Containerlab Demo Using Service Router OS for a L3VPN with Segment Routing SRv6

4 months ago 4

This lab is showing a simple configuration and verification of SRv6 on Nokia routers to signal both IGP’s shortest path and Algorithms with specific metric conditions (i.e. 10ms). All router network interfaces for transport are using IPv6 and we are encpasulating IPv4 traffic.

Objective: Create a traffic-engineered path between R1 and R6 that uses delay as a metric.

Conditions:

IGP Metrics: All IGP link metrics are 100
Delay Metrics: All delay metrics are 10msec with the exception of the R3-R5 link, which is 15msec.

See topology on the next image:

Next image shows the same with one option of the shortest path using ISIS.

SRv6 with Flexible Algorithm

Segment Routing (SR) is applied to the IPv6 data plane using 128-bit SIDs and the SR routing header (SRH). The 128-bit SRv6 SID consists of a Locator, a Function, and an Argument.

The Locator is encoded in the most significant bits of the SID. It is typically routable and leads to the node that instantiated the SID.
The Function identifies a local endpoint behaviour, such as End, End.X, End.DT4 or End.DT2U. The Locator is advertised into the IGP and is associated with an Algorithm. As a result, support for Flexible-Algorithm is inherited from day one, and a level of traffic engineering is possible without SRH overhead.
Flex-Algo 128 SRv6 Locators: Alg128: 2001:db8:4502:n::/64 where n is Node-ID, so 1 is R1, 6 is R6.

Versions used are:

containerlab 0.25.1
vr-sros 22.5.R2 (requires license)

SROS image was created using VR Network Lab IMPORTANT: vr-sos must be set as an image in docker to be pull directly by containerlab

# docker images | grep vr-sros vr-sros 22.5.R2 f33cd7a3732a 3 months ago 965MB

If you are new with container lab, we recommed to check the post regading Nokia SROS in the manual

Create Bridges to use for delay testing and trigger Algorithm 128.

brctl addbr R2-R4 brctl addbr R3-R5 ip link set R2-R4 up ip link set R3-R5 up

Use containerlab a specified topology

clab deploy --topo topo.yml

Checking elements in the lab

# clab inspect --topo topo.yml

Preping origin and destination containers:

docker exec -i clab-srv6-demo-destination1 sh -s < destination1_config.sh docker exec -i clab-srv6-demo-origin1 sh -s < origin1_config.sh

Test connectivity (origin is 10.1.4.101 and destination is using 10.6.4.101)

# docker exec -ti clab-srv6-demo-origin1 ping 10.6.4.101 PING 10.6.4.101 (10.6.4.101): 56 data bytes 64 bytes from 10.6.4.101: seq=0 ttl=60 time=11.766 ms 64 bytes from 10.6.4.101: seq=1 ttl=60 time=8.953 ms 64 bytes from 10.6.4.101: seq=2 ttl=60 time=8.865 ms 64 bytes from 10.6.4.101: seq=3 ttl=60 time=8.695 ms

All router smust be part of Algo128 to make it work

A:admin@R31# admin show configuration /configure router isis flexible-algorithms admin-state enable flex-algo 128 { participate true loopfree-alternate { } micro-loop-avoidance { } } [/]

A:admin@R6# admin show configuration /configure routing-options flexible-algorithm-definitions { flex-algo "Flex-Algo-128" { admin-state enable description "Flex-Algo for Delay Metric" metric-type delay } } [/] A:admin@R6# admin show configuration /configure router isis flexible-algorithms admin-state enable flex-algo 128 { participate true advertise "Flex-Algo-128" loopfree-alternate { } micro-loop-avoidance { } } [/]

Check ISIS database for validation:

A:admin@R31# show router isis database R31.00-00 level 1 detail | match "Router Cap" post-lines 10 Router Cap : 192.0.2.31, D:0, S:0 TE Node Cap : B E M P SR Cap: IPv4 MPLS-IPv6 SRGB Base:12000, Range:8000 SR Alg: metric based SPF, 128 Node MSD Cap: BMI : 12 ERLD : 15 SRH-MAX-SL : 10 SRH-MAX-END-POP : 9 SRH-MAX-H-ENCAPS : 1 SRH-MAX-END-D : 9 SRv6 Cap: 0x0000 I/F Addresses : I/F Address : 192.0.2.31 I/F Address : 192.168.0.66 I/F Address : 192.168.0.73 [/]

A:admin@R6# show router isis database R6.00-00 level 1 detail | match "Router Cap" post-lines 12 Router Cap : 192.0.2.6, D:0, S:0 TE Node Cap : B E M P SR Cap: IPv4 MPLS-IPv6 SRGB Base:12000, Range:8000 SR Alg: metric based SPF, 128 Node MSD Cap: BMI : 12 ERLD : 15 SRH-MAX-SL : 10 SRH-MAX-END-POP : 9 SRH-MAX-H-ENCAPS : 1 SRH-MAX-END-D : 9 SRv6 Cap: 0x0000 FAD Sub-Tlv: Flex-Algorithm : 128 Metric-Type : delay Calculation-Type : 0 Priority : 100 Flags: M [/]

Dynamic link delay measurement and propagation

For simplification, all links have a static unidirectional link delay value of 10mSec (10000uSec), except the R3-R5 link which has a static delay of 15mSec (15000uSec). The exception is the link R2-R4, which uses dynamic link delay measurement using STAMP probes. Link delay is introduced using a virtual network emulator.

A:admin@R2# show test-oam link-measurement interface to_R4 detail =============================================================================== Interface Link Measurement Information - to_R4 =============================================================================== Template Name: direct-link Oper State : Up Protocol : IPv4 Oper Source Address : 192.168.0.13 Source Auto-Assigned : Yes Oper Destination Address : 192.168.0.14 Destination Auto-Assigned: Yes Failure Condition(s) : None Detectable Tx Error : None ------------------------------------------------------------------------------- Reporting ------------------------------------------------------------------------------- Reporting Enabled : Yes Delay Measure Last Reported: 1136us Timestamp : 2023/01/03 22:26:57 Triggered By : SampleThresholdRelative ------------------------------------------------------------------------------- Aggregate Sample Window Delay Measurement Detail Currently Reporting: Avg ------------------------------------------------------------------------------- End Timestamp (UTC) State Count Min(us) Max(us) Avg(us) I Result ------------------------------------------------------------------------------- N/A InProgress 0 0 0 0 - 0 2023/01/03 22:26:57 SwReported 1 0 0 0 N 0 2023/01/03 22:26:47 Completed 1 856 856 856 Y 856 2023/01/03 22:26:37 SwReported 1 0 0 0 N 0 2023/01/03 22:26:27 SwReported 1 0 0 0 N 0 2023/01/03 22:26:17 Completed 1 879 879 879 Y 879 2023/01/03 22:26:07 SwReported 1 0 0 0 N 0 2023/01/03 22:25:57 SwReported 1 0 0 0 N 0 2023/01/03 22:25:47 Completed 1 853 853 853 Y 853 2023/01/03 22:25:37 SwReported 1 0 0 0 N 0 2023/01/03 22:25:27 SwReported 1 0 0 0 N 0 2023/01/03 22:25:17 SwReported 1 0 0 0 N 0 2023/01/03 22:25:07 Completed 1 841 841 841 Y 841 2023/01/03 22:24:57 Completed 1 811 811 811 Y 811 2023/01/03 22:24:47 Completed 1 866 866 866 Y 866 2023/01/03 22:24:37 Completed 1 870 870 870 Y 870 2023/01/03 22:24:27 Completed 1 850 850 850 Y 850 2023/01/03 22:24:17 Completed 1 949 949 949 Y 949 2023/01/03 22:24:07 Completed 1 834 834 834 Y 834 2023/01/03 22:23:57 SwReported 1 0 0 0 N 0 ------------------------------------------------------------------------------- Sample Window Delay Measurement Detail Currently Reporting: Avg ------------------------------------------------------------------------------- End Timestamp (UTC) State Rcv/Snt Min(us) Max(us) Avg(us) Err I Result ------------------------------------------------------------------------------- N/A InProgress 3/3 0 0 0 0 - 0 2023/01/03 22:26:57 SwReported 5/5 767 2417 1136 0 Y 1136 2023/01/03 22:26:47 Completed 5/5 758 1041 856 0 Y 856 2023/01/03 22:26:37 SwReported 5/5 700 960 856 0 Y 856 2023/01/03 22:26:27 SwReported 5/5 801 1496 987 0 Y 987 2023/01/03 22:26:17 Completed 5/5 746 972 879 0 Y 879 2023/01/03 22:26:07 SwReported 5/5 779 938 828 0 Y 828 2023/01/03 22:25:57 SwReported 5/5 808 1719 1055 0 Y 1055

These static/dynamic values are advertised into IS-IS.

A:admin@R2# show router isis database R2.00-00 level 2 detail | match "Nbr : R4.00" post-lines 28 Nbr : R4.00 Default Metric : 100 Sub TLV Len : 137 IF Addr : 192.168.0.13 Nbr IP : 192.168.0.14 TE APP LINK ATTR : SABML-flag:Non-Legacy SABM-flags:R S MaxLink BW: 10000000 kbps TE Metric : 20 TE APP LINK ATTR : SABML-flag:Non-Legacy SABM-flags:R Resvble BW: 10000000 kbps Unresvd BW: BW[0] : 10000000 kbps BW[1] : 10000000 kbps BW[2] : 10000000 kbps BW[3] : 10000000 kbps BW[4] : 10000000 kbps BW[5] : 10000000 kbps BW[6] : 10000000 kbps BW[7] : 10000000 kbps TE APP LINK ATTR : SABML-flag:Non-Legacy SABM-flags: X Admin Grp : 0x400 Delay Min : 858 Max : 858 TE Metric : 20 Adj-SID: Flags:v4BVLP Weight:0 Label:20204 Adj-SID: Flags:v6BVL Weight:0 Label:524285 End.X-SID: 2001:db8:4501:2:0:4000:: flags:B algo:0 weight:0 endpoint:End.X-USP

Verifying SRv6-ISIS tunnel

A:admin@R1# show router route-table ipv6 2001:db8:4502:6::/64 =============================================================================== IPv6 Route Table (Router: Base) =============================================================================== Dest Prefix[Flags] Type Proto Age Pref Next Hop[Interface Name] Metric ------------------------------------------------------------------------------- 2001:db8:4502:6::/64 Remote ISIS 00h05m44s 15 2001:db8:4502:6::/64 (tunneled:SRV6-ISIS) 40859 ------------------------------------------------------------------------------- No. of Routes: 1 Flags: n = Number of times nexthop is repeated B = BGP backup route available L = LFA nexthop available S = Sticky ECMP requested =============================================================================== [/]

A:admin@R1# show router tunnel-table ipv6 2001:db8:4502:6::/64 =============================================================================== IPv6 Tunnel Table (Router: Base) =============================================================================== Destination Owner Encap TunnelId Pref Nexthop Color Metric ------------------------------------------------------------------------------- 2001:db8:4502:6::/64 [L] srv6-isis SRV6 524302 0 fe80::5054:ff:fe9f:7c00-"to_R11" 40744 ------------------------------------------------------------------------------- Flags: B = BGP or MPLS backup hop available L = Loop-Free Alternate (LFA) hop available E = Inactive best-external BGP route k = RIB-API or Forwarding Policy backup hop =============================================================================== [/]

A:admin@R1# traceroute 2001:db8:4502:6:: source-address 2001:db8:4502:1:: traceroute to 2001:db8:4502:6:: from 2001:db8:4502:1::, 30 hops max, 60 byte packets 1 2001:db8:33ad::2 (2001:db8:33ad::2) 3.84 ms 1.79 ms 1.70 ms 2 2001:db8:33ad::12 (2001:db8:33ad::12) 3.50 ms 2.50 ms 2.38 ms 3 2001:db8:33ad::e (2001:db8:33ad::e) 4.61 ms 3.66 ms 3.63 ms 4 2001:db8:33ad::42 (2001:db8:33ad::42) 5.73 ms 4.48 ms 4.58 ms 5 2001:db8:33ad::4d (2001:db8:33ad::4d) 5.87 ms 5.65 ms 7.26 ms [/] A:admin@R1#

A:admin@R1# show router isis database R1.00-00 level 1 detail | match "SRv6 Locator" post-lines 10 SRv6 Locator : MT ID : 0 Metric: ( ) 1 Algo:0 Prefix : 2001:db8:4501:1::/64 Sub TLV : AttrFlags: N End-SID : 2001:db8:4501:1:0:1000::, flags:0x0, endpoint:End-USP Metric: ( ) 1 Algo:128 Prefix : 2001:db8:4502:1::/64 Sub TLV : AttrFlags: N [/]

# brctl show bridge name bridge id STP enabled interfaces R2-R4 8000.7645097640f5 no eth3 eth4 # tc qdisc add dev eth3 root netem delay 40ms

A:admin@R2# show router isis database R2.00-00 level 2 detail | match "Nbr : R4.00" post-lines 28 Nbr : R4.00 Default Metric : 100 Sub TLV Len : 137 IF Addr : 192.168.0.13 Nbr IP : 192.168.0.14 TE APP LINK ATTR : SABML-flag:Non-Legacy SABM-flags:R S MaxLink BW: 10000000 kbps TE Metric : 20 TE APP LINK ATTR : SABML-flag:Non-Legacy SABM-flags:R Resvble BW: 10000000 kbps Unresvd BW: BW[0] : 10000000 kbps BW[1] : 10000000 kbps BW[2] : 10000000 kbps BW[3] : 10000000 kbps BW[4] : 10000000 kbps BW[5] : 10000000 kbps BW[6] : 10000000 kbps BW[7] : 10000000 kbps TE APP LINK ATTR : SABML-flag:Non-Legacy SABM-flags: X Admin Grp : 0x400 Delay Min : 20896 Max : 20896 TE Metric : 20 Adj-SID: Flags:v4BVLP Weight:0 Label:20204 Adj-SID: Flags:v6BVL Weight:0 Label:524285 End.X-SID: 2001:db8:4501:2:0:4000:: flags:B algo:0 weight:0 endpoint:End.X-USP

Check changes in the route

A:admin@R1# traceroute 2001:db8:4502:6:: source-address 2001:db8:4502:1:: traceroute to 2001:db8:4502:6:: from 2001:db8:4502:1::, 30 hops max, 60 byte packets 1 2001:db8:33ad::6 (2001:db8:33ad::6) 3.58 ms 1.80 ms 1.55 ms 2 2001:db8:33ad::a (2001:db8:33ad::a) 4.03 ms 2.82 ms 2.84 ms 3 2001:db8:33ad::16 (2001:db8:33ad::16) 5.10 ms 7.63 ms 3.93 ms 4 2001:db8:33ad::46 (2001:db8:33ad::46) 6.80 ms 4.87 ms 4.62 ms 5 2001:db8:33ad::56 (2001:db8:33ad::56) 6.41 ms 5.96 ms 6.34 ms [/]

# tc qdisc del dev eth3 root # tc qdisc add dev eth3 root netem delay 20ms

Start ping with some specific packet size from origin1 container

# docker exec -it clab-srv6-demo-origin1 /bin/sh / # ping -s 30000 10.6.4.101 PING 10.6.4.101 (10.6.4.101): 30000 data bytes 30008 bytes from 10.6.4.101: seq=0 ttl=60 time=61.094 ms 30008 bytes from 10.6.4.101: seq=1 ttl=60 time=60.020 ms 30008 bytes from 10.6.4.101: seq=2 ttl=60 time=55.876 ms 30008 bytes from 10.6.4.101: seq=3 ttl=60 time=55.764 ms 30008 bytes from 10.6.4.101: seq=4 ttl=60 time=55.642 ms 30008 bytes from 10.6.4.101: seq=5 ttl=60 time=55.538 ms 30008 bytes from 10.6.4.101: seq=6 ttl=60 time=55.287 ms 30008 bytes from 10.6.4.101: seq=7 ttl=60 time=53.467 ms 30008 bytes from 10.6.4.101: seq=8 ttl=60 time=59.940 ms 30008 bytes from 10.6.4.101: seq=9 ttl=60 time=55.033 ms

Check traffic in R3, adding and removing delay

A:admin@R3# monitor port 1/1/c5/1 rate =============================================================================== Monitor statistics for Port 1/1/c5/1 =============================================================================== Input Output ------------------------------------------------------------------------------- ------------------------------------------------------------------------------- At time t = 0 sec (Base Statistics) ------------------------------------------------------------------------------- Octets 512702 557512 Packets 1827 2014 Errors 0 0 ------------------------------------------------------------------------------- At time t = 10 sec (Mode: Rate) ------------------------------------------------------------------------------- Octets 167 195 Packets 0 1 Errors 0 0 Bits 1336 1560 Utilization (% of port capacity) ~0.00 ~0.00 ------------------------------------------------------------------------------- At time t = 20 sec (Mode: Rate) ------------------------------------------------------------------------------- Octets 27 27 Packets 0 0 Errors 0 0 Bits 216 216 Utilization (% of port capacity) ~0.00 ~0.00 ------------------------------------------------------------------------------- At time t = 30 sec (Mode: Rate) ------------------------------------------------------------------------------- Octets 160 43 Packets 0 0 Errors 0 0 Bits 1280 344 Utilization (% of port capacity) ~0.00 ~0.00 ------------------------------------------------------------------------------- At time t = 40 sec (Mode: Rate) ------------------------------------------------------------------------------- Octets 9575 15598 Packets 4 6 Errors 0 0 Bits 76600 124784 Utilization (% of port capacity) ~0.00 ~0.00 ------------------------------------------------------------------------------- At time t = 50 sec (Mode: Rate) ------------------------------------------------------------------------------- Octets 30874 30874 Packets 10 10 Errors 0 0 Bits 246992 246992 Utilization (% of port capacity) ~0.00 ~0.00 ------------------------------------------------------------------------------- At time t = 60 sec (Mode: Rate) ------------------------------------------------------------------------------- Octets 30855 30855 Packets 10 10 Errors 0 0 Bits 246840 246840 Utilization (% of port capacity) ~0.00 ~0.00 ------------------------------------------------------------------------------- At time t = 70 sec (Mode: Rate) ------------------------------------------------------------------------------- Octets 30988 30872 Packets 10 10 Errors 0 0 Bits 247904 246976 Utilization (% of port capacity) ~0.00 ~0.00 ------------------------------------------------------------------------------- At time t = 80 sec (Mode: Rate) ------------------------------------------------------------------------------- Octets 21765 15599 Packets 7 5 Errors 0 0 Bits 174120 124792 Utilization (% of port capacity) ~0.00 ~0.00 ------------------------------------------------------------------------------- At time t = 90 sec (Mode: Rate) ------------------------------------------------------------------------------- Octets 167 167 Packets 0 0 Errors 0 0 Bits 1336 1336 Utilization (% of port capacity) ~0.00 ~0.00

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