> For the complete documentation index, see [llms.txt](https://docs.console.zenlayer.com/welcome/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.console.zenlayer.com/welcome/cn/ip-transit/high-availability.md).

# IP Transit 高可用（HA）

IP Transit 高可用（HA）功能允许您通过两个同城物理端口构建冗余出口架构，消除单点故障，实现业务连续性保障。SLA 可达 **99.95%**，高于单线路标准。

{% hint style="info" %} <mark style="color:blue;">**注意**</mark>

<mark style="color:blue;">当前仅支持自动化（BR）设备的高可用实例；存量单链路实例暂不支持升级为 HA。</mark>
{% endhint %}

## 运行模式

HA 实例支持两种运行模式，可在创建后随时切换：

| 模式       | 别名             | 说明                                          |
| -------- | -------------- | ------------------------------------------- |
| **主备容灾** | Active-Standby | 主端口承担全部流量；主端口故障时，秒级自动切换至备端口。适合对路径确定性要求高的业务。 |
| **负载均衡** | Active-Active  | 两条链路同时转发，按 ECMP 策略分担流量。最大化利用带宽，一侧故障时流量平滑迁移。 |

## 路由模式

HA 实例仅支持 **Static Routing（静态路由）** 模式。

## 前提条件

* 账户已完成实名认证，余额充足。
* 目标城市有**两个或以上**可用的 IP Transit 物理端口（状态为 UP）。
* 已规划好 VLAN ID（主端口与备端口各一个，建议使用相同值）。
* 了解所需带宽规格及计费方式（固定带宽 / 95 计费）。


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