SR-TE Weighted ECMP for EVPN Layer 2 Services

This chapter provides information about Segment Routing with Traffic Engineering (SR-TE) Weighted Equal Cost Multipath (ECMP) for EVPN Layer 2 services.

Topics in this chapter include:

Applicability

The information and configuration in this chapter are based on SR OS Release 24.7.R2.

SR-TE Weighted ECMP for EVPN Layer 2 services is supported on FP4-based platforms in SR OS Release 22.7.R1 and later.

Overview

Weighted ECMP can be configured for auto-bind tunnels in EVPN Layer 2 services (Epipe and VPLS), with the following parameters:
  • the auto-bind-tunnel ecmp parameter: configure service epipe|vpls <service id> bgp-evpn mpls bgp <bgp instance number> auto-bind-tunnel ecmp <maximum number of auto bind tunnel ECMP routes>
  • the auto-bind-tunnel weighted-ecmp parameter: configure service epipe|vpls <service id> bgp-evpn mpls bgp <bgp instance number> auto-bind-tunnel weighted-ecmp

ECMP then refers to spraying data traffic across multiple named SR-TE tunnels (or RSVP-TE tunnels) within the same ECMP set.

Weighted ECMP is applied only when all tunnels in an ECMP set have the same type (all SR-TE or all RSVP-TE). When ECMP is configured for several tunnel types, only one specific tunnel type is selected, according to partially configurable preference rules. The tunnel type selection for a specific tunnel destination (or endpoint) in the IPv4 or IPv6 tunnel table is based on the following criteria:
  1. tunnel type preference parameter tunnel-table-pref, applied from lowest to highest.
    Note: The tunnel-table-pref default value can be changed for all tunnel types, except for the SR policy tunnel type. Nokia recommends to avoid configuring different tunnel types with the same tunnel-table-pref value, because that can cause preference to be given to a tunnel type that has been introduced first in the history of SR OS: RSVP-TE, LDP, SR-OSPF/SR-OSPF3/SR-ISIS, SR-TE, regardless of the LSP metric and tunnel ID.
    Note: The SR policy tunnel type has a tunnel table preference that cannot be configured, because it always wins over other tunnel types when the service or routing context BGP route has a color attribute.
  2. When multiple tunnels exist for a selected tunnel type, the following applies:
    • RSVP-TE LSP <key={destination address, admin-tags}>: preference for tunnels with the lowest LSP metric, then the lowest tunnel ID.
    • SR-TE LSP <key={destination address, admin-tags}>: preference for tunnels with the lowest LSP metric, then the lowest tunnel ID.
    • LDP or BGP <key={destination address}>: one tunnel always exists (best route).
    • SR-OSPF/SR-OSPF3/SR-ISIS <key={destination address, SR algorithm}> : preference for tunnels with the lowest IGP instance ID.
    • MPLS forwarding policy <key={endpoint, admin-tags}>: one tunnel always exists (the lowest policy preference which is different from the parameter tunnel-table-pref).
    • SR policy <key={endpoint, color}>: one tunnel always exists (the highest policy preference which is different from the parameter tunnel-table-pref).
    Note: The preceding bullet list does not imply an order of tunnel type preference.

When multiple tunnels of the selected tunnel type are operational, data traffic is sprayed across them. The maximum number of tunnels of this type that can be used is configured with the auto-bind-tunnel ecmp parameter. When the number of SR-TE or RSVP-TE tunnels that are operational exceeds this maximum, only tunnels of the selected tunnel type (SR-TE LSP or RSVP-TE LSP) with the same lowest LSP metric can be part of the ECMP set. The LSP metric is configured with the LSP metric parameter: configure router "Base" mpls lsp <LSP name> metric <metric value>. When the number of tunnels in this ECMP set still exceeds the value configured in the auto-bind-tunnel ecmp parameter, the lowest tunnel ID tunnels are selected first.

When weighted-ecmp is configured, the spraying across the tunnels in the retained ECMP set is performed according to the per-LSP weight, as configured in the LSP load balancing weight parameter: configure router "Base" mpls lsp <LSP name> load-balancing-weight <weight value>. For each tunnel in the retained ECMP set, the actually used weight is normalised from the configured weights, as follows:
normalised weight of an LSP =
configured weight of the LSP / (sum of the configured weights of all used LSPs in the retained ECMP set)

When the LSP load balancing weight parameter is not configured for at least one tunnel in the retained ECMP set, regular ECMP spraying across the tunnels in the retained ECMP set is used.

For shortest path tunnels, such as LDP, SR-OSPF, SR-OSPF3, SR-ISIS, and UDP tunnels, the maximum number of tunnels in the ECMP set is configured in the ECMP parameter: configure router "Base" ecmp <maximum number of ECMP routes>.

Configuration

The Example topology shows the topology with four SR OS nodes:
Figure 1. Example topology
The initial configuration includes:
  • cards, MDAs, ports
  • router interfaces
  • BGP for the EVPN address family
  • IS-IS or OSPF or OSPF3, MPLS, RSVP, and LDP on the router interfaces. OSPF and OSPF3 are not used in this chapter.
  • RSVP-TE, SR-TE, LDP, and SR-ISIS tunnels. UDP tunnels are not used in this chapter.
  • an EVPN VPLS service on PE-1 and PE-4 that can make use of these tunnels.

Router configuration

To allow multiple different MPLS paths from PE-1 to PE-4, four router interfaces are configured between PE-1 and PE-2, and between PE-1 and PE-3.

The configuration on PE-1 is as follows:
# on PE-1:
configure router "Base"
        interface "int-PE-1-PE-2-1"
            address 192.168.12.1/30
            port 1/1/c1/1
            no shutdown
        exit
        interface "int-PE-1-PE-2-2"
            address 192.168.12.5/30
            port 1/1/c3/1
            no shutdown
        exit
        interface "int-PE-1-PE-2-3"
            address 192.168.12.9/30
            port 1/1/c5/1
            no shutdown
        exit
        interface "int-PE-1-PE-2-4"
            address 192.168.12.13/30
            port 1/1/c7/1
            no shutdown
        exit
        interface "int-PE-1-PE-3-1"
            address 192.168.13.1/30
            port 1/1/c2/1
            no shutdown
        exit
        interface "int-PE-1-PE-3-2"
            address 192.168.13.5/30
            port 1/1/c4/1
            no shutdown
        exit
        interface "int-PE-1-PE-3-3"
            address 192.168.13.9/30
            port 1/1/c6/1
            no shutdown
        exit
        interface "int-PE-1-PE-3-4"
            address 192.168.13.13/30
            port 1/1/c8/1
            no shutdown
        exit
        interface "system"
            address 192.0.2.1/32
            no shutdown
        exit
        autonomous-system 64500
        bgp
            group "iBGP"
                family evpn
                peer-as 64500
                neighbor 192.0.2.2
                exit
                neighbor 192.0.2.3
                exit
                neighbor 192.0.2.4
                exit
            exit
            no shutdown
        exit
        mpls-labels
            sr-labels start 32000 end 32999
        exit
        isis 0
            area-id 49.0001
            traffic-engineering
            advertise-passive-only
            advertise-router-capability as
            no ipv6-multicast-routing
            segment-routing
                prefix-sid-range global
                no shutdown
            exit
            interface "system"
                ipv4-node-sid label 32001
                passive
                no shutdown
            exit
            interface "int-PE-1-PE-2-1"
                interface-type point-to-point
                no shutdown
            exit
            interface "int-PE-1-PE-2-2"
                interface-type point-to-point
                no shutdown
            exit
            interface "int-PE-1-PE-2-3"
                interface-type point-to-point
                no shutdown
            exit
            interface "int-PE-1-PE-2-4"
                interface-type point-to-point
                no shutdown
            exit
            interface "int-PE-1-PE-3-1"
                interface-type point-to-point
                no shutdown
            exit
            interface "int-PE-1-PE-3-2"
                interface-type point-to-point
                no shutdown
            exit
            interface "int-PE-1-PE-3-3"
                interface-type point-to-point
                no shutdown
            exit
            interface "int-PE-1-PE-3-4"
                interface-type point-to-point
                no shutdown
            exit
            no shutdown
        exit
        mpls
            interface "system"
                no shutdown
            exit
            interface "int-PE-1-PE-2-1"
                no shutdown
            exit
            interface "int-PE-1-PE-2-2"
                no shutdown
            exit
            interface "int-PE-1-PE-2-3"
                no shutdown
            exit
            interface "int-PE-1-PE-2-4"
                no shutdown
            exit
            interface "int-PE-1-PE-3-1"
                no shutdown
            exit
            interface "int-PE-1-PE-3-2"
                no shutdown
            exit
            interface "int-PE-1-PE-3-3"
                no shutdown
            exit
            interface "int-PE-1-PE-3-4"
                no shutdown
            exit
        exit
        rsvp
            interface "system"
                no shutdown
            exit
            interface "int-PE-1-PE-2-1"
                no shutdown
            exit
            interface "int-PE-1-PE-2-2"
                no shutdown
            exit
            interface "int-PE-1-PE-2-3"
                no shutdown
            exit
            interface "int-PE-1-PE-2-4"
                no shutdown
            exit
            interface "int-PE-1-PE-3-1"
                no shutdown
            exit
            interface "int-PE-1-PE-3-2"
                no shutdown
            exit
            interface "int-PE-1-PE-3-3"
                no shutdown
            exit
            interface "int-PE-1-PE-3-4"
                no shutdown
            exit
            no shutdown
        exit
        ldp
            interface-parameters
                interface "int-PE-1-PE-2-1" dual-stack
                    ipv4
                        no shutdown
                    exit
                    no shutdown
                exit
                interface "int-PE-1-PE-2-2" dual-stack
                    ipv4
                        no shutdown
                    exit
                    no shutdown
                exit
                interface "int-PE-1-PE-2-3" dual-stack
                    ipv4
                        no shutdown
                    exit
                    no shutdown
                exit
                interface "int-PE-1-PE-2-4" dual-stack
                    ipv4
                        no shutdown
                    exit
                    no shutdown
                exit
                interface "int-PE-1-PE-3-1" dual-stack
                    ipv4
                        no shutdown
                    exit
                    no shutdown
                exit
                interface "int-PE-1-PE-3-2" dual-stack
                    ipv4
                        no shutdown
                    exit
                    no shutdown
                exit
                interface "int-PE-1-PE-3-3" dual-stack
                    ipv4
                        no shutdown
                    exit
                    no shutdown
                exit
                interface "int-PE-1-PE-3-4" dual-stack
                    ipv4
                        no shutdown
                    exit
                    no shutdown
                exit
            exit
            targeted-session
            exit
            no shutdown
        exit
The configuration of PE-2, PE-3, and PE-4 is similar.
MPLS paths as in Configured MPLS Paths are configured from PE-1 to PE-4, over the interfaces to PE-2 and PE-3 respectively, as follows:
# on PE-1:
configure router "Base" mpls
            path "path-1-PE-1-2-4"
                hop 1 192.168.12.2 strict
                hop 2 192.0.2.4 loose
                no shutdown
            exit
            path "path-2-PE-1-3-4"
                hop 1 192.168.13.2 strict
                hop 2 192.0.2.4 loose
                no shutdown
            exit
            path "path-3-PE-1-2-4"
                hop 1 192.168.12.6 strict
                hop 2 192.0.2.4 loose
                no shutdown
            exit
            path "path-4-PE-1-3-4"
                hop 1 192.168.13.6 strict
                hop 2 192.0.2.4 loose
                no shutdown
            exit
            path "path-5-PE-1-2-4"
                hop 1 192.168.12.10 strict
                hop 2 192.0.2.4 loose
                no shutdown
            exit
            path "path-6-PE-1-3-4"
                hop 1 192.168.13.10 strict
                hop 2 192.0.2.4 loose
                no shutdown
            exit
            path "path-7-PE-1-2-4"
                hop 1 192.168.12.14 strict
                hop 2 192.0.2.4 loose
                no shutdown
            exit
            path "path-8-PE-1-3-4"
                hop 1 192.168.13.14 strict
                hop 2 192.0.2.4 loose
                no shutdown
            exit
Table 1. Configured MPLS Paths
Path Via Interface
"path-1-PE-1-2-4" "int-PE-1-PE-2-1"
"path-2-PE-1-3-4" "int-PE-1-PE-3-1"
"path-3-PE-1-2-4" "int-PE-1-PE-2-2"
"path-4-PE-1-3-4" "int-PE-1-PE-3-2"
"path-5-PE-1-2-4" "int-PE-1-PE-2-3"
"path-6-PE-1-3-4" "int-PE-1-PE-3-3"
"path-7-PE-1-2-4" "int-PE-1-PE-2-4"
"path-8-PE-1-3-4" "int-PE-1-PE-3-4"
While not strictly needed, similar MPLS paths are configured from PE-4 to PE-1, over the interfaces to PE-2 and PE-3 respectively.
MPLS tunnels as in Configured MPLS Tunnels that make use of these paths are configured on PE-1, with LSP type, LSP tunnel ID, LSP metric, and LSP load balancing weight, as follows:
# on PE-1:
configure router "Base" mpls
# SR-TE LSPs
            lsp "lsp-sr-te-1-PE-1-2-4" sr-te
                to 192.0.2.4
                path-computation-method local-cspf
                metric 10
                load-balancing-weight 60
                primary "path-1-PE-1-2-4"
                exit
                no shutdown
            exit
            lsp "lsp-sr-te-2-PE-1-3-4" sr-te
                to 192.0.2.4
                path-computation-method local-cspf
                metric 10
                load-balancing-weight 120
                primary "path-2-PE-1-3-4"
                exit
                no shutdown
            exit
            lsp "lsp-sr-te-3-PE-1-2-4" sr-te
                to 192.0.2.4
                path-computation-method local-cspf
                metric 8
                load-balancing-weight 1
                primary "path-3-PE-1-2-4"
                exit
                no shutdown
            exit
            lsp "lsp-sr-te-4-PE-1-3-4" sr-te
                to 192.0.2.4
                path-computation-method local-cspf
                metric 10
                load-balancing-weight 180
                primary "path-4-PE-1-3-4"
                exit
                no shutdown
            exit
            lsp "lsp-sr-te-5-PE-1-2-4" sr-te
                to 192.0.2.4
                path-computation-method local-cspf
                metric 10
                load-balancing-weight 120
                primary "path-5-PE-1-2-4"
                exit
                no shutdown
            exit
            lsp "lsp-sr-te-6-PE-1-3-4" sr-te
                to 192.0.2.4
                path-computation-method local-cspf
                metric 8
                load-balancing-weight 3
                primary "path-6-PE-1-3-4"
                exit
                no shutdown
            exit
            lsp "lsp-sr-te-7-PE-1-2-4" sr-te
                to 192.0.2.4
                path-computation-method local-cspf
                metric 10
                load-balancing-weight 60
                primary "path-7-PE-1-2-4"
                exit
                no shutdown
            exit
            lsp "lsp-sr-te-8-PE-1-3-4" sr-te
                to 192.0.2.4
                path-computation-method local-cspf
                metric 11
                load-balancing-weight 5
                primary "path-8-PE-1-3-4"
                exit
                no shutdown
            exit
# RSVP-TE LSPs
            lsp "lsp-rsvp-te-1-PE-1-2-4"
                to 192.0.2.4
                path-computation-method local-cspf
                metric 12
                load-balancing-weight 4
                primary "path-1-PE-1-2-4"
                exit
                no shutdown
            exit
            lsp "lsp-rsvp-te-2-PE-1-3-4"
                to 192.0.2.4
                path-computation-method local-cspf
                metric 12
                load-balancing-weight 3
                primary "path-2-PE-1-3-4"
                exit
                no shutdown
            exit
            lsp "lsp-rsvp-te-3-PE-1-2-4"
                to 192.0.2.4
                path-computation-method local-cspf
                metric 14
                load-balancing-weight 2
                primary "path-3-PE-1-2-4"
                exit
                no shutdown
            exit
            lsp "lsp-rsvp-te-4-PE-1-3-4"
                to 192.0.2.4
                path-computation-method local-cspf
                metric 12
                load-balancing-weight 1
                primary "path-4-PE-1-3-4"
                exit
                no shutdown
            exit
The metric and load-balancing-weight options can be configured with the following commands:
# on PE-1:
configure router mpls lsp "lsp-sr-te-1-PE-1-2-4" metric ?
  - metric <metric>
  - no metric

 <metric>             : <0..16777215>
# on PE-1:
configure router mpls lsp "lsp-sr-te-1-PE-1-2-4" load-balancing-weight ?
  - load-balancing-weight <weight>
  - no load-balancing-weight

 <weight>             : [0..4294967295] Default - 0
Table 2. Configured MPLS Tunnels
LSP Name LSP Type LSP Tunnel ID LSP Metric LSP Load Balancing Weight Primary Path
"lsp-sr-te-1-PE-1-2-4" SR-TE 655362 10 60 "path-1-PE-1-2-4-"
"lsp-sr-te-2-PE-1-3-4" SR-TE 655363 10 120 "path-2-PE-1-3-4"
"lsp-sr-te-3-PE-1-2-4" SR-TE 655364 12 1 "path-3-PE-1-2-4"
"lsp-sr-te-4-PE-1-3-4" SR-TE 655365 10 180 "path-4-PE-1-3-4"
"lsp-sr-te-5-PE-1-2-4" SR-TE 655366 10 120 "path-5-PE-1-2-4"
"lsp-sr-te-6-PE-1-3-4" SR-TE 655367 12 3 "path-6-PE-1-3-4"
"lsp-sr-te-7-PE-1-2-4" SR-TE 655368 10 60 "path-7-PE-1-2-4"
"lsp-sr-te-8-PE-1-3-4" SR-TE 655369 11 5 "path-8-PE-1-3-4"
"lsp-rsvp-te-1-PE-1-2-4" RSVP-TE 1 12 4 "path-1-PE-1-2-4"
"lsp-rsvp-te-2-PE-1-3-4" RSVP-TE 2 12 3 "path-2-PE-1-3-4"
"lsp-rsvp-te-3-PE-1-2-4" RSVP-TE 3 14 2 "path-3-PE-1-2-4"
"lsp-rsvp-te-4-PE-1-3-4" RSVP-TE 4 12 1 "path-4-PE-1-3-4"

While not strictly needed, similar MPLS tunnels are configured on PE-4.

The SR OS automatically generates the SR-TE tunnel IDs (and RSVP-TE tunnel IDs) in the order in which the SR-TE tunnels (and RSVP-TE tunnels) are added. The SR OS also automatically generates the tunnel IDs for the other tunnel protocols.

The binding between MPLS paths and MPLS tunnels can be verified with the following show command:
*A:PE-1# show router mpls path lsp-binding 

===============================================================================
MPLS Path:   Bindings 
===============================================================================
Path Name                        Opr  LSP Name                         Binding
-------------------------------------------------------------------------------
path-1-PE-1-2-4                  Up   lsp-rsvp-te-1-PE-1-2-4           Primary
 
                                 Up   lsp-sr-te-1-PE-1-2-4             Primary
 
path-2-PE-1-3-4                  Up   lsp-rsvp-te-2-PE-1-3-4           Primary
 
                                 Up   lsp-sr-te-2-PE-1-3-4             Primary
 
path-3-PE-1-2-4                  Up   lsp-rsvp-te-3-PE-1-2-4           Primary
 
                                 Up   lsp-sr-te-3-PE-1-2-4             Primary
 
path-4-PE-1-3-4                  Up   lsp-rsvp-te-4-PE-1-3-4           Primary
 
                                 Up   lsp-sr-te-4-PE-1-3-4             Primary
 
path-5-PE-1-2-4                  Up   lsp-sr-te-5-PE-1-2-4             Primary
 
path-6-PE-1-3-4                  Up   lsp-sr-te-6-PE-1-3-4             Primary
 
path-7-PE-1-2-4                  Up   lsp-sr-te-7-PE-1-2-4             Primary
 
path-8-PE-1-3-4                  Up   lsp-sr-te-8-PE-1-3-4             Primary
-------------------------------------------------------------------------------
Paths : 8
===============================================================================

Service configuration

EVPN VPLS 14 is configured on PE-1 and PE-4, as follows:
# on PE-1:
configure service vpls 14 name "VPLS 14" customer 1 create
            bgp
            exit
            bgp-evpn
                evi 14
                mpls bgp 1
                    ingress-replication-bum-label
                    auto-bind-tunnel
                        resolution-filter
                            rsvp
                            ldp
                            sr-isis
                            sr-te
                            udp
                        exit
                        resolution filter
                        ecmp 3
                        weighted-ecmp
                    exit
                    no shutdown
                exit
            exit
            sap 1/1/c9/1:100 create
                no shutdown
            exit
            no shutdown
The resolution-filter, ecmp, and weighted-ecmp options can be configured with the following commands:
# on PE-1:
configure service vpls "VPLS 14" bgp-evpn mpls bgp 1 auto-bind-tunnel resolution-filter ?
  - resolution-filter

 [no] bgp             - Enable/disable setting BGP type for auto-bind-tunnel
 [no] ldp             - Enable/disable setting LDP type for auto-bind-tunnel
 [no] mpls-fwd-policy - Enable/disable MPLS Forwarding Policy for auto-bind-tunnel
 [no] rib-api         - Enable/disable setting RIB-API type for auto-bind-tunnel
 [no] rsvp            - Enable/disable setting RSVP-TE type for auto-bind-tunnel
 [no] sr-isis         - Enable/disable setting SR-ISIS type for auto-bind-tunnel
 [no] sr-ospf         - Enable/disable setting SR-OSPF type for auto-bind-tunnel
 [no] sr-ospf3        - Enable/disable setting SR-OSPFv3 type for auto-bind-tunnel
 [no] sr-policy       - Enable/disable setting SR-Policy type for auto-bind-tunnel
 [no] sr-te           - Enable/disable setting SR-TE type for auto-bind-tunnel
 [no] udp             - Enable/disable setting UDP type for auto-bind-tunnel
# on PE-1:
configure service vpls "VPLS 14" bgp-evpn mpls bgp 1 auto-bind-tunnel ecmp ?
  - ecmp <max-ecmp-routes>

 <max-ecmp-routes>    : [1..32]: default 1
# on PE-1:
configure service vpls "VPLS 14" bgp-evpn mpls bgp 1 auto-bind-tunnel weighted-ecmp ?
  - no weighted-ecmp
  - weighted-ecmp
When ecmp 3 is configured, the EVPN VPLS supports the establishment of a maximum of three RSVP-TE, SR-TE, LDP (,or SR-OSPF, or SR-OSPF3), SR-ISIS (, or UDP) tunnels with per-LSP load balancing of the data traffic from PE-1 to PE-4. This can be verified with the following show command:
*A:PE-1# show service id 14 bgp-evpn 

===============================================================================
BGP EVPN
===============================================================================
EVI                : 14                 
Adv L2 Attributes  : Disabled           
Ignore Mtu Mismatch: Disabled           
 
MAC/IP Routes
MAC Advertisement  : Enabled            Unknown MAC Route  : Disabled
---snip---
===============================================================================
BGP EVPN MPLS Information
===============================================================================
Admin Status       : Enabled            Bgp Instance       : 1
Force Vlan Fwding  : Disabled           
Force Qinq Fwding  : none               
Route NextHop Type : system-ipv4        
Control Word       : Disabled           
Max Ecmp Routes    : 1                  
Entropy Label      : Disabled           
Default Route Tag  : none               
Split Horizon Group: (Not Specified)
Ingress Rep BUM Lbl: Enabled            
Ingress Ucast Lbl  : 524273             Ingress Mcast Lbl  : 524272
RestProtSrcMacAct  : none               
Evpn Mpls Encap    : Enabled            Evpn MplsoUdp      : Disabled
Oper Group         : (none)             
MH Mode            : network            
Evi 3-byte Auto-RT : Disabled           
Dyn Egr Lbl Limit  : Disabled           
Hash Label         : Disabled           
Local AC Ingr Lbl  : <not-allocated>

BGP EVPN MPLS Auto Bind Tunnel Information
-------------------------------------------------------------------------------
Allow-Flex-Algo-FB : Disabled           
Resolution         : filter             Strict Tnl Tag     : Disabled
Max Ecmp Routes    : 3                  
Filter Tunnel Types: ldp rsvp sr-isis sr-te udp
Weighted Ecmp      : Enabled            
===============================================================================
On PE-4, configuring the auto-bind-tunnel weighted-ecmp parameter is not strictly needed, and the auto-bind-tunnel weighted-ecmp parameter value may be different.
*A:PE-4# show service id 14 bgp-evpn 

===============================================================================
BGP EVPN
===============================================================================
EVI                : 14                 
Adv L2 Attributes  : Disabled           
Ignore Mtu Mismatch: Disabled           
 
MAC/IP Routes
MAC Advertisement  : Enabled            Unknown MAC Route  : Disabled
---snip---
===============================================================================
BGP EVPN MPLS Information
===============================================================================
Admin Status       : Enabled            Bgp Instance       : 1
Force Vlan Fwding  : Disabled           
Force Qinq Fwding  : none               
Route NextHop Type : system-ipv4        
Control Word       : Disabled           
Max Ecmp Routes    : 1                  
Entropy Label      : Disabled           
Default Route Tag  : none               
Split Horizon Group: (Not Specified)
Ingress Rep BUM Lbl: Enabled            
Ingress Ucast Lbl  : 524277             Ingress Mcast Lbl  : 524276
RestProtSrcMacAct  : none               
Evpn Mpls Encap    : Enabled            Evpn MplsoUdp      : Disabled
Oper Group         : (none)             
MH Mode            : network            
Evi 3-byte Auto-RT : Disabled           
Dyn Egr Lbl Limit  : Disabled           
Hash Label         : Disabled           
Local AC Ingr Lbl  : <not-allocated>

BGP EVPN MPLS Auto Bind Tunnel Information
-------------------------------------------------------------------------------
Allow-Flex-Algo-FB : Disabled           
Resolution         : filter             Strict Tnl Tag     : Disabled
Max Ecmp Routes    : 2                  
Filter Tunnel Types: ldp rsvp sr-isis sr-te udp
Weighted Ecmp      : Disabled           
===============================================================================

Use cases

Tunnel selection with preference for SR-TE

The Default tunnel table preferences table shows the default tunnel table preference value for different tunnel protocols. SR OS prefers a lower preference value over a higher one. By default, operational RSVP-TE tunnels are preferred. SR-OSPF and SR-OSPF3 are not used in this chapter.
Table 3. Default tunnel table preferences
Tunnel Protocol Preference
RSVP-TE 7
SR-TE 8
LDP 9
SR-OSPF/SR-OSPF3 10
SR-ISIS 11

The tunnel-table-preference for different tunnel protocols can be configured with the following commands:

# on PE-1:
configure router mpls tunnel-table-pref ?
  - tunnel-table-pref

 [no] rsvp-te         - Configure Tunnel Table Preference for RSVP-TE type LSPs
 [no] sr-te           - Configure Tunnel Table Preference for SR-TE type LSPs

configure router mpls tunnel-table-pref rsvp-te ?
  - rsvp-te <[1..255]>
  - no rsvp-te

configure router mpls tunnel-table-pref sr-te ?
  - sr-te <[1..255]>
  - no sr-te
# on PE-1:
configure router ldp tunnel-table-pref ?
  - no tunnel-table-pref
  - tunnel-table-pref <preference>

 <preference>         : [1..255]
# on PE-1:
configure router ospf segment-routing tunnel-table-pref ?
  - no tunnel-table-pref
  - tunnel-table-pref <[1..255]>
# on PE-1:
configure router ospf3 segment-routing tunnel-table-pref ?
  - no tunnel-table-pref
  - tunnel-table-pref <[1..255]>
# on PE-1:
configure router isis segment-routing tunnel-table-pref ?
  - no tunnel-table-pref
  - tunnel-table-pref <[1..255]>

The Tunnel table preferences to prefer SR-TE table shows the modified tunnel preference table with SR-TE as the preferred tunnel type.

# on PE-1:
configure router "Base" mpls tunnel-table-pref
                sr-te 1
Table 4. Tunnel table preferences to prefer SR-TE
Tunnel Protocol Preference
SR-TE 8 → 1
RSVP-TE 7
LDP 9
SR-OSPF/SR-OSPF3 10
SR-ISIS 11
LSP load balancing weights configured on all selected SR-TE tunnels

As can be derived from the Configured MPLS Tunnels table, there are eight possible SR-TE tunnels, of which only five have the lowest LSP metric value of 10, leading to Configured SR-TE Tunnels. This can be verified with the output of the following show command, that also contains the configured RSVP-TE tunnels, and the automatically generated LDP and SR-ISIS tunnels:

*A:PE-1# show router tunnel-table 192.0.2.4/32

===============================================================================
IPv4 Tunnel Table (Router: Base)
===============================================================================
Destination           Owner     Encap TunnelId  Pref   Nexthop        Metric
   Color                                                              
-------------------------------------------------------------------------------
192.0.2.4/32          sr-te     MPLS  655362    1      192.168.12.2   10
192.0.2.4/32          sr-te     MPLS  655363    1      192.168.13.2   10
192.0.2.4/32          sr-te     MPLS  655365    1      192.168.13.6   10
192.0.2.4/32          sr-te     MPLS  655366    1      192.168.12.10  10
192.0.2.4/32          sr-te     MPLS  655368    1      192.168.12.14  10
192.0.2.4/32          sr-te     MPLS  655369    1      192.168.13.14  11
192.0.2.4/32          sr-te     MPLS  655364    1      192.168.12.6   12
192.0.2.4/32          sr-te     MPLS  655367    1      192.168.13.10  12
192.0.2.4/32          rsvp      MPLS  1         7      192.168.12.2   12
192.0.2.4/32          rsvp      MPLS  2         7      192.168.13.2   12
192.0.2.4/32          rsvp      MPLS  4         7      192.168.13.6   12
192.0.2.4/32          rsvp      MPLS  3         7      192.168.12.6   14
192.0.2.4/32          ldp       MPLS  65539     9      192.168.12.2   20
192.0.2.4/32          isis (0)  MPLS  524299    11     192.168.12.2   20
-------------------------------------------------------------------------------
---snip---
===============================================================================
Table 5. Configured SR-TE Tunnels
LSP Name LSP Type LSP Tunnel ID LSP Metric LSP Load Balancing Weight Primary Path
"lsp-sr-te-1-PE-1-2-4" SR-TE 655362 10 60 "path-1-PE-1-2-4"
"lsp-sr-te-2-PE-1-3-4" SR-TE 655363 10 120 "path-2-PE-1-3-4"
"lsp-sr-te-4-PE-1-3-4" SR-TE 655365 10 180 "path-4-PE-1-3-4"
"lsp-sr-te-5-PE-1-2-4" SR-TE 655366 10 120 "path-5-PE-1-2-4"
"lsp-sr-te-7-PE-1-2-4" SR-TE 655368 10 60 "path-7-PE-1-2-4"
Only the first three SR-TE tunnels with the lowest metric (10) and the lowest tunnel IDs (655362, 655363, and 655365) are selected. With the LSP load balancing weight for each LSP configured as in Configured SR-TE Tunnels, the following applies:
  • "lsp-sr-te-1-PE-1-2-4" carries 60/(60+120+180)=60/360=16.67% of the data traffic via "path-1-PE-1-2-4"
  • "lsp-sr-te-2-PE-1-3-4" carries 120/360=33.33% of the data traffic via "path-2-PE-1-3-4"
  • "lsp-sr-te-4-PE-1-3-4" carries 180/360=50% of the data traffic via "path-4-PE-1-3-4"
PE-1 receives 2000 packets per second on port 1/1/c9/1 and sends out 336 packets per second on 1/1/c1/1 (~16.67%; "lsp-sr-te-1-PE-1-2-4"), 670 packets per second on 1/1/c2/1 (~33.33%; "lsp-sr-te-2-PE-1-3-4"), and 997 packets per second on 1/1/c4/1 (~50%; "lsp-sr-te-4-PE-1-3-4"). This can be verified with the output of the following monitor command. The same monitor command can be used on PE-2, PE-3, and PE-4 to verify how the data traffic is further transported, as follows:
*A:PE-1# monitor port all-ethernet-rates interval 3 repeat 5 

=====================================================================
Monitor statistics for all Ethernet Port Rates
=====================================================================
Port-Id          D                 Bits   Packets     Errors    Util
---------------------------------------------------------------------
---snip---
-------------------------------------------------------------------------------
At time t = 15 sec (Mode: Rate)
-------------------------------------------------------------------------------
1/1/c1/1         I                 1176         1          0    0.00
                 O               391176       336          0    0.00

1/1/c2/1         I                  824         1          0    0.00
                 O               783064       670          0    0.00

1/1/c3/1         I                  488         0          0    0.00
                 O                  504         0          0    0.00

1/1/c4/1         I                  168         0          0    0.00
                 O              1164136       997          0    0.00

---snip---

1/1/c9/1         I              2048000      2000          0    0.00
                 O                    0         0          0    0.00

=====================================================================
Note: The measured values may not exactly correspond with the theoretically expected values, because of signaling overhead, the burstiness of the source traffic within the monitoring interval, or the lack of sufficiently high entropy in the source traffic to guarantee an even traffic load balance.
The following show command confirms that the selected tunnel type is indeed SR-TE, with (first) the lowest LSP metric (as from Configured MPLS Tunnels) and (second) the lowest tunnel ID.
*A:PE-1# show service id 14 evpn-mpls 

===============================================================================
BGP EVPN-MPLS Dest (Instance 1)
===============================================================================
TEP Address                     Transport:Tnl     Egr Label  Oper  Mcast  Num
                                                             State        MACs
-------------------------------------------------------------------------------
192.0.2.4                       sr-te:655362      524276     Up    bum    0
---snip---
Note: This command shows only the first tunnel in the ECMP set.
LSP load balancing weight not configured on at least one selected SR-TE tunnel
When the LSP load balancing weight value is removed from "lsp-sr-te-4-PE-1-3-4", the same three SR-TE tunnels are still selected, but each SR-TE tunnel carries 1/3=33.33% of the data traffic.
# on PE-1:
configure router "Base" mpls lsp "lsp-sr-te-4-PE-1-3-4"
                no load-balancing-weight
With the LSP load balancing weight not configured on "lsp-sr-te-4-PE-1-3-4", the following applies:
  • "lsp-sr-te-1-PE-1-2-4" carries 33.33% of the data traffic via "path-1-PE-1-2-4"
  • "lsp-sr-te-2-PE-1-3-4" carries 33.33% of the data traffic via "path-2-PE-1-3-4"
  • "lsp-sr-te-4-PE-1-3-4" carries 33.33% of the data traffic via "path-4-PE-1-3-4"
PE-1 receives 2000 packets per second on port 1/1/c9/1 and sends out 678 packets per second on 1/1/c1/1 (~33.33%; "lsp-sr-te-1-PE-1-2-4"), 657 packets per second on 1/1/c2/1 (~33.33%; "lsp-sr-te-2-PE-1-3-4"), and 668 packets per second on 1/1/c4/1 (~33.33%; "lsp-sr-te-4-PE-1-3-4").
*A:PE-1# monitor port all-ethernet-rates interval 3 repeat 5 

=====================================================================
Monitor statistics for all Ethernet Port Rates
=====================================================================
Port-Id          D                 Bits   Packets     Errors    Util
---------------------------------------------------------------------
---snip---
-------------------------------------------------------------------------------
At time t = 15 sec (Mode: Rate)
-------------------------------------------------------------------------------
1/1/c1/1         I                 1120         2          0    0.00
                 O               791328       678          0    0.00

1/1/c2/1         I                  888         2          0    0.00
                 O               766808       657          0    0.00

1/1/c3/1         I                 1016         1          0    0.00
                 O                 1016         1          0    0.00

1/1/c4/1         I                 1016         1          0    0.00
                 O               780592       668          0    0.00

---snip---

1/1/c9/1         I              2048000      2000          0    0.00
                 O                    0         0          0    0.00

=====================================================================
The following show command confirms that the selected tunnel type is indeed SR-TE, with (first) the lowest LSP metric (as from Configured MPLS Tunnels) and (second) the lowest tunnel ID.
*A:PE-1# show service id 14 evpn-mpls 

===============================================================================
BGP EVPN-MPLS Dest (Instance 1)
===============================================================================
TEP Address                     Transport:Tnl     Egr Label  Oper  Mcast  Num
                                                             State        MACs
-------------------------------------------------------------------------------
192.0.2.4                       sr-te:655362      524276     Up    bum    0
---snip---
Maximum number of tunnels increased but below the possible number of tunnels
When the LSP load balancing weights are configured on all selected SR-TE tunnels, the LSP load balancing weight value of 180 is configured again on "lsp-sr-te-4-PE-1-3-4", and the maximum number of tunnels is increased to 4 (<5), the first four SR-TE tunnels with the lowest metric (10) and the lowest tunnel IDs (655362, 655363, 655365, and 655366) are selected.
# on PE-1:
configure router "Base" mpls lsp "lsp-sr-te-4-PE-1-3-4"
                load-balancing-weight 180
# on PE-1:
configure service vpls 14 bgp-evpn mpls bgp 1 auto-bind-tunnel
                        ecmp 4
With the LSP load balancing weight for each LSP configured as in Configured SR-TE Tunnels, the following applies:
  • "lsp-sr-te-1-PE-1-2-4" carries 60/(60+120+180+120)=60/480=12.5% of the data traffic via "path-1-PE-1-2-4"
  • "lsp-sr-te-2-PE-1-3-4" carries 120/480=25% of the data traffic via "path-2-PE-1-3-4"
  • "lsp-sr-te-4-PE-1-3-4" carries 180/480=37.5% of the data traffic via "path-4-PE-1-3-4"
  • "lsp-sr-te-5-PE-1-2-4" carries 120/480=25% of the data traffic via "path-5-PE-1-2-4"
PE-1 receives 2000 packets per second on port 1/1/c9/1 and sends out 251 packets per second on 1/1/c1/1 (~12.5%; "lsp-sr-te-1-PE-1-2-4"), 502 packets per second on 1/1/c2/1 (~25%; "lsp-sr-te-2-PE-1-3-4"), 752 packets per second on 1/1/c4/1 (~37.5%; "lsp-sr-te-4-PE-1-3-4"), and 504 packets per second on 1/1/c5/1 (~25%; "lsp-sr-te-5-PE-1-2-4").
*A:PE-1# monitor port all-ethernet-rates interval 3 repeat 5 

=====================================================================
Monitor statistics for all Ethernet Port Rates
=====================================================================
Port-Id          D                 Bits   Packets     Errors    Util
---------------------------------------------------------------------
---snip---
-------------------------------------------------------------------------------
At time t = 15 sec (Mode: Rate)
-------------------------------------------------------------------------------
1/1/c1/1         I                 1544         3          0    0.00
                 O               291208       251          0    0.00

1/1/c2/1         I                 1904         3          0    0.00
                 O               586000       502          0    0.00

1/1/c3/1         I                  688         1          0    0.00
                 O                 1016         1          0    0.00

1/1/c4/1         I                 1336         1          0    0.00
                 O               877608       752          0    0.00

1/1/c5/1         I                  368         0          0    0.00
                 O               587480       504          0    0.00

---snip---

1/1/c9/1         I              2048000      2000          0    0.00
                 O                    0         0          0    0.00

=====================================================================

The following show command confirms that the selected tunnel type is indeed SR-TE, with (first) the lowest LSP metric (as from Configured MPLS Tunnels) and (second) the lowest tunnel ID.

*A:PE-1# show service id 14 evpn-mpls 

===============================================================================
BGP EVPN-MPLS Dest (Instance 1)
===============================================================================
TEP Address                     Transport:Tnl     Egr Label  Oper  Mcast  Num
                                                             State        MACs
-------------------------------------------------------------------------------
192.0.2.4                       sr-te:655362      524276     Up    bum    0
---snip---
Maximum number of tunnels exceeding the possible number of tunnels
When the LSP load balancing weights are configured on all selected SR-TE tunnels and the maximum number of tunnels is increased to 20 (>5), all five SR-TE tunnels with the lowest metric (10) and the lowest tunnel IDs (655362, 655363, 655365, 655366, and 655368) are selected.
# on PE-1:
configure service vpls 14 bgp-evpn mpls bgp 1 auto-bind-tunnel
                        ecmp 20
With the LSP load balancing weight for each LSP configured as in Configured SR-TE Tunnels, the following applies:
  • "lsp-sr-te-1-PE-1-2-4" carries 60/(60+120+180+120+60)=60/540=11.11% of the data traffic via "path-1-PE-1-2-4"
  • "lsp-sr-te-2-PE-1-3-4" carries 120/540=22.22% of the data traffic via "path-2-PE-1-3-4"
  • "lsp-sr-te-4-PE-1-3-4" carries 180/540=33.33% of the data traffic via "path-4-PE-1-3-4"
  • "lsp-sr-te-5-PE-1-2-4" carries 120/540=22.22% of the data traffic via "path-5-PE-1-2-4"
  • "lsp-sr-te-7-PE-1-2-4" carries 60/540=11.11% of the data traffic via "path-7-PE-1-2-4"
Even though there are five more SR-TE tunnels, those are not selected because they do not have the lowest LSP metric value of 10.

PE-1 receives 2000 packets per second on port 1/1/c9/1 and sends out 221 packets per second on 1/1/c1/1 (~11.11%; "lsp-sr-te-1-PE-1-2-4"), 438 packets per second on 1/1/c2/1 (~22.22%; "lsp-sr-te-2-PE-1-3-4"), 663 packets per second on 1/1/c4/1 (~33.33%; "lsp-sr-te-4-PE-1-3-4"), 455 packets per second on 1/1/c5/1 (~22.22%; "lsp-sr-te-5-PE-1-2-4"), and 231 packets per second on 1/1/c7/1 (~11.11%; "lsp-sr-te-7-PE-1-2-4").

*A:PE-1# monitor port all-ethernet-rates interval 3 repeat 5 

=====================================================================
Monitor statistics for all Ethernet Port Rates
=====================================================================
Port-Id          D                 Bits   Packets     Errors    Util
---------------------------------------------------------------------
---snip---
-------------------------------------------------------------------------------
At time t = 15 sec (Mode: Rate)
-------------------------------------------------------------------------------
1/1/c1/1         I                 1208         2          0    0.00
                 O               256488       221          0    0.00

1/1/c2/1         I                 1632         2          0    0.00
                 O               510928       438          0    0.00

1/1/c3/1         I                 1016         1          0    0.00
                 O                  368         0          0    0.00

1/1/c4/1         I                 1016         1          0    0.00
                 O               773912       663          0    0.00

1/1/c5/1         I                 1016         1          0    0.00
                 O               531608       455          0    0.00

1/1/c6/1         I                 1168         1          0    0.00
                 O                  528         1          0    0.00

1/1/c7/1         I                  528         1          0    0.00
                 O               269808       231          0    0.00

---snip---

1/1/c9/1         I              2048344      2000          0    0.00
                 O                    0         0          0    0.00

=====================================================================
The following show command confirms that the selected tunnel type is indeed SR-TE, with (first) the lowest LSP metric (as from Configured MPLS Tunnels) and (second) the lowest tunnel ID.
*A:PE-1# show service id 14 evpn-mpls 

===============================================================================
BGP EVPN-MPLS Dest (Instance 1)
===============================================================================
TEP Address                     Transport:Tnl     Egr Label  Oper  Mcast  Num
                                                             State        MACs
-------------------------------------------------------------------------------
192.0.2.4                       sr-te:655362      524276     Up    bum    0
---snip---
Minimum LSP metric values configured on SR-TE tunnels with a higher tunnel ID
Reducing the LSP metric value of "lsp-sr-te-3-PE-1-2-4" and "lsp-sr-te-6-PE-1-3-4" to 8 (new lowest value), leads to Configured SR-TE Tunnels.
# on PE-1:
configure router "Base" mpls
            lsp "lsp-sr-te-3-PE-1-2-4"
                metric 8
            exit
            lsp "lsp-sr-te-6-PE-1-3-4"
                metric 8
            exit
This can be verified with the output of the following show command:
*A:PE-1# show router tunnel-table 192.0.2.4/32
===============================================================================
IPv4 Tunnel Table (Router: Base)
===============================================================================
Destination           Owner     Encap TunnelId  Pref   Nexthop        Metric
   Color                                                              
-------------------------------------------------------------------------------
192.0.2.4/32          sr-te     MPLS  655364    1      192.168.12.6   8
192.0.2.4/32          sr-te     MPLS  655367    1      192.168.13.10  8
192.0.2.4/32          sr-te     MPLS  655362    1      192.168.12.2   10
192.0.2.4/32          sr-te     MPLS  655363    1      192.168.13.2   10
192.0.2.4/32          sr-te     MPLS  655365    1      192.168.13.6   10
192.0.2.4/32          sr-te     MPLS  655366    1      192.168.12.10  10
192.0.2.4/32          sr-te     MPLS  655368    1      192.168.12.14  10
192.0.2.4/32          sr-te     MPLS  655369    1      192.168.13.14  11
192.0.2.4/32          rsvp      MPLS  1         7      192.168.12.2   12
192.0.2.4/32          rsvp      MPLS  2         7      192.168.13.2   12
192.0.2.4/32          rsvp      MPLS  4         7      192.168.13.6   12
192.0.2.4/32          rsvp      MPLS  3         7      192.168.12.6   14
192.0.2.4/32          ldp       MPLS  65539     9      192.168.12.2   20
192.0.2.4/32          isis (0)  MPLS  524299    11     192.168.12.2   20
-------------------------------------------------------------------------------
---snip---
===============================================================================
Table 6. Configured SR-TE Tunnels
LSP Name LSP Type LSP Tunnel ID LSP Metric LSP Load Balancing Weight Primary Path
"lsp-sr-te-3-PE-1-2-4" SR-TE 655364 12 → 8 1 "path-3-PE-1-2-4"
"lsp-sr-te-6-PE-1-3-4" SR-TE 655367 12 → 8 3 "path-6-PE-1-3-4"
Only the two SR-TE tunnels with the lowest metric (8) and the lowest tunnel IDs (655364 and 655367) are selected. With the LSP load balancing weight for each LSP configured as in Configured SR-TE Tunnels, the following applies:
  • "lsp-sr-te-3-PE-1-2-4" carries 1/(1+3)=1/4=25% of the data traffic via "path-3-PE-1-2-4"
  • "lsp-sr-te-6-PE-1-3-4" carries 3/4=75% of the data traffic via "path-6-PE-1-3-4"
PE-1 receives 2000 packets per second on port 1/1/c9/1 and sends out 497 packets per second on 1/1/c3/1 (~25%; "lsp-sr-te-3-PE-1-2-4") and 1504 packets per second on 1/1/c6/1 (~75%; "lsp-sr-te-6-PE-1-3-4").
*A:PE-1# monitor port all-ethernet-rates interval 3 repeat 5 

=====================================================================
Monitor statistics for all Ethernet Port Rates
=====================================================================
Port-Id          D                 Bits   Packets     Errors    Util
---------------------------------------------------------------------
---snip---
-------------------------------------------------------------------------------
At time t = 15 sec (Mode: Rate)
-------------------------------------------------------------------------------
1/1/c1/1         I                  824         1          0    0.00
                 O                  488         0          0    0.00

1/1/c2/1         I                  824         1          0    0.00
                 O                 1144         1          0    0.00

1/1/c3/1         I                  488         0          0    0.00
                 O               580472       497          0    0.00

1/1/c4/1         I                  504         0          0    0.00
                 O                  824         1          0    0.00

1/1/c5/1         I                  824         1          0    0.00
                 O                  944         1          0    0.00

1/1/c6/1         I                  656         1          0    0.00
                 O              1757008      1504          0    0.00

---snip---

1/1/c9/1         I              2048000      2000          0    0.00
                 O                    0         0          0    0.00

=====================================================================
The following show command confirms that the selected tunnel type is indeed SR-TE, with (first) the lowest LSP metric (as from Configured MPLS Tunnels) and (second) the lowest tunnel ID.
*A:PE-1# show service id 14 evpn-mpls 

===============================================================================
BGP EVPN-MPLS Dest (Instance 1)
===============================================================================
TEP Address                     Transport:Tnl     Egr Label  Oper  Mcast  Num
                                                             State        MACs
-------------------------------------------------------------------------------
192.0.2.4                       sr-te:655364      524276     Up    bum    0
---snip---

SR-TE tunnel type no longer supported

When the sr-te option is removed from the auto-bind-tunnel resolution-filter, RSVP-TE tunnels are preferred, in accordance with Tunnel table preferences to prefer SR-TE.

# on PE-1:
configure service vpls 14 bgp-evpn mpls bgp 1 auto-bind-tunnel resolution-filter
                            no sr-te
As can be derived from the Configured MPLS Tunnels table, there are four possible SR-TE tunnels, of which only three have the lowest LSP metric value of 12, leading to Configured RSVP-TE Tunnels. This can be verified with the output of the following show command, that also contains the configured SR-TE tunnels, and the automatically generated LDP and SR-ISIS tunnels:
*A:PE-1# show router tunnel-table 192.0.2.4/32

===============================================================================
IPv4 Tunnel Table (Router: Base)
===============================================================================
Destination           Owner     Encap TunnelId  Pref   Nexthop        Metric
   Color                                                              
-------------------------------------------------------------------------------
192.0.2.4/32          sr-te     MPLS  655364    1      192.168.12.6   8
192.0.2.4/32          sr-te     MPLS  655367    1      192.168.13.10  8
192.0.2.4/32          sr-te     MPLS  655362    1      192.168.12.2   10
192.0.2.4/32          sr-te     MPLS  655363    1      192.168.13.2   10
192.0.2.4/32          sr-te     MPLS  655365    1      192.168.13.6   10
192.0.2.4/32          sr-te     MPLS  655366    1      192.168.12.10  10
192.0.2.4/32          sr-te     MPLS  655368    1      192.168.12.14  10
192.0.2.4/32          sr-te     MPLS  655369    1      192.168.13.14  11
192.0.2.4/32          rsvp      MPLS  1         7      192.168.12.2   12
192.0.2.4/32          rsvp      MPLS  2         7      192.168.13.2   12
192.0.2.4/32          rsvp      MPLS  4         7      192.168.13.6   12
192.0.2.4/32          rsvp      MPLS  3         7      192.168.12.6   14
192.0.2.4/32          ldp       MPLS  65539     9      192.168.12.2   20
192.0.2.4/32          isis (0)  MPLS  524299    11     192.168.12.2   20
-------------------------------------------------------------------------------
---snip---
===============================================================================
Table 7. Configured RSVP-TE Tunnels
LSP Name LSP Type LSP Tunnel ID LSP Metric LSP Load Balancing Weight Primary Path
"lsp-rsvp-te-1-PE-1-2-4" RSVP-TE 1 12 4 "path-1-PE-1-2-4"
"lsp-rsvp-te-2-PE-1-3-4" RSVP-TE 2 12 3 "path-2-PE-1-3-4"
"lsp-rsvp-te-3-PE-1-2-4" RSVP-TE 3 14 2 "path-3-PE-1-2-4"
"lsp-rsvp-te-4-PE-1-3-4" RSVP-TE 4 12 1 "path-4-PE-1-3-4"
Only the three RSVP-TE tunnels with the lowest metric (12) and the lowest tunnel IDs (1, 2, and 4) are selected. With the LSP load balancing weight for each LSP configured as in Configured RSVP-TE Tunnels, the following applies:
  • "lsp-rsvp-te-1-PE-1-2-4" carries 4/(4+3+1)=4/8=50% of the data traffic via "path-1-PE-1-2-4"
  • "lsp-rsvp-te-2-PE-1-3-4" carries 3/8=37.5% of the data traffic via "path-2-PE-1-3-4"
  • "lsp-rsvp-te-4-PE-1-3-4" carries 1/8=12.5% of the data traffic via "path-4-PE-1-3-4"
PE-1 receives 2000 packets per second on port 1/1/c9/1 and sends out 1002 packets per second on 1/1/c1/1 (~50%; "lsp-rsvp-te-1-PE-1-2-4"), 748 packets per second on 1/1/c2/1 (~37.5%; "lsp-rsvp-te-2-PE-1-3-4"), and 252 packets per second on 1/1/c4/1 (~12.5%; "lsp-rsvp-te-4-PE-1-3-4").
*A:PE-1# monitor port all-ethernet-rates interval 3 repeat 5 

=====================================================================
Monitor statistics for all Ethernet Port Rates
=====================================================================
Port-Id          D                 Bits   Packets     Errors    Util
---------------------------------------------------------------------
---snip---
-------------------------------------------------------------------------------
At time t = 15 sec (Mode: Rate)
-------------------------------------------------------------------------------
1/1/c1/1         I                  824         1          0    0.00
                 O              1169416      1002          0    0.00

1/1/c2/1         I                  992         1          0    0.00
                 O               874168       748          0    0.00

1/1/c3/1         I                  504         0          0    0.00
                 O                  504         0          0    0.00

1/1/c4/1         I                  504         0          0    0.00
                 O               294840       252          0    0.00

---snip---

1/1/c9/1         I              2048000      2000          0    0.00
                 O                    0         0          0    0.00

=====================================================================
The following show command confirms that the selected tunnel type is indeed RSVP-TE, with (first) the lowest LSP metric (as from Configured MPLS Tunnels) and (second) the lowest tunnel ID.
*A:PE-1# show service id 14 evpn-mpls 

===============================================================================
BGP EVPN-MPLS Dest (Instance 1)
===============================================================================
TEP Address                     Transport:Tnl     Egr Label  Oper  Mcast  Num
                                                             State        MACs
-------------------------------------------------------------------------------
192.0.2.4                       rsvp:1            524276     Up    bum    0
---snip---

Also RSVP-TE tunnel type no longer supported

When also the rsvp-te option is removed from the auto-bind-tunnel resolution-filter, LDP tunnels are preferred, in accordance with Tunnel table preferences to prefer SR-TE.
# on PE-1:
configure service vpls 14 bgp-evpn mpls bgp 1 auto-bind-tunnel resolution-filter
                            no sr-te
                            no rsvp-te
There is only one possible LDP tunnel with a metric value of 20. Only that LDP tunnel is selected:
  • ldp:65539 carries all data traffic via port 1/1/c1/1

PE-1 receives 2000 packets per second on port 1/1/c9/1 and sends out 2001 packets per second on 1/1/c1/1 (~100%; ldp:65539).

*A:PE-1# monitor port all-ethernet-rates interval 3 repeat 5 

=====================================================================
Monitor statistics for all Ethernet Port Rates
=====================================================================
Port-Id          D                 Bits   Packets     Errors    Util
---------------------------------------------------------------------
---snip---
-------------------------------------------------------------------------------
At time t = 15 sec (Mode: Rate)
-------------------------------------------------------------------------------
1/1/c1/1         I                  504         0          0    0.00
                 O              2336824      2001          0    0.00

---snip---

1/1/c9/1         I              2048000      2000          0    0.00
                 O                    0         0          0    0.00

=====================================================================
The following show command confirms that the selected tunnel is indeed the LDP tunnel.
*A:PE-1# show service id 14 evpn-mpls 

===============================================================================
BGP EVPN-MPLS Dest (Instance 1)
===============================================================================
TEP Address                     Transport:Tnl     Egr Label  Oper  Mcast  Num
                                                             State        MACs
-------------------------------------------------------------------------------
192.0.2.4                       ldp:65539         524276     Up    bum    0
---snip---

Also LDP tunnel type no longer supported

When also the ldp option is removed from the auto-bind-tunnel resolution-filter, SR-OSPF/SR-OSPF3 tunnels are preferred, in accordance with Tunnel table preferences to prefer SR-TE. Because OSPF and OSPF3 are not configured, SR-ISIS tunnels are preferred, in accordance with Tunnel table preferences to prefer SR-TE.
# on PE-1:
configure service vpls 14 bgp-evpn mpls bgp 1 auto-bind-tunnel resolution-filter
                            no sr-te
                            no rsvp-te
                            no ldp
There is only one possible SR-ISIS tunnel with a metric value of 20. Only that SR-ISIS tunnel is selected:
  • isis:524299 carries all data traffic via port 1/1/c1/1

PE-1 receives 2000 packets per second on port 1/1/c9/1 and sends out 2002 packets per second on 1/1/c1/1 (~100%; isis:524299).

*A:PE-1# monitor port all-ethernet-rates interval 3 repeat 5 

=====================================================================
Monitor statistics for all Ethernet Port Rates
=====================================================================
Port-Id          D                 Bits   Packets     Errors    Util
---------------------------------------------------------------------
---snip---
-------------------------------------------------------------------------------
At time t = 15 sec (Mode: Rate)
-------------------------------------------------------------------------------
1/1/c1/1         I                 1120         2          0    0.00
                 O              2337632      2002          0    0.00

---snip---

1/1/c9/1         I              2048000      2000          0    0.00
                 O                    0         0          0    0.00

=====================================================================
The following show command confirms that the selected tunnel is indeed the SR-ISIS tunnel.
*A:PE-1# show service id 14 evpn-mpls 

===============================================================================
BGP EVPN-MPLS Dest (Instance 1)
===============================================================================
TEP Address                     Transport:Tnl     Egr Label  Oper  Mcast  Num
                                                             State        MACs
-------------------------------------------------------------------------------
192.0.2.4                       isis:524299       524276     Up    bum    0
---snip---

Conclusion

SR OS supports weighted ECMP with per-LSP load balancing across multiple auto-bind SR-TE tunnels in EVPN Layer 2 services. The selection of a single tunnel type and the load balancing are configurable.