Segment Routing-MPLS (SR-MPLS)

[Karlos]

dear all,

currently I am configuring segment routing MPLS with ISIS on Cisco router ios xr 6.3.1. everything is okay, ISIS is set and pingable , SR global bock is configured, Segment routing is enabled with ISIS, prefix-SIDs are configured with ISIS.  However, when I would like to show my MPLS labels by using the command SHOW MPLS FORWARDING, it only displays the adjacency SIDs not the prefix SIDs that I have set, although as I said I configured the prefix-SIDs for all loopbacks.

please advise me.

[pman]

i changed the command, try this one:

RP/0/0/CPU0:R2#show isis database verbose detail R3.00-00

IS-IS 1 (Level-2) Link State Database
LSPID LSP Seq Num LSP Checksum LSP Holdtime ATT/P/OL
R3.00-00 0x0000001e 0x138c 1009 0/0/0
Area Address: 49
NLPID: 0xcc
Hostname: R3
IP Address: 3.3.3.3
Router Cap: 3.3.3.3, D:0, S:0
Segment Routing: I:1 V:0, SRGB Base: 90000 Range: 10000
Metric: 10 IS-Extended R3.03
LAN-ADJ-SID: F:0 B:1 V:1 L:1 S:0 weight:0 Adjacency-sid: 24000 System ID:R2
LAN-ADJ-SID: F:0 B:0 V:1 L:1 S:0 weight:0 Adjacency-sid: 24001 System ID:R2
Metric: 10 IP-Extended 2.3.2.0/24
Metric: 10 IP-Extended 3.3.3.3/32
Prefix-SID Index: 3, Algorithm:0, R:0 N:1 P:0 E:0 V:0 L:0

or this one:

RP/0/0/CPU0:R2# show mpls label table detail
Table Label     Owner          State Rewrite
----- ------- ------------------------------- ------ -------
0      0             LSD(A)        InUse Yes
0      1             LSD(A)        InUse Yes
0      2             LSD(A)        InUse Yes
0      13           LSD(A)        InUse Yes
0      24000     ISIS(A):1     InUse Yes
(SR Adj Segment IPv4, vers:0, index=1, type=0, intf=Gi0/0/0/1, nh=2.3.2.3)
0 24001 ISIS(A):1 InUse Yes
(SR Adj Segment IPv4, vers:0, index=3, type=0, intf=Gi0/0/0/1, nh=2.3.2.3)
0 24002 ISIS(A):1 InUse Yes
(SR Adj Segment IPv4, vers:0, index=1, type=0, intf=Gi0/0/0/3, nh=1.2.1.1)
0 24003 ISIS(A):1 InUse Yes
(SR Adj Segment IPv4, vers:0, index=3, type=0, intf=Gi0/0/0/3, nh=1.2.1.1)
0 90000 ISIS(A):1 InUse No
(Lbl-blk SRGB, vers:0, (start_label=90000, size=10000)
RP/0/0/CPU0:R2#

[Karlos]

Hi, thank you for the reply! I tried your comment and the router accepts the command but it show me as in the picture below.

would you mind if you help me out by setting a google meeting session so that I can show you my configuration.  I am a student and this small lab is for  my dissertation. Thus, i will be thankful if you agree. 

[Harold Ritter · Accepted solution]

Hi @Karlos ,

You can do the following command to see if the prefix-sids have been properly assigned:

RP/0/0/CPU0:XR2#sh isis segment-routing label table 

Thu Nov 11 13:50:06.430 UTC

IS-IS test IS Label Table

Label         Prefix/Interface

----------    ----------------

16001         192.168.100.1/32

16002         Loopback0

16003         192.168.100.3/32

RP/0/0/CPU0:XR2#

The configuration should look something like this:

RP/0/0/CPU0:XR2#sh runn router isis

Thu Nov 11 13:48:55.135 UTC

router isis test

 is-type level-2-only

 net 49.0001.1921.6810.0002.00

 address-family ipv4 unicast

  metric-style wide

  advertise passive-only

  segment-routing mpls

 !

 interface Loopback0

  passive

  address-family ipv4 unicast

   prefix-sid index 2

  !

 !

 interface GigabitEthernet0/0/0/0

  point-to-point

  address-family ipv4 unicast

  !

 !

 interface GigabitEthernet0/0/0/1

  point-to-point

  address-family ipv4 unicast

  !

 !

!

Regards,

[Karlos]

hello @Harold Ritter ,

Thank you for the reply I followed your reply and the labels have been assigned. However,  currently, I am working on a simple topology as in the picture attached below. I set the three routers as level 2. But when I try to ping, the router on the right can not ping on the router on the left and the router on the left can not ping the router n the right, although the IPs of the loopbacks are learnt by ISIS, and segment routing MPLS is enabled every thing has been done according to what you taught me in your reply above. The routing tables images are also attached below.

Please advise and I am looking forward to your reply. Thank you

[Harold Ritter]

Hi @Karlos ,

Make sure you specify the local loopback IP address as the source IP address when you ping from one router to the other. This is because the configuration I provided specifies "advertise passive-only", which means that only the loopback IP address will be advertised between the routers.

ping <destination loopback IP address> source <local loopback IP address>

Regards,

[Karlos]

Dear Mr. @Harold Ritter ,

Thank you so much for the reply. it was really helpful. May I ask you to give me the configuration of SR-MPLS with IPv6 as you did in your previous command. The reason I ask you, is because your answer is clear, helpful and does not make me feel lost. Actually,  I tried to configure like the configuration below  but it did nit work: (kindly note that I am working on Cisco XR 6.3.1)

(config) cdp

(config) segment routing global-block 16000 23999

int g0/0/0/0

Ipv6 add 2001:abc:1:1::1/64 

ipv6 enable 

cdp

no shutdown

commit

-------------

int lo 1

ipv6 add 2001:bca:1:1::1/128

ipv6 enable

commit

----------

router isis 1

net 49.0001.1111.1111.1111.00

is-type level-2-only

address-family ipv6 unicast 

metric-style wide

segment routing mpls

int g0/0/0/0

point-to-point

address-family ipv6 unicast 

int lo 1

address-family ipv6 unicast 

prefix-sid index 1

commit

----------------

after configuration, I run this command show IP route , the result comes out as there no matching! ( note that Show ipv6 route does not work on XR 6.3.1).

I hope you give me a clear guidance as you did to be my first step. Thank you very much Mr. @Harold Ritter 

[Karlos]

Dear Mr. @Harold Ritter ,

Thank you for the reply your comments were so helpful. Now I am trying SR-MPLS with IPV6 but it also did not work for me. I tried with the following configuration: ( kindly, note that I am using Cisco XR 6.3.1)

(Config) cdp

segment routing global-block 16000 23999

commit

int g0/0/0/0

ipv6 add 2001:abc:1:1::x/64

ipv6 enable

cdp

no shutdown

commit

int lo 1

ipv6 add 2001::X/128

ipv6 enable

commit

-------------

router isis 1

net 49.0001.1111.1111.1111.00

is-type level-2-only

address-family ipv6 unicast

metric-style wide

segment routing mpls

int g0/0/0/0

address-family ipv6 unicast

int lo 1

address-family ipv6 unicast 

prefix-sid 1

commit

----------

I configure using the same way on all the routers but when I type Show IP route  the result shows me that there is no matching. (as you know the command show ipv6 route  is not supported  on Cisco XR 6.3.1)

I hope you can correct me and give me a clear guidance as you did in your previous commands and they were helpful.

Thank you Mr. @Harold Ritter 

[Harold Ritter · Accepted solution]

Hi @Karlos ,

Here's the IPv4/IPv6 ISIS sample configuration:

router isis test
is-type level-2-only
net 49.0001.1921.6810.0002.00
address-family ipv4 unicast
metric-style wide
advertise passive-only
segment-routing mpls
!
address-family ipv6 unicast
metric-style wide
advertise passive-only
segment-routing mpls
!
interface Loopback0
passive
address-family ipv4 unicast
prefix-sid index 2
!
address-family ipv6 unicast
prefix-sid index 1002
!
!
interface GigabitEthernet0/0/0/0
point-to-point
address-family ipv4 unicast
!
address-family ipv6 unicast
!
!
interface GigabitEthernet0/0/0/1
point-to-point
address-family ipv4 unicast
!
address-family ipv6 unicast
!
!
interface GigabitEthernet0/0/0/2
point-to-point
address-family ipv4 unicast
!
address-family ipv6 unicast
!
!

!