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| − | The purpose of this page is to give an overview of the current '''design of the network''' of the Wikimedia servers, and to provide a place to develop a new and improved network scheme. | + | == AS 14907 == |
| | + | The US network. |
| | | | |
| − | == Current situation == | + | === 2011 === |
| − | Wikimedia servers reside in two racks along with Bomis servers, hosted at [http://www.candidhosting.com Candidhosting]. Wikimedia/Bomis have a dedicated IP range, <tt>207.142.131.192/26</tt>. There are two gateways: <tt>207.142.131.193</tt> and <tt>207.142.131.225</tt>, but they both resolve to the same MAC address, so they are almost certainly the same router. Total burstable bandwidth is 200 Mbit/s, delivered through two separate 100BaseTx uplinks, connected from the same broadcast domain that is ''shared with other customers''.
| + | [[File:Eqiad logical.png|thumb|400px|AS14907 Eqiad in 2011]] |
| | + | [[File:Wikimedia pmtpa management network.png|thumb|400px|AS14907 in 2010]] |
| | | | |
| − | Wikimedia owns three [[switches]]. As the two uplinks are not allowed to create a loop, they must be connected to different switches that are not connected to eachother (when not using [[Wikipedia:Spanning Tree Protocol|STP]]), which is not an ideal situation. A third switch is currently used to connect internal servers, that don't have public IPs and should not be accessible from the Internet. The IP range used for this internal network is <tt>10.0.0.0/8</tt>.
| + | === Subnets === |
| | | | |
| − | == Problems == | + | ==== [[pmtpa]] ==== |
| − | The current network setup is not optimal in many ways, as will be described here.
| + | |
| | | | |
| − | === Multiple uplinks === | + | ==== [[eqiad]] ==== |
| − | Recently, Wikimedia traffic spiked to 100Mbit/s multiple times, which is the limit of a single 100BaseTx connection. Also, [http://65.59.189.201/www.bomis-total/www.bomis-total.html average outgoing traffic] at this moment is about 45 Mbit/s, so it is clear that Wikimedia was slowly becoming network limited. However, the colo provider charges $400 dollar per month just to provide us with a Gigabit uplink, unless we commit to 60 Mbit/s average traffic or higher. Instead, they decided to give us a second 100BaseTx for free.
| + | {| class="wikitable" |
| | + | |- |
| | + | !subnet !! vlan ID !! IPv4 !! IPv6 |
| | + | |- |
| | + | | public1-a-eqiad || 1001 || 208.80.154.0/26 || 2620:0:861:1::/64 |
| | + | |- |
| | + | | public1-b-eqiad || 1002 || 208.80.154.128/26 || 2620:0:861:2::/64 |
| | + | |- |
| | + | | public1-c-eqiad || 1003 || || 2620:0:861:3::/64 |
| | + | |- |
| | + | | public1-d-eqiad || 1004 || || 2620:0:861:4::/64 |
| | + | |- |
| | + | | private1-a-eqiad || 1017 || 10.64.0.0/22 || 2620:0:861:101::/64 |
| | + | |- |
| | + | | private1-b-eqiad || 1018 || 10.64.16.0/22 || 2620:0:861:102::/64 |
| | + | |- |
| | + | | private1-c-eqiad || 1019 || 10.64.32.0/22 || 2620:0:861:103::/64 |
| | + | |- |
| | + | | private1-d-eqiad || 1020 || 10.64.48.0/22 || 2620:0:861:104::/64 |
| | + | |} |
| | | | |
| − | This does pose some problems though. Because the two uplinks are connected from the same [[Wikipedia:broadcast domain|broadcast domain]], we cannot connect them internally, or we would create a loop. One solution to this problem is to connect the uplinks to different switches that are not connected, but this means that hosts on the two different switches can only exchange traffic between eachother through the uplinks. This traffic is ''graphed and billed'' '''twice''', and is a ''bottleneck'', as it has to traverse both relatively slow uplinks.
| |
| | | | |
| − | === Shared broadcast domain === | + | == AS 43821 == |
| | + | The European network. |
| | | | |
| − | It appears that, even though Wikimedia has a dedicated IP range, the broadcast domain is shared with other customers. Running <tt>tethereal</tt> shows a lot of non-wikipedia traffic. It's odd that Wikipedia doesn't have it's own broadcast domain (probably implemented as a separate [[Wikipedia:VLAN|VLAN]] at the upstream provider), as there doesn't seem to be a reason not to.
| + | === 2008 === |
| | + | [[File:Knams-multihomed.png|thumb|400px|AS43821 in 2008]] |
| | | | |
| − | Within a shared broadcast domain, other customers can snoop Wikimedia traffic, spoof our IPs, and cause unnecessary traffic through our uplinks.
| + | BGP default transit from AS1145 (Kennisnet), with some partial transit and peering over a 1 Gbps AMS-IX link. Everything on one core router/switch, csw1-knams (Foundry BigIron RX-8). |
| | | | |
| − | === Inflexible internal network setup === | + | === 2009 === |
| − | The Wikimedia network was recently split in two parts: the ''external'', publicly visible network containing machines that need to be accessed from the Internet (the Squids, mostly), and an ''internal'' network for machines that are only accessed by other wikimedia servers (Apaches, DB servers, management devices). Some servers, like the Squids, need to be in both networks because they serve as gateways between the Internet and the internal machines.
| + | [[File:AS43821 2009.png|thumb|400px|AS43821 in 2009]] |
| | | | |
| − | The internal network is currently implemented as a physically separate switch. This switch is not connected to the other two, and the only paths to the external network are through the servers that are on both networks. These servers use separate interfaces to connect to the different networks (<tt>eth0</tt> for internal, <tt>eth1</tt> for external). | + | Temporary situation after the move from knams to esams. The network is split, with a new Foundry BigIron RX-4 as a pure router at knams for external connectivity, with Telia, DataHop, Init7 (partial) transit, and 2x 1 Gbps AMS-IX for peering. Connectivity between the two sites is supplied by a 10GBase-ER link over dark fiber, and a 3 Gbps MPLS backup link. A second dark fiber is being installed to form a ring. |
| | | | |
| − | Using physically separate switches for different networks is inflexible. This design does not permit efficient use of resources like switch ports and bandwidth. It requires extra switches when the internal network is full, even if the switches for the external network have plenty of ports free. Even the currently used switches support [[Wikipedia:Virtual LAN|VLANs]] (including '''802.1Q''') and all of its advantages, so it would be good to use them.
| |
| | | | |
| − | :Plan is to switch to a VLAN once we find out what's connected to each switch port - Kate | + | === 2010 === |
| | + | [[File:AS43821 Q3 2010.png|thumb|400px|AS43821 late 2010]] |
| | | | |
| − | === Failover default routing using BGP ===
| + | The purchase of several Juniper EX4200s in a stack, for extra access ports for servers, also brings some opportunities w.r.t. the network topology. Since the EX4200s have excellent L3 support they can help create redundancy. |
| − | Because the internal servers are not directly connected to the Internet, both Zwinger and Albert are setup to ''Source NAT'' traffic originated by these internal servers, to allow them to access Internet servers for management purposes.
| + | |
| | | | |
| − | Two hosts are configured as routers, to provide failover support. This, however, is done using [[BGP]] and [[Wikipedia:Quagga|Quagga]] on all boxes. This seems to be a bit excessive, as better and easier solutions exist for this job: [[Wikipedia:VRRP|VRRP]] and [[Wikipedia:Common Address Redundancy Protocol|CARP]]. These solutions only need to be implemented on the routers, and don't require complicated daemons and protocols run on each host.
| + | The 2nd dark fiber is linked between [[br1-knams]] and [[csw2-esams]] to create a ring. [[csw1-esams]] and [[csw2-esams]] can then share responsibility as core switches, for inter-vlan routing and switching, using VRRP. Since an EX4200 can not install a full BGP routing table in FIB, it defaults to either of the two Foundry routers using OSPF. |
| | | | |
| − | === Limited switch features ===
| + | Toolserver can be connected redundantly as well, using (R)STP to both core switches and VRRP, or alternatively a LAG to the EX4200 stack. |
| | | | |
| − | == Proposed solutions == | + | == Configuration guidelines == |
| | + | * Firewall filters, policies, prefix lists etc that are specific to a certain protocol family (e.g. only IPv4, or only IPv6) should have a '4' or '6' appended to their name. Filters, policies and prefix lists that are protocol family agnostic, should lack this suffix. |
| | | | |
| − | This section discusses some possible solutions to the [[#Problems|problems]] mentioned.
| + | == See also == |
| | + | * [[Multicast]] |
| | + | * [[TCP Tuning]] |
| | | | |
| − | === Gigabit uplink ===
| + | [[Category:Network]] |
| − | | + | [[Category:knams cluster| *]] |
| − | The easiest and probably best solution to the [[#multiple uplinks|multiple uplinks]] problem, is to just get a single Gigabit (1000BaseTx) uplink. This will solve all bandwith problems for quite a while, and save us from having to design our network to prevent loops from happening. It isn't as redundant as two links, but switch port failures are quite uncommon, and often happen with multiple at the same time anyway.
| + | [[Category:Pmtpa cluster| *]] |
| − | | + | |
| − | As it turns out, this options currently costs Wikimedia an extra $400 dollar each month until we generate more monthly average traffic (60 Mbit/s), and is therefore not likely to happen soon.
| + | |
| − | | + | |
| − | === LACP trunks ===
| + | |
| − | | + | |
| − | An alternative option to the [[#multiple uplinks|multiple uplinks]] problem, and one that actually takes advantage of the two uplinks we have, is to configure them as '''LACP trunks'''. This means that we aggregate the two links together into one logical 200 Mbit/s link, using the ''IEEE 802.3ad'' protocol. This has both the performance and reliability benefits of using two physical links, but does not pose problems to our current network design, as no loops would be created when aggregating the two uplinks on one switch. It turns out that our [[Switches|current switches]] indeed support 802.3ad link aggregation, so we could start using it right away, as long as the uplink colo provider is willing to cooperate.
| + | |
| − | | + | |
| − | This also means that our internal traffic does not have to pass any uplinks, and therefore cannot be graphed and billed. We can connect our switches without any problems using full capacity, so we won't have performance bottlenecks.
| + | |
| − | | + | |
| − | === Separate external VLAN ===
| + | |
| − | | + | |
| − | Nowadays it's becoming quite standard in the colocation business to put each into a separate [[Wikipedia:VLAN|VLAN]], along with their own IP subnet and gateway. That way, all customers are separated into broadcast domains, and prevents IP conflicts, traffic snooping, paying for broadcast traffic generated by other customers, etc. This solution is commonly used, even for small customers, with only single servers. It does however require some extra configuration work by the colo provider. A separate VLAN has to be created on the switch(es) and router(s), and a specific gateway IP has to be provided to each customer.
| + | |
| − | | + | |
| − | Wikimedia already has its own IP range and corresponding gateway(s), and isn't a small customer. It is therefore surprising we don't already reside in a separate VLAN, separated from other customers. We should ask the colo provider to put us into a dedicated VLAN, as this requires them little effort, and has quite some security and performance benefits.
| + | |
| − | | + | |
| − | No configuration changes on our network equipment or servers are required.
| + | |
| − | | + | |
| − | == Proposed design ==
| + | |
| − | | + | |
| − | -- [[User:Mark|Mark]] 15:46, 22 Oct 2004 (UTC)
| + | |
BGP default transit from AS1145 (Kennisnet), with some partial transit and peering over a 1 Gbps AMS-IX link. Everything on one core router/switch, csw1-knams (Foundry BigIron RX-8).
Temporary situation after the move from knams to esams. The network is split, with a new Foundry BigIron RX-4 as a pure router at knams for external connectivity, with Telia, DataHop, Init7 (partial) transit, and 2x 1 Gbps AMS-IX for peering. Connectivity between the two sites is supplied by a 10GBase-ER link over dark fiber, and a 3 Gbps MPLS backup link. A second dark fiber is being installed to form a ring.
The purchase of several Juniper EX4200s in a stack, for extra access ports for servers, also brings some opportunities w.r.t. the network topology. Since the EX4200s have excellent L3 support they can help create redundancy.
Toolserver can be connected redundantly as well, using (R)STP to both core switches and VRRP, or alternatively a LAG to the EX4200 stack.
