2018年8月23日 星期四

[Cisco] Load balancing 與 Load sharing 比較

常常聽到對於Server或網路規劃的負載平衡有些奇怪的誤解
尤其是 Load balancing 與 Load sharing 常常隨便混用著說
剛好CISCO 論壇有人有類似的疑問 我覺得回答的還蠻清楚的
learningnetwork.cisco.com/thread/63821 )

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.

簡而言之,負載平衡嘗試在多個路徑上均勻地分配流量,
而負載分配打算同等執行(缺少更好的說法)。真正的負載平衡很難實現。
假設有兩個連結(路徑 : 100 mbps 和 300 mpbs)和一個需要發送600 mbps流量的Router。
預設情況下 負載平衡將均勻分配流量,每條連結發送300 mbps。
相反,負載共享(Sharing)會根據可用資源平均分配流量,
在較慢的連結上發送200 mbps,在較慢的連結上發送400 mbps。

永久連結

Load sharing  能將流量控制平均在這兩條線路上,
而load balance 則不僅僅能分送,能考慮到兩條線路頻寬的不同而予以不同分擔(可能需要手動設定)

Load Balancing 也可依等比例作分配常見的Ether Channel (=Port Channel)就是Load balancing EIGRP 動態路由的 variance做 load balancing來說可以手動設定依照 Metric(可以說是路由成本) 的反比例分配流量


技術點來解釋:
Many Network administrators at times get tangled in the conceptual difference of Load Balancing and Load Sharing. Prima facie, both may be thought of as one of the same thing, however as we drill down, the terms tend to differ. So let’s differentiate how both Load Balancing and Load Sharing concepts differ from each other and where are they used.
Load balancing is more of dynamic technique of distributing the load across 2 or more links while Load Sharing works by statically splitting the traffic types and then distributing the load across multiple links. Though we understand that dynamic load distribution will be more efficient on equal load distribution. While Load Balancing utilises round robin or maximum connections etc. to distribute traffic, Load sharing 1st splits the traffic based on source or destination IP/Mac address etc. and then distributes traffic across links.


許多網管有時會搞混負載平衡和負載分享的概念差異。乍看之下兩者都可以被認為是同一件事,但是當我們深入研究時,其實有所不同。
負載平衡(balancing)更多是透過兩個或多個連結分配負載的動態技術,
而負載分配(sharing)通過靜態拆分流量類型然後跨多個連結分配負載來工作。
雖然我們知道動態負載分配在等負載分配上會更有效。

雖然負載平衡利用循環或最大連接等來分配流量,
負載分配會根據源或目標IP / Mac地址等拆分流量,然後跨連結分配流量。 


Below table gives simple comparison of both the concepts – Load Balancing vs Load Sharing
load-balancing-vs-load-sharing
(https://ipwithease.com/load-balancing-vs-load-sharing/)




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