BGP LOAD BALANCING

BGP chooses only a single best path to reach a specific destination. BGP is not designed to perform load balancing..
what i learned from every doc... but suppose this two ebgp neighbor have multiple path, creating neighborship by using loopback ip, to reach loopback router have 2 equal cost igp routes...in that case after recursive lookup router will load balance the traffic ...
Plzzz let me know am i right... or what is the meaning of this statement :
At one side it is said bgp is not made for load balancing specially in ccna, ccnp other exam books, but after doing google found following link, saying load balancing/load sharing can be done.... Why this confusion...
http://ccieblog.co.uk/bgp/bgp-unequal-load-cost-sharing
Please tell me what is truth...

Milan,
link will help me lot...
but...
The maximum-paths command for BGP works if your router has multiple parallel paths to different routers in the same remote AS; this command affects only the number of routes kept in the IP routing table, not the number of paths selected as best by BGP. For BGP, the paths parameter defaults to one.
            Suppose R1 have 2 paths to reach any destination; Without the maximum-paths command under the router bgp, there is only one path in R1’s routing table. After the maximum-paths 2 command is added to the R1 BGP configuration, both paths appear in the IP routing table, However, only one path is still selected as the best in the BGP table.
Vasilii & Reza,
means what is right statement for bgp load balancing ....or is it changed case to case..?? please clear me...
Guies ...can you also tell me bgp support for "load balancing" & "load sharing"???

Similar Messages

  • BGP load balance

    We are big ISP, and we are peering ebgp with several International ISPs for inetrnet connectivity. My question is how to load balance between the several ISPs, I mean based on what?, we need to make sure to load balance in both ways.

    Hi,
    usually load balancing has two parts:
    1) local traffic to the internet
    2) return traffic from the internet
    As we are talking about BGP any mechanism influencing path selection can be used to load balance local traffic.
    Basically you send traffic towards some destinations through one peering point and some traffic to other destinations through other peering points. Local Preference could be a good way to achieve this.
    Be aware that you need some traffic analysis in order to influence the local traffic in the desired way.
    Regarding option 2):
    We are talking about BGP and what you want is to influence the routing decisions of other ASes. Bad news: there is no way to make SURE it will happen the way you want this to happen. They are AUTONOMOUS and therefore can also use f.e. LocPref to achieve their goals. Those might contradict yours.
    But from a technical point of view the BGP updates you send should contain "hints" as to where the return traffic should be sent. As anything can be stripped of a BGP update except well-known mandatory attributes (origin, next-hop, AS path) usually AS path prepending is the measure to make return traffic for one of your prefixes prefer one way. And traffic for other prefixes you own another way.
    Also be aware that BGP in itself was not built for Load sharing per prefix, because every BGP speaker will only announce the best path per prefix. So even in the neighbor AS after a route-reflector all BGP speakers will only learn ONE path to your AS per prefix.
    Hope this helps
    Martin
    P.S.: Do not prepend too many ASes and do not split your IP address space in to many small junks. Also look at RIPE document 229, which talks about route flap dampening ... larger prefixes are always better.

  • Load balance not happening in BGP

    Dear Friends,
    As per I know local BGP process may implement equal-cost load-balancing to the paths that:
    Have the same set of path attributes up to the MED (weight, Local Preference, Origin, MED)
    Are of the same type (both learned via iBGP or eBGP)
    Have the same IGP cost to reach their NEXT_HOP IP address
    If the above conditions are met andmaximum-paths [ibgp]is  configured under the BGP process, BGP will install multiple equal-cost  routes into the local RIB and use them for load-balancing. We call the  above condition as load-balancing conditions for BGP.
    As all the above criteria are matched still BGP is not doing load balance. Please find below routing table:
    R1:
    R1#sh ip bgp
    BGP table version is 4, local router ID is 40.1.1.1
    Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
                  r RIB-failure, S Stale
    Origin codes: i - IGP, e - EGP, ? - incomplete
       Network          Next Hop            Metric LocPrf Weight Path
    *>i192.168.1.0      20.1.1.2                 0    100      0 i
    * i                        30.1.1.1                 0    100      0 i
    R1#sh ip route
    Gateway of last resort is not set
         20.0.0.0/24 is subnetted, 1 subnets
    R       20.1.1.0 [120/1] via 10.1.1.2, 00:00:03, FastEthernet0/0
         40.0.0.0/24 is subnetted, 1 subnets
    C       40.1.1.0 is directly connected, FastEthernet0/1
         10.0.0.0/24 is subnetted, 1 subnets
    C       10.1.1.0 is directly connected, FastEthernet0/0
    B    192.168.1.0/24 [200/0] via 20.1.1.2, 00:12:01
         30.0.0.0/24 is subnetted, 1 subnets
    R       30.1.1.0 [120/1] via 40.1.1.2, 00:00:15, FastEthernet0/1
    router bgp 100
    no synchronization
    bgp log-neighbor-changes
    neighbor 10.1.1.2 remote-as 100
    neighbor 40.1.1.2 remote-as 100
    maximum-paths 2
    no auto-summary
    Please help....!!!!!!!   why BGP is not load balancing here????
    R1#traceroute 192.168.1.1
    Type escape sequence to abort.
    Tracing the route to 192.168.1.1
      1 10.1.1.2 88 msec 60 msec 28 msec
      2 20.1.1.2 104 msec 56 msec 120 msec
    Regards,
    Sanjib

    Dear Jon,
    Thank you so much.
    When I changed the configuration BGP is now loadbalancing. But in configuartion Max-path showing as 1 instead of 2.
    R1#sh ip pro | sec bgp
    Routing Protocol is "bgp 100"
      Outgoing update filter list for all interfaces is not set
      Incoming update filter list for all interfaces is not set
      IGP synchronization is disabled
      Automatic route summarization is disabled
      Neighbor(s):
        Address          FiltIn FiltOut DistIn DistOut Weight RouteMap
        12.1.1.2                                            
        13.1.1.3                                            
    Maximum path: 1
      Routing Information Sources:
        Gateway         Distance      Last Update
        13.1.1.3             200      00:01:12
        12.1.1.2             200      00:02:15
      Distance: external 20 internal 200 local 200
    Regards,
    Sanjib

  • Dual ISP load balancing with 2 routers and 2 FW without using BGP

    Hi all,
    Based on the attachment diagram, is the design viable?
    Do anyone has a similar deployment before and can you share with me the config guide to this because I'm at lost on a few configs:
    1. On core switch A and B, I understood we need to have a default route pointing to the firewall interface. For this case, I have different IPs for the same context on both the firewalls.
    So, how should the config be?
    CoreSW_A(config)#ip route 0.0.0.0 0.0.0.0 192.168.1.110
    CoreSW_A(config)#ip route 0.0.0.0 0.0.0.0 192.168.1.111
    I don't think the above will work as the core switch will load balance the traffic to both firewalls even if one of the context is on standby mode?
    2. The area from the firewall to the internet would all be public IP. Thus, if i put a switch in between the firewall and the router, then i would waste some public IP addresses but if i remove the switch, I would not have enough ports on the ASA firewall. What is the best recommended solution for this?
    3. How do I load balance traffic to both R1 and R2 to their respective ISPs without using BGP? I may be using only a 2811 router.
    Thanks alot!!.. really much looking forward for some guidance and tips on this as I havent found any guides on this deployment yet.. mostly are LAN HA.

    For policy based routing, I would need to create route maps on the core switch itself right?
    Correct me if I'm wrong, if i use route-maps, i would be assigning e.g. internal network A to go through firewall context A and internal network B to go through firewall context B.
    Context A will only have path to Router A and context B will only have path to Router B. But if router B goes down, network B won't be able to access the Internet, right?
    I'm not sure whether it's a PI or PA for this as the ISP will assign us a block of IP address, for example 202.111.1.8/29 (these IPs can be used for webservers, etc). There will also be a public IP of /30 on the serial interface to connect to their router.
    Thanks alot..

  • Load balancing with multiple clusters (HTTPProxyServlet)

              Hello!
              I'm newbie in Weblogic. I would like to have clustering and load balancing in
              development environment. I've created 2 clusters, with one managed server each.
              I've created a web application for deploying the http proxy servlet and put it
              under another managed server without clustering. Below is my configuration:
              managed server without cluster (as proxy) - Port 8002
              admin server - Port 8001
              cluster_1 - multicast address 237.0.0.11, multicast port 8004, cluster address
              - t3://localhost:8006, t3://localhost:8007
              cluster_2 - multicast address 237.0.0.10, multicast port 8014, cluster address
              - t3://localhost:8006, t3://localhost:8007
              managed_cluster1 - under cluster_1, port 8006
              managed_cluster2 - under cluster_2, port 8007
              in the web.xml of the proxy, i put the following parameters:
              <param-name>WebLogicCluster</param-name>
              <param-value>localhost:8006|localhost:8007</param-value>
              However, when i send the requests to http://localhost:8002/sms, the requests always
              go to the same server, for eg: managed_cluster2?
              If i configure using single cluster, the load balancing will be in proper. What's
              the cause fo the problem? and any solution?
              Thanx in advance.
              Regards,
              joey
              

    You have 2 options here Jordi, either you can use BGP loadbalancing, this requires multipath as BGP by default would only install one route from the BGP table to the RIB hence FIB.
    But this may result in excessive IRL (inter rack link) usage in the cluster when traffic coming in on rack0 wants to take the bGP path out on rack1
    You could also use ABF (access-list based forwarding) to forcelly push traffic received on rack0 out on the link on rack0 and use an ipsla tracker to fallback to rack1 in case the uplink is gone.
    Alternatively to extend this by IGP signaling to redirect traffic preferably to rack1 to start with to minimize the IRL usage.
    And then you also have the ability to use RPL in the uplink path to make one link more preferred on teh internet then the other in case you want to control a bit which link is preferably used on rack0 or rack1
    regards
    xander

  • Discussion on load-balance and load-sharing

    Hi, I found a article, which discuss the difference between load-balance and load-sharing. I think the explanation is pretty good, please see below. But I still have a question: how can we decide to choose one the both balance in the production environment ?  Thank you
    "In short, load balancing tries to distribute traffic evenly over multiple paths, whereas, load sharing intends to do it (for the lack of a better term) equally.  True load balancing is difficult to achieve.  For example, let's say there were two links (100 mbps and 300 mpbs) and a router needed to send out 600 mbps of traffic.  Load balancing would distribute the traffic evenly, sending 300 mbps on each link.  On the contrary, load sharing would divide the traffic equally based on the available resources, sending 200 mbps on the slower link and 400 mbps on the faster one. "

    Disclaimer
    The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.
    Liability Disclaimer
    In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.
    Posting
    That's not how Cisco uses the terms, and generically they are often used almost interchangeably.
    Cisco uses load balancing as the catch all for how a single L3 device routes across multiple paths to the same destination.  Equal metrics or equal actual load distribution are not required.  Most often, load balancing will be discussed with ECMP, but unequal path loading balancing will include Cisco's proprietary IGPs, such as EIGRP.
    Cisco uses load sharing when using multiple paths when a single L3 devices doesn't normally route across multiple paths or multiple L3 devices are involved.  Cisco load sharing discussions usually revolve around BGP.
    Generically, I would say load balancing has more of a dynamic aspect to it, i.e. something is trying to actively balance traffic across multiple paths, while load sharing might mean multiple paths are utilized but not actively dynamically balanced.
    I'm unsure what's your question with a production environment.

  • Load Balancing with ASR9000 vN and multiple ISPs

    Hi,
    we will deploy a new DC as Active/Active.
    We will have ISPA and ISP B in each DC. Internet users are anybody in the internet coming to our e-commerce DC application.
    How could we do load balancing between ISPs using the ASR9001 and nV feature ?
    There is any IOS-XR feature that could help us about to do load balancing between ISPs?
    Thanks a lot.
    Regards,
    J

    You have 2 options here Jordi, either you can use BGP loadbalancing, this requires multipath as BGP by default would only install one route from the BGP table to the RIB hence FIB.
    But this may result in excessive IRL (inter rack link) usage in the cluster when traffic coming in on rack0 wants to take the bGP path out on rack1
    You could also use ABF (access-list based forwarding) to forcelly push traffic received on rack0 out on the link on rack0 and use an ipsla tracker to fallback to rack1 in case the uplink is gone.
    Alternatively to extend this by IGP signaling to redirect traffic preferably to rack1 to start with to minimize the IRL usage.
    And then you also have the ability to use RPL in the uplink path to make one link more preferred on teh internet then the other in case you want to control a bit which link is preferably used on rack0 or rack1
    regards
    xander

  • Multihomed eBGP load balancing with 3 ISP's

    We currently peer with 2 ISPs using BGP in an active/failover configuration.  My company wants to move to a 3 ISP model where Internet traffic is split across the 3 providers so that bandwidth is equally distributed on outgoing traffic across our 2 /22 ARIN IP ranges.  This is from our 2 edge switches that have VSS.  
    Within my limited knowledge of BGP, I have determined that we could do load sharing pretty easily by adding multiple default routes and breaking up our /22's into /24 and advertising them that way.  However, I don't think this satisfies the request that downtime must be seamless, should one link drop.  
    Currently, our ISP's advertise default routes.  From the research that I've done, we could get close to load balanced links if we receive full BGP routes and community settings and definitions.  I'm nervous about this because it looks really complicated, and I don't want our AS to turn into a transit AS.  I've been told the same can be accomplished with only partial BGP routes and community settings and definitions.  
    Personally, I think we just need a WAN load balancer.  However, given the request, is there a thread out there that can explain this, or can someone discuss this requested scenario a little bit?  
    Thanks!

    Hi there
    First question would be what is the required reconvergence time for the applications using the Internet? Should an outage occur, when do they lose their state? Once you know that, you then have a target to aim for in terms of recovery
    With regards load-balancing, with BGP we are always talking inbound and outbound.
    The outbound solution is relatively simple - each ISP advertises a default route to your Internet edge router(s). Create an eBGP session from each edge router to the core, advertise the default route and redistribute into the IGP. Ensure the IGP cost to each BGP next hop is equal and you have ECMP for outbound routing.
    Inbound influence is usually via MED (not likely in this case given 3 ISPs), adjusting local-pref in the ISP via BGP EXT communities configured your end, or via AS-PATH prepending for longer prefixes from your /22. Prepending would be simplest, but your unlikely to get an exact inbound traffic split, however a relatively even distribution should be sufficient. 

  • Load-balancing vs Load-sharing (L2/L3)

    What is the difference in load balancing and load sharing. Can you generalize load-balancing to layer two? Or layer three protocols also do this, except BGP?
    FHRPs like VRRP, GLBP, and HSRP are essentially load sharing protocols (except GLBP though). Loop prevention mechanisms like MSTP, G.8032, and REP also do not do load balancing I guess. Instead they offer a way to distribute (share) traffic over multiple links unevenly. Why do people still call it load-balancing?
    While link aggregation may truly be considered load balancing. Where traffic can be balanced based on a few attributes ( src-dst/mac, ip, port).
    And what role does fast-switching/process-switching play in load balancing. I am aware that these are the very processes that ultimately do load-balancing, given enough equal cost paths. Does CEF really take load balancing to another level? It still does the same job, but by caching flow data (RIB) to the CEF table, doesn't it?
    Incase of IGP, load-balancing may be possible, but BGP just doesn't support it. Because it only selects one best route (?). Even with multipath, BGP advertises best path only; it does install multiple routes in routing table though. So IGP does the balancing?

    What is the difference in load balancing and load sharing. Can you generalize load-balancing to layer two? Or layer three protocols also do this, except BGP?
    FHRPs like VRRP, GLBP, and HSRP are essentially load sharing protocols (except GLBP though). Loop prevention mechanisms like MSTP, G.8032, and REP also do not do load balancing I guess. Instead they offer a way to distribute (share) traffic over multiple links unevenly. Why do people still call it load-balancing?
    While link aggregation may truly be considered load balancing. Where traffic can be balanced based on a few attributes ( src-dst/mac, ip, port).
    And what role does fast-switching/process-switching play in load balancing. I am aware that these are the very processes that ultimately do load-balancing, given enough equal cost paths. Does CEF really take load balancing to another level? It still does the same job, but by caching flow data (RIB) to the CEF table, doesn't it?
    Incase of IGP, load-balancing may be possible, but BGP just doesn't support it. Because it only selects one best route (?). Even with multipath, BGP advertises best path only; it does install multiple routes in routing table though. So IGP does the balancing?

  • Load-balancing in MPLS Core

    How is load-balancing achieved in MPLS L3 vpns and equal cost multiple links exist to reach egress PE along with per-destination load-balancing enabled on interfaces.
    I have tried to simulate the network below
    Ingress PE--->P1--->>P2--->Egress PE
    Multiple equal cost links exist between P1 and P2, cisco platform,LDP, IGP-ospf being used.

    Hi,
    Destination based load balancing in MPLS L3VPNs can be categorized into two scenarios:
    1) multiple pathes between two PE routers
    2) multiple access links to a single CE or site
    Your question as I understand it was about the first scenario. So let me first quickly review how customer traffic is forwarded between VRFs on two different PE routers.
    The VRF routing table will have BGP entries for the routes learned from the remote PE usually with next hop addresses being the remote PE loopback IP used for PE-to-PE BGP peering.
    The traffic will be forwarded across P routers using the label for the BGP next hop.
    Thus the load balancing accross the MPLS core in a first step is decided by the IGP, which has to insert several equal cost pathes into the global routing table for the BGP next hop networks (PE loopbacks).
    Side note: MPLS traffic engineering in the core would allow for unequal cost load balancing.
    The decision, which labeled packet to send across which path in the core is done by CEF using a hash algorithm. To achieve the same load balancing as with unlabeled IP traffic, a Cisco MPLS enabled router will look for the bottom label - the one with bottom-of-stack bit set to 1 - and try to determine, if the transported packet behind the bottom label is IP. If so, the hash is calculated for the customer IP header like for normal IP traffic. This ensures all traffic for a certain customer destination will always go through the same path. No unwanted packet reordering will occur.
    Be aware, that the customer IP packet header will only be used for CEF hash calculation, no IP lookup will be performed, as core routers in MPLS L3VPNs do not have any knowledge about customer addresses.
    As a side note: if the traffic transported is not IP (e.g. Ethernet over MPLS), the bottom label will be used for the CEF load balancing (e.g. the VC label).
    For the second scenario - CE load balancing with multihomed CE/sites - it is first required to have two equal cost entries in the VRF routing tables. The difference will be the two different PE BGP next hop addresses. The first load balancing decision is the performed by CEF based on the IP packet received by the CE and the VRF routing table entries. Once CEF decided, which VRF entry to use, the required BGP next hop label (and the VPN label) is applied and the packet is transported across the MPLS core. load balancing there is done as described above.
    Hope this helps! Please rate all posts.
    Regards, Martin

  • Load balancing across multiple paths to Internet

    Hello,
    I have a 2821 router. Currently, I have two bonded T-1 circuits to the Internet.
    I would like to add a DSL circuit to augment the T1s. I would also like to load balance across all of the circuits. Currently, IOS performs inherent load balancing for the T1 circuits. The DSL circuit is from a different provider than the T1s.
    The T1s are coming from a local ISP that runs no routing protocols within their infrastructure. (They run static routes and rely on the upstream provider for BGP.) The DSL provider is a national telecom carrier.
    What is the best way to perform load balancing for this scenario?

    Here is the answer (sort of) for anyone reading this post with the same question:
    No matter which way I choose to do it, the trick is to have the local ISP subnet advertised via BGP through both pipes. The national telecom DSL provider will not advertise a /20 subnet down a DSL pipe. (Ahh, why not? =:)
    Had the secondary pipe been a T-1,T-3, or other traditional pipe, I could have used a load balancer like a BigIP, or FatPipe device or possibly CEF within the IOS.
    Case closed. Thanks to everyone that took a look.
    Doug.

  • Load balancing with use of router 881.

    Hello,
    I have two MPLS line and i want load balancing with the help of CISCO router 881. is it necessary that i require two router on both location.? if one location have firewall and one location have cisco router 881 then can i do a load balancing or i require two router each on both location ? What are the basic requirement that i need.
    Thanks,
    Kuntal

    Disclaimer
    The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.
    Liability Disclaimer
    In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.
    Posting
    An 881 should be able to load share across multiple ports.  Many routing protocol support ECMP, including BGP, but you need "special" hidden/secret commands to enable.  EIGRP also supports unequal cost load sharing.
    If an 881 supports OER or PfR, those too will do unequal load sharing, dynamically.

  • Internet Load Balancing - Routing Issue

    Dear all, good day...
    in our ministry we are going to contract with 2 ISPs to provide us with the internet service (one of them will be the main line 16 MB, and the other line will be working as a backup line). Now, here is my question, is there any router that can holds the 2 ISPs lines at the same time and have the fail over property and load balancing, or i have to use 2 different routers (we have CISCO 2821) to do the load balancing between the 2 internet lines. Thankx

    Hi Tareq
    There are many ways you can do.But depending on your requirement.If you are using 2 ISPs and all of ISPs are willing to do BGP then that is the right way you should do. For doing load-sharing.please check this link out.
    http://www.cisco.com/en/US/tech/tk365/technologies_configuration_example09186a00800945bf.shtml
    Just my thought.In case one of your ISPs can't do BGP then you can use the policy-based routing feature to do out-bound load-sharing(inside to ISPs) by classifying traffics you want.
    Try to understand technology first.
    http://www.cisco.com/en/US/products/ps6599/products_white_paper09186a00800a4409.shtml
    Hope this helps
    Thot

  • Load Balancing and Failover in Dual Ethernet

    I have a cisco 2911/K9 router with two 4Mbps Leased line connection from two different ISPs to my remote office. Remote office has cisco 2811 router
    Main office has MPLS connection with static Ip routing apart from the two leased lines
    All handoffs are ethernet
    Is it possible to do load sharing as well as fail over between the two ISPs, if so how am i to achieve that
    Kindly help me

    Disclaimer
    The   Author of this posting offers the information contained within this   posting without consideration and with the reader's understanding that   there's no implied or expressed suitability or fitness for any purpose.   Information provided is for informational purposes only and should not   be construed as rendering professional advice of any kind. Usage of  this  posting's information is solely at reader's own risk.
    Liability Disclaimer
    In   no event shall Author be liable for any damages whatsoever (including,   without limitation, damages for loss of use, data or profit) arising  out  of the use or inability to use the posting's information even if  Author  has been advised of the possibility of such damage.
    Posting
    If your MPLS vendor supports no dynamic routing, they why do you ask about BGP?  Or, do they only support dynamic routing with BGP?
    You can do equal cost multi-path with BGP (may require a hidden command to fully utilize).
    You could do GRE tunnels across the MPLS cloud and dynamically route between them using your choice of a dynamic routing protocol.
    Both your devices should support OER/PfR (may require a feature upgrade).  OER/PfR will actually dynamically load balance.
    SLA features should also be available on both your routers, those too might require a IOS feature upgrade.
    Configuration examples might be found on Cisco's main web site.

  • Load balancing over two separate outside routers and two separate WAN Links

    Hi everybody,
    I have one 2851 setup with two separate ISP links and have it configured for failover with BGP.  It works great but doesn't load balance.
    Well now I have to new routers (3925's) to replace the single 2851 and I want to configure them to load balance over separate WAN links.
    Can someone help figure out the best approach to make this happen?  I would really appreciate it.
    Thank you,
    Thomas Reiling

    Disclaimer
    The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.
    Liability Disclaimer
    In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.
    Posting
    The "best approach", IMO, would be to use PfR (if your routers support it).

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