Bandwidth distribution per ip

Denys Fedoryshchenko denys at visp.net.lb
Wed Dec 20 17:42:17 CST 2017


On 2017-12-20 19:16, Blake Hudson wrote:
> Denys Fedoryshchenko wrote on 12/20/2017 8:55 AM:
>> National operator here ask customers to distribute bandwidth between 
>> all ip's equally, e.g. if i have /22, and i have in it CDN from one of 
>> the big content providers, this CDN use only 3 ips for ingress 
>> bandwidth, so bandwidth distribution is not equal between ips and i am 
>> not able to use all my bandwidth.
>> 
>> And for me, it sounds like faulty aggregation + shaping setup, for 
>> example, i heard once if i do policing on some models of Cisco switch, 
>> on an aggregated interface, if it has 4 interfaces it will install 25% 
>> policer on each interface and if hashing is done by dst ip only, i 
>> will face such issue, but that is old and cheap model, as i recall.
>> 
>> Did anybody in the world face such requirements?
>> Is such requirements can be considered as legit?
> 
> Not being able to use all of your bandwidth is a common issue if you
> are provided a bonded connection (aka Link Aggregation Group). For
> example, you are provided a 4Gbps service over 4x1Gbps ethernet links.
> Ethernet traffic is not typically balanced across links per frame,
> because this could lead to out of order delivery or jitter, especially
> in cases where the links have different physical characteristics.
> Instead, a hashing algorithm is typically used to distribute traffic
> based on flows. This results in each flow having consistent packet
> order and latency characteristics, but does force a flow over a single
> link, resulting in the flow being limited to the performance of that
> link. In this context, flows can be based on src/dst MAC address, IP
> address, or TCP/UDP port information, depending on the traffic type
> (some IP traffic is not TCP/UDP and won't have a port) and equipment
> type (layer 3 devices typically hash by layer 3 or 4 info).
> 
> Your operator may be able to choose an alternative hashing algorithm
> that could work better for you (hashing based on layer 4 information
> instead of layer 3 or 2, for example). This is highly dependent on
> your provider's equipment and configuration - it may be a global
> option on the equipment or may not be an option at all. Bottom line,
> if you expected 4Gbps performance for each host on your network,
> you're unlikely to get it on service delivered through 4x 1Gbps links.
> 10Gbps+ links between you and your ISP's peers would better serve
> those needs (any 1Gbps bonds in the path between you and your
> provider's edge are likely to exhibit the same characteristics).
> 
> --Blake

No bonding to me, usually it is dedicated 1G/10G/etc link.
Also i simulated this bandwidth for "hashability", and any layer4 aware 
hashing
on cisco/juniper provided perfectly balanced bandwidth distribution.
On my tests i can see that they have some balancing clearly by dst ip 
only.



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