What causes duplicate packets. Mar 1, 2019 · This issue occurs with Local SPAN also.

What causes duplicate packets. The DUP packets will indicate that PING has received replies from the same IP address, but with different MAC addresses. You may have made other changes to the network as well so the root cause might be elsewhere but a scenario like this is a plausible explanation for your issue. In the first scenario, a client uploads some data to the server using TCP so the DF flag is set on all of the packets. The subsequent "gentle" ramp up (usually by one packet per RT) means that overall throughput suffers severely. 10. 0 - voice vlan, ip-phones. 9. 44? 06-28-2012 10:51 PM. ALSO READ. This issue occurs because both a non-querier RRAS server and the querier RRAS server are forwarding the IGMP packets. I have Wireshark running on my host Editcap is a program that reads some or all of the captured packets from the infile, optionally converts them in various ways and writes the resulting packets to the capture outfile (or outfiles). Then it finally gets an acknowledgement and the transmission proceeds. , one IP address has been used by two hosts. Drop Code: 338, Octeon Decryption Failed for Inbound Packet. Sorted by: 1. This can have a lot of causes, so we really need a good indication of your network architecture to be able to tell you what the cause is. I'm looking for some help with interpreting mstat/mtrace output and looking for the source of randomly duplicated multicast packets from one site in a 'WAN' network. 30. No. However, if the receiver has already received the packet, it will send a duplicate ACK to the sender. When the filtering extension injects this packet into the ingress data path, destination ports will be added to the packet by either an underlying forwarding extension (if enabled in the driver stack) or the miniport edge of the extensible switch. 149/443 with different initial sequence number. Jan 17, 2012 · I am working on a C# application that sends and receives network packets. Problems with Packet Duplication The following are common causes of duplicate packets in monitoring traffic: 5. At an average packet capture cost of $30,000 per terabyte (TB), duplicate packets waste large amounts of money. So the goal is to remove duplicate packets which are 1085 in count. Multicast source is out of VPC and receivers are inside the vlan in vpc ports. The network: Two physical sites, connected via an ISP private fiber link. It's sort of a network sniffer type application, so data integrity is very important. If a duplicate packet comes in the server will get request_id from the index_num and drop the packet if request_id is the same. address 172. 74. 128. When there are multiple packet loss events, a chart of the "Bytes-in-Flight" value forms a sawtooth pattern with fast decreases and slow increases. What is the ARP cache/CAM table in the 10. If the client fails to predict an appropriate MTU, an intermediate router will drop the big packets and send an ICMP “Packet too big” notification back to the client. Before and after a network monitoring switch. How is this filtering done. 0/25 attached devices? Regards, Martin Nov 26, 2007 · When you span, you are usually spanning in and out traffic so you can get both directions. Oct 13, 2012 · Packet loss and duplication are problem related to unreliable protocols datagram oriented like UDP. Duplicate packets, commonly created by SPAN ports, are a common problem for network monitoring tools. Access points are also susceptible to Jul 17, 2015 · 1. Modified 9 years, 5 months ago. Is it the same as re-transmitting packets when a loss is detected in TCP? Yes and no. Linux, Windows, and the CSRs are all using the same virtual host adapter type (vmxnet3). However, due to the Packet Forwarding Engine (PFE) limitation, the packets were mirrored for ICMP redirect and sent to the Routing Engine. Duplicate packets should be flagged as "TCP Spurious Retransmission" or "TCP Out-of-Order" in the info column. Lost packets, or enough out-of-order packets, cause the TCP sender to believe packets have been lost, which cause the TCP sender to slow its transmission, either backing down by half, congestion avoidance, or being pushed all the way back to slow start. I get on average 80-100 of these messages per second for the duration of the outage. id) in the IP header. The example there covers a different case: a server receiving a duplicate previous session SYN before the 'correct' SYN. 06-28-2012 07:13 AM. We can detect the dropped packet and re-transmit it if the sender has (at least) 4 more packets to send after packet p + d (i. It is part of any network environment and is unavoida-ble. This device monitors and stores your network traffic. To send two back-to-back packets, the time rises to 440 µsec: we add Sep 26, 2023 · Unlike the parity packets in FEC, which are not exact copies of the original packets, the duplicate packets are verbatim copies of the original packets. So imho there is more to it than just a duplicate IP. Say that a TCP sender is currently transmitting a window of size 64 packets, starting at sequence number p. Nov 27, 2017 · But if you replicate datagrams and send as a pair, then you maximize the chance of losing both (by a noise burst of x duration). You signed out in another tab or window. Jun 28, 2012 · 10. delay sending the replicated datagram by time x. The common cause of duplicate packets in network monitoring traffic is through the use of the port mirroring feature of network switching devices, which is also known as a Switched Port Analyzer (SPAN). Oct 22, 2021 · You can use the Wireshark display filters tcp. As an example, this is a UDP datagram sent on a healthy machine (using WireShark): This is the duplication on one of the faulty machines: A pcapng file from Wireshark can be found here (look for DNS request from client machine 10. So you are seeing incoming and outgoing traffic for every layer 2 packet. 8:51260->172. My pc is running Windows server 2003 sp2. Following the horizontal "Ack line" on the chart we see the single retransmitted packet and the step up of the Ack line. My question is what can I do to stop the dupliate packets? Thanks in advance. If you don't have exact byte-by-byte duplicates this should be possible; often you can use the VLAN ID (if you have duplicate packets on different VLANs) or the TTL (which is usually 1 less after the . I would like to know if there is any way (command line option) using which I can discard duplicate packets and make new pcap with all unique packets. SIte1: 4510R-E core. network 172. 2. Now I am applying the filter below. After two duplicate ACKs, a TCP sender begins retransmission. Additionally, various link aggregation misconfigurations can cause duplicates, especially when i open a packetsocket on a loopback interface (lo) and listen all the packets are seen twice. Say that packet p + d is dropped. analysis. Dec 7, 2021 · Yes, this likely is a driver problem. The DUP responses do not happen for Windows hosts under the same circumstances. Dec 14, 2021 · This causes the original packet's destination ports to not be copied to the cloned packets. Damaged packets are obviously serious cause for alarm and often indicate May 16, 2016 · Have you ever looked at a Wireshark trace and thought, "There's an awful lot of retransmissions there"? The problem is that the Info field in Wireshark marks a packet as a TCP Retransmission when it truly is one, when the packet is looping or even when a SPAN port has been misconfigured. In this week's video we Aug 20, 2015 · If the packet with SEQ# 12617: 3 385. 992, Windows 10 1809 running Wireshark 3. cause the client will receive the packet which he originally sent . Recommended Actions Use the following guidelines when you observe the above behaviors while troubleshooting TCP performance. The problems from networks, duplicate packets are often captured and aggregated together. The destination virtual machine then receives two copies of the ICMP Echo request packet and responds twice which causes the duplicate ICMP response. All these errors indicate congestion: somewhere along the way packets are dropped. If these line cards are present in the system within bus switching mode, they generate an additional copy for the ingress SPAN packets. But a host which is placed in VLAN 10 and pinging the AT switch gets duplicate packets in response. The VMware workstation is running Linux with the network adapter in "Bridged: Connected directly to the physical network" mode. In most cases, once the sender receives three duplicate acknowledgments, it will immediately retransmit the missing packet instead of waiting for a timer to expire. SSLVPN feature: NetExtender Packets Dropped with Enforced Firewall Rule or Policy Drop. Here the Routing Engine (RE) is forwarding the packet based on an available route. wireshark. Client will send its index_num along with request_id. 181/65086 to outside:184. (i. The more duplicate packets are sent, the more space they take up, leaving little room for useful packets. You may like to do some config as sample below to prevent your network from SYN Flood attack. why is it so? But a capture on the interface using tcpdump correctly ignores the duplicate entries. May 6, 2011 · 1. Packets are layer-3 datagrams. Feb 17, 2015 · Duplicate packets should never occur when pinging a unicast address, and seem to be caused by inappropriate link-level retransmissions. Some of these re-transmitted packets get delayed. The router sees that you don't need it in order to reach the destination, and therefore sends the redirect. The following is a check list for troubleshooting Packet Retransmission messages: Jun 25, 2020 · A retransmission should be flagged as "TCP Retransmission" in the info column in Wireshark. Initially, this will, to most people, imply a duplicate IP, i. 14. Slower tools and duplicate packets reduce effective bandwidth capability, which causes data jams that result in dropped packets and lost data. I wrote a short java program that simply do a A routing table is a set of rules, often viewed in table format, that is used to determine where data packets traveling over an Internet Protocol (IP) network will be directed. Case 1: A──────B. This results in extra traffic, which is equal to the number of such line cards, multiplied by the ingress SPAN traffic. , with internet explorer to google. Jul 25, 2007 · FTP active/passive modes shouldn't affect the layer 2 and 3 protocols. These duplicate packets cause several prob-lems if the network monitoring switch is not able to eliminate the copies. Apr 27, 2019 · To add to the issue - I also see duplicate inbound packets, but only when communicating with a VM that I have running within VMware Workstation (the VM's network adapter is in bridged mode, not NAT mode). Apr 23, 2019 · Rooster_50. A host which is placed in VLAN 1 can ping the Allied Telesis Switch which is directly connected to the firewall without problems, and the other switch, too. My output before filtering is below. While some network packet brokers include advanced functions to enhance and automate network monitoring activities, the presence of We would like to show you a description here but the site won’t allow us. auto br0. 255) packets, we receive the packets twice. Packet de-duplication can also be enabled on the receiving FortiGate. Duplicate ACKs are signs that the receiver received something, just not the right sequence number. Depending on the ARP cache/CAM table of the sending device only one station would get the IP packet. Mar 4, 2024 · To analyze duplicate RTP packets in Wireshark, follow these steps: Open the PCAPNG file in Wireshark. 4 385. Jul 13, 2007 · I'm monitoring a vlan via rspan, but I'm seeing duplicate packets. duplicate_ack to identify instances of packet loss or duplicate acknowledgments. tcpdump -i lo -s 0 When a multicast application in the environment sends multicast packets from one side of the IGMP router, multicast clients on the other side of the IGMP router receive duplicate multicast packets. Dec 19, 2018 · This setting will discard packets coming from uplinks that are not associated with the particular client when promiscuous mode is enabled and will prevent duplicate packets from being received by the guest operating system. 09-18-2019 04:41 AM. It can be a Site-to-Site VPN, Client-to-Site VPN, L2TP or PPTP setup. Bandwidth is 1 byte/µsec (1 MB/sec, 8 Mbit/sec) Packet size is 200 bytes (200 µsec bandwidth delay) Then the total one-way transmit time for one packet is 240 µsec = 200 µsec + 40 µsec. As a result, both the correct machine and another (a router) get the packet. You might minimize the chance of losing both by separating the duplicate datagrams, i. see the 'packets received by filter' (which contains the duplicate packets) and 'packets captured'. Identify the duplicate packets by looking for packets with the same sequence number and timestamp. 4. they traced the errors to the OVS logging on ALL nodes in cluster Sep 1, 2002 · was really high. When the switch receives incoming traffic on vlan 1 for another device on vlan 1, it must replicate that packet and send it back out to the destination device. Please remember to rate useful posts clicking on the stars below. 06-29-2012 07:01 AM. Feb 8, 2012 · The solution is to keep circular buffer of the packet's index on the server in the exact order as the client has it. Aside from clicking “I agree” to a legal disclaimer or entering in some credentials Apr 21, 2017 · These packets should not be sent to the CPU. +3 subsequent packets to generate 3 duplicate ACKs + 1 re-transmission). Cause. This threshold is also used for packet loss recovery as packet loss will appear to TCP as out-of-order packets. When the VPN client is configured for IPsec over TCP (cTCP), the VPN client software will not respond if a duplicate TCP ACK is received asking for the VPN client to re-transmit data. Ever since we migrated from Windows XP to Windows 7, when we UDP Broadcast (255. Luckily there are a few tell tale signs to help us figure out the true situation. AL switches are only L2 and DL swicthes are L3/L2. Feb 3, 2016 · TCP Dup Acks could be from lost packets or out-of-order packets, even when packets are not lost. 0. Additionally, various link aggregation misconfigurations can cause duplicates, especially with "static", non-protocol LAGs. 2. 498644 Client -> Server: [DUP ACK] SEQ 3086, LEN 0, ACK 12617 Running VMs on some hosts causes duplicate network packets. regards, Leo. Reload to refresh your session. Without the duplicate packets being identified and removed first, the tools will alarm on the duplicates or produce compromised data and results. Jan 27, 2018 · %ASA-4-419002: Duplicate TCP SYN from inside:192. Jul 25, 2017 · Both switches have a management IP which is located in VLAN 1. A lot of models are made for only one Windows version and there may be lesser or larger problems when one tries to install newer Windows versions. 127:5432: read: connection timed out. Additionally, the "Replicate physical network connection state" option is checked. Jun 14, 2017 · Typically, duplicate acknowledgements mean that one or more packets have been lost in the stream and the connection is attempting to recover. Thus, a duplicate message is seen. 3 days ago · Duplicate packets should never occur, and seem to be caused by inappropriate link-level retransmissions. request_id is incremented per request. Typical root causes of a broadcast storm. Fast start should not be used on inter-switch links as it effectively causes loops for short periods. I am using latest wireshark version 1. They reduce tool bandwidth, decrease tool processing power, limit data storage capacity, and lower the overall effectiveness of security and monitoring tools. Oct 15, 2013 · I am setting packet count to 10000 and seeing 11085 count in wireshark. The funny thing is that this only happens on my network, I've tried on 4 other networks and everything is ok. This is done for a number of reasons, namely analyzing, compliance, and security. 22. If too many packets are received out of order, TCP will cause a Aug 29, 2019 · TCP Duplicate ACK: When a TCP receiver receives packets out of order, which it interprets as data loss, it sends an ACK indicating the expected sequence number. There are a number of possible causes of TCP DUP ACKs, including: Packet loss: When a packet is lost, the sender will retransmit the packet. Duplicates may occur in many situations and are rarely (if ever) a good sign, although the presence of low levels of duplicates may not always be cause for alarm. And imagine such a situation: The transmitter sends a packet and then re-transmits it because it didn't get an acknowledgement. (M/R)STP can cause duplicate packets when it's not configured correctly. The problems May 7, 2015 · Hi, We are testing currently the ASM in Nexus7k/5k VPC environment and we see duplicate packets time to time. You switched accounts on another tab or window. Asked 9 years, 5 months ago. Share. Causes of TCP DUP ACKs. It indicates packet 3 was received before packet 2. my bridge interface config is: iface enp5s0 inet manual. Jan 14, 2022 · Duplicate packets not only greatly increase the storage capacity, but the stored duplicate packets also often result in incorrect analysis results. It should be one value for the "originals" and another for the duplicates. Description of problem: cu reported networking issue in cluster applications like the following: Connection failed: read tcp 10. Figure 2. I send 610 packets, I receive 1220 packets). I've got some CentOS 7 VMs with macvlan network interfaces. Duplicate packets should never occur, and seem to be caused by inappropriate link-level retransmissions. 255. If a device—like a router, switch, or workstation—is connected to Ethernet through a bad cable, bad port, broken fiber cable, or dirty fiber connector, then a packet can be damaged. Damaged packets are obviously serious cause for alarm and often indicate center networks. And yes, you may try to find a driver to work correctly in Windows 11. During this time any packet is droped host will retransmit the packets . Jan 19, 2018 · Yes, many hosts or applications in a host can subscribe to a multicast group, but you also need a transport protocol, and if you use UDP (the usual for multicast), only one application in a host can use a UDP port at any one time. Applications do not receive packets. Networks that are tapped in multiple locations Sep 18, 2019 · Randomly Duplicated Multicast packets. Aug 9, 2021 · The packet then goes through the physical switch and come back through the other uplink. 168. Think about when you take your laptop to a coffee shop and hop on WiFi. And there is a protocol that uses a "sliding window" algorithm for tracking packets acknowledgement. 1 Delay examples. But you might be better off understanding why you're losing the datagrams in Aug 18, 2017 · 1. window_update. Only F2 cards are in use in our lab and VPC is configured from host to nexus 5k and then to DL (7k) swicthes. netmask 255. Inspect network devices and hardware: If you suspect misconfigured devices or faulty hardware, review their settings and perform necessary tests to rule out these causes. Mar 1, 2019 · This issue occurs with Local SPAN also. 1. My guess is that you transmit with a broadcast destination MAC. iface br0 inet static. Duplicate Packets Interfere with Network Analysis and Tactical Troubleshooting Duplicate packets are equivalent to false data when it comes to analyzing network performance or troubleshooting. Filter the packets to display only RTP packets using the filter "rtp". It has the same SEQ and ACK values as the lost packet, but a different IP ID (ip. gle/5TbSqvYYCnTyyxSN7 May 15, 2012 · 1 Answer. By default, it reads all packets from the infile and writes them to the outfile in pcapng file format. This is called Fast Retransmit and is thus faster than the timeout based Would you like to help test Confluence and Jira updates? Please fill out the form here: https://forms. The Dynamic Host Configuration Protocol (DHCP) is the most common way for a networked host to obtain an IP address from a network controller. Dec 6, 2019 · Typically, duplicate acknowledgments mean that one or more packets have been lost in the stream and the connection is attempting to recover. Intermittent packet loss is a fairly Apr 28, 2013 · the acknowledgment number is equal to the greatest acknowledgment received on the given connection. 51. Jan 28, 2022 · After investigation, we noticed that duplicated UDP packets are being sent out. Jul 3, 2018 · You signed in with another tab or window. I've used Wireshark to track packets and it shows double packets. They are a common symptom of packet loss. 183). Client -> Server DF+ / ICMP. Client send syn packet; Server response back with SYN-ACK 3)Again post receving SYN -ACK from client . gle/5TbSqvYYCnTyyxSN7 Aug 17, 2012 · One Answer: 0. 25. May 9, 2018 · The purpose of this duplicate ACK is to let the other end know that a segment was received out of order, and to tell it what sequence number is expected. It has the same SEQ and ACK values as Jan 3, 2008 · Out of order packets do not tend to occur very often on hub and spoke networks and are more common on meshed networks MPLS networks. Wireshark Dissector Tutorial [Practical Examples] After applying the display filter, go to top right and click on the “ plus ” button. Examine the packets to determine the cause of the duplicates, such as Mar 3, 2020 · A halving of bytes-per-round-trip or packets-per-RT results in a halving of throughput. Here we see about 9, 16 and 23 segments. Regards. Duplicate ACK's in combination with slow network performance sounds like a network congestion problem to me. X firmware. Therefore we can use the number of duplicate ACKs to estimate the bytes in flight at the time of the packet loss. Dan Oct 19, 2014 · Lost Packets And Duplicate Packets Scenario in Three way Hand-shaking. See below a Routing Table: How to troubleshoot Collisions. This can cause the sender to retransmit the packet again, which can lead to a Packets here are naturally lost before the capture point. com), my host sends the syn packet twice. Make sure to look at physical layer and network layer broadcasts as well as multicasts. Troubleshooting (ISP Connectivity): Sep 5, 2007 · The problem with duplicate IPs is the MAC address. There's likely a routing loop of some sort or a problem with the switch that's causing the packets to come in out of order or Apr 3, 2017 · Cause if the packet goes out from the client to NX-OS-A, then NX-OS-A will send the packet across peer link to NX-OS-B, so NX-OS-B must not send the packet out any of egress any vPC member port, or the loop will happen . Who is 10. Each data segment that was in flight at the time of the loss triggers a duplicate ACK. Are you using any kind of recording system? it could be the RTP is duplicated to be send to a applciation. Client send ACk message to server . Log Shows IPSec Packet To or From Illegal Host. To recreate: Host system: Npcap 0. lost_segment and tcp. Jan 26, 2022 · Steps are below. Jan 21, 2018 · Here is my problem: In the following example I receive duplicate packets, but only in my network and I don't understand why. Look at the volume and rate of broadcast traffic on the network. e. Jun 24, 2021 · Summary: Duplicate TCP SYN packets in the network causes TCP connection issues. 3. A duplicate ACK might be generated if there is packet loss somewhere between the VPN client and the ASA headend. Packet loss does appear in almost any network but should usually be below 1 ppm. 1. flags && !tcp. Resolution Hotfix Jun 26, 2012 · Problem. Here is the code: Server: Would you like to help test Confluence and Jira updates? Please fill out the form here: https://forms. Propagation delay is 40 µsec. The rspan is configured to monitor both incoming and outgoing traffic from th e vlan. In order to minimize packet loss, the packets belonging to one stream are often interleaved with packets belonging to its duplicate stream, and with a delay, so that if there is a packet loss, such a delay would allow the same packet from the duplicate stream to reach the receiver because the chances that the same packet is lost in transit May 26, 2023 · This can prevent duplicate packets from reaching the application. Hope it's clear now Apr 11, 2018 · When I do configure a network bridge on my Ubuntu server I got each packet to be retransmitted and getting many duplicate ACKs as this wireshark image. May 16, 2011 · Duplicate packets should never occur, and seem to be caused by inappropriate link-level retransmissions. If I have these VMs running on the vSAN cluster they get all the packets as duplicates but if I vMotion the VMs to the other host they're Jul 19, 2012 · A duplicate TCP SYN was received during the three-way-handshake that has a different initial sequence number than the SYN that opened the embryonic connection. It is not a part of the networks responsibility to ensure that no duplicate packets ever reach an end host. This log message is related to either TCP retransmission issues (for protocols such as HTTP) or the VPN configuration. There are two types of packet errors that usually occur: Packets can easily become damaged on their way through a network. Jun 7, 2021 · Troubleshooting (VPN): Troubleshooting VPN Packet Drops with Drop Code Message: Octeon Decryption Failed. Viewed 396 times. Linux VM running in VMware Workstation Player 12 with tcpdump Oct 14, 2021 · The below resolution is for customers using SonicOS 7. g. 01 ms interval (according to wireshark timestamping). All IP-enabled devices, including routers and switches, use routing tables. Go to display filter and type analysis. Cause 2 Aug 31, 2020 · If a server receives a fresh SYN packet for a connection that is already established, what should it do? I have already seen What will happen at server side if it received 2 SYN packet from the same client application?. 184. It is (probably not) a retransmit as the two syn packet are sent within a 0. 4) One RTT after that, there's another single packet retransmission. Understanding Duplicate Packets A duplicate packet is any packet that is identical to another packet. Anytime the TCP duplicate ACK threshold is exceeded, the missing packet (set of bytes) is retransmitted. What’s more, is that storing packets can be expensive. Network statistics can be significantly skewed when a large percentage of the traffic being analyzed is duplicate information. Hello, I'm having an issue where I see duplicate packets sent from a virtual machine. But reset the connection if it is considered as duplicate packet. It is a part of the responsibility of the application to handle duplicate packets and ignore unneeded data. But this is a well known problem with Acer Aspire series. Nov 5, 2010 · As there is mainly ACK traffic coming back from the file transfer it is logical to presume that many of these will be duplicated in this way. This will affect all promiscuous mode virtual machine and vmkernel interfaces on the ESXi host. Hello, i started Embedded packet capture on When packets are sent, they go to a capture device. Whenever I establish an internet connection (e. Conclusion Oct 29, 2017 · Duplicate and Damaged Packets ping will report duplicate and damaged packets. You will need to find a criteria you can filter on. from networks, duplicate packets are often captured and aggregated together. This could indicate that SYNs are being spoofed. 497836 Server -> Client: SEQ 12617, LEN 1348 is lost and is not received by the receiver, then the receiver will send a duplicate ACK which is an indication to the sender to re-transmit the packet (indicating the packet has been lost). This can happen, but it can also be caused by a number of other things, such as: A device proxying the PING. The DUP responses from the Linux hosts go away when the HSRP configuration is removed from the routers. Check the way you build your MAC headers. Oct 23, 2021 · You can use the Wireshark display filters tcp. This way, the duplicate packets can be used for data loss protection and for out-of-band inspection or packet capture. After three duplicate ACKs (usually 3) the sender retransmits the segment. The other affected line card is the WS-X6548-GE-TX. Since TCP does not know whether a duplicate ACK is caused by a lost segment or just a reordering of segments, it waits for a small number of duplicate ACKs to be received. In UDP when you send a datagram this could arrive duplicated, out of order or even don't arrive at all. Problems with Packet Duplication The following are common causes of duplicate packets in monitoring traffic: Dec 5, 2018 · The large number of original lost packets trigger many Dup-ACKs and in response, the sender retransmits a single packet to begin to fill the gap. Could this be the cause of our 'slow' system ? Now if I recall my TCP/IP networking classes correctly, duplicate acks happen *only* when packets get dropped on the network (a result of either congestion or unreliable links), forcing the receiving side to re-ack-knowledge the last correctly received packet, resulting in a If enough duplicate ACKs are generated (TCP duplicate ACK threshold: 3 “Dup ACKs”), it causes TCP to retransmit the packet. My ESXi hosts consist of a 3-node vSAN cluster + a backup/secondary standalone server. en on rp ih tn gq ne dr zl zb

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