Re: [Lsr] FW: New Version Notification for draft-bonica-lsr-ip-flexalgo-00.txt

[Ron Bonica <[e-mail]>]

Hi Yingzhen,

IP Flexible Algorithms are like SR Flexible Algorithms in the following respects:

- Links have IGP metrics, TE metrics, delay metrics and administrative colors
- FADs define Flexible Algorithms

More specifically, the FAD:

- Indicates which metric type the Flexible Algorithm uses
- Specifies constraints in terms of link colors that are included or excluded from the Flexible Algorithm.

The significant difference between IP Flexible Algorithms and SR Flexible Algorithms is:

- SR Flexible Algorithms bind FADs to prefix SIDs or SRv6 locators
- IP Flexible Algorithms bind FADs to IPv4 or IPv6 addresses.

So, IP Flexible Algorithms can be deployed in any IP network, even in the absence of SR.

                                        Ron


Juniper Business Use Only

-----Original Message-----
From: Yingzhen Qu <[e-mail]> 
Sent: Saturday, October 3, 2020 2:08 PM
To: Peter Psenak <[e-mail]>; Gyan Mishra <[e-mail]>; Ron Bonica <[e-mail]>
Cc: [e-mail]; Jeff Tantsura <[e-mail]>
Subject: Re: [Lsr] FW: New Version Notification for draft-bonica-lsr-ip-flexalgo-00.txt

[External Email. Be cautious of content]


Hi Peter,

Using flex-algo, a SRv6 locator can be associated with a single algo, which means an IPv6 or IPv4 address can also be associated with a single algo. So my understanding is Ron's proposal is making the configuration of flex-algo easier? Instead of using the exclude or include list you can configure a loopback address to a flex-algo directly?

Thanks,
Yingzhen

On 10/3/20, 2:47 AM, "Peter Psenak" <[e-mail]> wrote:

    Hi Yingzhen,

    On 02/10/2020 22:15, Yingzhen Qu wrote:
    > Hi Peter,
    >
    > My understanding of flex-algo is that for traffic destined to a prefix on a particular algo, it can only be routed on routers belong to that algo, which also means only routers in that algo calculates how to reach that prefix and install it into the routing table. It seems to me that using flex-algo (section 12 of the draft) it's possible to have a loopback address associated with only one algo, please correct me if I'm missing or misunderstood something.

    you are right. That is exactly what is being done for flex-algo with
    SRv6 - locator is associated with a single algo only. The proposal uses
    the same concept.

    thanks,
    Peter

    >
    > Thanks,
    > Yingzhen
    >
    > On 10/2/20, 9:43 AM, "Lsr on behalf of Peter Psenak" <[e-mail] on behalf of ppsenak=[e-mail]> wrote:
    >
    >      Gyan,
    >
    >      On 02/10/2020 18:30, Gyan Mishra wrote:
    >      > All,
    >      >
    >      > With SRv6 and IP based flex algo a generic question as it applies to
    >      > both. Is it possible to have within a single IGP domain different sets
    >      > of nodes or segments of the network running different algorithms.
    >
    >      absolutely.
    >
    >      > From
    >      > both drafts it sounds like all nodes have to agree on same algorithm
    >      > similar to concept of metric and reference bandwidth all have to have
    >      > the same style metric and play to the same sheet of music.
    >
    >      all participating nodes need to agree on the definition of the flex-algo
    >      and advertise the participation. That's it.
    >
    >      > If there was
    >      > a way to use multiple algorithms simultaneously based on SFC or services
    >      > and instantiation of specific algorithm based on service to be
    >      > rendered.  Doing so without causing a routing loop or sub optimal
    >      > routing.
    >
    >      you can certainly use multiple algorithms simultaneously and use algo
    >      specific paths to forward specific traffic over it. How that is done
    >      from the forwarding perspective depends in which forwarding plane you
    >      use. Flex-algo control plane is independent of the forwarding plane.
    >
    >
    >      >I thought with flex algo that there exists a feature that on
    >      > each hop there is a way to specify which algo to use hop by hop similar
    >      > to a hop by hop policy based routing.
    >
    >      no, there is no hop-by-hop classification, that is problematic and does
    >      not scale for high speeds. Classification is done at the ingress only.
    >
    >      thanks,
    >      Peter
    >
    >      >
    >
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