Subject: [trill] [rbridge] Query on draft-ietf-trill-esadi-00

From: Abhinav Bhatia <[email-masked]>
Date: Fri, 13 Jul 2012 15:21:54 +0530

Hi Authors,

I have query regarding  “The ESADI (End Station Address Distribution
Information) Protocol” as per  “draft-ietf-trill-esadi-00”

According to draft in Section
5.2<http://tools.ietf.org/html/draft-ietf-trill-esadi-00#section-5.2>Forgetting
End Station Addresses

   If RBridge RBn participating in the TRILL ESADI protocol for VLAN-x

   is no longer appointed forwarder for VLAN-x on any port where it is

   providing end station service, it ceases to participate in ESADI

   after sending a final ESADI-LSP nulling out its ESADI-LSP

   information.

Above will remove/flush the learned L2 entries for that ESADI Rbridge for
that vlan and also remove the neighbor ESADI instance entry.

Q) What does “nulling out” its ESADI-LSP information mean? Does it means
removing the macs and sending an empty MAC Reachability TLV or does it mean
that the ESADI LSP

     wont contain any MAC Reachability TLV at all?

Q) In case if ESADI rbridge is AF for a vlan-x and  the only  End Station
which was connected earlier, is removed now, then what will be sent in
ESADI-LSP to flush L2 entries for that

    vlan-x, will it be without MAC Reachability TLV? Please bear in mind
that the RBridge has not lost AF for that particular vlan, but has no End
Station to send in MAC Reachability

    TLV.

    Please let me know for an ESADI RBridge  how to distinguish between

1>     when to remove learned L2 entries and

2>     when to remove ESADI instance neighbor on receiving ESADI-LSP?

Thanks,

Abhinav

---

From: [email-masked]
Date: Mon, 16 Jul 2012 10:01:31 +0800

Hi,Bhatia, Thanks for your comments.

Please see my comments in-line

 
>According to draft in Section 5.2 Forgetting End Station Addresses

that vlan and also remove the neighbor ESADI instance entry.
Q) What does “nulling out” its ESADI-LSP information mean? Does it means 
removing the macs and sending an empty MAC Reachability TLV or does it 
mean that the ESADI LSP     wont contain any MAC Reachability TLV at all?
[hfw] If RBn participant in the TRILL ESADI protcol, it can use the ESADI 
protocol to fast update the MAC table of remote RBridges. If some of the 
end stations attached to RBn remove, RBn use the ESADI-LSP to announce its 
leaving, the ESADI-LSP doesn't contain the MAC address of the leaving end 
station.
It only removes the macs, and the Topology-id/Nickname,Confidence, and 
VLAN-ID field will be filled in.  The ESADI LSP should contain MAC 
reachability TLV.   

Q) In case if ESADI rbridge is AF for a vlan-x and  the only  End Station 
which was connected earlier, is removed now, then what will be sent in 
ESADI-LSP to flush L2 entries for that   
    vlan-x, will it be without MAC Reachability TLV? Please bear in mind 
that the RBridge has not lost AF for that particular vlan, but has no End 
Station to send in MAC Reachability  
    TLV.
[hfw] Yes, the ESADI-LSP will contain MAC reachability TLV, but the MAC 
field is empty.
Whether there is end station attached to the ESADI RBridge or nor,  can 
not change the status and role of AF for the RBridge in the link, in my 
mind. So RBrdige should sends its ESADI-LSP contain MAC reachability to 
its neighbor, even if there is no MAC address in the MAC field.

    Please let me know for an ESADI RBridge  how to distinguish between 
1>     when to remove learned L2 entries and 
2>     when to remove ESADI instance neighbor on receiving ESADI-LSP?
[hfw] If RBridge receives a new ESADI-LSP from its logical neighbor that 
it can not contain some of the MAC(L2 entries), it should remove the l2 
entries.
 
      If RB receives ESADI-LSP from its neighbor, it can not changes or 
removes the status of its neighbor whether the ESADI-LSP contain MAC 
address or not, while if its neighbor becomes IS-IS or data unreachable, 
or the ESADI Participation bit of the neighbor is reset, the ESADI 
instance will be removed from its local neighbor status list.

Thanks

Abhinav Bhatia <[email-masked]> 
发件人:  [email-masked]
2012-07-13 17:51

收件人
[email-masked]
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主题
[trill]  [rbridge] Query on draft-ietf-trill-esadi-00

Hi Authors,

According to draft in Section 5.2 Forgetting End Station Addresses

 
Q) What does “nulling out” its ESADI-LSP information mean? Does it means 
removing the macs and sending an empty MAC Reachability TLV or does it 
mean that the ESADI LSP  
     wont contain any MAC Reachability TLV at all?

    Please let me know for an ESADI RBridge  how to distinguish between 
1>     when to remove learned L2 entries and 
2>     when to remove ESADI instance neighbor on receiving ESADI-LSP?
Thanks,
Abhinav_______________________________________________
trill mailing list
[email-masked]
https://www.ietf.org/mailman/listinfo/trill

---

From: Donald Eastlake <[email-masked]>
Date: Fri, 27 Jul 2012 11:51:46 -0400

Hi,

>      wont contain any MAC Reachability TLV at all?

I don't see how it makes any difference. Since the RBridge doing this
is going to drop out of the ESADI instance anyway, the MAC
Reachability information it was originating is going to be ignored or
discarded soon anyway. I think sending out this final "empty" LSP
information just gets the word out a little faster.

> Station to send in MAC Reachability

Again, I don't see how it makes any difference whether it sends an
empty MAC Reachability TLV or send no MAC Reacability TLVs. Why can't
implementations do whichever is most convenient? (I suppose not
sending any MAC Reachability TLVs saves a tiny number of bytes...)

> 1>     when to remove learned L2 entries and

The way I look at it, an RBridge has number of sources of "MAC&VLAN ->
egress nickname" mapping entries. There are entries it has learned
from the data plane (possibly empty if data plane learning has been
disabled) or from Layer 2 registration protocols. There may be entries
in its ESADI state for various VLANs if it is participating in ESADI.
There can be manually configured mappings.

When any of these sources of mapping change, the RBridge makes the
appropriate change in its forwarding tables. You "remove learned L2
entries" on a different basis for different sources. For data plane
learning, it is timeout. For ESADI, it is state flooding. Etc.

> 2>     when to remove ESADI instance neighbor on receiving ESADI-LSP?

I think the mechanisms for recognizing ESADI instance neighbors in the
current draft are too complicated and can probably be simplified as
well as clarified.

Thanks,
Donald
=============================
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 155 Beaver Street, Milford, MA 01757 USA
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