三层交换机之VLAN_XLATE

博通交换芯片中，QinQ域功能实现主要依赖于VLAN_XLATE和VCAP(VFP)资源实现。其中，VLAN_XLATE实现常规QinQ域；VCAP实现灵活QinQ域，因为灵活QinQ域需要匹配除VLAN和MAC之外的其他字段，比如EtherType、IpProtocol、UDP Src/Dst Port等，这种方式又称为基于流（Based on Flow）。

VLAN_XLATE和EGR_VLAN_XLATE表均包含多个表项资源，使用Hash算法查找。

VLAN_XLATE

VLAN_XLATE表查找有两种相互独立的方式，首先使用PORT_TAB.VT_KEY_TYPE作为Key值进行Hash查找，查找失败的情况下，继续使用PORT_TAB.VT_KEY_TYPE2作为Key值进行Hash查找。

/* Key types for vlan translation lookup. */
typedef enum bcm_vlan_translate_key_e {
    bcmVlanTranslateKeyInvalid,         /* Invalid Key Type. */
    bcmVlanTranslateKeyDouble,          /* Use O-VID[11:0] and I-VID[11:0]. */
    bcmVlanTranslateKeyOuter,           /* Use O-VID[11:0] */
    bcmVlanTranslateKeyInner,           /* Use I-VID[11:0] */
    bcmVlanTranslateKeyOuterTag,        /* Use O-TAG[15:0] */
    bcmVlanTranslateKeyInnerTag,        /* Use I-TAG[15:0] */
    bcmVlanTranslateKeyOuterPri,        /* Use (VLAN-PRI, VLAN-CFI => O-TAG[15:12]) */
    bcmVlanTranslateKeyPortDouble,      /* Use Port, O-VID[11:0] and I-VID[11:0]. */
    bcmVlanTranslateKeyPortOuter,       /* Use Port, O-VID[11:0] */
    bcmVlanTranslateKeyPortInner,       /* Use Port, I-VID[11:0] */
    bcmVlanTranslateKeyPortOuterTag,    /* Use Port, O-TAG[15:0] */
    bcmVlanTranslateKeyPortInnerTag,    /* Use Port, I-TAG[15:0] */
    bcmVlanTranslateKeyPortOuterPri     /* Use Port, (VLAN-PRI, VLAN-CFI =>O-TAG[15:12]) */
} bcm_vlan_translate_key_t;

EGR_VLAN_XLATE

首先进行DT查找，然后进行OVID查找。

VLAN RANGE CHECKING

允许将CVID(Customer VLAN ID)或者IVID(Inner VLAN ID)范围段映射到相同的PVID/SVID/OVID，这样可以使用一条VLAN_XLATE表项和VLAN_PROFILE表项实现，从而节省VLAN_XLATE资源：

1） 最多支持128个VLAN RANGE profiles

2） 每个VLAN RANGE profile最多支持8个VLAN RANGEs

3） 同一个VLAN RANGE profile内的8个VLAN RANGEs不能重叠

4） CVID和PVID/SVID不能重叠

过程如下：

1） 入端口报文CVID进入VLAN range checking逻辑，通过(MODID, port)索引VLAN_RANGE_IDX表，返回指向IGR_VLAN_RANGE_TBL的索引号；

2） IGR_VLAN_RANGE_TBL的每个表项包含6个VLAN对（MIN,MAX）支持6个VLAN范围段；如果CVID与任意VLAN对匹配，则命中，该报文的CVID被替换为VLAN_MIN值；如果未命中，则CVID用来进行VLAN_XLATE查找；

BCM SDK API

Ingress

/* Add an entry to the VLAN Translation table. */
extern int bcm_vlan_translate_add(
int unit, 
int port, 
bcm_vlan_t old_vid, 
bcm_vlan_t new_vid, 
int prio);

 将指定端口入端口old_vid的报文转换为new_vid的报文。

对于StrataXGS III系列交换芯片，支持优先级替换，prio为-1表示转换后不更改报文优先级，prio为0~7表示转换后的报文优先级。

对于支持VLAN action API的交换芯片，prio表示内部优先级，不支持-1。

/* Add an entry to the VLAN Translation table. */
extern int bcm_vlan_translate_get(
int unit, 
int port, 
bcm_vlan_t old_vid, 
bcm_vlan_t *new_vid, 
int *prio);

/* Delete an entry or entries from the VLAN Translation table. */
extern int bcm_vlan_translate_delete(
int unit, 
int port, 
bcm_vlan_t old_vid);

 删除old_vid相关的所有VLAN_XLATE表项

/* Remove all entries from the VLAN Translation table. */
extern int bcm_vlan_translate_delete_all(
int unit);

/* Add an entry to the VLAN Translation table and assign VLAN actions. */
extern int bcm_vlan_translate_action_add(
int unit, 
bcm_gport_t port, 
bcm_vlan_translate_key_t key_type, 
bcm_vlan_t outer_vlan, 
bcm_vlan_t inner_vlan, 
bcm_vlan_action_set_t *action);

 key_type必须为bcmVlanPortTranslateKeyFirst或者bcmVlanPortTranslateKeySecond之一，它们由bcm_vlan_control_port_set配置，可以通过bcm_vlan_control_port_get获取。

使用bcm_vlan_translate_action_add创建VLAN_XLATE表项转换的报文必须是tagged。

/* Get an entry to the VLAN Translation table and assign VLAN actions. */
extern int bcm_vlan_translate_action_get(
int unit, 
bcm_gport_t port, 
bcm_vlan_translate_key_t key_type, 
bcm_vlan_t outer_vlan, 
bcm_vlan_t inner_vlan, 
bcm_vlan_action_set_t *action);

/* Delete an entry from the VLAN Translation table. */
extern int bcm_vlan_translate_action_delete(
int unit, 
bcm_gport_t port, 
bcm_vlan_translate_key_t key_type, 
bcm_vlan_t outer_vlan, 
bcm_vlan_t inner_vlan);

获取指定端口、key_type和VLAN的VLAN_XLATE动作。

Egress

/* Add an entry to the egress VLAN Translation table. */
extern int bcm_vlan_translate_egress_add(
int unit, 
int port, 
bcm_vlan_t old_vid, 
bcm_vlan_t new_vid, 
int prio);

/* Get an entry to the egress VLAN Translation table. */
extern int bcm_vlan_translate_egress_get(
int unit, 
int port, 
bcm_vlan_t old_vid, 
bcm_vlan_t *new_vid, 
int *prio);

/* Remove an entry or entries from the VLAN egress Translation table. */
extern int bcm_vlan_translate_egress_delete(
int unit, 
int port, 
bcm_vlan_t old_vid);

/* Remove all entries from the egress VLAN Translation table. */
extern int bcm_vlan_translate_egress_delete_all(
int unit);

/* 
* Add an entry to the egress VLAN Translation table and assign VLAN
* actions.
*/
extern int bcm_vlan_translate_egress_action_add(
int unit, 
int port_class, 
bcm_vlan_t outer_vlan, 
bcm_vlan_t inner_vlan, 
bcm_vlan_action_set_t *action);

/* 
* Get an entry to the egress VLAN Translation table and assign VLAN
* actions.
*/
extern int bcm_vlan_translate_egress_action_get(
int unit, 
int port_class, 
bcm_vlan_t outer_vlan, 
bcm_vlan_t inner_vlan, 
bcm_vlan_action_set_t *action);

/* Delete an entry from the egress VLAN Translation table. */
extern int bcm_vlan_translate_egress_action_delete(
int unit, 
int port_class, 
bcm_vlan_t outer_vlan, 
bcm_vlan_t inner_vlan);

Dtag & Vlan Range

/* Add an entry to the VLAN Translation table for double-tagging. */
extern int bcm_vlan_dtag_add(
int unit, 
int port, 
bcm_vlan_t old_vid, 
bcm_vlan_t new_vid, 
int prio);

对入端口VLAN为old_vid的single inner-tagged的报文添加new_vid的外层VLAN。 

/* Get an entry to the VLAN Translation table for double-tagging. */
extern int bcm_vlan_dtag_get(
int unit, 
int port, 
bcm_vlan_t old_vid, 
bcm_vlan_t *new_vid, 
int *prio);

/* Remove an entry from the VLAN Translation table for double-tagging. */
extern int bcm_vlan_dtag_delete(
int unit, 
int port, 
bcm_vlan_t old_vid);

/* Remove all entries from the VLAN Translation table for double-tagging. */
extern int bcm_vlan_dtag_delete_all(
int unit);

/* Add a VLAN range to the VLAN Translation table. */
extern int bcm_vlan_translate_range_add(
int unit, 
int port, 
bcm_vlan_t old_vid_low, 
bcm_vlan_t old_vid_high, 
bcm_vlan_t new_vid, 
int int_prio);

将入端口VLAN在old_vid_low~old_vid_high范围以内的报文，转换为new_vid的报文。

/* Get a VLAN range to the VLAN Translation table. */
extern int bcm_vlan_translate_range_get(
int unit, 
int port, 
bcm_vlan_t old_vid_low, 
bcm_vlan_t old_vid_high, 
bcm_vlan_t *new_vid, 
int *int_prio);

/* Delete a VLAN range from the VLAN Translation table. */
extern int bcm_vlan_translate_range_delete(
int unit, 
int port, 
bcm_vlan_t old_vid_low, 
bcm_vlan_t old_vid_high);

/* Remove all VLAN ranges from the VLAN Translation table. */
extern int bcm_vlan_translate_range_delete_all(
int unit);

/* Add VLAN range to the VLAN Translation table for double-tagging. */
extern int bcm_vlan_dtag_range_add(
int unit, 
int port, 
bcm_vlan_t old_vid_low, 
bcm_vlan_t old_vid_high, 
bcm_vlan_t new_vid, 
int int_prio);

对于入端口VLAN在old_vid_low~old_vid_high范围内的single inner-tagged的报文，添加new_vid的外层VLAN。 

/* Get VLAN range to the VLAN Translation table for double-tagging. */
extern int bcm_vlan_dtag_range_get(
int unit, 
int port, 
bcm_vlan_t old_vid_low, 
bcm_vlan_t old_vid_high, 
bcm_vlan_t *new_vid, 
int *prio);

/* 
* Remove a VLAN range from the VLAN Translation table for
* double-tagging.
*/
extern int bcm_vlan_dtag_range_delete(
int unit, 
int port, 
bcm_vlan_t old_vid_low, 
bcm_vlan_t old_vid_high);

/* 
* Remove all VLAN ranges from the VLAN Translation table for
* double-tagging.
*/
extern int bcm_vlan_dtag_range_delete_all(
int unit);

/* bcm_vlan_translate_action_range_add */
extern int bcm_vlan_translate_action_range_add(
int unit, 
bcm_gport_t port, 
bcm_vlan_t outer_vlan_low, 
bcm_vlan_t outer_vlan_high, 
bcm_vlan_t inner_vlan_low, 
bcm_vlan_t inner_vlan_high, 
bcm_vlan_action_set_t *action);

 如果要转换double-tagged或者single outer-tagged报文，那么outer_vlan_low/high用来指定入端口报文外层VLAN的范围，inner_vlan_low/high必须指定为BCM_VLAN_INVALID。同时，入端口必须通过bcm_vlan_control_port_set配置为bcmVlanPortTranslateKeyOuter。

如果要转换single inner-tagged报文，那么inner_vlan_low/high指定VLAN范围，outer_vlan_low/high必须指定为BCM_VLAN_INVALID。同时，入端口必须通过bcm_vlan_control_port_set配置为bcmVlanPortTranslateKeyInner。

对于untagged报文，该VLAN_XLATE表项无效。

/* bcm_vlan_translate_action_range_get */
extern int bcm_vlan_translate_action_range_get(
int unit, 
bcm_gport_t port, 
bcm_vlan_t outer_vlan_low, 
bcm_vlan_t outer_vlan_high, 
bcm_vlan_t inner_vlan_low, 
bcm_vlan_t inner_vlan_high, 
bcm_vlan_action_set_t *action);

/* bcm_vlan_translate_action_range_delete */
extern int bcm_vlan_translate_action_range_delete(
int unit, 
bcm_gport_t port, 
bcm_vlan_t outer_vlan_low, 
bcm_vlan_t outer_vlan_high, 
bcm_vlan_t inner_vlan_low, 
bcm_vlan_t inner_vlan_high);

/* bcm_vlan_translate_action_range_delete_all */
extern int bcm_vlan_translate_action_range_delete_all(
int unit);