CAP_INT start Started capture point : CAP_INT
Next, from the user's host with connect to the FTP server using FileZilla FTP client. Ensure to disable FTP client timeout for connection in the Edit > Settings of FTP client options:
By default, FileZilla FTP client closes the session itself after 20 seconds and you are not able to reproduce the problem seen by the user with other applications.
After about 2-3 minutes of inactivity, try refresh directory listing:
Then, in the FTP client you see the error message like on the screenshot:
Next, check that some packets were captured on both inside and outside interfaces, stop EPC and export buffers:
Branch#show monitor capture CAP_EXT buffer buffer size (KB) : 10240 buffer used (KB) : 128 packets in buf : 37 packets dropped : 0 packets per sec : 24 Branch#show monitor capture CAP_INT buffer buffer size (KB) : 10240 buffer used (KB) : 128 packets in buf : 39 packets dropped : 0 packets per sec : 1 Branch#monitor capture CAP_INT stop_export Exported Successfully Branch#monitor capture CAP_EXT stop_export Exported Successfully
And upload captures to your PC so you can analyze it with Wireshark:
Branch#copy flash:CAP_INT.pcap sftp://admin:admin@203.0.113.36: vrf Mgmt-intf Address or name of remote host [203.0.113.36]? Destination username [admin]? Destination filename [CAP_INT.pcap]? SFTP send: Writing to /CAP_INT.pcap size 4362 ! 4362 bytes copied in 0.296 secs (14736 bytes/sec) Branch#copy flash:CAP_EXT.pcap sftp://admin:admin@203.0.113.36: vrf Mgmt-intf Address or name of remote host [203.0.113.36]? Destination username [admin]? Destination filename [CAP_EXT.pcap]? SFTP send: Writing to /CAP_EXT.pcap size 3839 ! 3839 bytes copied in 0.299 secs (12839 bytes/sec)
Open both files in the separate Wireshark windows and set Time Display Format to make it easier to correlate packets on the outside interface with packets on the inside interface by timestamps:
Then align windows and notice the difference between packet captures made on the external and on the internal interfaces (look for FTP PASV request in your captures):
You can see that request is sent to the outside and a bunch of retransmissions happened. At this point, it’s not clear why packets from the external hosts (e.g. packets number 88,90,92 and so on) are not reaching to the internal host, but EPC gave us valuable information and confirmed that some packets are being dropped by cEdge router.
Troubleshoot with Help of Cisco IOS-XE Packet Tracer Utility
To investigate further, you must use packet-capture and filter data based on FTP server public address:
debug platform condition ipv4 198.51.100.7/32 both debug platform packet-trace packet 1024 fia-trace data-size 4096 debug platform condition start !if you want to capture HEX data of the packet, use as well: debug platform packet-trace copy packet both size 2048 L2
Then, connect to the FTP in a second time and wait for longer than 2-3 minutes before you click the refresh button or downloading something again. In the log, you can notice the same error message, as shown in the image:
Now, from packet-trace you can see one of the packets was dropped:
134 Gi3 internal0/0/svc_eng:0 PUNT 64 (Service Engine packet) 135 Tu6000001 Gi7 FWD 136 Gi7 internal0/0/svc_eng:0 PUNT 64 (Service Engine packet) 137 Tu6000001 Gi3 FWD 138 Gi3 internal0/0/svc_eng:0 PUNT 64 (Service Engine packet) 139 Tu6000001 Gi7 FWD 140 Gi7 internal0/0/svc_eng:0 PUNT 64 (Service Engine packet) 141 Tu6000001 Gi3 FWD 142 Gi3 Gi3 DROP 479 (SdwanImplicitAclDrop) 143 Gi3 Gi3 DROP 479 (SdwanImplicitAclDrop) 144 Gi3 Gi3 DROP 479 (SdwanImplicitAclDrop) 145 Gi3 Gi3 DROP 479 (SdwanImplicitAclDrop) 146 Gi3 Gi3 DROP 479 (SdwanImplicitAclDrop) 147 Gi3 Gi3 DROP 479 (SdwanImplicitAclDrop) 148 Gi3 Gi3 DROP 479 (SdwanImplicitAclDrop) 149 Gi3 Gi3 DROP 479 (SdwanImplicitAclDrop) 150 Gi3 Gi3 DROP 479 (SdwanImplicitAclDrop) 151 Gi3 Gi3 DROP 479 (SdwanImplicitAclDrop)
You can also check details of particular packet:
Branch#show platform packet-trace packet 151
Packet: 151 CBUG ID: 151
Summary
Input : GigabitEthernet3
Output : GigabitEthernet3
State : DROP 479 (SdwanImplicitAclDrop) <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
Timestamp
Start : 179731083510 ns (11/07/2019 13:08:27.567722 UTC)
Stop : 179731145820 ns (11/07/2019 13:08:27.567785 UTC)
Path Trace
Feature: IPV4(Input)
Input : GigabitEthernet3
Output : <unknown>
Source : 198.51.100.7
Destination : 100.64.2.10
Protocol : 6 (TCP)
SrcPort : 21
DstPort : 5801
Feature: DEBUG_COND_INPUT_PKT
Entry : Input - 0x817e8838
Input : GigabitEthernet3
Output : <unknown>
Lapsed time : 8280 ns
Feature: IPV4_INPUT_DST_LOOKUP_CONSUME
Entry : Input - 0x817e885c
Input : GigabitEthernet3
Output : <unknown>
Lapsed time : 4160 ns
Feature: SDWAN Implicit ACL <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
Action : DISALLOW
Reason : SDWAN_SERV_TCP
Defer Action to Ingress ACL : No
Feature: STILE_LEGACY_DROP_EXT
Entry : Input - 0x81835c68
Input : GigabitEthernet3
Output : <unknown>
Lapsed time : 12900 ns
Feature: INGRESS_MMA_LOOKUP_DROP_EXT
Entry : Input - 0x8182be6c
Input : GigabitEthernet3
Output : <unknown>
Lapsed time : 14940 ns
Feature: INPUT_DROP_FNF_AOR_EXT
Entry : Input - 0x81819480
Input : GigabitEthernet3
Output : <unknown>
Lapsed time : 22040 ns
Feature: INPUT_FNF_DROP_EXT
Entry : Input - 0x818185bc
Input : GigabitEthernet3
Output : <unknown>
Lapsed time : 17580 ns
Feature: INPUT_DROP_FNF_AOR_RELEASE_EXT
Entry : Input - 0x81818e08
Input : GigabitEthernet3
Output : <unknown>
Lapsed time : 4680 ns
Feature: INPUT_DROP_EXT
Entry : Input - 0x817ed780
Input : GigabitEthernet3
Output : <unknown>
Lapsed time : 5540 ns
Feature: IPV4_SDWAN_IMPLICIT_ACL <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
Entry : Input - 0x8183c774
Input : GigabitEthernet3
Output : <unknown>
Lapsed time : 449760 ns
Packet Copy In
00505608 6e500050 56add375 08004500 00363481 40002d06 122c5a82 46496440
020a0015 16a9f873 89d3efaa e3785019 00e523cb 00003432 31205469 6d656f75
Packet Copy Out
00505608 6e500050 56add375 08004500 00363481 40002c06 132c5a82 46496440
020a0015 16a9f873 89d3efaa e3785019 00e523cb 00003432 31205469 6d656f75
Those packets are retransmitted from the targeted FTP server. You have seen a similar set of retransmits in the packet capture already.
Based on the packet-trace output, it seems that for some reason SD-WAN implicit ACL (that is actually a list of services allowed under tunnel-interface configuration) is dropping packets. You can conclude this from the lines highlighted with <<<<< marks. In order to test, exclude SD-WAN implicit ACL and allow all services in the configuration of the corresponding outside interface:
Branch#config-transaction admin connected from 127.0.0.1 using console on Branch Branch(config)# sdwan Branch(config-sdwan)# interface GigabitEthernet3 Branch(config-interface-GigabitEthernet3)# tunnel-interface Branch(config-tunnel-interface)# allow-service all Branch(config-tunnel-interface)# commit Commit complete.
Once configuration committed, let's repeat the test, but ensure to stop packet-trace and start over before:
debug platform condition stop debug platform packet-trace packet 1024 fia-trace data-size 4096 debug platform condition start
When the problem is reproduced one more time (e.g. when you try to change directory) and the connection is lost as per logs of FTP client (FTP client attempted to reconnect), let's see packet-trace statistics once again:
Branch# show platform packet-trace statistics
Packets Summary
Matched 292
Traced 292
Packets Received
Ingress 282
Inject 10
Count Code Cause
10 6 QFP Fwall generated packet
Packets Processed
Forward 134
Punt 134
Count Code Cause
5 22 QFP Fwall generated packet
129 64 Service Engine packet
Drop 24
Count Code Cause
21 55 ForUs
Consume 0
Now you can notice another drop code, “DROP 55 (ForUs)”, despite that you disabled implicit ACL with allow-service all configuration, packets are still being dropped. Take a closer look and try to understand the difference between dropped packets and forwarded packets:
Branch#show platform packet-trace summary <skipped> 269 Gi3 internal0/0/svc_eng:0 PUNT 64 (Service Engine packet) 270 Gi3 internal0/0/svc_eng:0 PUNT 64 (Service Engine packet) 271 Tu6000001 Gi7 FWD 272 Tu6000001 Gi7 FWD 273 Gi7 internal0/0/svc_eng:0 PUNT 64 (Service Engine packet) 274 Gi7 internal0/0/svc_eng:0 PUNT 64 (Service Engine packet) 275 Tu6000001 Gi3 FWD 276 Tu6000001 Gi3 FWD 277 Gi7 internal0/0/svc_eng:0 PUNT 64 (Service Engine packet) 278 Tu6000001 Gi3 FWD 279 Gi3 internal0/0/svc_eng:0 PUNT 64 (Service Engine packet) 280 Tu6000001 Gi7 FWD 281 Gi7 internal0/0/svc_eng:0 PUNT 64 (Service Engine packet) 282 Tu6000001 Gi3 FWD 283 Gi3 Gi3 DROP 55 (ForUs) 284 Gi3 Gi3 DROP 55 (ForUs) 285 Gi3 Gi3 DROP 55 (ForUs) 286 Gi3 Gi3 DROP 55 (ForUs) 287 Gi3 Gi3 DROP 55 (ForUs) 288 Gi3 Gi3 DROP 55 (ForUs) 289 Gi3 Gi3 DROP 55 (ForUs) 290 Gi3 Gi3 DROP 55 (ForUs) 291 Gi3 Gi3 DROP 55 (ForUs) 292 Gi3 Gi3 DROP 55 (ForUs) 293 Gi3 Gi3 DROP 55 (ForUs)
In the previous output, Gi7 is a service-side interface, Gi3 is a transport side interface. For example, compare the difference between packet 279 and packet 283 (important differences are marked with <<<<<):
Branch#show platform packet-trace packet 279
Packet: 279 CBUG ID: 794
Summary
Input : GigabitEthernet3
Output : internal0/0/svc_eng:0
State : PUNT 64 (Service Engine packet)
Timestamp
Start : 142279273535701 ns (11/07/2019 12:46:47.57026 UTC)
Stop : 142279273732912 ns (11/07/2019 12:46:47.57223 UTC)
Path Trace
Feature: IPV4(Input)
Input : GigabitEthernet3
Output : <unknown>
Source : 198.51.100.7
Destination : 100.64.2.10
Protocol : 6 (TCP)
SrcPort : 28143
DstPort : 5668
Feature: DEBUG_COND_INPUT_PKT
Entry : Input - 0x817e8838
Input : GigabitEthernet3
Output : <unknown>
Lapsed time : 5880 ns
Feature: IPV4_INPUT_DST_LOOKUP_CONSUME
Entry : Input - 0x817e885c
Input : GigabitEthernet3
Output : <unknown>
Lapsed time : 7320 ns
Feature: SDWAN Implicit ACL <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
Action : ALLOW
Reason : SDWAN_NAT_DIA <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
Defer Action to Ingress ACL : No
Feature: IPV4_SDWAN_IMPLICIT_ACL
Entry : Input - 0x8183c774
Input : GigabitEthernet3
Output : <unknown>
Lapsed time : 112800 ns
Feature: IPV4_INPUT_FOR_US_MARTIAN
Entry : Input - 0x817e8860
Input : GigabitEthernet3
Output : <unknown>
Lapsed time : 78480 ns
Feature: DEBUG_COND_APPLICATION_IN
Entry : Input - 0x817e8848
Input : GigabitEthernet3
Output : <unknown>
Lapsed time : 1460 ns
Feature: DEBUG_COND_APPLICATION_IN_CLR_TXT
Entry : Input - 0x817e884c
Input : GigabitEthernet3
Output : <unknown>
Lapsed time : 120 ns
Feature: IPV4_INPUT_VFR <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
Entry : Input - 0x817e89b0
Input : GigabitEthernet3
Output : <unknown>
Lapsed time : 3880 ns
Feature: NAT <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
Direction : OUT to IN
Action : Translate Destination
Steps :
Match id : 1
Old Address : 100.64.2.10 05668
New Address : 10.5.40.14 49588
Feature: IPV4_NAT_INPUT_FIA <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
Entry : Input - 0x8182c8a8
Input : GigabitEthernet3
Output : <unknown>
Lapsed time : 117600 ns
Feature: IPV4_INPUT_DST_LOOKUP_ISSUE_EXT
Entry : Input - 0x817e8858
Input : GigabitEthernet3
Output : <unknown>
Lapsed time : 19620 ns
Feature: RELOOKUP_NOTIFY_EXT
Entry : Input - 0x817eed90
Input : GigabitEthernet3
Output : <unknown>
Lapsed time : 14040 ns
Feature: IPV4_INTERNAL_DST_LOOKUP_CONSUME_EXT
Entry : Input - 0x817e8870
Input : GigabitEthernet3
Output : <unknown>
Lapsed time : 4620 ns
Feature: IPV4_INPUT_FOR_US_EXT
Entry : Input - 0x817e89a4
Input : GigabitEthernet3
Output : <unknown>
Lapsed time : 280 ns
Feature: IPV4_VFR_REFRAG_EXT
Entry : Input - 0x817e89c0
Input : GigabitEthernet3
Output : <unknown>
Lapsed time : 2720 ns
Feature: CFT
API : cft_handle_pkt
packet capabilities : 0x0000018c
input vrf_idx : 0
calling feature : STILE
direction : Input
triplet.vrf_idx : 3
triplet.network_start : 0x01003f8e
triplet.triplet_flags : 0x00000000
triplet.counter : 32
cft_bucket_number : 942419
cft_l3_payload_size : 20
cft_pkt_ind_flags : 0x00000100
cft_pkt_ind_valid : 0x00009bff
tuple.src_ip : 198.51.100.7
tuple.dst_ip : 10.5.40.14
tuple.src_port : 28143
tuple.dst_port : 49588
tuple.vrfid : 3
tuple.l4_protocol : TCP
tuple.l3_protocol : IPV4
pkt_sb_state : 0
pkt_sb.num_flows : 1
pkt_sb.tuple_epoch : 32
returned cft_error : 0
returned fid : 0xec4eeb70
Feature: NBAR
Packet number in flow: N/A
Classification state: Final
Classification name: ftp-data
Classification ID: [IANA-L4:20]
Classification source: Unknown
Number of matched sub-classifications: 0
Number of extracted fields: 0
Is PA (split) packet: False
TPH-MQC bitmask value: 0x0
Is optimized packet: False
Feature: IPV4_INPUT_STILE_LEGACY_EXT
Entry : Input - 0x81835ba8
Input : GigabitEthernet3
Output : <unknown>
Lapsed time : 315800 ns
Feature: IPV4_INPUT_FNF_FIRST_EXT
Entry : Input - 0x81818128
Input : GigabitEthernet3
Output : <unknown>
Lapsed time : 62200 ns
Feature: SDWAN_APP_ROUTE_POLICY_EXT
Entry : Input - 0x8183c758
Input : GigabitEthernet3
Output : <unknown>
Lapsed time : 12440 ns
Feature: SDWAN_DATA_POLICY_OUT_EXT
Entry : Input - 0x8183c754
Input : GigabitEthernet3
Output : <unknown>
Lapsed time : 12520 ns
Feature: IPV4_INPUT_LOOKUP_PROCESS_EXT
Entry : Input - 0x817e8864
Input : GigabitEthernet3
Output : GigabitEthernet7
Lapsed time : 8900 ns
Feature: IPV4_INPUT_IPOPTIONS_GOTO_OUTPUT_FEATURE_EXT
Entry : Output - 0x817e895c
Input : GigabitEthernet3
Output : GigabitEthernet7
Lapsed time : 9840 ns
Feature: CBUG_OUTPUT_FIA
Entry : Output - 0x817e8840
Input : GigabitEthernet3
Output : GigabitEthernet7
Lapsed time : 6520 ns
Feature: IPV4_OUTPUT_VFR
Entry : Output - 0x817e89b4
Input : GigabitEthernet3
Output : GigabitEthernet7
Lapsed time : 3660 ns
Feature: ZBFW
Action : Fwd
Zone-pair name : ZP_GUEST-INSIDE_OUTSID_642078363
Class-map name : BRANCH-DIA-GUEST-seq-11-cm_
Input interface : GigabitEthernet3
Egress interface : GigabitEthernet7
AVC Classification ID : 0
AVC Classification name: N/A
Feature: IPV4_OUTPUT_INSPECT
Entry : Output - 0x8181c97c
Input : GigabitEthernet3
Output : GigabitEthernet7
Lapsed time : 296980 ns
Feature: CFT
API : cft_handle_pkt
packet capabilities : 0x00000014
input vrf_idx : 0
calling feature : UTD
direction : Input
triplet.vrf_idx : 3
triplet.network_start : 0x01003f8e
triplet.triplet_flags : 0x00000004
triplet.counter : 32
cft_bucket_number : 942419
cft_l3_payload_size : 20
cft_pkt_ind_flags : 0x00000100
cft_pkt_ind_valid : 0x0000bbff
tuple.src_ip : 198.51.100.7
tuple.dst_ip : 10.5.40.14
tuple.src_port : 28143
tuple.dst_port : 49588
tuple.vrfid : 3
tuple.l4_protocol : TCP
tuple.l3_protocol : IPV4
pkt_sb_state : 0
pkt_sb.num_flows : 1
pkt_sb.tuple_epoch : 32
returned cft_error : 0
returned fid : 0xec4eeb70
Feature: UTD Policy (First FIA)
Action : Divert
Input interface : GigabitEthernet3
Egress interface: GigabitEthernet7
Feature: OUTPUT_UTD_FIRST_INSPECT
Entry : Output - 0x8183a0d8
Input : GigabitEthernet3
Output : GigabitEthernet7
Lapsed time : 117420 ns
Feature: UTD Inspection
Action : Divert
Input interface : GigabitEthernet3
Egress interface: GigabitEthernet7
Feature: OUTPUT_UTD_FINAL_INSPECT
Entry : Output - 0x8183a108
Input : GigabitEthernet3
Output : GigabitEthernet7
Lapsed time : 122900 ns
Feature: IPV4_OUTPUT_LOOKUP_PROCESS_EXT
Entry : Output - 0x817ee0e8
Input : GigabitEthernet3
Output : Tunnel6000001
Lapsed time : 10980 ns
Feature: IPV4_OUTPUT_GOTO_OUTPUT_FEATURE_EXT
Entry : Output - 0x817edfd0
Input : GigabitEthernet3
Output : Tunnel6000001
Lapsed time : 16200 ns
Feature: CBUG_OUTPUT_FIA
Entry : Output - 0x817e8840
Input : GigabitEthernet3
Output : Tunnel6000001
Lapsed time : 4960 ns
Feature: IPV4_OUTPUT_VFR
Entry : Output - 0x817e89b4
Input : GigabitEthernet3
Output : Tunnel6000001
Lapsed time : 520 ns
Feature: IPV4_OUTPUT_INSPECT
Entry : Output - 0x8181c97c
Input : GigabitEthernet3
Output : Tunnel6000001
Lapsed time : 4420 ns
Feature: IPV4_OUTPUT_THREAT_DEFENSE
Entry : Output - 0x81838278
Input : GigabitEthernet3
Output : Tunnel6000001
Lapsed time : 3300 ns
Feature: IPV4_VFR_REFRAG
Entry : Output - 0x817e89c0
Input : GigabitEthernet3
Output : Tunnel6000001
Lapsed time : 320 ns
Feature: DEBUG_COND_APPLICATION_OUT_CLR_TXT
Entry : Output - 0x817e8854
Input : GigabitEthernet3
Output : Tunnel6000001
Lapsed time : 4740 ns
Feature: UTD Encaps
Action : Encaps
Input interface : GigabitEthernet3
Egress interface: Tunnel6000001
Feature: IPV4_OUTPUT_L2_REWRITE
Entry : Output - 0x817e83b0
Input : GigabitEthernet3
Output : Tunnel6000001
Lapsed time : 296420 ns
Feature: DEBUG_COND_MAC_EGRESS
Entry : Output - 0x817e8844
Input : GigabitEthernet3
Output : Tunnel6000001
Lapsed time : 860 ns
Feature: DEBUG_COND_APPLICATION_OUT
Entry : Output - 0x817e8850
Input : GigabitEthernet3
Output : Tunnel6000001
Lapsed time : 300 ns
Feature: IPV4_OUTPUT_FRAG
Entry : Output - 0x817e89a8
Input : GigabitEthernet3
Output : Tunnel6000001
Lapsed time : 2560 ns
Feature: IPV4_OUTPUT_SDWAN_FNF_FINAL
Entry : Output - 0x818181b8
Input : GigabitEthernet3
Output : Tunnel6000001
Lapsed time : 100980 ns
Feature: IPV4_TUNNEL_OUTPUT_FINAL
Entry : Output - 0x81838bac
Input : Tunnel6000001
Output : Tunnel6000001
Lapsed time : 55460 ns
Feature: IPV4_TUNNEL_GOTO_OUTPUT
Entry : Output - 0x81838bb0
Input : Tunnel6000001
Output : Tunnel6000001
Lapsed time : 3920 ns
Feature: IPV4_TUNNEL_FW_CHECK_EXT
Entry : Output - 0x81838de8
Input : Tunnel6000001
Output : Tunnel6000001
Lapsed time : 9520 ns
Feature: IPV4_INPUT_DST_LOOKUP_ISSUE_EXT
Entry : Output - 0x817e8858
Input : Tunnel6000001
Output : Tunnel6000001
Lapsed time : 14960 ns
Feature: IPV4_INPUT_ARL_EXT
Entry : Output - 0x817e89d0
Input : Tunnel6000001
Output : Tunnel6000001
Lapsed time : 5680 ns
Feature: IPV4_INTERNAL_DST_LOOKUP_CONSUME_EXT
Entry : Output - 0x817e8870
Input : Tunnel6000001
Output : Tunnel6000001
Lapsed time : 1260 ns
Feature: IPV4_TUNNEL_ENCAP_FOR_US_EXT
Entry : Output - 0x81838db8
Input : Tunnel6000001
Output : Tunnel6000001
Lapsed time : 5460 ns
Feature: IPV4_INPUT_LOOKUP_PROCESS_EXT
Entry : Output - 0x817e8864
Input : Tunnel6000001
Output : VirtualPortGroup1
Lapsed time : 960 ns
Feature: IPV4_TUNNEL_ENCAP_GOTO_OUTPUT_FEATURE_EXT
Entry : Output - 0x817ee30c
Input : Tunnel6000001
Output : VirtualPortGroup1
Lapsed time : 13020 ns
Feature: CBUG_OUTPUT_FIA
Entry : Output - 0x817e8840
Input : Tunnel6000001
Output : VirtualPortGroup1
Lapsed time : 1980 ns
Feature: IPV4_OUTPUT_VFR
Entry : Output - 0x817e89b4
Input : Tunnel6000001
Output : VirtualPortGroup1
Lapsed time : 660 ns
Feature: IPV4_OUTPUT_INSPECT
Entry : Output - 0x8181c97c
Input : Tunnel6000001
Output : VirtualPortGroup1
Lapsed time : 15960 ns
Feature: IPV4_OUTPUT_THREAT_DEFENSE
Entry : Output - 0x81838278
Input : Tunnel6000001
Output : VirtualPortGroup1
Lapsed time : 1720 ns
Feature: IPV4_VFR_REFRAG
Entry : Output - 0x817e89c0
Input : Tunnel6000001
Output : VirtualPortGroup1
Lapsed time : 660 ns
Feature: DEBUG_COND_APPLICATION_OUT_CLR_TXT
Entry : Output - 0x817e8854
Input : Tunnel6000001
Output : VirtualPortGroup1
Lapsed time : 1560 ns
Feature: IPV4_OUTPUT_L2_REWRITE
Entry : Output - 0x817e83b0
Input : Tunnel6000001
Output : VirtualPortGroup1
Lapsed time : 10420 ns
Feature: DEBUG_COND_MAC_EGRESS
Entry : Output - 0x817e8844
Input : Tunnel6000001
Output : VirtualPortGroup1
Lapsed time : 520 ns
Feature: DEBUG_COND_APPLICATION_OUT
Entry : Output - 0x817e8850
Input : Tunnel6000001
Output : VirtualPortGroup1
Lapsed time : 180 ns
Feature: IPV4_OUTPUT_FRAG
Entry : Output - 0x817e89a8
Input : Tunnel6000001
Output : VirtualPortGroup1
Lapsed time : 940 ns
Feature: IPV4_OUTPUT_SDWAN_FNF_FINAL
Entry : Output - 0x818181b8
Input : Tunnel6000001
Output : VirtualPortGroup1
Lapsed time : 2560 ns
Feature: OUTPUT_SERVICE_ENGINE
Entry : Output - 0x81834550
Input : Tunnel6000001
Output : internal0/0/svc_eng:0
Lapsed time : 65820 ns
Feature: IPV4_INTERNAL_ARL_SANITY_EXT
Entry : Output - 0x817e89f4
Input : Tunnel6000001
Output : internal0/0/svc_eng:0
Lapsed time : 12280 ns
Feature: ZBFW
Action : Fwd
Zone-pair name : N/A
Class-map name : N/A
Input interface : Tunnel6000001
Egress interface : internal0/0/svc_eng:0
AVC Classification ID : 0
AVC Classification name: N/A
Feature: IPV4_OUTPUT_INSPECT_EXT
Entry : Output - 0x8181c97c
Input : Tunnel6000001
Output : internal0/0/svc_eng:0
Lapsed time : 38200 ns
Feature: IPV4_OUTPUT_THREAT_DEFENSE_EXT
Entry : Output - 0x81838278
Input : Tunnel6000001
Output : internal0/0/svc_eng:0
Lapsed time : 1980 ns
Feature: IPV4_VFR_REFRAG_EXT
Entry : Output - 0x817e89c0
Input : Tunnel6000001
Output : internal0/0/svc_eng:0
Lapsed time : 400 ns
Feature: IPV4_OUTPUT_DROP_POLICY_EXT
Entry : Output - 0x817e893c
Input : Tunnel6000001
Output : internal0/0/svc_eng:0
Lapsed time : 26240 ns
Feature: INTERNAL_TRANSMIT_PKT_EXT
Entry : Output - 0x817e88e4
Input : Tunnel6000001
Output : internal0/0/svc_eng:0
Lapsed time : 156540 ns
Branch#show platform packet-trace packet 283
Packet: 283 CBUG ID: 798
Summary
Input : GigabitEthernet3
Output : GigabitEthernet3
State : DROP 55 (ForUs)
Timestamp
Start : 142367023778233 ns (11/07/2019 12:48:14.807268 UTC)
Stop : 142367023853492 ns (11/07/2019 12:48:14.807343 UTC)
Path Trace
Feature: IPV4(Input)
Input : GigabitEthernet3
Output : <unknown>
Source : 198.51.100.7
Destination : 100.64.2.10
Protocol : 6 (TCP)
SrcPort : 21
DstPort : 5635
Feature: DEBUG_COND_INPUT_PKT
Entry : Input - 0x817e8838
Input : GigabitEthernet3
Output : <unknown>
Lapsed time : 12340 ns
Feature: IPV4_INPUT_DST_LOOKUP_CONSUME
Entry : Input - 0x817e885c
Input : GigabitEthernet3
Output : <unknown>
Lapsed time : 7140 ns
Feature: SDWAN Implicit ACL <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
Action : ALLOW
Reason : SDWAN_SERV_ALL <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
Defer Action to Ingress ACL : No
Feature: IPV4_SDWAN_IMPLICIT_ACL
Entry : Input - 0x8183c774
Input : GigabitEthernet3
Output : <unknown>
Lapsed time : 139700 ns
Feature: IPV4_INPUT_FOR_US_MARTIAN
Entry : Input - 0x817e8860
Input : GigabitEthernet3
Output : <unknown>
Lapsed time : 97840 ns
Feature: DEBUG_COND_APPLICATION_IN
Entry : Input - 0x817e8848
Input : GigabitEthernet3
Output : <unknown>
Lapsed time : 2260 ns
Feature: DEBUG_COND_APPLICATION_IN_CLR_TXT
Entry : Input - 0x817e884c
Input : GigabitEthernet3
Output : <unknown>
Lapsed time : 140 ns
Feature: IPV4_INPUT_VFR <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
Entry : Input - 0x817e89b0
Input : GigabitEthernet3
Output : <unknown>
Lapsed time : 5860 ns
Feature: OCE_TRACE(Input) <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
Input : GigabitEthernet3
Output : <unknown>
Type : OCE_ADJ_RECEIVE
Feature: IPV4_NAT_INPUT_FIA <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
Entry : Input - 0x8182c8a8
Input : GigabitEthernet3
Output : <unknown>
Lapsed time : 166780 ns
Feature: STILE_LEGACY_DROP_EXT
Entry : Input - 0x81835c68
Input : GigabitEthernet3
Output : <unknown>
Lapsed time : 1920 ns
Feature: INGRESS_MMA_LOOKUP_DROP_EXT
Entry : Input - 0x8182be6c
Input : GigabitEthernet3
Output : <unknown>
Lapsed time : 8340 ns
Feature: INPUT_DROP_FNF_AOR_EXT
Entry : Input - 0x81819480
Input : GigabitEthernet3
Output : <unknown>
Lapsed time : 10920 ns
Feature: INPUT_FNF_DROP_EXT
Entry : Input - 0x818185bc
Input : GigabitEthernet3
Output : <unknown>
Lapsed time : 6460 ns
Feature: INPUT_DROP_FNF_AOR_RELEASE_EXT
Entry : Input - 0x81818e08
Input : GigabitEthernet3
Output : <unknown>
Lapsed time : 2240 ns
Feature: INPUT_DROP_EXT
Entry : Input - 0x817ed780
Input : GigabitEthernet3
Output : <unknown>
Lapsed time : 1200 ns
Feature: IPV4_INPUT_LOOKUP_PROCESS
Entry : Input - 0x817e8864
Input : GigabitEthernet3
Output : <unknown>
Lapsed time : 176340 ns
As you can see, the main difference is that usually packets from the outside are allowed with code SDWAN_NAT_DIA versus dropped packets SDWAN_SERV_ALL. Besides this, between IPV4_INPUT_VFR and IPV4_NAT_INPUT_FIA functions, for allowed packets, different IOS-XE feature is involved NAT versus OCE_TRACE. All of the difference can already give you an idea that the problem is related to the NAT, so let’s check NAT translations after an FTP session is established:
Branch#show ip nat translations tcp verbose | b 198.51.100.7 tcp 100.64.2.10:5801 10.5.40.14:49648 198.51.100.7:21 198.51.100.7:21 create: 11/07/19 13:02:05, use: 11/07/19 13:02:06, timeout: 00:00:57 Map-Id(In): 1 Flags: unknown Appl type: none WLAN-Flags: unknown Mac-Address: 0000.0000.0000 Input-IDB: VRF: 40, entry-id: 0xee541ec0, use_count:1 In_pkts: 24 In_bytes: 698, Out_pkts: 13 Out_bytes: 605 Output-IDB: GigabitEthernet3 tcp 100.64.2.10:5795 10.5.40.14:49644 52.179.129.229:443 52.179.129.229:443 create: 11/07/19 13:01:18, use: 11/07/19 13:01:18, timeout: 00:00:09 Map-Id(In): 1 Flags: timing-out Appl type: none WLAN-Flags: unknown Mac-Address: 0000.0000.0000 Input-IDB: VRF: 40, entry-id: 0xee542640, use_count:1 In_pkts: 29 In_bytes: 5114, Out_pkts: 12 Out_bytes: 7113 Output-IDB: GigabitEthernet3 tcp 100.64.2.10:5802 10.5.40.14:49649 198.51.100.7:21319 198.51.100.7:21319 create: 11/07/19 13:02:06, use: 11/07/19 13:02:06, timeout: 00:00:57 Map-Id(In): 1 Flags: timing-out Appl type: none WLAN-Flags: unknown Mac-Address: 0000.0000.0000 Input-IDB: VRF: 40, entry-id: 0xee541380, use_count:1 In_pkts: 8 In_bytes: 184, Out_pkts: 4 Out_bytes: 837 Output-IDB: GigabitEthernet3 tcp 100.64.2.10:5800 10.5.40.14:49636 198.51.100.7:21 198.51.100.7:21 create: 11/07/19 13:02:05, use: 11/07/19 13:02:05, timeout: 00:00:56 Map-Id(In): 1 Flags: timing-out Appl type: none WLAN-Flags: unknown Mac-Address: 0000.0000.0000 Input-IDB: VRF: 40, entry-id: 0xee5423c0, use_count:1 In_pkts: 2 In_bytes: 66, Out_pkts: 1 Out_bytes: 20 Output-IDB: GigabitEthernet3 tcp 100.64.2.10:5633 10.5.40.14:49432 52.242.211.89:443 52.242.211.89:443 create: 11/07/19 12:44:18, use: 11/07/19 13:01:17, timeout: 00:00:08 Map-Id(In): 1 Flags: unknown Appl type: none WLAN-Flags: unknown Mac-Address: 0000.0000.0000 Input-IDB: VRF: 40, entry-id: 0xee527840, use_count:1 In_pkts: 53 In_bytes: 6257, Out_pkts: 29 Out_bytes: 7030 Output-IDB: GigabitEthernet3 tcp 100.64.2.10:5792 10.5.40.14:49647 51.143.111.7:443 51.143.111.7:443 create: 11/07/19 13:02:00, use: 11/07/19 13:02:09, timeout: 00:01:00 Map-Id(In): 1 Flags: syn_in Appl type: none WLAN-Flags: unknown Mac-Address: 0000.0000.0000 Input-IDB: VRF: 40, entry-id: 0xee542500, use_count:1 In_pkts: 6 In_bytes: 224, Out_pkts: 3 Out_bytes: 96 Output-IDB: GigabitEthernet3 Total number of translations: 12
And pay attention to the timeout. Does not it look suspiciously low? After about 2-3 minutes of FTP client inactivity, check again and you can notice there are no translations in the NAT table:
Branch# show ip nat translations | i 198.51.100.7 Branch#
Voila! So that the root cause for the problem: sessions are expiring too fast and despite that from the perspective of FTP client session still exists, cEdge router does not know anything about that TCP session already and drops return traffic. If you check configuration, you find that NAT session timeout is configured as 120 seconds, probably by mistake:
Branch#show run | i tcp-timeout ip nat translation tcp-timeout 120 Branch#
And this timer must be fixed in the corresponding device template on vManage:
Change it to 60 min for example and then the problem is resolved.
FeedbackContact Cisco
- Open a Support Case
- (Requires a Cisco Service Contract)