在UCS上配置ELAM
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已更新: 2019 年 5 月 10 日
文档 ID:214397
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简介
本文档介绍在统一计算系统(UCS)第4代交换矩阵互联(FI)6454中使用嵌入式逻辑分析器模块(ELAM)工具，以及如何最好地使用它。
先决条件
读者无需满足任何前提条件即可理解本文档内容。
要求
Cisco 建议您了解以下主题：
- UCS 6454交换矩阵互联
使用的组件
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。本文档中使用的所有设备最初均采用原始（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。
背景信息
UCS第4代FI能够运行ELAM捕获。ELAM捕获嵌入在ASIC中。
ELAM工具允许实时查看在ASIC级别转发的数据包。您可以查看数据包的详细信息，例如：
- 入口和出口接口
- 最大传输单位(MTU)大小
- VLAN标记
- 源设备和目的设备的MAC和IP地址
- 丢包及原因
- 服务质量(QoS)标记
ELAM提供数据包转发的详细信息。它对数据平面无干扰。
配置
通过命令行界面(CLI)登录UCS。
运行以下命令：
#connect nxos a|b
#attach module 1
#debug platform internal tah elam asic 0
#trigger init asic 0 slice 0 lu-a2d 1 in-select 6 out-select 1
#set outer ...
#start
#report
注意：第4代FI是单机架单元，具有一个模块（模块1）、一个ASIC(asic 0)和一个片（片0）。 请参阅以下输出。
RCH-SV-FFAIII-A(nx-os)# show hardware internal tah interface ethernet 1/30
#########################################
IfIndex: 436222464
DstIndex: 6028
IfType: 26
Interface name Ethernet1/30
Asic: 0
Asic: 0 <<<<<
AsicPort: 49
SrcId: 98
Slice: 0 <<<<<
PortOnSlice: 49
Table entries for interface Ethernet1/30
对于ELAM，使用基于数据包属性“lu-a2d 1”的触发器。值6和1将分别用于“in-select”和“out-select”，以用于出现兴趣
“set outer”命令是我们的过滤器，我们在此定义并告诉FI我们要捕获什么数据包，有许多选项，我们可以根据需要进行粒度化：
module-1(TAH-elam-insel6)# set outer ?
arp ARP Fields
fcoe FCoE Fields
ipv4 IPv4 Fields
ipv6 IPv6 Fields
l2 All Layer 2 Fields
l4 L4 Fields
module-1(TAH-elam-insel6)# set outer l2 ?
cfi CFI Setting
cntag_vld CNTag Information Valid
cos Class of Service
dst_mac Destination MAC Address
qtag_vld VLAN Tag Information Valid
snap_vld SNAP Header Information Valid
src_mac Source MAC Address
vlan VLAN Id (Present only in case of FEX)
vntag_dvif VNTAG Destination vif
vntag_looped VNTAG Header Looped Valid
vntag_pointer VNTAG Header Pointer Valid
vntag_svif VNTAG Source vif
vntag_vld VNTAG Information Valid
module-1(TAH-elam-insel6)# set outer ipv4 ?
checksum Checksum
dscp Diff. Serv. Code Point
dst_ip Destination IP Address
ecn Explicit Congestion Ntfn
fragment-off Fragments Offset
header-len Header Length
more-frags More Fragments Available
next-protocol Next Protocol
packet-len Packet Total Length
pyld-len Payload Length
src_ip Source IP Address
ttl Time to Live
version Version
定义过滤器后，运行命令start以运行ELAM工具。如果未捕获填充过滤器条件的内容，则会看到：
module-1(TAH-elam-insel6)# report
ELAM not triggered yet on slot - 1, asic - 0, slice - 0
注意：“set”命令将在ELAM中生存，一个好的做法是，每次我们要捕获具有不同IP、MAC等的流量时，都运行“reset”命令。
示例
1.从VM 172.16.35.31 ping网关172.16.35.126:
RCH-SV-FFAIII-A(nx-os)# attach module 1
module-1# debug platform internal tah elam asic 0
module-1(TAH-elam)# trigger init asic 0 slice 0 lu-a2d 1 in-select 6 out-select 1
param values: start asic 0, start slice 0, lu-a2d 1, in-select 6, out-select 1
module-1(TAH-elam-insel6)# set outer ipv4 src_ip 172.16.35.31 dst_ip 172.16.35.126
module-1(TAH-elam-insel6)# start
GBL_C++: [MSG] rocky_elam_wrapper_init:54:asic type 8 inst 0 slice 0 a_to_d 1 insel 6 outsel 1
GBL_C++: [MSG] rocky_elam_wrapper_enable:149:asic type 8 inst 0 slice 0 a_to_d 1
GBL_C++: [MSG] - writing data=0x0000000000000000000000000000000000000000000000000000000000000000000000000000000000000005608118F800000
000000000000000000560811BF00000000000000000000001000000000000000000000000000000000000000000000000000000000001
GBL_C++: [MSG] - writing mask=0x0000000000000000000000000000000000000000000000000000000000000000000000000000000000000007FFFFFFF800000
0000000000000000007FFFFFFF80000000000000000000003800000000000000000000000000000000000000000000000000000000001
module-1(TAH-elam-insel6)# report
HOMEWOOD ELAM REPORT SUMMARY
slot - 1, asic - 0, slice - 0
============================
Incoming Interface: Eth1/33
Src Idx : 0x1002, Src BD : 35
Outgoing Interface Info: dmod 1, dpid 4
Dst Idx : 0x604, Dst BD : 35
Packet Type: IPv4
Dst MAC address: 8C:60:4F:CD:FD:7C
Src MAC address: 00:25:C5:00:00:1E
.1q Tag0 VLAN: 35, cos = 0x1
Dst IPv4 address: 172.16.35.126
Src IPv4 address: 172.16.35.31
Ver = 4, DSCP = 0, Don't Fragment = 0
Proto = 1, TTL = 64, More Fragments = 0
Hdr len = 20, Pkt len = 84, Checksum = 0x5f19
L4 Protocol : 1
ICMP type : 8
ICMP code : 0
Drop Info:
----------
LUA:
LUB:
LUC:
LUD:
Final Drops:
验证
具有src_ip 172.16.35.31和dst_ip 172.16.35.126的数据包在VLAN 35上，到达端口1/33（传入接口），并发往（传出接口）接口“dpid4”……什么？“dpid”是ASIC端口内部标识符，映射可通过“show interface hardware-mappings”找到：
Incoming Interface: Eth1/33
Src Idx : 0x1002, Src BD : 35
interface Ethernet1/33
description S: Server, Port-channel 1025
no pinning server sticky
switchport mode fex-fabric
priority-flow-control mode on
fex associate 1
channel-group 1025
no shutdown
Outgoing Interface Info: dmod 1, dpid 4
Dst Idx : 0x604, Dst BD : 35
RCH-SV-FFAIII-A(nx-os)# show interface hardware-mappings
Legends:
SMod - Source Mod. 0 is N/A
Unit - Unit on which port resides. N/A for port channels
HPort - Hardware Port Number or Hardware Trunk Id:
HName - Hardware port name. None means N/A
FPort - Fabric facing port number. 255 means N/A
NPort - Front panel port number
VPort - Virtual Port Number. -1 means N/A
Slice - Slice Number. N/A for BCM systems
SPort - Port Number wrt Slice. N/A for BCM systems
SrcId - Source Id Number. N/A for BCM systems
------------------------------------------------------------------------
Name Ifindex Smod Unit HPort FPort NPort VPort Slice SPort SrcId
------------------------------------------------------------------------
.
Eth1/13 1a001800 1 0 4 255 48 -1 0 4 8
此“dpid 4”还与“show hardware internal than interface ethernet 1/13”的建议相对应：
RCH-SV-FFAIII-A(nx-os)# show hardware internal tah interface ethernet 1/13
#########################################
IfIndex: 436213760
DstIndex: 6096
IfType: 26
Interface name Ethernet1/13
Asic: 0
Asic: 0
AsicPort: 4 <<<<<
SrcId: 8
Slice: 0
PortOnSlice: 4 <<<<<
该数据包被ELAM第4层(L4)协议识别为Internet控制消息协议(ICMP)。请参阅IANA协议号列表。您还可以使用特定MTU大小进行过滤。 ELAM仅在达到确切MTU时触发。
module-1(TAH-elam-insel6)# set outer ipv4 src_ip 172.16.35.31 dst_ip 172.16.35.126 packet-len 1500
Dst IPv4 address: 172.16.35.126
Src IPv4 address: 172.16.35.31
Ver = 4, DSCP = 0, Don't Fragment = 1
Proto = 1, TTL = 64, More Fragments = 0
Hdr len = 20, Pkt len = 1500, Checksum = 0x1758
L4 Protocol : 1
ICMP type : 8
ICMP code : 0
从虚拟机(VM)到上游网络的ARP请求，MAC地址设置为过滤器：
RCH-SV-FFAIII-B(nx-os)# attach module 1
module-1# debug platform internal tah elam asic 0
module-1(TAH-elam)# trigger init asic 0 slice 0 lu-a2d 1 in-select 6 out-select 1
param values: start asic 0, start slice 0, lu-a2d 1, in-select 6, out-select 1
module-1(TAH-elam-insel6)# set outer l2 src_mac 00:25:c5:00:00:1e dst_mac ff:ff:ff:ff:ff:ff
module-1(TAH-elam-insel6)# start
GBL_C++: [MSG] rocky_elam_wrapper_init:36:asic type 8 inst 0 slice 0 a_to_d 1 insel 6 outsel 1
GBL_C++: [MSG] rocky_elam_wrapper_enable:95:asic type 8 inst 0 slice 0 a_to_d 1
GBL_C++: [MSG] - writing data=0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
00000015820463E004B8A00003C0000000000000000000002000000000000000000000000000000000000000000000000000000000001
GBL_C++: [MSG] - writing mask=0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
0000001FFFFFFFFFFFFFFFFFFFE0000000000000000000003800000000000000000000000000000000000000000000000000000000001
module-1(TAH-elam-insel6)# report
HOMEWOOD ELAM REPORT SUMMARY
slot - 1, asic - 0, slice - 0
============================
Incoming Interface: Eth1/33
Src Idx : 0x1002, Src BD : 35
Outgoing Interface Info: dmod 1, dpid 4
Dst Idx : 0x604, Dst BD : 35
Packet Type: ARP
Dst MAC address: FF:FF:FF:FF:FF:FF
Src MAC address: 00:25:C5:00:00:1E
.1q Tag0 VLAN: 35, cos = 0x1
Target Hardware address: 00:00:00:00:00:00
Sender Hardware address: 00:25:C5:00:00:1E
Target Protocol address: 172.16.35.110
Sender Protocol address: 172.16.35.31
ARP opcode: 1
Drop Info:
----------
LUA:
LUB:
LUC:
LUD:
Final Drops:
数据包由系统识别为ARP，这在VM或网关级别存在不完整的ARP条目时特别有用。
如果适用，TCP/UDP端口也将列出，SSH将在以下位置进行测试：
RCH-SV-FFAIII-B(nx-os)# attach module 1
module-1# debug platform internal tah elam asic 0
module-1(TAH-elam)# trigger init asic 0 slice 0 lu-a2d 1 in-select 6 out-select 1
param values: start asic 0, start slice 0, lu-a2d 1, in-select 6, out-select 1
module-1(TAH-elam-insel6)# set outer ipv4 src_ip 172.16.35.126 dst_ip 172.16.35.31
module-1(TAH-elam-insel6)# start
GBL_C++: [MSG] rocky_elam_wrapper_init:36:asic type 8 inst 0 slice 0 a_to_d 1 insel 6 outsel 1
GBL_C++: [MSG] rocky_elam_wrapper_enable:95:asic type 8 inst 0 slice 0 a_to_d 1
GBL_C++: [MSG] - writing data=0x000000000000000000000000000000000000000000000000000000000000000000000000000000000000000560811BF0000
000000000000000000005608118F80000000000000000000001000000000000000000000000000000000000000000000000000000000001
GBL_C++: [MSG] - writing mask=0x0000000000000000000000000000000000000000000000000000000000000000000000000000000000000007FFFFFFF8000
000000000000000000007FFFFFFF80000000000000000000003800000000000000000000000000000000000000000000000000000000001
module-1(TAH-elam-insel6)# report
HOMEWOOD ELAM REPORT SUMMARY
slot - 1, asic - 0, slice - 0
============================
Incoming Interface: Eth1/14
Src Idx : 0x604, Src BD : 35
Outgoing Interface Info: dmod 1, dpid 44
Dst Idx : 0x1002, Dst BD : 35
Packet Type: IPv4
Dst MAC address: 00:25:C5:00:00:1E
Src MAC address: 8C:60:4F:CD:FD:7C
.1q Tag0 VLAN: 35, cos = 0x0
Dst IPv4 address: 172.16.35.31
Src IPv4 address: 172.16.35.126
Ver = 4, DSCP = 0, Don't Fragment = 0
Proto = 6, TTL = 64, More Fragments = 0
Hdr len = 20, Pkt len = 60, Checksum = 0x27f5
L4 Protocol : 6
TCP Dst Port : 22
TCP Src Port : 15067
Drop Info:
----------
LUA:
LUB:
LUC:
LUD:
Final Drops:
故障排除
还记录丢包。FI丢弃ARP请求：
RCH-SV-FFAIII-B(nx-os)# attach module 1
module-1# debug platform internal tah elam asic 0
module-1(TAH-elam)# trigger init asic 0 slice 0 lu-a2d 1 in-select 6 out-select 1
param values: start asic 0, start slice 0, lu-a2d 1, in-select 6, out-select 1
module-1(TAH-elam-insel6)# set outer l2 src_mac 00:25:c5:00:00:1e dst_mac ff:ff:ff:ff:ff:ff
module-1(TAH-elam-insel6)# start
GBL_C++: [MSG] rocky_elam_wrapper_init:54:asic type 8 inst 0 slice 0 a_to_d 1 insel 6 outsel 1
GBL_C++: [MSG] rocky_elam_wrapper_enable:149:asic type 8 inst 0 slice 0 a_to_d 1
GBL_C++: [MSG] - writing data=0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
0000000000000000000000000000000000000000000000000000000000000000000000000000000000971400007BFFFFFFFFFFFC00001
GBL_C++: [MSG] - writing mask=0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
00000000000000000000000000000000000000000000000000000000000000000000000000000003FFFFFFFFFFFFFFFFFFFFFFFC00001
module-1(TAH-elam-insel6)# report
HOMEWOOD ELAM REPORT SUMMARY
slot - 1, asic - 0, slice - 0
============================
Incoming Interface: Eth1/18
Src Idx : 0x603, Src BD : 35
Outgoing Interface Info: dmod 0, dpid 0
Dst Idx : 0x0, Dst BD : 35
Packet Type: ARP
Dst MAC address: FF:FF:FF:FF:FF:FF
Src MAC address: 00:25:C5:00:00:1E
.1q Tag0 VLAN: 35, cos = 0x1
Target Hardware address: 00:00:00:00:00:00
Sender Hardware address: 00:25:C5:00:00:1E
Target Protocol address: 172.16.35.99
Sender Protocol address: 172.16.35.31
ARP opcode: 1
Drop Info:
----------
LUA:
LUB:
LUC:
LUD:
MC_RPF_FAIILURE
SRC_VLAN_MBR
Final Drops:
MC_RPF_FAIILURE
SRC_VLAN_MBR
FI在端口1/18（这是上行链路端口）上收到ARP请求，源MAC为00:25:c5:00:00:1e，在虚拟以太网(vEth)端口上本地获取。此条件触发反向路径转发(RPF)丢弃。请注意，传出接口信息报告dpid 0，这是丢弃。
端口1/18上不允许VLAN 35，这也触发了丢弃SRC_VLAN_MBR。
RCH-SV-FFAIII-A(nx-os)# show run interface ethernet 1/18
interface Ethernet1/18
description U: Uplink
pinning border
switchport mode trunk
switchport trunk allowed vlan 1
channel-group 105 mode active
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