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+---
+published: true
+date: '2018-01-25 00:01 +0100'
+title: Large Routing Tables on "Scale" NCS 5500 Systems (S01E05)
+author: Nicolas Fevrier
+excerpt: >-
+  Post #5 on the NCS5500 Resources: very large routing table in eTCAM systems,
+  illustrated in a YouTube Video
+tags:
+  - ncs5500
+  - ncs 5500
+  - internet table
+  - demo
+  - video
+  - youtube
+  - lem
+  - lpm
+  - etcam
+  - routes
+  - scale
+  - prefixes
+  - high scale
+position: top
+---
+{% include toc icon="table" title="Understanding NCS5500 Resources" %}  
+
+## S01E05 Large Routing Tables on "Scale" NCS 5500 Systems
+
+### Previously on "Understanding NCS5500 Resources"
+
+In previous posts, we presented:
+- the [different routers and line cards in NCS5500 portfolio](https://xrdocs.github.io/cloud-scale-networking/tutorials/2017-08-02-understanding-ncs5500-resources-s01e01/)  
+- we explained [how IPv4 prefixes are sorted in LEM, LPM and eTCAM](https://xrdocs.github.io/cloud-scale-networking/tutorials/2017-08-03-understanding-ncs5500-resources-s01e02/)
+- we covered [how IPv6 prefixes are stored in the same databases](https://xrdocs.github.io/cloud-scale-networking/tutorials/2017-08-07-understanding-ncs5500-resources-s01e03/).
+- and finally [we demonstrated in a video](https://xrdocs.github.io/cloud-scale-networking/tutorials/2017-12-30-full-internet-view-on-base-ncs-5500-systems-s01e04/) how we can handle a full IPv4 and IPv6 Internet view on base systems and line cards (i.e. without external TCAM, only using the LEM and LPM internal to the forwarding ASIC)
+
+Today, we are pushing the limits further. We will take a much larger existing (ie. real) routing table (internet + a very large number of host routes), we will add a projection of the internet table to year 2025 and we will see how it can fit in a Jericho-based system with External TCAM
+
+### The demo
+
+In this YouTube video, we will:
+- describe the line cards and systems using Jericho (or Qumran-MX) forwarding ASICs with external TCAM
+- explain the different memories we can use to store the routes and what logic is used to decide where the different prefix types will go
+- run the demo
+	- first with a real very large routing table of 1.2M IPv4 and 64k IPv6 routes
+    (the v4 table size comes from a full internet view, a large number of peering routes and 436k host routes)
+    - then we will project ourself to 2025 and guesstimate how large the v4 and v6 public table will be
+    - we will advertise these extra routes, see how the router absorbs them and how much free space we have left in the different memories
+
+[![NCS5500 Route Scale with eTCAMDemo](https://img.youtube.com/vi/lVC3ppgi7ak/0.jpg)](https://www.youtube.com/watch?v=lVC3ppgi7ak){: .align-center}
+
+[https://www.youtube.com/watch?v=lVC3ppgi7ak](https://www.youtube.com/watch?v=lVC3ppgi7ak)
+
+### CLI outputs
+
+We jump directly to the larger use-case: large internet table from 2025 with 436k IPv4 host routes.
+Such large number of host routes can be caused by DDoS mitigation systems (the /32s being used to divert the traffic targeted to specific victims) or by L3 migration of VMs between domains.
+
+<div class="highlighter-rouge">
+<pre class="highlight">
+<code>
+
+RP/0/RP0/CPU0:TME-5508-6.2.3#sh route sum
+
+Route Source                     Routes     Backup     Deleted     Memory(bytes)
+local                            2          0          0           480
+connected                        2          0          0           480
+bgp 100                          1612272    0          0           386945280
+dagr                             0          0          0           0
+static                           0          0          0           0
+Total                            1612276    0          0           386946240
+
+RP/0/RP0/CPU0:TME-5508-6.2.3#sh route ipv6 un sum
+
+Route Source                     Routes     Backup     Deleted     Memory(bytes)
+local                            2          0          0           528
+connected                        2          0          0           528
+connected l2tpv3_xconnect        0          0          0           0
+bgp 100                          108243     0          0           28576152
+static                           0          1          0           264
+Total                            108247     1          0           28577472
+
+RP/0/RP0/CPU0:TME-5508-6.2.3#sh dpa resources iproute loc 0/6/CPU0
+
+"iproute" DPA Table (Id: 18, Scope: Global)
+--------------------------------------------------
+IPv4 Prefix len distribution
+Prefix   Actual            Capacity    Prefix   Actual            Capacity
+ /0       1                 16           /1       0                 16
+ /2       0                 16           /3       0                 16
+ /4       1                 16           /5       0                 16
+ /6       0                 16           /7       0                 16
+ /8       16                16           /9       14                16
+ /10      37                163          /11      107               327
+ /12      288               654          /13      557               1309
+ /14      1071              2620         /15      1909              4585
+ /16      13572             33905        /17      8005              20309
+ /18      23343             34068        /19      38018             69283
+ /20      40443             101879       /21      45082             113343
+ /22      148685            185575       /23      116728            165738
+ /24      651486            884472       /25      2085              3439
+ /26      3362              3603         /27      5736              2620
+ /28      15909             2292         /29      17377             5568
+ /30      42507             2292         /31      112               163
+ /32      435847            16
+                          NPU ID: NPU-0           NPU-1           NPU-2           NPU-3
+                          In Use: 1612298         1612298         1612298         1612298
+                 Create Requests
+                           Total: 2285630         2285630         2285630         2285630
+                         Success: 2285630         2285630         2285630         2285630
+                 Delete Requests
+                           Total: 673332          673332          673332          673332
+                         Success: 673332          673332          673332          673332
+                 Update Requests
+                           Total: 2680653         2680653         2680653         2680653
+                         Success: 2680651         2680651         2680651         2680651
+                    EOD Requests
+                           Total: 0               0               0               0
+                         Success: 0               0               0               0
+                          Errors
+                     HW Failures: 0               0               0               0
+                Resolve Failures: 0               0               0               0
+                 No memory in DB: 0               0               0               0
+                 Not found in DB: 0               0               0               0
+                    Exists in DB: 0               0               0               0
+
+RP/0/RP0/CPU0:TME-5508-6.2.3#sh dpa resources ip6route loc 0/6/CPU0
+
+"ip6route" DPA Table (Id: 19, Scope: Global)
+--------------------------------------------------
+IPv6 Prefix len distribution
+Prefix   Actual       Prefix   Actual
+ /0       1            /1       0
+ /2       0            /3       0
+ /4       0            /5       0
+ /6       0            /7       0
+ /8       0            /9       0
+ /10      1            /11      0
+ /12      0            /13      0
+ /14      0            /15      0
+ /16      4            /17      0
+ /18      0            /19      2
+ /20      9            /21      3
+ /22      4            /23      4
+ /24      20           /25      6
+ /26      15           /27      17
+ /28      80           /29      2889
+ /30      189          /31      132
+ /32      10091        /33      684
+ /34      454          /35      423
+ /36      3738         /37      292
+ /38      686          /39      165
+ /40      7578         /41      219
+ /42      417          /43      129
+ /44      7899         /45      187
+ /46      1498         /47      376
+ /48      52338        /49      13
+ /50      12           /51      4
+ /52      16           /53      0
+ /54      1            /55      8
+ /56      11622        /57      16
+ /58      2            /59      0
+ /60      3            /61      0
+ /62      1            /63      0
+ /64      5152         /65      0
+ /66      0            /67      0
+ /68      0            /69      0
+ /70      0            /71      0
+ /72      0            /73      0
+ /74      0            /75      0
+ /76      0            /77      0
+ /78      0            /79      0
+ /80      0            /81      0
+ /82      0            /83      0
+ /84      0            /85      0
+ /86      0            /87      0
+ /88      0            /89      0
+ /90      0            /91      0
+ /92      0            /93      0
+ /94      0            /95      0
+ /96      1            /97      0
+ /98      0            /99      0
+ /100     0            /101     0
+ /102     0            /103     0
+ /104     1            /105     0
+ /106     0            /107     0
+ /108     0            /109     0
+ /110     0            /111     0
+ /112     0            /113     0
+ /114     0            /115     4
+ /116     0            /117     0
+ /118     0            /119     0
+ /120     0            /121     0
+ /122     71           /123     0
+ /124     15           /125     0
+ /126     24           /127     18
+ /128     731
+                          NPU ID: NPU-0           NPU-1           NPU-2           NPU-3
+                          In Use: 108265          108265          108265          108265
+                 Create Requests
+                           Total: 171646          171646          171646          171646
+                         Success: 171646          171646          171646          171646
+                 Delete Requests
+                           Total: 63381           63381           63381           63381
+                         Success: 63381           63381           63381           63381
+                 Update Requests
+                           Total: 4               4               4               4
+                         Success: 2               2               2               2
+                    EOD Requests
+                           Total: 0               0               0               0
+                         Success: 0               0               0               0
+                          Errors
+                     HW Failures: 0               0               0               0
+                Resolve Failures: 0               0               0               0
+                 No memory in DB: 0               0               0               0
+                 Not found in DB: 0               0               0               0
+                    Exists in DB: 0               0               0               0
+
+RP/0/RP0/CPU0:TME-5508-6.2.3#sh contr npu resources lem loc 0/6/CPU0
+
+HW Resource Information
+    Name                            : lem
+
+OOR Information
+    NPU-0
+        Estimated Max Entries       : 786432
+        Red Threshold               : 95 %
+        Yellow Threshold            : 80 %
+        OOR State                   : Green
+    NPU-1
+        Estimated Max Entries       : 786432
+        Red Threshold               : 95 %
+        Yellow Threshold            : 80 %
+        OOR State                   : Green
+    NPU-2
+        Estimated Max Entries       : 786432
+        Red Threshold               : 95 %
+        Yellow Threshold            : 80 %
+        OOR State                   : Green
+    NPU-3
+        Estimated Max Entries       : 786432
+        Red Threshold               : 95 %
+        Yellow Threshold            : 80 %
+        OOR State                   : Green
+
+Current Usage
+    NPU-0
+        Total In-Use                : 488186   (62 %)
+        iproute                     : 435847   (55 %)
+        ip6route                    : 52338    (7 %)
+        mplslabel                   : 0        (0 %)
+    NPU-1
+        Total In-Use                : 488186   (62 %)
+        iproute                     : 435847   (55 %)
+        ip6route                    : 52338    (7 %)
+        mplslabel                   : 0        (0 %)
+    NPU-2
+        Total In-Use                : 488186   (62 %)
+        iproute                     : 435847   (55 %)
+        ip6route                    : 52338    (7 %)
+        mplslabel                   : 0        (0 %)
+    NPU-3
+        Total In-Use                : 488186   (62 %)
+        iproute                     : 435847   (55 %)
+        ip6route                    : 52338    (7 %)
+        mplslabel                   : 0        (0 %)
+
+RP/0/RP0/CPU0:TME-5508-6.2.3#sh contr npu resources lpm loc 0/6/CPU0
+
+HW Resource Information
+    Name                            : lpm
+
+OOR Information
+    NPU-0
+        Estimated Max Entries       : 486043
+        Red Threshold               : 95 %
+        Yellow Threshold            : 80 %
+        OOR State                   : Green
+    NPU-1
+        Estimated Max Entries       : 486043
+        Red Threshold               : 95 %
+        Yellow Threshold            : 80 %
+        OOR State                   : Green
+    NPU-2
+        Estimated Max Entries       : 486043
+        Red Threshold               : 95 %
+        Yellow Threshold            : 80 %
+        OOR State                   : Green
+    NPU-3
+        Estimated Max Entries       : 486043
+        Red Threshold               : 95 %
+        Yellow Threshold            : 80 %
+        OOR State                   : Green
+
+Current Usage
+    NPU-0
+        Total In-Use                : 55950    (12 %)
+        iproute                     : 0        (0 %)
+        ip6route                    : 55927    (12 %)
+        ipmcroute                   : 0        (0 %)
+    NPU-1
+        Total In-Use                : 55950    (12 %)
+        iproute                     : 0        (0 %)
+        ip6route                    : 55927    (12 %)
+        ipmcroute                   : 0        (0 %)
+    NPU-2
+        Total In-Use                : 55950    (12 %)
+        iproute                     : 0        (0 %)
+        ip6route                    : 55927    (12 %)
+        ipmcroute                   : 0        (0 %)
+    NPU-3
+        Total In-Use                : 55950    (12 %)
+        iproute                     : 0        (0 %)
+        ip6route                    : 55927    (12 %)
+        ipmcroute                   : 0        (0 %)
+
+RP/0/RP0/CPU0:TME-5508-6.2.3#sh contr npu resources exttcamipv4 loc 0/6/CPU0
+
+HW Resource Information
+    Name                            : ext_tcam_ipv4
+
+OOR Information
+    NPU-0
+        Estimated Max Entries       : 1638400
+        Red Threshold               : 95 %
+        Yellow Threshold            : 80 %
+        OOR State                   : Green
+    NPU-1
+        Estimated Max Entries       : 1638400
+        Red Threshold               : 95 %
+        Yellow Threshold            : 80 %
+        OOR State                   : Green
+    NPU-2
+        Estimated Max Entries       : 1638400
+        Red Threshold               : 95 %
+        Yellow Threshold            : 80 %
+        OOR State                   : Green
+    NPU-3
+        Estimated Max Entries       : 1638400
+        Red Threshold               : 95 %
+        Yellow Threshold            : 80 %
+        OOR State                   : Green
+
+Current Usage
+    NPU-0
+        Total In-Use                : 1176451  (72 %)
+        iproute                     : 1176451  (72 %)
+        ipmcroute                   : 0        (0 %)
+    NPU-1
+        Total In-Use                : 1176451  (72 %)
+        iproute                     : 1176451  (72 %)
+        ipmcroute                   : 0        (0 %)
+    NPU-2
+        Total In-Use                : 1176451  (72 %)
+        iproute                     : 1176451  (72 %)
+        ipmcroute                   : 0        (0 %)
+    NPU-3
+        Total In-Use                : 1176451  (72 %)
+        iproute                     : 1176451  (72 %)
+        ipmcroute                   : 0        (0 %)
+
+RP/0/RP0/CPU0:TME-5508-6.2.3#
+
+</code>
+</pre>
+</div>
+
+The 2025 internet estimation [is described in the previous post](https://xrdocs.github.io/cloud-scale-networking/tutorials/2017-12-30-full-internet-view-on-base-ncs-5500-systems-s01e04/). As mentioned in this post and in the video, the method is certainly a matter of debate. Let's take it for what it is: an estimation.
+
+In these use-cases with large public routing table and extreme amount of host routes, we are far from reaching the limits of the systems based on Jericho ASICs with External TCAMs.
+We are using 62% of LEM, 12% of LPM and 72% of eTCAM.
+Important to understand that default carving in IOS XR 6.2.3 is allocating 20% for hybrid ACLs. This default behavior will change in releases 6.3.x onwards where we will allocate 100% of the space to IPv4 prefixes and it will be only when configuring hybrid ACLs that we will re-carve to allocation eTCAM space.
+
+We can verify the current carving status with the following:
+
+<div class="highlighter-rouge">
+<pre class="highlight">
+<code>
+
+RP/0/RP0/CPU0:TME-5508-6.2.3#sh contr npu externaltcam loc 0/6/CPU0
+
+External TCAM Resource Information
+=============================================================
+NPU  Bank   Entry  Owner       Free     Per-DB  DB   DB
+     Id     Size               Entries  Entry   ID   Name
+=============================================================
+0    0      80b    FLP         461952   1176448  15   IPV4 DC
+0    1      80b    FLP         28672    0       76   INGRESS_IPV4_SRC_IP_EXT
+0    2      80b    FLP         28672    0       77   INGRESS_IPV4_DST_IP_EXT
+0    3      160b   FLP         26624    0       78   INGRESS_IPV6_SRC_IP_EXT
+0    4      160b   FLP         26624    0       79   INGRESS_IPV6_DST_IP_EXT
+0    5      80b    FLP         28672    0       80   INGRESS_IP_SRC_PORT_EXT
+0    6      80b    FLP         28672    0       81   INGRESS_IPV6_SRC_PORT_EXT
+1    0      80b    FLP         461952   1176448  15   IPV4 DC
+1    1      80b    FLP         28672    0       76   INGRESS_IPV4_SRC_IP_EXT
+1    2      80b    FLP         28672    0       77   INGRESS_IPV4_DST_IP_EXT
+1    3      160b   FLP         26624    0       78   INGRESS_IPV6_SRC_IP_EXT
+1    4      160b   FLP         26624    0       79   INGRESS_IPV6_DST_IP_EXT
+1    5      80b    FLP         28672    0       80   INGRESS_IP_SRC_PORT_EXT
+1    6      80b    FLP         28672    0       81   INGRESS_IPV6_SRC_PORT_EXT
+2    0      80b    FLP         461952   1176448  15   IPV4 DC
+2    1      80b    FLP         28672    0       76   INGRESS_IPV4_SRC_IP_EXT
+2    2      80b    FLP         28672    0       77   INGRESS_IPV4_DST_IP_EXT
+2    3      160b   FLP         26624    0       78   INGRESS_IPV6_SRC_IP_EXT
+2    4      160b   FLP         26624    0       79   INGRESS_IPV6_DST_IP_EXT
+2    5      80b    FLP         28672    0       80   INGRESS_IP_SRC_PORT_EXT
+2    6      80b    FLP         28672    0       81   INGRESS_IPV6_SRC_PORT_EXT
+3    0      80b    FLP         461952   1176448  15   IPV4 DC
+3    1      80b    FLP         28672    0       76   INGRESS_IPV4_SRC_IP_EXT
+3    2      80b    FLP         28672    0       77   INGRESS_IPV4_DST_IP_EXT
+3    3      160b   FLP         26624    0       78   INGRESS_IPV6_SRC_IP_EXT
+3    4      160b   FLP         26624    0       79   INGRESS_IPV6_DST_IP_EXT
+3    5      80b    FLP         28672    0       80   INGRESS_IP_SRC_PORT_EXT
+3    6      80b    FLP         28672    0       81   INGRESS_IPV6_SRC_PORT_EXT
+RP/0/RP0/CPU0:TME-5508-6.2.3#
+
+</code>
+</pre>
+</div>
+
+We have still 461952 routes left in the external TCAM.
+
+In a follow up post, we will detail the mechanisms available to mix base and scale line cards in the same chassis, and how your network needs to be designed for such requirements.
+
+
+