{"id":2100,"date":"2016-08-16T17:33:17","date_gmt":"2016-08-16T09:33:17","guid":{"rendered":"http:\/\/www.thunder-link.com\/blog\/?p=2100"},"modified":"2023-04-12T09:29:20","modified_gmt":"2023-04-12T01:29:20","slug":"warning-of-an-arp-entry-dually-transmitting-failure","status":"publish","type":"post","link":"https:\/\/www.thunder-link.com\/blog\/warning-of-an-arp-entry-dually-transmitting-failure\/","title":{"rendered":"Warning of an ARP Entry Dually-Transmitting Failure"},"content":{"rendered":"

Keywords:<\/strong>\u00a0ATN 950B<\/a>, ARP entry dually-transmitting\u00a0failure, mixed\u00a0VPN solution<\/p>\n

Summary:<\/strong>\u00a0A timing sequence error occurs when software performs batch backup on an<\/p>\n

ATN 950B NE\u00a0functioning as a CSG\u00a0running V200R002C00SPC300 or an earlier version.<\/p>\n

After a master\/slave MPU switchover is performed several times, there is a possibility that the<\/p>\n

ARP entry dually-transmitting function fails. In this case, when network-to-user traffic transmitted<\/p>\n

along an MPLS LDP LSP reaches the slave ASG\u00a0in the mixed VPN solution, the ARP entry<\/p>\n

dually-transmitting failure causes a service interruption.<\/p>\n

[Problem<\/strong>\u00a0Description]<\/strong><\/p>\n

Usage<\/strong>\u00a0scenario:<\/strong><\/p>\n

 <\/p>\n

In a mixed VPN solution, LDP LSPs are established on the access ring network. ATN 950B NEs<\/p>\n

functioning as CSGs use the L2VPN function to transmit services and support the ARP entry<\/p>\n

dually-transmitting function configured using the mpls l2vpn arp-dual-sending<\/strong>\u00a0<\/strong>command<\/p>\n

shown in the following table.<\/p>\n\n\n\n
\n

interface Ethernet0\/3\/0.1<\/p>\n

mtu 2000<\/p>\n

vlan-type dot1q 1<\/p>\n

mpls l2vc 100.0.0.3 100 control-word raw\/\/Configure the primary PW destined for ASG3.<\/p>\n

mpls l2vc 100.0.0.4 101 control-word raw secondary\/\/Configure the secondary PW destined for ASG4.<\/p>\n

mpls l2vpn redundancy master\/\/Configure PW redundancy protection to work in master\/slave\u00a0mode.<\/p>\n

mpls l2vpn reroute delay 300\/\/Set the delay for a PW switchback to 300s.<\/p>\n

mpls l2vpn stream-dual-receiving\/\/Configure the dually-receiving\u00a0function for the primary and secondary PWs to prevent traffic loss during a traffic switchback.<\/p>\n

mpls l2vpn arp-dual-sending <\/strong>\/\/Configure ARP entry dually-transmitting function on both PWs to minimize traffic loss if a fault occurs on the primary PW.<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Trigger<\/strong>\u00a0conditions:<\/strong><\/p>\n

There is a high probability that the problem occurs if the following conditions are\u00a0met. In the<\/p>\n

laboratory, the probability is approximate 70%.<\/p>\n

1.\u00a0An MPU is reseated or the slave switchover <\/strong>command is run to perform a master\/slave MPU<\/p>\n

switchover twice. Alternatively, the slave MPU is reseated or a command is run to reset the slave MPU.<\/p>\n

2.\u00a0Another master\/slave MPU switchover\u00a0is performed.<\/p>\n

Note that there is no limit on the interval between master\/slave MPU switchovers, and the ATN 950B<\/p>\n

NE must not be reset between master\/slave MPU switchovers.<\/p>\n

Sym<\/strong>ptom:<\/strong><\/p>\n

The slave ASG fails to learn the ARP entry mapped to the nodeB\u00a0or eNodeB. As a result,<\/p>\n

network-to-user traffic on the slave ASG is interrupted.<\/p>\n

Identification<\/strong>\u00a0method:<\/strong><\/p>\n

1.\u00a0Check\u00a0the tunnel token value of an L2VPN tunnel on the ATN 950B NE.<\/p>\n

Run the display mpls l2vc interface <\/strong>interface-type<\/em>\u00a0interface-number<\/em>\u00a0command in the user view.<\/p>\n\n\n\n
\n

<HUAWEI>display mpls l2vc interface Ethernet0\/3\/0.1<\/strong>\u00a0<\/strong><\/p>\n

\/\/In real-world situations, change Ethernet0\/3\/0.1<\/strong>\u00a0to the name of the actual interface that transmits L2VPN services.
\n*client interface \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0:\u00a0Ethernet0\/3\/0.1 is up
\nAdministrator PW \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0: no
\nsession state \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0: up
\nAC status \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0: up
\nVC state \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0: up
\nLabel state \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0: 0
\nToken state \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0: 0
\nVC ID \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0: 1
\nVC type \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0: Ethernet
\ndestination \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0: 172.1.1.178
\nlocal VC label \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0: 26 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0remote VC label \u00a0\u00a0\u00a0\u00a0\u00a0: 26
\nlocal AC OAM State \u00a0\u00a0\u00a0\u00a0: up
\nlocal PSN OAM State \u00a0\u00a0\u00a0: up
\nlink state \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0: up
\nlocal VC MTU \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0: 1500 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0remote VC MTU \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0: 1500
\nlocal VCCV \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0: cw alert ttl lsp-ping bfd
\nremote VCCV \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0: cw alert ttl lsp-ping bfd
\nlocal control word \u00a0\u00a0\u00a0\u00a0: enable \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0remote control word \u00a0: enable
\ntunnel policy name \u00a0\u00a0\u00a0\u00a0: —
\nPW template name \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0: —
\nprimary or secondary \u00a0\u00a0: primary
\nload balance type \u00a0\u00a0\u00a0\u00a0\u00a0: flow
\nAccess-port \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0: false
\nSwitchover Flag \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0: false
\nVC tunnel\/token info \u00a0\u00a0: 1 tunnels\/tokens
\nNO.0 \u00a0TNL type \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0: lsp \u00a0\u00a0, TNL ID : 0x5 <\/strong>\u00a0<\/strong>\/\/0x5<\/strong>\u00a0is the token value used by the L2VPN tunnel. The token value is a hexadecimal number.
\n<\/strong>\u00a0\u00a0\u00a0\u00a0Backup TNL type \u00a0\u00a0\u00a0\u00a0\u00a0: lsp \u00a0\u00a0, TNL ID : 0x9<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

 <\/p>\n

Check the MAC address carried in dually transmitted ARP packets.Run the display mplsada lsp <\/strong><\/p>\n

token<\/strong>\u00a05<\/strong>\u00a0command in the diagnostic view. Note that 5<\/strong>\u00a0is the token value obtained in Step 1.<\/p>\n

Note that when the problem occurs, the destination MAC address carried in dually transmitted ARP<\/p>\n

packets is all 0s.<\/p>\n\n\n\n
\n

<HUAWEI>system-view<\/p>\n

[HUAWEI]diagnose<\/p>\n

[HUAWEI-diagnose]display \u00a0mplsada lsp token \u00a05<\/strong>\u00a0\/\/5<\/strong>\u00a0is the tunnel token value obtained in Step 1. This tunnel token value is a decimal number.<\/p>\n

ulPdtHandle \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0: 434410400
\nProtect Type \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0:3
\nLsp or gre index \u00a0\u00a0\u00a0\u00a0\u00a0:5
\nProtect groupid \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0:1
\nApsId \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0:515
\nPrimary pdthandle \u00a0\u00a0\u00a0\u00a0:0x19e493a0
\nBackup pdthandle \u00a0\u00a0\u00a0\u00a0\u00a0:0x19df16d8<\/p>\n

Nhi list begin
\nNhi list end. \u00a0List count \u00a0:2<\/p>\n

Main product info(TunnelId 5):
\nOvid \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0:0
\nMacIndex \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0:7
\nOutIfIndex \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0:337
\nTrunkorTp \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0:14
\nTrunk flag \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0:0
\nNexthop \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0:0xc8010102
\nTunnelId \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0:5
\nMac fake flag \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0:0
\nExp Mode \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0:0
\nExp value \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0:0
\nTnlType \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0:0
\nDestMac \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0:00:00:00:00:00:00<\/strong>\u00a0\/\/The DestMac<\/strong>\u00a0field indicates the destination MAC address for dually transmitted ARP\u00a0packets. When the problem occurs, the destination MAC address is all 0s.<\/p>\n

SrcMac \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0:f4:a1:a2:cf:33:01
\nEgress Intf index \u00a0\u00a0\u00a0\u00a0:138
\nMpls Tunnel index \u00a0\u00a0\u00a0\u00a0:8
\nLspId or GreId \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0:4294967295
\nFqId \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0:0
\nDsid \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0:0
\nOut stattisticId \u00a0\u00a0\u00a0\u00a0\u00a0:4294967295<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u00a0<\/em><\/p>\n

[Root<\/strong>\u00a0Cause]<\/strong><\/p>\n

1.\u00a0When an ATN 950B is running properly, its master MPU is in slot 7, and the slave MPU is in slot 8.<\/p>\n

After a master\/slave MPU switchover is performed by reseating an MPU\u00a0or running commands, the<\/p>\n

MPU in slot 7 becomes the slave one, and the MPU in slot 8 becomes the master one. The MPU in<\/p>\n

slot 7 synchronizes data in a batch with the MPU in slot 8. Due to a timing sequence error, LDP<\/p>\n

data is backed up earlier than ARP data. As a result, the destination MAC address on the MPU in<\/p>\n

slot 7 is all 0s. Although the destination MAC address is incorrect, the MPU in slot 7 does not<\/p>\n

transmit services, and therefore, services are not affected.<\/p>\n

2.\u00a0After the other master\/slave MPU switchover is performed, the MPU in slot 7 becomes the<\/p>\n

master one. This MPU\u00a0forwards dually transmitted ARP packets carrying the destination MAC<\/p>\n

address of all 0s. Upon receipt, the next-hop device considers the packets incorrect and discards<\/p>\n

them. As a result, the slave ASG fails to learn the ARP entry.<\/p>\n

[Impact<\/strong>\u00a0and<\/strong>\u00a0Risk]<\/strong><\/p>\n

When network-to-user traffic arrives at the slave ASG, traffic is interrupted.<\/p>\n

[Measures<\/strong>\u00a0and<\/strong>\u00a0Solutions]<\/strong><\/p>\n

Recovery<\/strong>\u00a0measures:<\/strong><\/p>\n

Note that the recovery measures will adversely affect services transmitted on the ingress,<\/p>\n

transitnode, and egress along an existing tunnel within seconds.<\/p>\n

Run the reset mpls ldp all<\/strong>\u00a0command in the user view to reset MPLS LDP.<\/p>\n\n\n\n
<HUAWEI> reset mpls ldp all<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u00a0<\/strong><\/p>\n

Workarounds:<\/strong><\/p>\n

Solutions:<\/strong><\/p>\n

Perform either of the\u00a0following steps to resolve the problem:<\/p>\n

l\u00a0Install the patch V200R002SPH006 or later on the ATN 950B NEs running V200R002C00SPC300.<\/p>\n

l\u00a0Upgrade a version earlier than V200R002C00SPC300 to V200R002C00SPC300 and then install the patch V200R002SPH006 or later.<\/p>\n","protected":false},"excerpt":{"rendered":"

Keywords:\u00a0ATN 950B, ARP entry dually-transmitting\u00a0failure, mixed\u00a0VPN solution Summary:\u00a0A timing sequence error occurs when software performs batch backup on an ATN 950B NE\u00a0functioning as a CSG\u00a0running V200R002C00SPC300 or an earlier version. After a master\/slave MPU switchover is performed several times, there is a possibility that the ARP entry dually-transmitting function fails. In this case, when network-to-user […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[492],"tags":[513],"_links":{"self":[{"href":"https:\/\/www.thunder-link.com\/blog\/wp-json\/wp\/v2\/posts\/2100"}],"collection":[{"href":"https:\/\/www.thunder-link.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.thunder-link.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.thunder-link.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.thunder-link.com\/blog\/wp-json\/wp\/v2\/comments?post=2100"}],"version-history":[{"count":0,"href":"https:\/\/www.thunder-link.com\/blog\/wp-json\/wp\/v2\/posts\/2100\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.thunder-link.com\/blog\/wp-json\/wp\/v2\/media?parent=2100"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.thunder-link.com\/blog\/wp-json\/wp\/v2\/categories?post=2100"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.thunder-link.com\/blog\/wp-json\/wp\/v2\/tags?post=2100"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}