Bandwidth distribution per ip

Blake Hudson blake at ispn.net
Wed Dec 20 17:45:08 CST 2017


Denys Fedoryshchenko wrote on 12/20/2017 11:38 AM:
> 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.
>

Are you claiming that your bandwidth is being equally divided 1024 ways 
(you mentioned a /22) or just that each host (IP) is not receiving the 
full bandwidth? What is the bandwidth ordered and what is the bandwidth 
you're seeing per host(IP)?




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