Restrictions for SR-TE
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In the default SDM template, Cisco ASR 900 Router with RSP3 module can push a maximum of 4 MPLS labels in the egress direction. This includes service labels (L3VPN, L2VPN, 6PE/6VPE), RFC 3107 BGP-LU label and SR labels for FRR primary or backup paths. In default template, packet recirculation within forwarding ASIC is not used.
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Effective Cisco IOS XE Gibraltar 16.11.1, Cisco ASR 900 Router with RSP3 module can push a maximum of seven MPLS labels in the egress direction when segment routing traffic engineering is being used. This is supported through the template sr_5_label_push_enable. This template uses packet recirculation within forwarding ASIC. For more information, see Support for Seven SR-TE Lables.
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The routers do not support unequal load balancing when using the load-share option.
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ECMP at single SR-TE tunnel level is not supported.
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SR-TE FRR with PoCH as the primary path is not supported. However, you can provision SR-TE tunnel without FRR over PoCH and backup tunnel over PoCH. Ensure that the min-link value configured is equal to the actual number of member links.
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The SR-TE dynamic tunnels do not support node protection. Therefore, node protection cannot achieve less than 50ms convergence with dynamic SR-TE tunnels.
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Limitations for SR-TE statistic counters in Cisco IOS XE Bengaluru 17.5.1:
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For Cisco ASR 900 Router with RSP3 module, counters on traffic engineering policies or tunnels to the next hops are not supported by default. To enable the counters for single-hop tunnels, you must configure the following CLI command:
platform mpls traffic-engg single-hop-tunnel-statistics-enable
For more information, see Statistics Counters on Cisco RSP3.
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Statistic counters for ECMP to first hop node is not supported.
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Statistic counters for traffic steered over PFP policy is not supported.
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Starting from Cisco IOS XE Release 17.5.1, statistic counters for Labelled Traffic over PDP SR policy is supported. See the Feature History for more information.
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For L2VPN prefixes going over more than one auto-route tunnel, an ECMP LB path is formed with SR-TE. Since this is a preselection, only one path is picked up for L2VPN.
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Per-traffic class aggregate counters per-SR policy are not supported.
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Per-binding SID aggregate counters per SR-policy are not supported.
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Multiple segment list is not supported.
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Multiple segment lists and tunnels pointing to ECMP next-hop are not supported.
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