排除不同ESI负载均衡模式故障
简介
本文档介绍不同的以太网段标识符(ESI)负载均衡模式，这对于优化流量分配和维护网络可靠性至关重要。
不同的负载均衡模式包括
- 端口主用
- 单活动
- 全活动
- 单流主用
先决条件
要求
思科建议您掌握以下方面的基础知识：
- 多协议标签交换(MPLS)。
- 第2层虚拟专用网络(L2VPN)。
- 以太网虚拟专用网络(EVPN)。
使用的组件
- 本文档中的信息基于Device:聚合服务路由器9000(ASR9K)。
- 本文档中的信息都是基于特定实验室环境中的设备编写的。用于本文的所有设备始于初始（默认）配置。如果您的网络处于活动状态，请确保您了解所有命令的潜在影响。
网络拓扑
使用图1网络拓扑图说明不同负载均衡模式的工作原理。
图1网络拓扑
端口活动
图2端口主用冗余模式
图2端口主用冗余模式描述了在接口级别配置主用/备用冗余的冗余模式。在此设置中，以太网虚拟实例(EVI)（例如EVI 100）的流量仅通过主用接口（在本例中，该接口连接到提供商边缘 — PE3）转发。 所有发往EVI 100的流量都会散列到主用路由器(PE3)上，而备用路由器(PE2)随时可以接管，以防主用接口发生故障。
配置
evpn
interface Bundle-Ether23
ethernet-segment
identifier type 0 00.23.23.23.23.23.23.23.23
load-balancing-mode port-active >> configuration required to enable this mode
验证端口主用ESI
接口状态
RP/0/RSP1/CPU0:ASR-9904-5-PE2#show interfaces BE23
Bundle-Ether23 is down, line protocol is down
注意：在备用PE(PE2)上，捆绑包以太网(BE)接口状态为down。
RP/0/RSP0/CPU0:ASR9910-3-PE3#show interfaces BE23
Bundle-Ether23 is up, line protocol is up
捆绑包状态
RP/0/RSP1/CPU0:ASR-9904-5-PE2#show bundle bundle-ether 23
Bundle-Ether23
Status: LACP OOS (out of service)
<snip>
Port Device State Port ID B/W, kbps
-------------------- --------------- ----------- -------------- ----------
Hu0/1/0/7 Local Standby 0x8000, 0x0001 100000000
Link is in standby due to bundle out of service state
注意：
- PE2上的接口BE23因为“捆绑包停止服务状态”而关闭，因为当PE3上的BE23（主用PE）关闭PE2上的BE23变为主用状态时，此PE2处于备用状态。
- 默认情况下，捆绑包状态为“服务中断”，但您可以使用以太网段下的显式配置“access-signal bundle-down”命令将接入信号设置为“down”。
RP/0/RSP0/CPU0:ASR9910-3-PE3#show bundle bundle-ether 23
Bundle-Ether23
Status: Up
<snip>
Port Device State Port ID B/W, kbps
-------------------- --------------- ----------- -------------- ----------
Hu0/1/0/7 Local Active 0x8000, 0x0001 100000000
Link is Active
活动接口，所有流量都必须从客户边缘(CE)23进行散列。
以太网网段
RP/0/RSP1/CPU0:ASR-9904-5-PE2#show evpn ethernet-segment carving detail
Ethernet Segment Id Interface Nexthops
------------------------ ---------------------------------- --------------------
0000.2323.2323.2323.2323 BE23 10.10.22.22
10.10.33.33
ES to BGP Gates : Ready
ES to L2FIB Gates : Ready
Main port :
Interface name : Bundle-Ether23
Interface MAC : 08ec.f50e.6af6
IfHandle : 0x040001a0
State : Standby
Redundancy : Not Defined
ESI type : 0
Value : 0000.2323.2323.2323.2323
ES Import RT : 0023.2323.2323 (from ESI)
Source MAC : 0000.0000.0000 (N/A)
Topology :
Operational : MH
Configured : Port-Active
<snip>
Service Carving Results:
Forwarders : 2
Elected : 0
Not Elected : 2
EVI NE : 100, 200
<snip>
Local SHG label : 24003
Remote SHG labels : 1
24003 : nexthop 10.10.33.33
Access signal mode: Bundle OOS
PE2 — 非指定转发器路由器对来自CE23和指向CE23的所有流量实施定向阻塞。
RP/0/RSP0/CPU0:ASR9910-3-PE3#show evpn ethernet-segment carving detail
Ethernet Segment Id Interface Nexthops
------------------------ ---------------------------------- --------------------
0000.2323.2323.2323.2323 BE23 10.10.22.22
10.10.33.33
Main port :
Interface name : Bundle-Ether23
Interface MAC : 08ec.f52e.55b5
IfHandle : 0x000001a0
State : Up
Redundancy : Not Defined
<snip>
Topology :
Operational : MH
Configured : Port-Active
<snip>
Service Carving Results:
Forwarders : 2
Elected : 2
EVI E : 100, 200
Not Elected : 0
<snip>
HRW Reset timer : 5 sec [not running]
Local SHG label : 24003
Remote SHG labels : 1
24003 : nexthop 10.10.22.22
Access signal mode: Bundle OOS (Default)
注意：PE3被选为此以太网网段的指定转发器(DF)，所有指向CE23的流量都通过PE3发送和接收。
从PE2和PE3向远程路由器PE1通告的路由
RP/0/RSP1/CPU0:ASR9906-1-PE1#show bgp l2vpn evpn
Route Distinguisher: 10.10.11.11:100 (default for vrf EVPN-ELAN-1)
*>i[1][0000.2323.2323.2323.2323][0]/120 >>>>>>>>>>>>>>>>>>>>>>>>> per ESI route
10.10.22.22 100 0 i
* i 10.10.33.33 100 0 i
*>i[1][0000.2323.2323.2323.2323][4294967295]/120 >>>>>>>>>>>>>>>> per EVI route
10.10.22.22 100 0 i
* i 10.10.33.33 100 0 i
*>i[2][0][48][6c03.093e.7213][0]/104 >>>>>>>>>>>>>>>>>>>>>>>>>>>>> Route-Type 2 for the CE23 mac address is only advertised by PE3
10.10.33.33 100 0 i
*> [2][0][48][ecce.13e7.d85c][0]/104
0.0.0.0 0 i
RP/0/RSP1/CPU0:ASR9906-1-PE1#show evpn internal-label vpn-id 100 detail
VPN-ID Encap Ethernet Segment Id EtherTag Label
---------- ------ --------------------------- ---------- --------
100 MPLS 0000.2323.2323.2323.2323 0 24010
Multi-paths resolved: TRUE (Remote single-active)
Multi-paths Internal label: 24010
MAC 10.10.33.33 24001
EAD/ES 10.10.22.22 0
10.10.33.33 0
EAD/EVI 10.10.22.22 24001
10.10.33.33 24001
Summary pathlist:
0x02000002 (P) 10.10.33.33 24001
0x00000000 (B) 10.10.22.22 24001
注意：CE23的Route-Type 2仅由PE3通告，因此PE3设置为此以太网段的主路由，而PE2设置为辅助路由。
MAC 地址学习
L2vpn
RP/0/RSP1/CPU0:ASR9906-1-PE1#show l2vpn forwarding bridge-domain EVPN-ELAN-1:EVPN-ELAN-1 mac-address location 0/0/CPU0
Mac Address Type Learned from/Filtered on LC learned Resync Age/Last Change Mapped to
-------------- ------- --------------------------- ---------- ---------------------- --------------
ecce.13e7.d85c dynamic Hu0/1/0/2.100 N/A 24 Dec 08:58:17 N/A
6c03.093e.7213 EVPN BD id: 1 N/A N/A N/A
RP/0/RSP1/CPU0:ASR-9904-5-PE2#show l2vpn forwarding bridge-domain EVPN-ELAN:EVPN-ELAN mac-address location 0/1/CPU0
Mac Address Type Learned from/Filtered on LC learned Resync Age/Last Change Mapped to
-------------- ------- --------------------------- ---------- ---------------------- --------------
6c03.093e.7213 EVPN BD id: 0 N/A N/A N/A
ecce.13e7.d85c EVPN BD id: 0 N/A N/A N/A
PE2从PE1和PE3获取CE1和CE23的MAC地址作为EVPN路由。
RP/0/RSP0/CPU0:ASR9910-3-PE3#show l2vpn forwarding bridge-domain EVPN-ELAN:EVPN-ELAN mac-address location 0/1/CPU0
Mac Address Type Learned from/Filtered on LC learned Resync Age/Last Change Mapped to
-------------- ------- --------------------------- ---------- ---------------------- --------------
ecce.13e7.d85c EVPN BD id: 0 N/A N/A N/A
6c03.093e.7213 dynamic BE23.100 N/A 24 Dec 07:26:58 N/A
L2rib
RP/0/RSP1/CPU0:ASR9906-1-PE1#show l2route evpn mac all
Topo ID Mac Address Producer Next Hop(s)
-------- -------------- ----------- ----------------------------------------
1 6c03.093e.7213 L2VPN 24010/I/ME, N/A
1 ecce.13e7.d85c LOCAL HundredGigE0/1/0/2.100, N/A
EVPN :
RP/0/RSP1/CPU0:ASR9906-1-PE1#show evpn evi vpn-id 100 mac
VPN-ID Encap MAC address IP address Nexthop Label SID
---------- ---------- -------------- ---------------------------------------- --------------------------------------- -------- ---------------------------------------
100 MPLS 6c03.093e.7213 :: 10.10.33.33 24001
100 MPLS ecce.13e7.d85c :: HundredGigE0/1/0/2.100 24002
BGP ：
RP/0/RSP1/CPU0:ASR9906-1-PE1#show bgp l2vpn evpn rd 10.10.11.11:100 [2][0][48][6c03.093e.7213][0]/104
Local
10.10.33.33 (metric 10) from 10.10.33.33 (10.10.33.33)
Received Label 24001
Origin IGP, localpref 100, valid, internal, best, group-best, import-candidate, imported, rib-install
Received Path ID 0, Local Path ID 1, version 1321
Extended community: SoO:10.10.33.33:100 0x060e:0000.0000.0064 RT:100:100
EVPN ESI: 0000.2323.2323.2323.2323
Source AFI: L2VPN EVPN, Source VRF: default, Source Route Distinguisher: 10.10.33.33:100
在此模式中，当必须从CE1向CE23发送流量时，从PE1的流量仅别名PE3，因为我们只从PE3接收Route-Type 2。当BE23在PE3上关闭时，流量会转移到PE2(PE2)。
单活动
图3单主用冗余模式
如图3单主用冗余模式所示，在此冗余模式下，两个PE接入接口均保持活动状态，指向PE的每条链路在CE23上分配一个唯一的以太网捆绑接口，两个接口上均允许VLAN 100和200。由于这些链路属于单独的以太网捆绑包，因此CE23最初会将流量泛洪到两个PE。但是，只有以太网段的指定转发器(DF)将流量转发到核心。因此，CE在其转发表中维护一个以太网捆绑接口，确保每个VLAN单活动多宿主。
配置
interface Bundle-Ether23
ethernet-segment
identifier type 0 00.23.23.23.23.23.23.23.23
load-balancing-mode single-active >> configuration required to enable this mode
单活动ESI验证
接口状态
RP/0/RSP1/CPU0:ASR-9904-5-PE2#show interfaces bundle-ether 23
Bundle-Ether23 is up, line protocol is up
RP/0/RSP0/CPU0:ASR9910-3-PE3#show interfaces bundle-ether 23
Bundle-Ether23 is up, line protocol is up
注意：BE23在PE2和PE3上的物理状态和捆绑状态为启用和活动状态。
以太网网段
RP/0/RSP1/CPU0:ASR-9904-5-PE2#show evpn ethernet-segment carving detail
Ethernet Segment Id Interface Nexthops
------------------------ ---------------------------------- --------------------
0000.2323.2323.2323.2323 BE23 10.10.22.22
10.10.33.33
<snip>
Topology :
Operational : MH, Single-active
Configured : Single-active (AApS)
<snip>
Service Carving Results:
Forwarders : 2
Elected : 1
EVI E : 200
Not Elected : 1
<snip>
Local SHG label : 24003
Remote SHG labels : 1
24003 : nexthop 10.10.33.33
Access signal mode: Bundle OOS
RP/0/RSP0/CPU0:ASR9910-3-PE3#show evpn ethernet-segment carving detail
Ethernet Segment Id Interface Nexthops
------------------------ ---------------------------------- --------------------
0000.2323.2323.2323.2323 BE23 10.10.22.22
10.10.33.33
<snip>
Topology :
Operational : MH, Single-active
Configured : Single-active (AApS)
<snip>
Service Carving Results:
Forwarders : 2
Elected : 1
EVI E : 100
Not Elected : 1
<snip>
Local SHG label : 24003
Remote SHG labels : 1
24003 : nexthop 10.10.22.22
Access signal mode: Bundle OOS (Default)
注意：
- PE2被选举为EVI 200的DF。
- PE3被选举为EVI 100的DF。
- 对于EVI 100和EVI 200，远程PE(PE1)只能分别通过PE3和PE2发送和接收流量。
PE2和PE3通告给PE1的路由
RP/0/RSP1/CPU0:ASR9906-1-PE1#show bgp l2vpn evpn
Route Distinguisher: 10.10.11.11:100 (default for vrf EVPN-ELAN-1)
*>i[1][0000.2323.2323.2323.2323][0]/120>>>>>>>>>>>>>>>>>>>>>>>>>>> Per EVI route
10.10.22.22 100 0 i
* i 10.10.33.33 100 0 i
*>i[1][0000.2323.2323.2323.2323][4294967295]/120>>>>>>>>>>>>>>>>>> per ESI route
10.10.22.22 100 0 i
* i 10.10.33.33 100 0 i
*>i[2][0][48][6c03.093e.7213][0]/104>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Route-type 2 Advertised only by PE3 for vlan 100
10.10.33.33 100 0 i
在单主用负载均衡模式下，同时使用PE1和PE2接入接口，EVI 100流量散列到PE3,EVI 200流量散列到PE2。EVI 100上的CE23 mac地址只能通过PE3到达，因为此PE3是EVI 100的指定转发器，EVI 100通告了相关的Mac/IP路由，所以PE3称为PE1上的主PE。
通过各种组件的mac地址学习和传播与端口活动冗余模式保持相同。
全部 — 活动
图4全主动冗余模式
如图4全主动冗余模式所示，在EVI的全主动冗余模式下，PE2和PE3都可以发送和接收已知的单播流量，流量在两个PE上的每个流进行散列处理。
配置
Evpn
interface Bundle-Ether23
ethernet-segment
identifier type 0 00.23.23.23.23.23.23.23.23
注意：默认模式为all-active（全活动）。
验证全活动ESI
接口状态
RP/0/RSP1/CPU0:ASR-9904-5-PE2#show interfaces Be23
Bundle-Ether23 is up, line protocol is up
RP/0/RSP0/CPU0:ASR9910-3-PE3#show interfaces BE23
Bundle-Ether23 is up, line protocol is up
注意：BE23在PE2和PE3上的物理状态和捆绑状态为启用和活动状态。
以太网网段
RP/0/RSP1/CPU0:ASR-9904-5-PE2#show evpn ethernet-segment carving detail
Ethernet Segment Id Interface Nexthops
------------------------ ---------------------------------- --------------------
0000.2323.2323.2323.2323 BE23 10.10.22.22
10.10.33.33
<snip>
Topology :
Operational : MH, All-active
Configured : All-active (AApF) (default)
Service Carving : Auto-selection
<snip>
Service Carving Results:
Forwarders : 2
Elected : 2
EVI E : 100, 200
Not Elected : 0
<snip>
Local SHG label : 24003
Remote SHG labels : 1
24003 : nexthop 10.10.33.33
Access signal mode: Bundle OOS
RP/0/RSP0/CPU0:ASR9910-3-PE3#show evpn ethernet-segment carving detail
Ethernet Segment Id Interface Nexthops
------------------------ ---------------------------------- --------------------
0000.2323.2323.2323.2323 BE23 10.10.22.22
10.10.33.33
<snip>
Topology :
Operational : MH, All-active
Configured : All-active (AApF) (default)
Service Carving : Auto-selection
<snip>
Service Carving Results:
Forwarders : 2
Elected : 0
Not Elected : 2
EVI NE : 100, 200
<snip>
Local SHG label : 24003
Remote SHG labels : 1
24003 : nexthop 10.10.22.22
Access signal mode: Bundle OOS (Default)
注意：
- 指定转发器仅影响从核心设备向接入设备发送的广播、未知单播和组播(BUM)流量，也就是说，当从PE1发送的BUM流量同时发送到PE2和PE3时，只有PE2将该流量转发到CE23。
- 而来自CE23的BUM流量可以散列到PE2和PE3，然后转发到远程PE1。
- 有关水平分割机制和SHG标签的详细信息，请参阅以下内容：https://www.cisco.com/c/en/us/support/docs/multiprotocol-label-switching-mpls/layer-2-vpns/222561-configure-evpn-route-types-and-their-fun.html#toc-hId--1100150104
PE2和PE3通告给PE1的路由
RP/0/RSP1/CPU0:ASR9906-1-PE1#show bgp l2vpn evpn
Route Distinguisher: 10.10.11.11:100 (default for vrf EVPN-ELAN-1)
*>i[1][0000.2323.2323.2323.2323][0]/120 >>>>>>>>>>>>>>>>>>>>>> Per EVI
10.10.22.22 100 0 i
* i 10.10.33.33 100 0 i
*>i[1][0000.2323.2323.2323.2323][4294967295]/120>>>>>>>>>>>>> Per ESI
10.10.22.22 100 0 i
* i 10.10.33.33 100 0 i
*>i[2][0][48][6c03.093e.7213][0]/104 >>>>>>>>>>>>>>>>>>>>>>>>> Route-Type2 is advertised by both PE2 and PE3
10.10.22.22 100 0 i
* i 10.10.33.33 100 0 i
RP/0/RSP1/CPU0:ASR9906-1-PE1#show evpn internal-label detail
VPN-ID Encap Ethernet Segment Id EtherTag Label
---------- ------ --------------------------- ---------- --------
100 MPLS 0000.2323.2323.2323.2323 0 24010
Multi-paths resolved: TRUE (Remote all-active)
Multi-paths Internal label: 24010
MAC 10.10.22.22 24001
10.10.33.33 24001
EAD/ES 10.10.22.22 0
10.10.33.33 0
EAD/EVI 10.10.22.22 24001
10.10.33.33 24001
Summary pathlist:
0x02000001 (P) 10.10.22.22 24001
0x02000002 (P) 10.10.33.33 24001
从输出中可以看到，要到达PE1上的CE23,PE2和PE3被视为主路径，流量将散列到PE2和PE3
RP/0/RSP1/CPU0:ASR9906-1-PE1#show mpls forwarding labels 24010 detail
Local Outgoing Prefix Outgoing Next Hop Bytes
Label Label or ID Interface Switched
------ ----------- ------------------ ------------ --------------- ------------
24010 24001 EVPN:100 10.10.22.22 0
Updated: Dec 29 12:19:20.649
Version: 333, Priority: 3
Label Stack (Top -> Bottom): { 24001 }
NHID: 0x0, Encap-ID: N/A, Path idx: 0, Backup path idx: 0, Weight: 0
MAC/Encaps: 0/4, MTU: 0
Packets Switched: 0
24001 EVPN:100 10.10.33.33 0
Updated: Dec 29 12:19:20.649
Version: 333, Priority: 3
Label Stack (Top -> Bottom): { 24001 }
NHID: 0x0, Encap-ID: N/A, Path idx: 1, Backup path idx: 0, Weight: 0
MAC/Encaps: 0/4, MTU: 0
Packets Switched: 0
Mac地址同步
L2vpn :
RP/0/RSP1/CPU0:ASR-9904-5-PE2#show l2vpn forwarding bridge-domain EVPN-ELAN:EVPN-ELAN mac-address location 0/1/CPU0
Mac Address Type Learned from/Filtered on LC learned Resync Age/Last Change Mapped to
-------------- ------- --------------------------- ---------- ---------------------- --------------
ecce.13e7.d85c EVPN BD id: 0 N/A N/A N/A
6c03.093e.7213 static BE23.100 N/A N/A N/A
RP/0/RSP0/CPU0:ASR9910-3-PE3#show l2vpn forwarding bridge-domain EVPN-ELAN:EVPN-ELAN mac-address location 0/1/CPU0
Mac Address Type Learned from/Filtered on LC learned Resync Age/Last Change Mapped to
-------------- ------- --------------------------- ---------- ---------------------- --------------
ecce.13e7.d85c EVPN BD id: 0 N/A N/A N/A
6c03.093e.7213 dynamic BE23.100 N/A 30 Dec 06:49:50 N/A
从CE23只启动了1个数据流，它被散列到PE3，因此在PE3上学习是动态的，在PE2上，此ESI的mac地址已同步，在PE2上条目是静态的。
L2RIB:
RP/0/RSP1/CPU0:ASR-9904-5-PE2#show l2route evpn mac all
Topo ID Mac Address Producer Next Hop(s)
-------- -------------- ----------- ----------------------------------------
0 6c03.093e.7213 L2VPN Bundle-Ether23.100, N/A
RP/0/RSP0/CPU0:ASR9910-3-PE3#show l2route evpn mac all
Topo ID Mac Address Producer Next Hop(s)
-------- -------------- ----------- ----------------------------------------
0 6c03.093e.7213 LOCAL Bundle-Ether23.100, N/A
EVPN :
RP/0/RSP1/CPU0:ASR-9904-5-PE2#show evpn evi vpn-id 100 mac
VPN-ID Encap MAC address IP address Nexthop Label SID
---------- ---------- -------------- ---------------------------------------- --------------------------------------- -------- ---------------------------------------
100 MPLS 6c03.093e.7213 :: 10.10.33.33 24001
RP/0/RSP0/CPU0:ASR9910-3-PE3#show evpn evi vpn-id 100 mac
VPN-ID Encap MAC address IP address Nexthop Label SID
---------- ---------- -------------- ---------------------------------------- --------------------------------------- -------- ---------------------------------------
100 MPLS 6c03.093e.7213 :: Bundle-Ether23.100 24001
EVPN组件级别的此输出清楚地显示，PE3动态获知CE23的mac地址并向PE2和PE1通告路由类型2（PE2和PE1）。
PE2导入了带有同步标志设置的此Route-Type2，并为CE23的MAC地址重新通告了Route-Type 2，且PE2具有Next-Hop。
来自PE2的L2RIB跟踪，其中显示了此行为：
[12/29/24 11:14:07.763 UTC 225f 7879] Received MAC ROUTE msg: addr: (0, 6c03.093e.7213) vni: 0 admin_dist: 0 seq_num: 0 rt_flags: S soo: 0 dg_count: 0 res: 0 esi: (F) >>> sync flag is set
[12/29/24 11:14:07.763 UTC 2262 7879] (0,6c03.093e.7213,9):Updated recv attrs seq:0 flags:S NH-type:2 NH:Bundle-Ether23.100 NH2-type:0 NH2:N/A >>> the NH is updated to the ESI interface
[12/29/24 11:14:07.763 UTC 2264 7879] (0,6c03.093e.7213,9):set route flags: BEST
[12/29/24 11:14:07.763 UTC 2265 7879] (0,6c03.093e.7213,9):MAC route created seq num:0 flags:BS (Rcv) rcv_seq:0 rcv_flags:S slot_id:0 >>>>>>>>> the mac route is created with PE2 has the NH
[12/29/24 11:14:07.763 UTC 2266 7879] (0,6c03.093e.7213,9):MAC route created BR:9 Dup Moves:0 NH-type:2 NH:Bundle-Ether23.100 NH2-type:0 NH2:N/A
[12/29/24 11:14:07.765 UTC 2267 7879] (0,6c03.093e.7213,9):Encoding MAC BR (ADD) Client = 3 BR = 0x56487439e9a0 SBRD = 0 PROD_CHANGED = 0 RLDP 0
BGP ：
RP/0/RSP1/CPU0:ASR9906-1-PE1#show bgp l2vpn evpn rd 10.10.11.11:100 [2][0][48][6c03.093e.7213][0]/104
Local
10.10.22.22 (metric 10) from 10.10.22.22 (10.10.22.22)
Received Label 24001
Origin IGP, localpref 100, valid, internal, best, group-best, import-candidate, imported, rib-install
Received Path ID 0, Local Path ID 1, version 1699
Extended community: SoO:10.10.33.33:100 0x060e:0000.0000.0064 RT:100:100
EVPN ESI: 0000.2323.2323.2323.2323
Source AFI: L2VPN EVPN, Source VRF: default, Source Route Distinguisher: 10.10.22.22:100
Path #2: Received by speaker 0
Not advertised to any peer
Local
10.10.33.33 (metric 10) from 10.10.33.33 (10.10.33.33)
Received Label 24001
Origin IGP, localpref 100, valid, internal, import-candidate, imported, rib-install
Received Path ID 0, Local Path ID 0, version 0
Extended community: SoO:10.10.33.33:100 0x060e:0000.0000.0064 RT:100:100
EVPN ESI: 0000.2323.2323.2323.2323
Source AFI: L2VPN EVPN, Source VRF: default, Source Route Distinguisher: 10.10.33.33:100
Source of Origin Attribute显示此Route-Type 2由PE3发起，但Route Distinguisher明确指示PE2已重新通告此Route-Type 2。
注意：当PE3和PE2收到来自CE23的流量时，由于将各种流散列到两个链路，PE2和PE3都可以动态获知MAC地址并通告Route-Type2。
单流主用(SFA)
在此冗余模式下，Vlan可以在冗余组中的所有PE上处于活动状态，但该Vlan的每个唯一的L2流一次只能在冗余组中的一个PE上处于活动状态。
配置
Evpn
interface Bundle-Ether23
ethernet-segment
identifier type 0 00.23.23.23.23.23.23.23.23
load-balancing-mode single-flow-active >>> this command enables SFA redundancy mode
单流活动ESI验证
接口状态
RP/0/RSP1/CPU0:ASR-9904-5-PE2#show interfaces BE23
Bundle-Ether23 is up, line protocol is up
RP/0/RSP0/CPU0:ASR9910-3-PE3#show interfaces BE23
Bundle-Ether23 is up, line protocol is up
注意：BE23在PE2和PE3上的物理状态和捆绑状态为启用和活动状态。
以太网网段
RP/0/RSP1/CPU0:ASR-9904-5-PE2#show evpn ethernet-segment carving detail
Ethernet Segment Id Interface Nexthops
------------------------ ---------------------------------- --------------------
0000.2323.2323.2323.2323 BE23 10.10.22.22
10.10.33.33
<snip>
Topology :
Operational : MH, Single-flow-active
Configured : Single-flow-active
Service Carving : Auto-selection
<snip>
Service Carving Results:
Forwarders : 2
Elected : 0
Not Elected : 0
<snip>
Local SHG label : 24003
Remote SHG labels : 1
24003 : nexthop 10.10.33.33
Access signal mode: Bundle OOS
RP/0/RSP0/CPU0:ASR9910-3-PE3#show evpn ethernet-segment carving detail
Ethernet Segment Id Interface Nexthops
------------------------ ---------------------------------- --------------------
0000.2323.2323.2323.2323 BE23 10.10.22.22
10.10.33.33
<snip>
Topology :
Operational : MH, Single-flow-active
Configured : Single-flow-active
Service Carving : Auto-selection
<snip>
Service Carving Results:
Forwarders : 2
Elected : 0
Not Elected : 0
<snip>
Local SHG label : 24003
Remote SHG labels : 1
24003 : nexthop 10.10.22.22
Access signal mode: Bundle OOS (Default)
注意：
- 在此冗余模式下没有DF选举。
- SFA — 水平分割已禁用。
PE2和PE3通告给PE1的路由。
每个ESI路由：
RP/0/RSP1/CPU0:ASR9906-1-PE1#show bgp l2vpn evpn rd 10.10.11.11:100 [1][0000.2323.2323.2323.2323][4294967295]/120
Local
10.10.22.22 (metric 10) from 10.10.22.22 (10.10.22.22)
Received Label 0
Extended community: EVPN ESI Label:0x02:24003 RT:100:100 RT:200:200
Source AFI: L2VPN EVPN, Source VRF: default, Source Route Distinguisher: 10.10.22.22:1
Path #2: Received by speaker 0
Not advertised to any peer
Local
10.10.33.33 (metric 10) from 10.10.33.33 (10.10.33.33)
Received Label 0
Extended community: EVPN ESI Label:0x02:24003 RT:100:100 RT:200:200
Source AFI: L2VPN EVPN, Source VRF: default, Source Route Distinguisher: 10.10.33.33:1
注意：
- EVPN ESI标签：0x02 — 这表示远程PE2和PE3处于SFA冗余模式。
- 一旦远程PE1收到此扩展团体后，在第2层和第3层禁用别名。
MAC 地址学习
L2vpn
RP/0/RSP1/CPU0:ASR-9904-5-PE2#show l2vpn forwarding bridge-domain EVPN-ELAN-200:EVPN-ELAN-200 mac-address location 0/1/CPU0
Mac Address Type Learned from/Filtered on LC learned Resync Age/Last Change Mapped to
-------------- ------- --------------------------- ---------- ---------------------- --------------
ecce.13e7.d85c EVPN BD id: 1 N/A N/A N/A
6c03.093e.7213 dynamic BE23.200 N/A 30 Dec 10:05:07 N/A
RP/0/RSP0/CPU0:ASR9910-3-PE3#show l2vpn forwarding bridge-domain EVPN-ELAN-200:EVPN-ELAN-200 mac-address location 0/1/CPU0
Mac Address Type Learned from/Filtered on LC learned Resync Age/Last Change Mapped to
-------------- ------- --------------------------- ---------- ---------------------- --------------
6c03.093e.7213 EVPN BD id: 1 N/A N/A N/A
ecce.13e7.d85c EVPN BD id: 1 N/A N/A N/A
注意：在PE2上，Mac是动态学习的，在PE3上，Mac是通过EVPN学习的。
ARP:
RP/0/RSP1/CPU0:ASR-9904-5-PE2#show arp vrf TEST
192.168.200.23 00:03:37 6c03.093e.7213 Dynamic ARPA BVI200
RP/0/RSP0/CPU0:ASR9910-3-PE3#show arp vrf TEST
192.168.200.23 - 6c03.093e.7213 EVPN_SYNC ARPA BVI200
L2rib:
RP/0/RSP1/CPU0:ASR-9904-5-PE2#show l2route evpn mac-ip all detail
1 6c03.093e.7213 192.168.200.23 L2VPN Bundle-Ether23.200, 24006/I/ME 1 SSfa
RP/0/RSP0/CPU0:ASR9910-3-PE3#show l2route evpn mac-ip all detail
1 6c03.093e.7213 192.168.200.23 L2VPN Bundle-Ether23.200, 24010/I/ME 2 BSSfa
注意：BSSfa >>对于此mac，最佳路由是设置了同步标志的远程路由。
EVPN :
RP/0/RSP1/CPU0:ASR-9904-5-PE2#show evpn evi vpn-id 200 mac ipv4 192.168.200.23
VPN-ID Encap MAC address IP address Nexthop Label SID
---------- ---------- -------------- ---------------------------------------- --------------------------------------- -------- ---------------------------------------
200 MPLS 6c03.093e.7213 192.168.200.23 Bundle-Ether23.200 24007
RP/0/RSP0/CPU0:ASR9910-3-PE3#show evpn evi vpn-id 200 mac ipv4 192.168.200.23
VPN-ID Encap MAC address IP address Nexthop Label SID
---------- ---------- -------------- ---------------------------------------- --------------------------------------- -------- ---------------------------------------
200 MPLS 6c03.093e.7213 192.168.200.23 10.10.22.22 24007
注意：从PE3到192.168.200.23，下一跳是PE2，而不是本地接口。
RP/0/RSP1/CPU0:ASR-9904-5-PE2#show bgp l2vpn evpn rd 10.10.22.22:200 [2][0][48][6c03.093e.7213][32][192.168.200.23]/136
BGP routing table entry for [2][0][48][6c03.093e.7213][32][192.168.200.23]/136, Route Distinguisher: 10.10.22.22:200
<snip>
Local
0.0.0.0 from 0.0.0.0 (10.10.22.22)
Second Label 24012
Origin IGP, localpref 100, valid, redistributed, best, group-best, import-candidate, rib-install
Received Path ID 0, Local Path ID 1, version 2022
Extended community: Flags 0xe: SoO:10.10.22.22:200 EVPN MAC Mobility:0x00:2 0x060e:0000.0000.00c:200:200
EVPN ESI: 0000.2323.2323.2323.2323
Path #2: Received by speaker 0
Not advertised to any peer
Local
10.10.33.33 (metric 10) from 10.10.33.33 (10.10.33.33)
Received Label 24006, Second Label 24008
Origin IGP, localpref 80, valid, internal, import-candidate, imported, rib-install
Received Path ID 0, Local Path ID 0, version 0
Extended community: SoO:10.10.22.22:200 EVPN MAC Mobility:0x00:2 0x060e:0000.0000.00c8 RT:200:200
EVPN ESI: 0000.2323.2323.2323.2323
Source AFI: L2VPN EVPN, Source VRF: default, Source Route Distinguisher: 10.10.33.33:200
注意：
- 在SFA中，当在PE2上获取MAC地址时，它通过通告Route-type 2（路由类型2）与PE3同步，然后PE3为CE23重新通告Route-Type 2（路由类型2）。
- 远程路由器PE1通过为CE23通告的路由类型2的Local Preference(LP)值确定CE23的主要PE，即PE2的LP为100,PE3 LP为80。
- 在PE1上，向CE23发送流量优先于PE3。
在PE3上，当PE3同步并重新通告用于CE23的Route-Type2时，会使用本地优先级100通告该路由，该本地优先级100由PE3上的BGP出站策略更改，可以在后续输出中观察到此行为。
RP/0/RSP0/CPU0:ASR9910-3-PE3# show bgp l2vpn evpn rd 10.10.33.33:200 [2][0][48][6c03.093e.7213][32][192.168.200.23]/136
<snip>
Local
0.0.0.0 from 0.0.0.0 (10.10.33.33)
Second Label 24008
Origin IGP, localpref 100, valid, redistributed, best, group-best, import-candidate, rib-install
Received Path ID 0, Local Path ID 1, version 1365
Extended community: Flags 0xe: SoO:10.10.22.22:200 EVPN MAC Mobility:0x00:2 0x060e:0000.0000.00c8 RT:200:200
EVPN ESI: 0000.2323.2323.2323.2323
当BGP在将路由类型2通告到其他远程PE之前应用出站策略时，PE3上的此本地优先级会更改
RP/0/RSP0/CPU0:ASR9910-3-PE3#show evpn evi vpn-id 200 mac ipv4 192.168.200.23 private
VPN-ID Encap MAC address IP address Nexthop Label SID
---------- ---------- -------------- ---------------------------------------- --------------------------------------- -------- ---------------------------------------
200 MPLS 6c03.093e.7213 192.168.200.23 10.10.22.22 24007
Ethernet Tag : 0
Multi-paths Resolved : True
Multi-paths Internal label : 24010
<snip>
Ext Flags : 0x00000510 (Lcl Spec,Pref-Rib,LP-80,)
注意：
- Pref-Rib — 首选rib而不是本地，因为这是远程路由。
- LP-80 — 应用于PE3上Route-Type2的出站策略，以更改本地优先级。
-
本文档也适用于其他XR产品，如NCS 5500、NCS 5700。
结论
EVPN以太网段标识符(ESI)模式提供强大的冗余和流量分配机制，确保现代网络架构中的高可用性和高效资源利用率。通过利用单主用和全主用冗余模式等功能，EVPN可实现无缝故障切换、负载均衡和操作弹性。了解和实施适用于特定网络需求的ESI模式对于优化性能和保持网络可靠性至关重要。
修订历史记录
| 版本 | 发布日期 | 备注 |
|---|---|---|
1.0 |
19-Mar-2025
|
初始版本 |
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