ASR 9900 Series Fabric Explanation and Troubleshoot Examples
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Contents
Introduction
This document describes the use of separate fabric cards with the ASR 9922 and ASR 9912, similar to the fabric architecture implemented with the Cisco Carrier Routing System (CRS).
Cisco's ASR 9000 (ASR9K) uses a three-stage fabric system. In other chassis types (for example, 9006 and 9010) the three-stage fabric is divided into stage one and stage three on the linecards (LCs), and stage two on the Route Switch Processor (RSP). With the advent of the 9922 and 9912, stage two of the fabric has been moved from the RSP to dedicated fabric cards and a Route Processor (RP) card is used instead of the RSP.
Each Fabric Card (FC) is its own spine. These terms can be used interchangeably as well as the term 'plane' which is used in CRS terminology. Below is a high level view of the system with the crossbar being labeled as 'Fabric Intf'.
Fabric Overview
Each FC has two switch fabric ASICs, commonly referred to as crossbar ASICs, which are mapped as instance 0 and 1 while each LC and RP have one crossbar interface, instance 0.
On each LC there are two Serializer/Deserializer (SerDes) interfaces that connect to every FC, one SerDes interface per FC crossbar (0 and 1). These FC crossbars act as our stage two in the three-stage fabric, while stage one and stage three exist as the LC's crossbar. In addition, every RP has one SerDes interface per FC with this connection always on the FCs crossbar instance 0.
Fabric Details
Network Processors (NPs) and Fabric Interface ASICs (FIAs) are agnostic of scheduling over crossbar links, traffic is load-balanced on all eight links that make up the SerDes interface. If a single link within the SerDes interface has an issue then the entire interface will be shut down. Upon detection of this failure, the fabric drivers issue a retrain in order to try and fix the link.
Typhoon
With the current Typhoon architecture, five FCs are supported. These cards provide 8x7.5 G links per SerDes interface which equates to 55 G of available bandwidth after encoding is accounted for. With all five FCs each LC will have 2x55x5 = 550 Gbps of bandwidth available. When accounting for 4+1 fabric redundancy 440 Gbps are available per LC.
Tomahawk
Next generation cards support 115 Gbps SerDes connections. With the added support of seven fabric cards, this provides 2x115x7 = 1.61 Tbps of bandwidth per slot. Accounting for 6+1 fabric redundancy, this provides 1.38 Tbps per slot.
Fabric Card Requirements
Since the bandwidth on the crossbar is shared among all FIAs and NPs, a few calculations are needed in order to determine the true bandwidth and fabric redundancy.
In order to calculate the minimum number of FCs needed for a particular LC, use this formula:
(num_ports_used*port_bandwidth)/(FC_bandwidth)
In the case of the 36x10 GigE card with 30 ports this is (30*10)/(110)=2.72 FCs, or three FCs rounded up.
In order to calculate n+1 redundnacy, use this formula:
(num_ports_used*port_bandwidth)/(FC_bandwidth) + 1
In the case of the 36x10 GigE card this would be five if all 36 ports were used.
This table outlines the number of needed FCs for full line rate.
LC Type |
Min. FC Required in Chassis |
Number FC Required for n+1 Redundancy |
A9K-MOD80 |
1 |
2 |
A9K-MOD160 |
2 |
3 |
A9K-2x100GE |
2 |
3 |
A9K-24x10GE |
3 |
4 |
A9K-36x10GE |
4 |
5 |
Check the Fabric Card
Crossbar Link Status
The first thing to check is if all SerDes links on all planes, FCs, are up. In order to check this, enter the show controller fabric plane [all | [0-6]] command. In this example, because there are two RPs and three LCs, there are (1x2)+(2x3) = 8 links and all links are up to all planes.
RP/0/RP1/CPU0:ASR9922-B#show platform
Tue Apr 15 14:24:00.935 UTC
Node Type State Config State
-----------------------------------------------------------------------------
0/RP0/CPU0 ASR-9922-RP-SE(Standby) IOS XR RUN PWR,NSHUT,MON
0/RP1/CPU0 ASR-9922-RP-SE(Active) IOS XR RUN PWR,NSHUT,MON
0/0/CPU0 A9K-2x100GE-SE IOS XR RUN PWR,NSHUT,MON
0/2/CPU0 A9K-36x10GE-SE IOS XR RUN PWR,NSHUT,MON
0/3/CPU0 A9K-MOD160-TR IOS XR RUN PWR,NSHUT,MON
0/3/1 A9K-MPA-4X10GE OK PWR,NSHUT,MON
RP/0/RP1/CPU0:ASR9922-B#show controller fabric plane all
Mon Apr 14 14:37:00.116 UTC
Flags: Admin State: 1-Up 2-Down 12-UnPowered 16-Shutdown
Oper State: 1-Up 2-Down 3-Admin Down
Summary for All Fabric Planes:
Plane Id Admin State Oper State Links Up Links Down In Pkt Count Out Pkt count
===================================================================================
0 01 01 08 00 346770 431250
1 01 01 08 00 44397 44397
2 01 01 08 00 44459 44459
3 01 01 08 00 94005 94005
4 01 01 08 00 73814 73814
If a link shows as down the command show controller fabric crossbar link-status instance <0-1> spine <FC_num> can be used to identify exactly which one. In this example there are five crossbar links up to FC4 instance 0 and three links up to FC4 instance 1 (5+3=8 from before). There are two more on instance 0 because of the RPs.
RP/0/RP1/CPU0:ASR9922-B#show controllers fabric crossbar link-status instance 0 spine 4
Fri Apr 18 18:08:31.953 UTC
PORT Remote Slot Remote Inst Logical ID Status
======================================================
01 05 00 0 Up
04 04 00 0 Up
05 02 00 0 Up
08 00 00 0 Up
09 01 00 0 Up
RP/0/RP1/CPU0:ASR9922-B#show controllers fabric crossbar link-status instance 1 spine 4
Fri Apr 18 18:09:13.637 UTC
PORT Remote Slot Remote Inst Logical ID Status
======================================================
00 05 00 0 Up
04 04 00 0 Up
05 02 00 0 Up
Crossbar Statistics
With the link-status collected in the previous output as a mapping and these statistics, it is easy to narrow down any component that has a traffic issue. For every crossbar port, SerDes interface, there will be ingress (from LC) and egress (towards LC) statistics. These are collected per FC crossbar instance.
RP/0/RP1/CPU0:ASR9922-B#show controller fabric crossbar statistics instance 0 spine 4
Tue Apr 22 16:52:23.162 UTC
Port statistics for xbar:0 port:0
==============================
Hi priority stats (unicast)
===========================
Low priority stats (multicast)
===========================
Port statistics for xbar:0 port:1
==============================
Hi priority stats (unicast)
===========================
Ingress Packet Count Since Last Read : 14016
Egress Packet Count Since Last Read : 24971
Low priority stats (multicast)
===========================
Port statistics for xbar:0 port:2
==============================
Hi priority stats (unicast)
===========================
Low priority stats (multicast)
===========================
Port statistics for xbar:0 port:4
==============================
Hi priority stats (unicast)
===========================
Ingress Packet Count Since Last Read : 21056
Egress Packet Count Since Last Read : 32195
Low priority stats (multicast)
===========================
Port statistics for xbar:0 port:5
==============================
Hi priority stats (unicast)
===========================
Ingress Packet Count Since Last Read : 7024
Egress Packet Count Since Last Read : 10477
Low priority stats (multicast)
===========================
Port statistics for xbar:0 port:6
==============================
Hi priority stats (unicast)
===========================
Low priority stats (multicast)
===========================
Port statistics for xbar:0 port:7
==============================
Hi priority stats (unicast)
===========================
Low priority stats (multicast)
===========================
Port statistics for xbar:0 port:8
==============================
Hi priority stats (unicast)
===========================
Low priority stats (multicast)
===========================
Ingress Packet Count Since Last Read : 37388
Egress Packet Count Since Last Read : 37388
Port statistics for xbar:0 port:9
==============================
Hi priority stats (unicast)
===========================
Ingress Packet Count Since Last Read : 72882
Egress Packet Count Since Last Read : 47335
Low priority stats (multicast)
===========================
Ingress Packet Count Since Last Read : 37386
Egress Packet Count Since Last Read : 37386
Port statistics for xbar:0 port:10
==============================
Hi priority stats (unicast)
===========================
Low priority stats (multicast)
===========================
Port statistics for xbar:0 port:11
==============================
Hi priority stats (unicast)
===========================
Low priority stats (multicast)
===========================
Port statistics for xbar:0 port:12
==============================
Hi priority stats (unicast)
===========================
Low priority stats (multicast)
===========================
Port statistics for xbar:0 port:13
==============================
Hi priority stats (unicast)
===========================
Low priority stats (multicast)
===========================
Port statistics for xbar:0 port:14
==============================
Hi priority stats (unicast)
===========================
Low priority stats (multicast)
===========================
Port statistics for xbar:0 port:15
==============================
Hi priority stats (unicast)
===========================
Low priority stats (multicast)
===========================
Port statistics for xbar:0 port:16
==============================
Hi priority stats (unicast)
===========================
Low priority stats (multicast)
===========================
Port statistics for xbar:0 port:17
==============================
Hi priority stats (unicast)
===========================
Low priority stats (multicast)
===========================
Port statistics for xbar:0 port:18
==============================
Hi priority stats (unicast)
===========================
Low priority stats (multicast)
===========================
Port statistics for xbar:0 port:19
==============================
Hi priority stats (unicast)
===========================
Low priority stats (multicast)
===========================
Port statistics for xbar:0 port:20
==============================
Hi priority stats (unicast)
===========================
Low priority stats (multicast)
===========================
Port statistics for xbar:0 port:22
==============================
Hi priority stats (unicast)
===========================
Low priority stats (multicast)
===========================
Port statistics for xbar:0 port:24
==============================
Hi priority stats (unicast)
===========================
Low priority stats (multicast)
===========================
Total Unicast In: 114978
Total Unicast Out: 114978
Total Multicast In: 74774
Total Multicast Out: 74774
Check the Linecard
On the LC itself, between the crossbar and each FIA, there are 2x8x6.25 links which provide 100 G of raw bandwidth per FIA. Between each NP and FIA there is a single 8x6.25 link that gives 50 G of raw bandwidth per NP.
Crossbar Link Status
The collection of the crossbar link status for a LC is similar to that of a FC, but in this case the links from the FC crossbar to the LC crossbar will be seen as well as the LC crossbar to FIA links. As previously mentioned, each FIA connects to the crossbar via two links. In this example, port 00 and 24 both connect to FIA 2. As with the previous examples, remote slots 22-26 are the FCs and 0/2/CPU0 corresponds to slot 4 itself.
RP/0/RP1/CPU0:ASR9922-B#show controller fabric crossbar link-status inst 0 loc 0/2/CPU0
Wed Apr 23 14:22:42.250 UTC
PORT Remote Slot Remote Inst Logical ID Status
======================================================
00 04 02 1 Up
01 04 01 1 Up
02 04 01 0 Up
03 04 00 0 Up
04 04 00 1 Up
05 04 03 1 Up
06 04 05 1 Up
07 25 01 0 Up
08 04 03 0 Up
09 25 00 0 Up
10 04 05 0 Up
11 26 01 0 Up
12 26 00 0 Up
14 24 00 0 Up
15 24 01 0 Up
16 23 00 0 Up
17 23 01 0 Up
20 22 00 0 Up
22 22 01 0 Up
23 04 04 1 Up
24 04 02 0 Up
25 04 04 0 Up
Crossbar Statistics
Using the link-status collected in the previous output as a reference mapping, the below statistics output can be used as an easy way to narrow down any components that exhibit traffic loss.
RP/0/RP1/CPU0:ASR9922-B#show controller fabric crossbar statistics instance 0 loc 0/2/CPU0
Wed Apr 23 15:53:41.955 UTC
Port statistics for xbar:0 port:0
==============================
Hi priority stats (unicast)
===========================
Ingress Packet Count Since Last Read : 15578
Egress Packet Count Since Last Read : 11957
Low priority stats (multicast)
===========================
Port statistics for xbar:0 port:1
==============================
Hi priority stats (unicast)
===========================
Ingress Packet Count Since Last Read : 15775
Egress Packet Count Since Last Read : 11647
Low priority stats (multicast)
===========================
Port statistics for xbar:0 port:2
==============================
Hi priority stats (unicast)
===========================
Ingress Packet Count Since Last Read : 15646
Egress Packet Count Since Last Read : 19774
Low priority stats (multicast)
===========================
Ingress Packet Count Since Last Read : 31424
Egress Packet Count Since Last Read : 188544
Port statistics for xbar:0 port:3
==============================
Hi priority stats (unicast)
===========================
Ingress Packet Count Since Last Read : 15663
Egress Packet Count Since Last Read : 15613
Low priority stats (multicast)
===========================
Ingress Packet Count Since Last Read : 31424
Egress Packet Count Since Last Read : 188547
Port statistics for xbar:0 port:4
==============================
Hi priority stats (unicast)
===========================
Ingress Packet Count Since Last Read : 15758
Egress Packet Count Since Last Read : 15813
Low priority stats (multicast)
===========================
Port statistics for xbar:0 port:5
==============================
Hi priority stats (unicast)
===========================
Ingress Packet Count Since Last Read : 15742
Egress Packet Count Since Last Read : 15628
Low priority stats (multicast)
===========================
Port statistics for xbar:0 port:6
==============================
Hi priority stats (unicast)
===========================
Ingress Packet Count Since Last Read : 15773
Egress Packet Count Since Last Read : 13687
Low priority stats (multicast)
===========================
Ingress Packet Count Since Last Read : 78666
Port statistics for xbar:0 port:7
==============================
Hi priority stats (unicast)
===========================
Low priority stats (multicast)
===========================
Port statistics for xbar:0 port:8
==============================
Hi priority stats (unicast)
===========================
Ingress Packet Count Since Last Read : 15679
Egress Packet Count Since Last Read : 15793
Low priority stats (multicast)
===========================
Ingress Packet Count Since Last Read : 31424
Egress Packet Count Since Last Read : 188544
Port statistics for xbar:0 port:9
==============================
Hi priority stats (unicast)
===========================
Ingress Packet Count Since Last Read : 72826
Egress Packet Count Since Last Read : 58810
Low priority stats (multicast)
===========================
Port statistics for xbar:0 port:10
==============================
Hi priority stats (unicast)
===========================
Ingress Packet Count Since Last Read : 15653
Egress Packet Count Since Last Read : 23041
Low priority stats (multicast)
===========================
Egress Packet Count Since Last Read : 188544
Port statistics for xbar:0 port:11
==============================
Hi priority stats (unicast)
===========================
Low priority stats (multicast)
===========================
Port statistics for xbar:0 port:12
==============================
Hi priority stats (unicast)
===========================
Ingress Packet Count Since Last Read : 54172
Egress Packet Count Since Last Read : 35440
Low priority stats (multicast)
===========================
Port statistics for xbar:0 port:14
==============================
Hi priority stats (unicast)
===========================
Ingress Packet Count Since Last Read : 15161
Egress Packet Count Since Last Read : 17790
Low priority stats (multicast)
===========================
Port statistics for xbar:0 port:15
==============================
Hi priority stats (unicast)
===========================
Low priority stats (multicast)
===========================
Port statistics for xbar:0 port:16
==============================
Hi priority stats (unicast)
===========================
Ingress Packet Count Since Last Read : 15220
Egress Packet Count Since Last Read : 17790
Low priority stats (multicast)
===========================
Port statistics for xbar:0 port:17
==============================
Hi priority stats (unicast)
===========================
Ingress Packet Count Since Last Read : 1
Egress Packet Count Since Last Read : 1
Low priority stats (multicast)
===========================
Port statistics for xbar:0 port:20
==============================
Hi priority stats (unicast)
===========================
Ingress Packet Count Since Last Read : 36457
Egress Packet Count Since Last Read : 58699
Low priority stats (multicast)
===========================
Ingress Packet Count Since Last Read : 188549
NULL FPOE Drop Count : 2
Egress Packet Count Since Last Read : 235786
Port statistics for xbar:0 port:22
==============================
Hi priority stats (unicast)
===========================
Ingress Packet Count Since Last Read : 1
Egress Packet Count Since Last Read : 1
Low priority stats (multicast)
===========================
Port statistics for xbar:0 port:23
==============================
Hi priority stats (unicast)
===========================
Ingress Packet Count Since Last Read : 15775
Egress Packet Count Since Last Read : 15835
Low priority stats (multicast)
===========================
Ingress Packet Count Since Last Read : 31424
Port statistics for xbar:0 port:24
==============================
Hi priority stats (unicast)
===========================
Ingress Packet Count Since Last Read : 15843
Egress Packet Count Since Last Read : 19464
Low priority stats (multicast)
===========================
Ingress Packet Count Since Last Read : 31424
Egress Packet Count Since Last Read : 188544
Port statistics for xbar:0 port:25
==============================
Hi priority stats (unicast)
===========================
Ingress Packet Count Since Last Read : 15646
Egress Packet Count Since Last Read : 15586
Low priority stats (multicast)
===========================
Egress Packet Count Since Last Read : 188544
Total Unicast In: 382369
Total Unicast Out: 382369
Total Multicast In: 424335
Total Multicast Out: 1367053
Troubleshoot
Crossbar Port Down
The first output indicates that there are two RPs and two LCs. The second output indicates that the link from FC4 to remote slot 0 (RP0) is down.
RP/0/RP0/CPU0:ASR9k-1#show controllers fabric plane all
Plane Id Admin State Oper State Links Up Links Down In Pkt Count Out Pkt count
======================================================================================
0 01 01 06 00 62266063301 62266209776
1 01 01 06 00 18730254608 18730254616
2 01 01 06 00 18730354183 18730354187
3 01 01 06 00 62257126982 62257127007
4 01 01 05 01 37448788006 37448788023
RP/0/RP0/CPU0:ASR9k-1#show controllers fabric crossbar link-status instance 0 spine 4
PORT Remote Slot Remote Inst Logical ID Status
======================================================
04 04 00 0 Up
08 00 00 0 Down
09 01 00 0 Up
10 03 00 0 Up
Since the bandwidth from the FCs is shared among all FIA's and NPs on the LC when a crossbar link is down, the net bandwidth for the LC will be reduced 55 G in a Typhoon system. The system can run with a link down given the redundancy of the system, but should be immediately investigated.
When a crossbar link goes down, a brief traffic drop might be seen and the fabric driver retrains the link in order to attempt automatic recovery. If this fails then an Online Insertion and Removal (OIR) might recover the issue as well. For any further issue please contact the Technical Assistance Center (TAC).
Spine Unavailable Syslog
These messages indicate that the system runs below the recommended five FCs. While it is recommended to always run five FCs, this does not necessarily mean any bandwidth loss for the LCs in the system. See the section Fabric Card Requirements for more information.
RP/0/RP1/CPU0:May 13 14:42:22.810 : pfm_node_rp[353]:
%PLATFORM-FABMGR-1-SPINE_UNAVAILABLE : Set|fabmgr[303204]|Fabric Manager(0x1032000)|
Number of active spines has dropped below the recommended number 5
RP/0/RP1/CPU0:May 13 14:53:18.897 : pfm_node_rp[353]:
%PLATFORM-FABMGR-1-SPINE_UNAVAILABLE : Clear|fabmgr[303204]|Fabric Manager(0x1032000)|
Number of active spines has dropped below the recommended number 5
FC Inactive Syslog
When performing an OIR of a FC there are two mechanical buttons that must be pushed before the card is partially unseated which requires an OIR to recover. The reason for these buttons is to allow a graceful shutdown of the FC.
On the 9922 router the top button is purely mechanical, while the lower button sends a signal to the system to gracefully shutdown the card. A syslog in this format is seen. If the buttons were not pushed and an OIR does not recover the issue, contact the TAC.
RP/0/RP0/CPU0:Dec 24 10:45:27.108 MST: fab_xbar_sp3[220]: FC3 Inactive due to
Front Panel Switch Press. Please OIR to recover.
Related Information
- ASR9000/XR Understanding and troubleshooting Fabric issues in the A9K
- Technical Support & Documentation - Cisco Systems
Appendix
Logical to Physical Slot Mappings
These outputs are the logical to physical slot mappings for the 9922 and 9912 routers. This information is needed when looking at fabric show commands.
9922
slot 00 -> 0/RP0/CPU0 (0x1)
slot 01 -> 0/RP1/CPU0 (0x11)
slot 02 -> 0/0/CPU0 (0x821)
slot 03 -> 0/1/CPU0 (0x831)
slot 04 -> 0/2/CPU0 (0x841)
slot 05 -> 0/3/CPU0 (0x851)
slot 06 -> 0/4/CPU0 (0x861)
slot 07 -> 0/5/CPU0 (0x871)
slot 08 -> 0/6/CPU0 (0x881)
slot 09 -> 0/7/CPU0 (0x891)
slot 10 -> 0/8/CPU0 (0x8a1)
slot 11 -> 0/9/CPU0 (0x8b1)
slot 12 -> 0/10/CPU0 (0x8c1)
slot 13 -> 0/11/CPU0 (0x8d1)
slot 14 -> 0/12/CPU0 (0x8e1)
slot 15 -> 0/13/CPU0 (0x8f1)
slot 16 -> 0/14/CPU0 (0x901)
slot 17 -> 0/15/CPU0 (0x911)
slot 18 -> 0/16/CPU0 (0x921)
slot 19 -> 0/17/CPU0 (0x931)
slot 20 -> 0/18/CPU0 (0x941)
slot 21 -> 0/19/CPU0 (0x951)
slot 22 -> 0/FC0/SP (0x1960)
slot 23 -> 0/FC1/SP (0x1970)
slot 24 -> 0/FC2/SP (0x1980)
slot 25 -> 0/FC3/SP (0x1990)
slot 26 -> 0/FC4/SP (0x19a0)
slot 27 -> 0/FC5/SP (0x19b0)
slot 28 -> 0/FC6/SP (0x19c0)
slot 34 -> 0/BPID0/SP (0x1220)
slot 35 -> 0/BPID1/SP (0x1230)
slot 36 -> 0/FT0/SP (0x640)
slot 37 -> 0/FT1/SP (0x650)
slot 38 -> 0/FT2/SP (0x660)
slot 39 -> 0/FT3/SP (0x670)
slot 40 -> 0/PM0/SP (0xe80)
slot 41 -> 0/PM1/SP (0xe90)
slot 42 -> 0/PM2/SP (0xea0)
slot 43 -> 0/PM3/SP (0xeb0)
slot 44 -> 0/PM4/SP (0xec0)
slot 45 -> 0/PM5/SP (0xed0)
slot 46 -> 0/PM6/SP (0xee0)
slot 47 -> 0/PM7/SP (0xef0)
slot 48 -> 0/PM8/SP (0xf00)
slot 49 -> 0/PM9/SP (0xf10)
slot 50 -> 0/PM10/SP (0xf20)
slot 51 -> 0/PM11/SP (0xf30)
slot 52 -> 0/PM12/SP (0xf40)
slot 53 -> 0/PM13/SP (0xf50)
slot 54 -> 0/PM14/SP (0xf60)
slot 55 -> 0/PM15/SP (0xf70)
9912
slot 00 -> 0/RP0/CPU0 (0x1)
slot 01 -> 0/RP1/CPU0 (0x11)
slot 02 -> 0/0/CPU0 (0x821)
slot 03 -> 0/1/CPU0 (0x831)
slot 04 -> 0/2/CPU0 (0x841)
slot 05 -> 0/3/CPU0 (0x851)
slot 06 -> 0/4/CPU0 (0x861)
slot 07 -> 0/5/CPU0 (0x871)
slot 08 -> 0/6/CPU0 (0x881)
slot 09 -> 0/7/CPU0 (0x891)
slot 10 -> 0/8/CPU0 (0x8a1)
slot 11 -> 0/9/CPU0 (0x8b1)
slot 12 -> 0/FC0/SP (0x18c0)
slot 13 -> 0/FC1/SP (0x18d0)
slot 14 -> 0/FC2/SP (0x18e0)
slot 15 -> 0/FC3/SP (0x18f0)
slot 16 -> 0/FC4/SP (0x1900)
slot 17 -> 0/FC5/SP (0x1910)
slot 18 -> 0/FC6/SP (0x1920)
slot 25 -> 0/BPID0/SP (0x1190)
slot 26 -> 0/FT0/SP (0x5a0)
slot 27 -> 0/FT1/SP (0x5b0)
slot 40 -> 0/PM0/SP (0xe80)
slot 41 -> 0/PM1/SP (0xe90)
slot 42 -> 0/PM2/SP (0xea0)
slot 43 -> 0/PM3/SP (0xeb0)
slot 44 -> 0/PM4/SP (0xec0)
slot 45 -> 0/PM5/SP (0xed0)
slot 46 -> 0/PM6/SP (0xee0)
slot 47 -> 0/PM7/SP (0xef0)
slot 48 -> 0/PM8/SP (0xf00)
slot 49 -> 0/PM9/SP (0xf10)
slot 50 -> 0/PM10/SP (0xf20)
slot 51 -> 0/PM11/SP (0xf30)
Multicast
LCs use a fixed path over the fabric based on a hash calculated over source and group (S, G) of the multicast flow. Hence, for higher multicast throughput over an LC, it is important to have a higher number of flows with source and group that varies in order to evenly spread traffic over all active fabric planes. If the selected FC is removed or disabled, the link selection algorithm selects a different link among the available active fabric planes.
Multicast forwarding uses a 12-bit fabric header field called Fabric Group ID (FGID). Bit 0 and 1 are reserved for RP0/1. The 10 bits that remain, from 2 to 11, are used to address 20 LCs. Since 1 bit is available to address 2 LCs, there is redundant multicast packet replication (supercast) between paired LC [(LC0, LC10), (LC1, LC11), (LC2, LC12), and so on]. Local crossbar on the paired LC drops redundant multicast traffic if no interface on that LC has joined that multicast group.
FGID Bit |
0 |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
10 |
11 |
Slot |
RP0 |
RP1 |
LC0 |
LC1 |
LC2 |
LC3 |
LC4 |
LC5 |
LC6 |
LC7 |
LC8 |
LC9 |
Paired Slot |
X |
X |
LC10 |
LC11 |
LC12 |
LC13 |
LC14 |
LC15 |
LC16 |
LC17 |
LC18 |
LC19 |
Revision History
| Revision | Publish Date | Comments |
|---|---|---|
1.0 |
19-Mar-2015 |
Initial Release |
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