Overview
This simulation experiment demonstrates the configuration and behavior of SRv6 Traffic Engineering (TE) policies using H3C Cloud Lab. The goal is to understand how SRv6 Policy can be used to influence traffic paths via color-based steering, even though some connectivity issues may arise due to simulator limitations.
Topology and IP Configuration
The network consists of five routers (VSR-88_1 through VSR-88_5), each with loopback and physical interfaces configured with IPv6 addresses. OSPFv3 is used as the IGP to establish internal connectivity across the network.
Example OSPFv3 Configuration on VSR-88_1
[VSR-88_1]ospfv3 1
[VSR-88_1-ospfv3-1] router-id 1.1.1.1
[VSR-88_1-ospfv3-1] area 0.0.0.0
[VSR-88_1-ospfv3-1] quit
[VSR-88_1]interface LoopBack0
[VSR-88_1-LoopBack0] ospfv3 1 area 0.0.0.0
[VSR-88_1-LoopBack0] ipv6 address 2001::1/128
[VSR-88_1-LoopBack0] quit
[VSR-88_1]interface GigabitEthernet0/0/0
[VSR-88_1-GigabitEthernet0/0/0] ospfv3 1 area 0.0.0.0
[VSR-88_1-GigabitEthernet0/0/0] ipv6 address 2013::1/124
SRv6 Configuration
Segment Routing over IPv6 (SRv6) is configured using manually defined Locators and Function SIDs. Each node is assigned a unique Locator prefix and several Function SIDs for both node and adjacency segments.
Locator and SID Configuration on VSR-88_1
[VSR-88_1]segment-routing ipv6
[VSR-88_1-segment-routing-ipv6] encapsulation source-address 2001::1
[VSR-88_1-segment-routing-ipv6] locator h3c ipv6-prefix A100:: 96 static 16
[VSR-88_1-segment-routing-ipv6-locator-h3c] opcode 1 end
[VSR-88_1-segment-routing-ipv6-locator-h3c] opcode 12 end-x interface GigabitEthernet0/0/0 nexthop 2013::3
SRv6 TE Policy Configuration
On VSR-88_1, a TE policy is created to steer traffic towards VSR-88_5 using a predefined segment list. The policy is associated with a color value to enable traffic steering.
TE Policy Configuration on VSR-88_1
[VSR-88_1]segment-routing ipv6
[VSR-88_1-segment-routing-ipv6]traffic-engineering
[VSR-88_1-srv6-te] srv6-policy locator h3c
[VSR-88_1-srv6-te] segment-list 1
[VSR-88_1-srv6-te-sl-1] index 10 ipv6 A300::1
[VSR-88_1-srv6-te-sl-1] index 20 ipv6 A200::1
[VSR-88_1-srv6-te-sl-1] index 30 ipv6 A400::1
[VSR-88_1-srv6-te-sl-1] index 40 ipv6 A500::1
[VSR-88_1-srv6-te-sl-1] quit
[VSR-88_1-srv6-te] policy h3c
[VSR-88_1-srv6-te-policy-h3c] binding-sid ipv6 A100::10
[VSR-88_1-srv6-te-policy-h3c] color 100 end-point ipv6 2001::5
[VSR-88_1-srv6-te-policy-h3c] candidate-paths
[VSR-88_1-srv6-te-policy-h3c-path] preference 200
[VSR-88_1-srv6-te-policy-h3c-path-pref-200] explicit segment-list 1
VRF and BGP Configuration
Each router is configured with a VRF instance for MPLS VPN. BGP is used to exchange routes between VSR-88_1 and VSR-88_5, with SRv6 policies applied to control traffic forwarding.
Example VRF Configuration on VSR-88_1
[VSR-88_1]ip vpn-instance h3c
[VSR-88_1-vpn-instance-h3c] route-distinguisher 100:1
[VSR-88_1-vpn-instance-h3c] vpn-target 100:1 import-extcommunity
[VSR-88_1-vpn-instance-h3c] vpn-target 100:1 export-extcommunity
[VSR-88_1]interface LoopBack1
[VSR-88_1-LoopBack1] ip binding vpn-instance h3c
[VSR-88_1-LoopBack1] ip address 11.11.11.11 255.255.255.255
BGP Configuration on VSR-88_1
[VSR-88_1]bgp 100
[VSR-88_1-bgp-default] router-id 1.1.1.1
[VSR-88_1-bgp-default] peer 2001::5 as-number 100
[VSR-88_1-bgp-default] peer 2001::5 connect-interface LoopBack0
[VSR-88_1-bgp-default] address-family vpnv4
[VSR-88_1-bgp-default-vpnv4] peer 2001::5 enable
[VSR-88_1-bgp-default-vpnv4] peer 2001::5 prefix-sid
[VSR-88_1-bgp-default-vpnv4] quit
[VSR-88_1-bgp-default] ip vpn-instance h3c
[VSR-88_1-bgp-default-h3c] address-family ipv4 unicast
[VSR-88_1-bgp-default-ipv4-h3c] segment-routing ipv6 traffic-engineering
[VSR-88_1-bgp-default-ipv4-h3c] segment-routing ipv6 locator h3c
[VSR-88_1-bgp-default-ipv4-h3c] import-route direct
Routing Policy and Color Assignment
A routing policy is applied to incoming BGP routes to assign a color attribute, which matches the SRv6 TE policy for traffic steering.
Color Assignment Policy on VSR-88_1
[VSR-88_1]route-policy color permit node 10
[VSR-88_1-route-policy-color-10] apply extcommunity color 00:100
Apply Policy to BGP Neighbor
[VSR-88_1]bgp 100
[VSR-88_1-bgp-default] address-family vpnv4
[VSR-88_1-bgp-default-vpnv4] peer 2001::5 route-policy color import
Verification and Troubleshooting
After configuration, BGP neighbor relationships and route tables are verified. Although the routes are learned and the TE policy appears active, connectivity tests (e.g., ping) fail due to missing route iterations in the PE device.
According to H3C documentation, private network routes may not automatically resolve to End.DT4 SIDs without explicit configuration. Additionally, mismatched RD values between VRFs can result in invalid routes, even though this is typically not an issue in standard VRF operations.
Despite the connectivity issues, the experiment successfully demonstrates the SRv6 TE policy configuration process, which is valuable for understanding SRv6-based traffic engineering.