【FRRouting User Guide】【Basic 】（八）Route Maps

路由映射提供了一种方法，可以过滤和/或将操作应用到路由，从而允许策略应用于路由。
对于路由反射器将route-map应用到反射路由，请确保在router bgp 模式下包含bgp route-reflector allow-outbound-policy。
路由映射是路由映射条目的有序列表。每个条目最多可指定四组不同的条款：

Matching Conditions

route-map entry 可以可选地指定一个或多个条件，如果要进一步考虑条目，则这些条件必须被匹配，如由匹配策略所控制的那样。如果route-map entry 没有明确指定任何匹配条件，则它始终匹配。

Set Actions

route-map entry 可以指定一个或多个设置操作来设置或修改route的属性。

Matching Policy

这将指定满足或不满足匹配条件时隐含的策略，以及要采取的 route-map 操作（如果有）。这两种可能性是：

• permit: 如果entry 匹配，则执行设置的操作。然后完成处理route-map，允许route，除非退出策略操作另有指示。
• deny: 如果entry 匹配，则完成对route-map 的处理并拒绝该route （return deny）。

匹配策略被指定为命令的一部分，该命令定义 route-map中的有序条目。见下文。

Call Action

在执行任何设置操作后，调用另一个route-map。如果调用的route-map返回拒绝，则处理route-map将完成，并且拒绝路由，而不管匹配策略或退出策略如何。如果调用的路由映射返回许可，那么匹配策略和退出策略将正常地管理进一步的行为。

Exit Policy

如果entry 匹配，entry 可以选择性地指定要采取的替代退出策略，而不是退出route-map并允许route的常规策略。这两种可能性是：

• next: 继续处理 route-map entries。
• goto N: 跳转到route-map 中顺序>=N的第一个route-map 条目。不允许跳转到上一个条目。

如果没有匹配的条目，route-map的默认操作是拒绝。I.e. route-map的最后一个条目基本上有一个空拒绝条目，该条目与所有路由匹配。要更改此行为，必须将空许可证条目指定为route-map中的最后一个条目。

总结以上内容：

	Match	No Match
Permit	action	cont
Deny	deny	cont

action

• Apply set statements
• If call is present, call given route-map. If that returns a deny, finish processing and return deny.
• If Exit Policy is next, goto next route-map entry
• If Exit Policy is goto, goto first entry whose order in the list is >= the given order.
• Finish processing the route-map and permit the route.

deny

The route is denied by the route-map (return deny).

cont

goto next route-map entry

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• show route-map [WORD]

Display data about each daemons knowledge of individual route-maps. If WORD is supplied narrow choice to that particular route-map.

• clear route-map counter [WORD]

清除存储的有关route-maps利用率的计数器，以便后续show命令将指示自上次清除以来的情况。如果指定了WORD，则只清除该特定route-maps的计数器。

Route Map Command

• route-map ROUTE-MAP-NAME (permit|deny) ORDER

使用permit或deny的匹配策略配置route-map-name中的order条目。

Route Map Match Command

• match ip address ACCESS_LIST

匹配指定的访问列表

• match ip address prefix-list PREFIX_LIST

匹配指定的前缀列表

• match ip address prefix-len 0-32

匹配指定的前缀len。这是zebra特有的命令。

• match ipv6 address ACCESS_LIST
• match ipv6 address prefix-list PREFIX_LIST
• match ipv6 address prefix-len 0-128
• match ip next-hop address IPV4_ADDR

这是特定于BGP的匹配命令。这是特定于BGP的匹配命令。匹配指定的ipv4地址。

• match ipv6 next-hop IPV6_ADDR

这是特定于BGP的匹配命令。这是特定于BGP的匹配命令。匹配指定的ipv6\u addr。

• match as-path AS_PATH
• match metric METRIC

匹配指定的度量。

• match tag TAG

匹配与路由关联的指定标记值。此标记值可以在（1-4294967295）范围内。

• match local-preference METRIC

Matches the specified local-preference.

• match community COMMUNITY_LIST
• match peer IPV4_ADDR

这是特定于BGP的匹配命令。这是特定于BGP的匹配命令。匹配以这种方式指定邻居的对等ip地址。

• match peer IPV6_ADDR

这是特定于BGP的匹配命令。这是特定于BGP的匹配命令。匹配以这种方式指定邻居的对等ipv6地址。

• match peer INTERFACE_NAME

这是特定于BGP的匹配命令。这是特定于BGP的匹配命令。匹配以这种方式指定邻居时指定的对等接口名称。

• match source-protocol PROTOCOL_NAME

这是特定于zebra的匹配命令。这是特定于zebra的匹配命令。与指定的原始协议匹配。

• match source-instance NUMBER

这是特定于zebra的匹配命令。这是特定于zebra的匹配命令。数字的范围是（0-255）。匹配指定的原始协议实例。

Route Map Set Command

• set tag TAG

在匹配的路由上设置一个标记。此标记值可以来自（1-4294967295）。另外，如果您使用--enable realms 配置选项编译。来自（1-255）的标记值作为域值发送到Linux内核。然后可以应用路由策略。请参阅tc手册页。

• set ip next-hop IPV4_ADDRESS

将BGP next xthop地址设置为指定的IPV4_ADDRESS。输入和输出route-maps。

• set ip next-hop peer-address

Set the BGP nexthop address to the address of the peer. For an incoming route-map this means the ip address of our peer is used. For an outgoing route-map this means the ip address of our self is used to establish the peering with our neighbor.

• set ip next-hop unchanged

Set the route-map as unchanged. Pass the route-map through without changing it’s value.

• set ipv6 next-hop peer-address

Set the BGP nexthop address to the address of the peer. For an incoming route-map this means the ipv6 address of our peer is used. For an outgoing route-map this means the ip address of our self is used to establish the peering with our neighbor.

• set ipv6 next-hop prefer-global

For Incoming and Import Route-maps if we receive a v6 global and v6 LL address for the route, then prefer to use the global address as the nexthop.

• set ipv6 next-hop global IPV6_ADDRESS

Set the next-hop to the specified IPV6_ADDRESS for both incoming and outgoing route-maps.

• set local-preference LOCAL_PREF

Set the BGP local preference to local_pref.

• set local-preference +LOCAL_PREF

Add the BGP local preference to an existing local_pref.

• set local-preference -LOCAL_PREF

Subtract the BGP local preference from an existing local_pref.

• set distance DISTANCE

Set the Administrative distance to DISTANCE to use for the route. This is only locally significant and will not be dispersed to peers.

• set weight WEIGHT

Set the route’s weight.

• set metric <[+|-](1-4294967295)|rtt|+rtt|-rtt>

Set the BGP attribute MED to a specific value. Use +/- to add or subtract the specified value to/from the MED. Use rtt to set the MED to the round trip time or +rtt/-rtt to add/subtract the round trip time to/from the MED.

• set as-path prepend AS_PATH

Set the BGP AS path to prepend.

• set community COMMUNITY

Set the BGP community attribute.

• set ipv6 next-hop local IPV6_ADDRESS

Set the BGP-4+ link local IPv6 nexthop address.

• set origin ORIGIN <egp|igp|incomplete>

Set BGP route origin.

• set table (1-4294967295)

Set the BGP table to a given table identifier

• set sr-te color (1-4294967295)

Set the color of a SR-TE Policy to be applied to a learned route. The SR-TE Policy is uniquely determined by the color and the BGP nexthop.

Route Map Call Command

• call NAME

Call route-map name. If it returns deny, deny the route and finish processing the route-map.

Route Map Exit Action Command

• on-match next
• continue

Proceed on to the next entry in the route-map.

• on-match goto N
• continue N

Proceed processing the route-map at the first entry whose order is >= N

Route Map Optimization Command

• route-map optimization

Enable route-map processing optimization. The optimization is enabled by default. Instead of sequentially passing through all the route-map indexes until a match is found, the search for the best-match index will be based on a look-up in a prefix-tree. A per-route-map prefix-tree will be constructed for this purpose. The prefix-tree will compose of all the prefixes in all the prefix-lists that are included in the match rule of all the sequences of a route-map.

Route Map Examples

A simple example of a route-map:

route-map test permit 10
 match ip address 10
 set local-preference 200

This means that if a route matches ip access-list number 10 it’s local-preference value is set to 200.

See Miscellaneous Configuration Examples for examples of more sophisticated usage of route-maps, including of the call action.