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-headstrong-
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Secondary path config for TE tunnel?

Tue Dec 22, 2009 7:41 pm

Hi Guys

I am trying to get TE tunnels to work with secondary paths aswell as primary, but I have run out of ideas to get it working.

Here are my configs
mpls traffic-eng tunnel-path print detail
Flags: X - disabled
0 name="dyn" use-cspf=yes record-route=yes

3 name="stat" use-cspf=yes record-route=yes
hops=192.168.98.246:strict,192.168.99.6:strict,192.168.98.42:strict,192.168.99.30:strict,192.168.99.26:strict
interface traffic-eng print detail
Flags: X - disabled, D - dynamic, R - running

4 R name="te_test" mtu=1500 disable-running-check=no from-address=xxx to-address=yyy bandwidth=0bps primary-path=stat secondary-paths=dyn
primary-retry-interval=1m record-route=yes bandwidth-limit=disabled auto-bandwidth-range=0bps auto-bandwidth-reserve=0% auto-bandwidth-avg-interval=5m
auto-bandwidth-update-interval=1h
interface traffic-eng monitor te_test
tunnel-id: 24
primary-path-state: established
primary-path: stat
secondary-path-state: not-necessary
active-path: stat
active-lspid: 1
active-label: 206
explicit-route: "S:192.168.98.246/32,S:192.168.99.5/32,S:192.168.99.6/32,S:192.168.98.41/32,S:192.168.98.42/32,S:192.168.99.29/32,S:192.168.99.30/32,
S:192.168.99.25/32,S:192.168.99.26/32"
recorded-route: "192.168.99.5[206],192.168.98.41[1077],192.168.99.29[9118],192.168.99.25[4611],192.168.99.26[0]"
reserved-bandwidth: 0bps
Why is the 'secondary-path-state' not necessary? How do I get it to become active?


thanks
 
Mplsguy
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Re: Secondary path config for TE tunnel?

Wed Dec 23, 2009 10:40 am

It is not necessary, because primary path is fine - tunnel establishes using it. The purpose of secondary paths is to provide alternative for tunnel if establishing tunnel using primary path is impossible.
 
-headstrong-
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Re: Secondary path config for TE tunnel?

Wed Dec 23, 2009 11:48 am

Would configuring a static secondary path improve the time taken to bring the TE tunnel back up should the dynamic primary path become impossible?

Also, what is the difference between :static and :loose when configuring the hops of a tunnel-path?

Thanks
 
Mplsguy
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Re: Secondary path config for TE tunnel?

Wed Dec 23, 2009 3:53 pm

Would configuring a static secondary path improve the time taken to bring the TE tunnel back up should the dynamic primary path become impossible?
Upon failure of primary-path (and this does not exactly mean data forwarding disruption, but failure of RSVP tunnel, which takes time to detect), primary path enters "on-hold" state and attempt is made to establish secondary path (if any). The difference between primary and secondary path is that in case primary path is active, secondary path is considered "not necessary", but if secondary path is active, there are periodic attempts to establish primary path.

As to your question - if primary path becomes impossible, secondary path is the only option how to get TE tunnel back up.
Also, what is the difference between :static and :loose when configuring the hops of a tunnel-path?
It is "strict", not "static" actually. It specifies how strict each hop must be about looking up the next hop. If next hop in explicit route is "strict", it must be adjacent (reachable by connected route). If next hop is "loose", it can be somewhere further (reachable by any other IGP route). Basically what it gives you is the ability to either specify exact path (this is the result of CSPF - it produces explicit route with all "strict" hops) or just specify the "key hops" in the path. Of course, you can also use combination of both approaches. For a complete discussion about "strict" and "loose" in explicit path see RFC 3209.
 
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Re: Secondary path config for TE tunnel?

Wed Dec 23, 2009 11:54 pm

Thanks again

I have a wierd situation regarding a TE tunnel between two sites. VPLS works, so does BGP peering, aswell as IP routing between the loopback ips. But I cannot get the TE tunnel to come up with "use-cspf=no" and also tried "use-cspf=yes"

Would this be an OSPF issue? It is possble to create TE tunnels without OSPF?
 
Mplsguy
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Re: Secondary path config for TE tunnel?

Thu Dec 24, 2009 10:36 am

Thanks again

I have a wierd situation regarding a TE tunnel between two sites. VPLS works, so does BGP peering, aswell as IP routing between the loopback ips. But I cannot get the TE tunnel to come up with "use-cspf=no" and also tried "use-cspf=yes"

Would this be an OSPF issue? It is possble to create TE tunnels without OSPF?
In order to establish TE tunnel using CSPF you must:
- configure interfaces on all routers for TE (/mpls traffic-eng interface add ...)
- configure OSPF to distribute TE information (/routing ospf set mpls-te-area=... mpls-te-router-id=...)
- make sure that bandwidth and affinity constraints are met (CSPF will only find path if there is enough bandwidth as reported by OSPF available over links)

It is possible to create TE tunnels without OSPF, even without specifying explicit path (w/o specifying any intermediate hops), but again - all routers in the way must have TE enabled interfaces.
 
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Re: Secondary path config for TE tunnel?

Thu Dec 24, 2009 6:55 pm

- make sure that bandwidth and affinity constraints are met (CSPF will only find path if there is enough bandwidth as reported by OSPF available over links)
Please could you explain the 3 affinity settings: affinity-include, affinity-exclude, affinity-any? I tried searching but found no material on it.

I have left them as default when setting up my TE tunnels, should I configure these settings two?
thanks
 
Mplsguy
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Re: Secondary path config for TE tunnel?

Fri Dec 25, 2009 12:18 pm

Please could you explain the 3 affinity settings: affinity-include, affinity-exclude, affinity-any? I tried searching but found no material on it.
See RFC 3209, section 4.7.4. "Resource Affinity Procedures" - it explains how these settings are matched against tunnel setting.
I have left them as default when setting up my TE tunnels, should I configure these settings two?
thanks
The default values are fine. You have to configure them only if you specify non-default value for your TE tunnel.
 
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Re: Secondary path config for TE tunnel?

Sun Dec 27, 2009 12:06 am

Please could you explain the 3 affinity settings: affinity-include, affinity-exclude, affinity-any? I tried searching but found no material on it.
See RFC 3209, section 4.7.4. "Resource Affinity Procedures" - it explains how these settings are matched against tunnel setting.
I have left them as default when setting up my TE tunnels, should I configure these settings two?
thanks
The default values are fine. You have to configure them only if you specify non-default value for your TE tunnel.
I've read that RFC, section 4.7.4 and i have a few questions regarding the syntax
2. Include-any

This test accepts a link if the link carries any of the
attributes in the set.

(include-any == 0) | ((link-attr & include-any) != 0)
What is the syntax for the link attributes? I do not know what to type after the below??
/mpls traffic-eng tunnel-path add name=test affinity-include-all=


pushing "TAB" twice does not give me any options???
 
Mplsguy
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Re: Secondary path config for TE tunnel?

Sun Dec 27, 2009 8:56 am

2. Include-any

This test accepts a link if the link carries any of the
attributes in the set.

(include-any == 0) | ((link-attr & include-any) != 0)
What is the syntax for the link attributes? I do not know what to type after the below??
These settings are unsigned 32 bit numbers, so any number syntax will be fine. The operations applied to those numbers are bitwise operations, so probably using hexadecimal notation is the most descriptive. For example, if you specify as "include-any" value 0xff (255 decimal), this means that particular tunnel can be established over links that have any of lower 8 bits set in their affinity setting, for example over links that have affinity value: 0x1 (1), 0x3 (3), 0x8 (8), 0xff (255), 0x101 (257), 0xffff (65535), but not over links that have affinity value: 0x100 (256), 0xff00 (65280).
 
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Re: Secondary path config for TE tunnel?

Sun Dec 27, 2009 1:26 pm

Wow this is getting interesting :P

By default does ROS assign TE-Metric = IGP metric?

All my TE-interfaces have a TE-Metric of 1. So after 5 hops, the TE-metric would be 5, right?

However, OSPF has a default cost of 10, so after 5 hops the OSPF cost would be 50, right?

So what affinity value would I need to set my tunnel to?

Alternatively, how do I configure my tunnel to accept any link irrespective of cost?

thanks
 
Mplsguy
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Re: Secondary path config for TE tunnel?

Sun Dec 27, 2009 5:12 pm

headstrong, affinity stuff has nothing to do with metrics. You can think of affinity stuff as of color labels you give to links (each bit in value telling if link has particular color label or not). Then you can make tunnel such that it only uses links that have e.g. red label ("include" part). Or make a tunnel that does not use links with blue label ("exclude" part). Or make tunnel that uses links that have either red or blue label ("include-any" part). Or combination of these rules.

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