hao-trill-analysis-active-active-02.txt

Internet DRAFT - draft-hao-trill-analysis-active-active

draft-hao-trill-analysis-active-active

Last Version:	draft-hao-trill-analysis-active-active-02.txt	Tracker Entry
Date:	`20-May-2014`
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Previous Versions:	draft-hao-trill-analysis-active-active-01.txt (diff) - 14-Feb-2014

TRILL Weiguo Hao
Yizhou Li
Donald Eastlake
Internet Draft Huawei
S. Hares
Hickory Hill Consulting
Muhammad Durrani
Brocade
H. Zhai
ZTE Corporation

Intended status: Informational May 20,2014
Expires: November 2014

Analysis of Active-Active Connection Solutions
draft-hao-trill-analysis-active-active-02.txt

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Abstract

Draft [TRILL-Active-PS] lists basic problems which any active-active
solutions should address, these problems include frame duplications,
loop, MAC address flip-flop and unsynchronized information among
member RBridges. For each problem, there may be multiple ways to
deal with it. Some solutions solve all or most of the problems

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listed, and at the same time introduces extra issues. This draft
tries to analyze and compare the different solutions for each of the
issues, gives a brief summary on the pros and cons, and/or the
applicable scenarios.

Table of Contents

1. Introduction ................................................ 3
2. Conventions used in this document............................ 5
3. Frame duplications .......................................... 5
4. Loop ........................................................ 6
4.1. Independent nickname allocation......................... 7
4.2. Consistent nickname allocation per MC-LAG............... 7
4.3. Consistent nickname allocation per edge group RBridges...8
4.4. Comparison ............................................. 9
5. Address flip-flop ........................................... 9
5.1. Data plane learning mode................................ 9
5.1.1. CMT .............................................. 10
5.1.2. Centralized replication........................... 11
5.1.3. Tunneling among edge RBs.......................... 12
5.1.4. Comparison........................................ 13
5.2. Control plane learning mode............................ 14
6. Unsynchronized information among member RBridges............ 14
6.1. RBridge channel based communication protocol........... 15
6.2. TRILL LSP extension.................................... 15
6.3. ESADI extension........................................ 15
6.4. Comparison ............................................ 15
7. Solution summary ........................................... 16
8. Security Considerations..................................... 17
9. IANA Considerations ........................................ 17
10. References ................................................ 18
10.1. Normative References.................................. 18
10.2. Informative References................................ 18

1. Introduction

The IETF TRILL (Transparent Interconnection of Lots of Links)
[RFC6325] protocol provides loop free and per hop based multipath
data forwarding with minimum configuration. TRILL uses IS-IS
[RFC6165] [RFC6326bis] as its control plane routing protocol and
defines a TRILL specific header for user data.

Classic Ethernet(CE) devices typically are multi-homed to multiple
edge RBridges which form an edge group. All of the uplinks of CE are
bundled as a Multi-Chassis Link Aggregation (MC-LAG). An active-
active flow-based load sharing mechanism is normally implemented to

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achieve better load balancing and high reliability. A CE device can
be a layer 3 end system by itself or a bridge switch through which
layer 3 end systems access to TRILL campus.

Draft [TRILL-Active-PS] lists the following problems which any
active-active solution should address:

+------+
| CEx |
+------+
|
+------+
|(RBx) |
+------+
|
-------------------
/ \

| |
| TRILL Campus |
| |
\ /
--------------------
| | |
-------- | --------
| | |
+------+ +------+ +------+
|(RB1) | |(RB2) | | (RBk)|
+------+ +------+ +------+
| | | |
| -----------| |------ |
| |LAG1 LAG2 | |
+------+ +------+
| CE1 | | CE2 |
+------+ +------+
Figure 1 TRILL Active-Active Access Scenario

1. Frame duplications

2. Loop

3. Address flip-flop

4. Unsynchronized information among member RBridges

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For each problem, there may be multiple ways to deal with it. And
some solutions solve all or most of the problems listed, and at the
same time introduces extra issues. This draft tries to analyze and
compare the different solutions for each of the issue, gives a brief
summary on the pros and cons, and/or the applicable scenarios. The
co-authors believe such analysis is helpful to design a more
completed solution in future.

2. Conventions used in this document

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL
NOT","SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in
this document are to be interpreted as described in RFC 2119
[RFC2119].

The acronyms and terminology in [RFC6325] is used herein with the
following additions:

BUM - Broadcast, Unknown unicast, and Multicast.

CE - Refer to [CMT]. The device can be either physical or virtual
equipment.

CMT - Coordinated Multicast Trees [CMT].

Edge group - a group of edge RBridges to which at least one CE is
multiply attached using MC-LAG. When multiple CEs attach to the
exact same set of edge RBridges, those edge RBridges can be
considered as a single edge group. One RBridge can be in more than
one edge group.

LACP - Link Aggregation Control Protocol.

LAG - Link Aggregation, as specified in [8021AX].

3. Frame duplications

Problem:

Frame duplication may occur when a remote host sends multi-
destination frame to a local CE which has an active-active
connection to the TRILL campus.

Solution:

To avoid local CE receiving multiple copies from a remote RBridge,
the designated forwarder (DF) mechanism should be supported. DF

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election mechanism allows only one port in one RB of a MC-LAG to
forward multicast traffic from TRILL campus to local access side for
each VLAN. The basic idea of DF is to elect one RBridge per VLAN
from an edge group to be responsible for egressing the multicast
traffic.

Each RB in an edge group elects a DF using same algorithm which
guarantees the same RB elected as DF per MC-LAG per VLAN. [draft-
hao-trill-dup-avoidance-active-active-00] describes the detail DF
mechanism and TRILL protocol extension for DF election. The RB that
is elected as a DF for a given VLAN will forward multi-destination
traffic in the egress direction towards the CE. All non-DF RBs drop
multi-destination traffic in the egress direction towards the CE.
All edge RBs, including DF and non-DF, can ingress the traffic to
TRILL campus as usual. As DF election is based on VLAN, DF ports for
different VLANs can be on different edge RBs. Thus egress bound
multicast traffic can be load balanced among multiple edge RBridges
in an edge group on per VLAN basis.

4. Loop

Problem:

If a CE sends a broadcast, unknown unicast, or multicast (BUM)
packet through DF port to a ingress RB, the RB will forward that
packet to all or subset of the other RBridges that only have non-DF
ports for that MC-LAG. Because BUM traffic forwarding to non-DF port
isn't allowed, in this case the frame won't loop back to the CE.

If a CE sends a BUM packet through non-DF port to a ingress RB, say
RB1, then RB1 will forward that packet through TRILL campus to DF
RBridge for the MC-LAG. In this case the frame will loop back to the
CE.

Solution:

A traffic split-horizon filtering mechanism should be used to avoid
looping back among RBridges in a edge group.

Split-horizon mechanism relies on ingress nickname to check if a
packet's egress port belongs to same MC-LAG with the packet's
incoming port to TRILL campus. The following sections describe
different nickname allocation schemes:

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4.1. Independent nickname allocation

Each ingress RBridge allocates a unique nickname for each MC-LAG
independently. It is not required that the nickname provisioned on
all involved edge RBridges remains the same for one corresponding
MC-LAG.

When the ingress RBridge receives BUM traffic from an active-active
accessing CE device, the traffic will be injected into TRILL campus,
ingress nickname is the allocated unique nickname on ingress RB.

When an egress RBridge receives the BUM traffic from the TRILL
campus, it checks the ingress nickname in the TRILL header and
filters out the traffic on all local interfaces connected to the
same CE. Each egress RBridge should track the nickname(s) associated
with the other RBridge(s) with which it has a shared multi-homed LAG.
The solution has limited nickname allocation scalability issue,
because each RBridge needs allocate per nickname per MC-LAG.

4.2. Consistent nickname allocation per MC-LAG

Edge RBridges forming an MC-LAG in an edge group are assigned a
globally unique pseudo-nickname. If multiple MC-LAGs exist, edge
BRridges for each individual MC-LAG should be assigned such a
pseudo-nickname. It should be guaranteed that pseudo-nickname
provisioned on all involved edge RBridges remains the same for one
corresponding MC-LAG.

When a ingress RBridge receives traffic from a active-active
accessed CE, it performs TRILL encapsulation with the pseudo-
nickname as ingress nickname. When the traffic comes to each egress
RBridge, the egress RBridge checks ingress nickname in TRILL header
and filters out the traffic on all local interfaces connected to the
same CE. Each egress RBridge relies on the pseudo-nickname to filter
out the frame on all local interfaces connected to the same CE.

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4.3. Consistent nickname allocation per edge group RBridges

+-----------+
| (RB4) |
+-----------+

| | |
-------- | --------
| | |
+------+ +-------+ +------+
|(RB1) | | (RB2) | | (RB3)|
+------+ +-------+ +------+
* | * | ^ * | ^
* | * | ^^^^^^^^^^^^^^^^
* ----------*--------------*-| ^
****************************** | ^
MC-LAG1 * MC-LAG2 | MC-LAG3 ^
+------+ +------+ +------+
| CE1 | | CE2 | | CE3 |
+------+ +------+ +------+
Figure 2 Consistent nickname allocation per edge group RBridges
scenario

An edge group forming one or multiple MC-LAGs is assigned a globally
unique pseudo-nickname. All MC-LAGs corresponding to the edge group
share same pseudo-nickname to save nickname space. It should be
guaranteed that pseudo-nickname provisioned on all involving edge
RBridges in an edge group remains same.

In above figure 2,CE1 and CE2 are active-active accessed to RB1,RB2
and RB3,CE3 is active-active accessed to RB2 and RB3. Globally
unique pseudo-nickname of p-nick1 is assigned to the edge group
which contains RB1,RB2 and RB3, p-nick2 is assigned to the edge
group which contains RB2 and RB3. P-nick1 is used for MC-LAG1 and
MC-LAG2, p-nick2 is used for MC-LAG3.As only one pseudo-nickname is
assigned for MC-LAG1 and MC-LAG2, so nickname consumption is lower
than the consistent nickname allocation method per MC-LAG.

If one or more CE's uplinks occur link failure, the CE will connect
to new edge group RBs. At this time, the CE will use new pseudo-
nickname corresponding to the new edge group as ingress nickname.

Take the topology shown in figure 2 as example. If the link between
CE1 and RB1 fails, CE1 will connect to the edge group which contains
RB2 and RB3 only. Then p-nick2 will be used as ingress nickname for
CE1. If RB1 encounters node failure, both CE1 and CE2 will connect

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to the rest edge RBs which are RB2 and RB3. Then p-nick2 is used as
ingress nickname for all of CE1, CE2 and CE3.

To enhance network convergence, access link failure and edge node
failure should be detected by each edge RBridge in a edge group as
fast as possible.

4.4. Comparison

+----------------------+------------------------------------+----------------------------+----------------------------+

+----------------------+------------------------------------+----------------------------+----------------------------+

+----------------------+------------------------------------+----------------------------+----------------------------+

+----------------------+------------------------------------+----------------------------+----------------------------+

5. Address flip-flop

MAC learning in TRILL can be performed either in data plane or
control plane. When a local host h1 attaches to multiple edge
RBridges, learning at the remote host for h1 may have MAC flip-flop
problem.

There are different ways to avoid this for data plane learning and
control plane learning scenarios.

5.1. Data plane learning mode

Problem:

For data plane learning mode, to avoid mac address flip-flop on
remote RBs, a pseudo-nickname [TRILLPN] solution was proposed. The
basic idea is to use a virtual RBridge of RBv with a single pseudo-
nickname to represent an edge group that MC-LAG connects to. Any
member RBridge of that edge group should use this pseudo-nickname
rather than its own nickname as ingress nickname when it injects
TRILL data frames to TRILL campus. The use of the nickname solves

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the address flip flop issue by making the MAC address learnt by the
remote RBridge bound to pseudo-nickname.

If DF-election mechanism is used for frame duplication prevention,
access ports on an RB are categorized as three types: non mc-lag,
mc-lag DF port and mc-lag non-DF port. The last two types can be
called mc-lag port. For each of the mc-lag port, there is a pseudo-
nickname associated. If consistent nickname allocation per edge
group RBridges is used, it is possible that same pseudo-nickname
associated to more than one port on a single RB. A typical scenario
is that CE1 is connected to RB1 & RB2 by mc-lag1 while CE2 is
connected to RB1 & RB2 by mc-lag 2. In order to save the number of
pseudo-nickname used, member ports for both mc-lag1 and mc-lag2 on
RB1 & RB2 are all associated to pseudo-nickname pn1.

On the other hand, pseudo-nickname introduces another issue, which
is incorrect packet drop by RPF check failure. Due to edge RBridges
which use a pseudo-nickname other than own nicknames as the ingress
nickname (Eg. Nick-Y) when the RBbridge forwards BUM traffic from
local CE, the traffic will be treated by an RBridge (RBn) sitting
between the ingress RB and distribution tree root as traffic whose
ingress point is RBv. If same distribution tree is used by these
different edge RBridges, the traffic may arrive at RBn from
different ports. Then the RPF check fails, and some of the traffic
receiving from unexpected ports will be dropped by RBn.

Solutions:

To overcome the RPF check failure issue, the following three
solutions have been proposed: CMT, centralized replication and
tunneling among edge RBs. For local replication behavior on the
ingress RBridge, CMT, centralized replication and tunneling among
edge RBs solutions should consider all the above access ports type
and may be different. The following subsections will give more
details.

5.1.1. CMT

CMT [CMT] solution allows edge RBridges to specify different
distribution trees to forward BUM traffic from a connecting CE
device by using a new IS-IS Affinity sub-TLV. Remote RBridges
calculate their forwarding tables and derive the RPF for
distribution trees based on the distribution tree association
advertisements. The BUM traffic injected to TRILL campus by ingress
RB will not return to ingress RB again.

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When an ingress RBridge of RB1 receives BUM traffic from an active-
active accessing CE1 device, local replication behavior on RB1 is as
follows:

1. Local replication to non mc-lag ports as per RFC6325.

2. Local replication to the ports associated with the same pseudo-
nickname as that associated to the incoming port as per RFC6325.

3. Local replication to the mc-lag DF port associated with different
pseudo-nickname as per RFC6325. Do not replicate to mc-lag non-DF
port associated with different pseudo-nickname.

The above local forwarding behavior on the ingress RB of RB1 can be
called CMT local forwarding behavior.

In this solution, it's required to establish multiple distribution
trees in a TRILL campus, i.e. if a CE is active-active accessed to 4
edge RBridges, at least 4 distribution trees are required. No
hardware upgrade is needed for RBridges in the TRILL campus, only
software upgrade is needed.

5.1.2. Centralized replication

The solution has all ingress RBs send BUM traffic receiving from
local active-active connecting CE to a centralized node via unicast
TRILL encapsulation. When the centralized node receives the BUM
traffic, it decapsulates the traffic and forwards the BUM traffic to
all destination RBs using a distribution tree established via the
TRILL base protocol. To avoid RPF check failure on a RBridge sitting
between the ingress RBridge and the centralized replication node,
some change of RPF calculation algorithm is required. RPF
calculation on each RBridge should use the centralized node as
ingress RB instead of the real ingress RBridge of RBv to perform the
calculation. The BUM traffic injected to TRILL campus by ingress RB
will return to the ingress RB via distribution tree established as
per TRILL base protocol. [draft-hao-trill-centralized-replication-00]
describes the detail centralized replication solution.

When the ingress RBridge of RB1 receives BUM traffic from an active-
active accessing CE1 device, one copy of the traffic is forwarded
locally to other CE devices connecting via MC-LAG ports that share
same pseudo-nickname with the port connecting to CE1, another copy
of the traffic will be sent to a centralized node via unicast TRILL
encapsulation. Then it is replicated and forwarded to all
destination RBridges including RB1 itself along TRILL distribution
tree established as per TRILL base protocol. When RB1 receives the

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TRILL multicast traffic, it will decapsulate TRILL encapsulation and
forward it to all local CE devices except CE1, if these CE devices
connect to RB1 via non-MC-LAG ports and MC-LAG DF ports. For other
CE devices which are connected to RB1 via MC-LAG non-DF ports, the
traffic will be dropped and will not be forwarded to these CEs.

In summary, local replication behavior on RB1 is as follows:

1. Local replication to the ports associated with the same pseudo-
nickname as that associated to the incoming port as per RFC6325.

2. Do not replicate to mc-lag port associated with different pseudo-
nickname.

3. Do not replicate to non mc-lag ports.

The above local forwarding behavior on the ingress RB of RB1 can be
called centralized local forwarding behavior it is different from
CMT local forwarding behavior.

If ingress RB of RB1 itself is the centralized node, BUM traffic
injected to TRILL campus won't loop back to RB1. In this case, the
local forwarding behavior is same with CMT local forwarding behavior.

In this solution, it's required to consume more network bandwidth
between ingress RB and distribution tree root node than CMT solution.
Both hardware and software upgrade are required on edge RBs
participating in active-active connection and the distribution tree
root node. This solution doesn't require multiple distribution trees
in TRILL campus.

5.1.3. Tunneling among edge RBs

This solution allows only a selected edge RBridge in an edge group
participating in active-active access to be responsible for
forwarding BUM traffic from connecting CE to TRILL campus along
distribution tree per TRILL base protocol. All other edge RBridges
in the edge group send BUM traffic from connecting CE to the
selected edge RBridge through unicast TRILL encapsulation. When the
selected edge RBridge receives unicast TRILL traffic from RB1 in a
same edge group, the selected RBridge decapsulates the unicast TRILL
packet. Then it forwards the BUM traffic through TRILL multicast
encapsulation to TRILL campus along distribution tree established as
per TRILL protocol.

The traffic will reach all destination RBridges and will loop back
to ingress RBridge of RB1 similar to the above centralized

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replication solution, so local forwarding behavior on RB1 is same
with the centralized local forwarding behavior.

If ingress RBridge of RB1 is selected RBridge, the BUM traffic that
is injected into TRILL campus won't loop back to RB1, the local
forwarding behavior is same with the CMT local forwarding behavior.

In this solution, it's required to consume more network bandwidth
among edge RBs. Both hardware and software upgrade are required on
edge RBs participating active-active connection. This solution only
needs one distribution tree in TRILL campus.

5.1.4. Comparison

Data Plane Mode:

+------------------------+---------+--------------------------+----------------------------+

+------------------------+---------+--------------------------+----------------------------+

|for N-active scenario | N | 1 | 1 |

+------------------------+---------+--------------------------+----------------------------+

+------------------------+---------+--------------------------+----------------------------+

+------------------------+---------+--------------------------+----------------------------+

+------------------------+---------+--------------------------+----------------------------+

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+------------------------+---------+--------------------------+----------------------------+

5.2. Control plane learning mode

If a CE device is multi-homed to multiple edge RBs in active-active
mode, each edge RB should announce the MAC of its attached end
systems to all other RBs through ESADI-like control protocol. Remote
RBriges will learn the MAC association with different ingress RB
nicknames and generate multiple MAC forwarding entries in ECMP mode.
All edge RBs should disable the data plane MAC learning function.
MAC to nickname association should be learned only through the
control plane.

Pseudo-nickname mechanism was basically designed to avoid MAC
address learning flip-flop when a MAC address could be learnt to
more than one RBridge. With control plane MAC learning, pseudo-
nickname is not required since multiple mac to nickname entries can
be leaned for the same MAC. The problem of RPF check failure for
multicast frame caused by pseudo-nickname mechanism is not an issue
here.

In the control plane MAC learning solution, if an edge RB
participating TRILL active-active access receives BUM traffic from
connecting CE device, it uses its own nickname as ingress nickname
instead of pseudo-nickname to ingress data frame into a TRILL campus.

This method requires hardware and software changes.

6. Unsynchronized information among member RBridges

Problem:

A local Rbridge, say RB1 in MC-LAG1, may have learned a VLAN and MAC
to nickname correspondence for a remote host h1 when h1 sends a
packet to CE1. The returning traffic from CE1 may go to any other
member RBridge of MC-LAG1, for example RB2. To avoid always flooding
for unicast traffic on RB2, MAC address should be synchronized among
the edge RBridges in a edge group.

To ensure DF election consistency, dynamic joined VLAN through VLAN
registration protocol (VRP) (GVRP or MVRP) and multicast group
through IGMP or MLD protocol should be synchronized among all
RBridges in a edge group.

Solution:

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Synchronization mechanism should be provided to ensure information
consistency among all edge RBridges in a edge group. Three
synchronization solutions as follows are provided.

6.1. RBridge channel based communication protocol

RBridge channel based communication protocol among all RBridges in a
edge group is introduced to implement synchronization. The
communication protocol is restricted to RBridge nodes in each edge
group, other RBridges in TRILL campus needn't involve. A new type of
RBridge Channel message should be given by a Protocol field in the
RBridge Channel Header to indicate synchronization information in
the payload. RBridge channel message is forwarded through TRILL data
plane. Transmission delay is relatively low.

6.2. TRILL LSP extension

TRILL LSP can be extended to implement synchronization among all
edge RBridges. Synchronization information is conveyed through new
TLVs or sub-TLVs in TRILL LSP. Because TRILL LSP is flooded to all
RBridges in TRILL campus, so it may cause campus wide fluctuation.
TRILL LSP is forwarded through control plane. Transmission delay is
relatively high.

6.3. ESADI extension

TRILL ESADI can be extended to implement synchronization among all
edge RBridges. Currently ESADI only support MAC synchronization, it
doesn't support VLAN and multicast group information synchronization.
Similar to the solution of RBridge channel based communication
protocol, ESADI message is forwarded through TRILL data plane.
Transmission delay is relatively low.

6.4. Comparison

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+----------------------+------------------------------------+----------------------------+----------------------------+

+----------------------+------------------------------------+----------------------------+----------------------------+

+----------------------+------------------------------------+----------------------------+----------------------------+

+----------------------+------------------------------------+----------------------------+----------------------------+

7. Solution summary

The possible mechanisms for each individual problem listed in
[TRILAA] are described and compared in this document. The readers
can compile a complete solution from these mechanisms.

If there are multiple mechanisms for an individual problem, the
readers can picked up the most appropriate one based on the scenario.
For example, to solve MAC address flip-flop problem, if control
plane learning is not possibly supported, pseudo-nickname mechanism
via data plane MAC learning should be used.

When a mechanism is used to solve an individual problem, other
additional issues may be introduced and a complete solution should
be carefully designed to solve those non-generic issues. For example,
when pseudo-nickname mechanism is used to solve MAC address flip-
flop problem, RPF check failure issue is incurred. Three mechanisms,
CMT, centralized replication and tunneling among edge RBs, can be
used to solve the RPF check failure issue. If any one of them is
used, local forwarding behavior on ingress RBridges should be
carefully designed to ensure BUM traffic not duplicated or looped to
ingress RBridge's local connecting CE devices.

In summary, the candidate mechanism for each of the problem is
listed as follows.

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+----------------------+-----------------------------------------------------------------+

| Problem | Mechanisms |

+----------------------+-----------------------------------------------------------------+

| Frame duplication | DF election |

+----------------------+---------------------------------------+-------------------------+

| Loop | Data plane MAC learning | Control plane |

| | | MAC learning |

| |---------------------------------------+-------------------------+

+----------------------+---------------------------------------+-------------------------+

+----------------------+------------------------+--------------+--+----------------------+

+----------------------+------------------------+-----------------+----------------------+

8. Security Considerations

This draft does not introduce any extra security risks. For general
TRILL Security Considerations, see [RFC6325].

9. IANA Considerations

This document requires no IANA Actions. RFC Editor: Please remove
this section before publication.

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10. References

10.1. Normative References

[1] [RFC6165] Banerjee, A. and D. Ward, "Extensions to IS-IS
for Layer-2 Systems", RFC 6165, April 2011.

[2] [RFC6325] Perlman, R., et.al. "RBridge: Base Protocol
Specification", RFC 6325, July 2011.

[3] [RFC6326bis] Eastlake, D., Banerjee, A., Dutt, D., Perlman,
R., and A. Ghanwani, "TRILL Use of IS-IS", draft-eastlake-
isis-rfc6326bis, work in progress.

10.2. Informative References

[4] [TRILAA] Li,Y., et.al., " Problem Statement and Goals for
Active-Active TRILL Edge ", draft-ietf-trill-active-active-
connection-prob-03, Work in progress, May 2014.

[5] [TRILLPN] Zhai,H., et.al., "RBridge: Pseudonode Nickname",
draft-hu-trill-pseudonode-nickname, Work in progress, November

2011.

[6] [CMT] [CMT] Senevirathne, T., Pathangi, J., and J. Hudson,

"Coordinated Multicast Trees (CMT)for TRILL", draft-ietf-
trill-cmt-03.txt Work in Progress, April 2014

[7] [RFC7178] - D. Eastlake, V. Manral, L. Yizhou, S. Aldrin, D.
Ward, "Transparent Interconnection of Lots of Links (TRILL):

RBridge Channel Support", RFC7178, May 2014.

[8] [RFC6439] Perlman, R., Eastlake, D., Li, Y., Banerjee, A., and
F. Hu, "Routing Bridges (RBridges): Appointed Forwarders", RFC
6439, November 2011.

[9] [ESADI] H. Zhai, F. Hu, et al, "TRILL (Transparent
Interconnection of Lots of Links): ESADI (End Station Address
Distribution Information) Protocol", draft-ietf-trill-esadi-
05.txt, February 2014, working in progress.

Hao & Li Expires November 20, 2014 [Page 18]

Internet-Draft Analysis of Active-Active connection May 2014

Authors' Addresses

Weiguo Hao
Huawei Technologies
101 Software Avenue,
Nanjing 210012
China
Phone: +86-25-56623144
Email: haoweiguo@huawei.com

Yizhou Li
Huawei Technologies
101 Software Avenue,
Nanjing 210012
China
Phone: +86-25-56625375
Email: liyizhou@huawei.com

Susan Hares
Hickory Hill Consulting
7453 Hickory Hill
Saline, CA 48176
USA
Email: shares@ndzh.com

Muhammad Durrani
Brocade communications Systems, Inc
mdurrani@Brocade.com

Hongjun Zhai
ZTE Corporation
68 Zijinghua Road
Nanjing 200012 China

Phone: +86-25-52877345
Email: zhai.hongjun@zte.com.cn

Hao & Li Expires November 20, 2014 [Page 19]