H3C S5830V2 series User manual

H3C S5830V2 & S5820V2 Switch Series
TRILL Configuration Guide
Hangzhou H3C Technologies Co., Ltd.
http://www.h3c.com
Software version: Release 23xx
Document version: 6W102-20150315

Copyright © 2014-2015, Hangzhou H3C Technologies Co., Ltd. and its licensors
All rights reserved
No part of this manual may be reproduced or transmitted in any form or by any means without prior
written consent of Hangzhou H3C Technologies Co., Ltd.
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SecEngine, SecPath, SecCenter, SecBlade, Comware, ITCMM and HUASAN are trademarks of
Hangzhou H3C Technologies Co., Ltd.
All other trademarks that may be mentioned in this manual are the property of their respective owners
Notice
The information in this document is subject to change without notice. Every effort has been made in the
preparation of this document to ensure accuracy of the contents, but all statements, information, and
recommendations in this document do not constitute the warranty of any kind, express or implied.

Preface
The H3C S5830V2 & S5820V2 documentation set includes 16 configuration guides. These guides
describe the software features for the H3C S5830V2 & S5820V2 Switch Series and guide you through
the software configuration procedures. These guides also provide configuration examples to help you
apply software features to different network scenarios.
The TRILL Configuration Guide describes the background, fundamentals, and configuration of TRILL.
This preface includes:
•Audience
•Added and modified features
•Conventions
•About the H3C S5830V2 & S5820V2 documentation set
•Obtaining documentation
•Technical support
•Documentation feedback
Audience
This documentation is intended for:
•Network planners
•Field technical support and servicing engineers
•Network administrators working with the S5830V2 & S5820V2 series
Added and modified features
Release 2311P05 does not contain any changes to TRILL over Release 2311P04.
Release 2311P04 does not contain any changes to TRILL over Release 2310.
Release 2310 does not contain any changes to TRILL over Release 2307.
Release 2307 contains the following changes to TRILL over Release 2210:

Configuration guide Added and modified features
TRILL
Added features:
•Fast switching the root of a TRILL distribution tree
•Configuring the system ID and nickname for an RB
•Configuring the link cost for a TRILL port
•Configuring the designated VLANs for exchanging TRILL frames
•Configuring the maximum length of an LSP originated by an RB
•Configuring the maximum length of an LSP that can be received by an RB
•Setting the Overload bit of LSPs and setting the lifetime for the set Overload bit
•Setting the SPF calculation interval for TRILL
•Configuring the maximum number of TRILL unicast equal-cost routes
•Configure SNMP for TRILL
•Displaying the TRILL unicast routing table for the specified RB
Conventions
This section describes the conventions used in this documentation set.
Command conventions
Convention Description
Boldface Bold text represents commands and keywords that you enter literally as shown.
Italic Italic text represents arguments that you replace with actual values.
[ ] Square brackets enclose syntax choices (keywords or arguments) that are optional.
{ x | y | ... }
Braces enclose a set of required syntax choices separated by vertical bars, from
which you select one.
[ x | y | ... ]
Square brackets enclose a set of optional syntax choices separated by vertical bars,
from which you select one or none.
{ x | y | ... } *
Asterisk marked braces enclose a set of required syntax choices separated by
vertical bars, from which you select at least one.
[ x | y | ... ] *
Asterisk marked square brackets enclose optional syntax choices separated by
vertical bars, from which you select one choice, multiple choices, or none.
&<1-n> The argument or keyword and argument combination before the ampersand (&)
sign can be entered 1 to n times.
# A line that starts with a pound (#) sign is comments.
GUI conventions
Convention Description
Boldface Window names, button names, field names, and menu items are in Boldface. For
example, the New User window appears; click OK.
> Multi-level menus are separated by angle brackets. For example, File > Create >
Folder.

Symbols
Convention Description
WARNING An alert that calls attention to important information that if not understood or
followed can result in personal injury.
CAUTION
An alert that calls attention to important information that if not understood or
followed can result in data loss, data corruption, or damage to hardware or
software.
IMPORTANT An alert that calls attention to essential information.
NOTE An alert that contains additional or supplementary information.
TIP An alert that provides helpful information.
Network topology icons
Represents a generic network device, such as a router, switch, or firewall.
Represents a routing-capable device, such as a router or Layer 3 switch.
Represents a generic switch, such as a Layer 2 or Layer 3 switch, or a router that
supports Layer 2 forwarding and other Layer 2 features.
Port numbering in examples
The port numbers in this document are for illustration only and might be unavailable on your switch.
About the H3C S5830V2 & S5820V2
documentation set
The H3C S5830V2 & S5820V2 documentation set includes:
Category Documents Purposes
Product description and
specifications Marketing brochures Describe product specifications and benefits.

Category Documents Purposes
Hardware specifications and
installation
Compliance and safety manual
Provides regulatory information and the
safety instructions that must be followed
during installation.
Installation quick start Provides basic installation instructions.
Installation guide
Provides a complete guide to hardware
installation and hardware
specifications.
H3C LSWM1HFANSC &
LSWM1HFANSCB Fan
Assemblies Installation
Provides the physical views,
specifications, installation procedures,
and removal procedures for
hot-swappable fan assemblies.
H3C LSVM1FANSC &
LSVM1FANSCB Fan Assemblies
Installation
Provides physical views, specifications,
installation procedures, and removal
procedures for hot-swappable fan
assemblies.
H3C SFP/SFP+/XFP
Transceiver Modules Installation
Guide
Describes the installation and
replacement procedures for
SFP/SFP+/XFP transceiver modules.
H3C LSVM1AC650 &
LSVM1DC650 Power Modules
User Manual
Provides the physical views,
specifications, installation procedures,
and removal procedures for the
LSVM1AC650 and LSVM1DC650
power modules.
H3C LSVM1AC300 &
LSVM1DC300 Power Modules
User Manual
Provides the physical views,
specifications, installation procedures,
and removal procedures for the
LSVM1AC300 and LSVM1DC300
power modules.
Software configuration
Configuration guides Describe software features and
configuration procedures.
Command references Provide a quick reference to all
available commands.
Operations and maintenance
MIB Companion Describes the MIBs for the software
release.
Release notes Provide information about the product
release and software upgrading.
Obtaining documentation
Access the most up-to-date H3C product documentation on the World Wide Web
at http://www.h3c.com.
Click the links on the top navigation bar to obtain different categories of product documentation:
[Technical Support & Documents > Technical Documents]—Provides hardware installation, software
upgrading, and software feature configuration and maintenance documentation.

[Products & Solutions]—Provides information about products and technologies, as well as solutions.
[Technical Support & Documents > Software Download]—Provides the documentation released with the
software version.
Technical support
servic[email protected]
http://www.h3c.com
Documentation feedback
You can e-mail your comments about product documentation to [e-mail].
We appreciate your comments.

i
Contents
Configuring TRILL·························································································································································· 1
Overview············································································································································································1
Basic concepts ··························································································································································1
TRILL frame formats···················································································································································1
How TRILL works·······················································································································································3
TRILL forwarding mechanisms ·································································································································3
Protocols and standards ··········································································································································5
Configuration restrictions and guidelines·······················································································································5
TRILL configuration task list···············································································································································6
Enabling TRILL····································································································································································6
Configuration restrictions and guidelines ··············································································································6
Configuration procedure ·········································································································································7
Configuring the system ID and nickname for an RB······································································································8
Configuring the link type of a TRILL port·························································································································8
Configuring the DRB priority of a TRILL port···················································································································9
Configuring the link cost for a TRILL port························································································································9
Configuring the announcing VLANs and designated VLAN ····················································································· 10
Configuring TRILL timers ················································································································································ 11
Adjusting LSP parameters·············································································································································· 11
Adjusting the SPF algorithm parameters······················································································································ 13
Configuring the TRILL unicast equal-cost routes··········································································································· 13
Configuring TRILL distribution trees ······························································································································ 14
Enabling logging of TRILL neighbor changes·············································································································· 15
Configuring SNMP for TRILL·········································································································································· 15
Configuring TRILL GR ····················································································································································· 16
Displaying and maintaining TRILL································································································································· 16
TRILL configuration example·········································································································································· 17
Network requirements··········································································································································· 17
Configuration procedure ······································································································································ 18
Verifying the configuration··································································································································· 20
Index ···········································································································································································22

1
Configuring TRILL
Transparent Interconnect of Lots of Links (TRILL) uses IS-IS to provide transparent Layer 2 forwarding.
TRILL requires a license. For information about feature licensing, see Fundamentals Configuration Guide.
Overview
TRILL combines the simplicity and flexibility of Layer 2 switching with the stability, scalability, and rapid
convergence capability of Layer 3 routing. All these advantages make TRILL very suitable for large flat
Layer 2 networks in data centers.
Basic concepts
•RBridge—Routing bridge (RB) that runs TRILL. RBs are classified into ingress RBs, transit RBs, and
egress RBs, depending on their positions in the TRILL network. A frame enters the TRILL network
through an ingress RB, travels along transit RBs, and leaves the TRILL network through an egress RB,
as shown in Figure 2.
•TRILL network—A Layer 2 network comprised of RBs, as shown in Figure 3.
•System ID—Unique identifier of an RB in the TRILL network. The system ID is 6-byte.
•Nickname—Address of an RB in the TRILL network. The nickname is 2-byte.
•Link State Database—The LSDB contains all link state information in the TRILL network.
•Link State Protocol Data Unit—An LSP describes local link state information and is advertised
between neighbor devices.
•Designated Routing Bridge (DRB)—Similar to the designated IS (DIS) in IS-IS, a DRB exists in the
broadcast network. It helps simplify network topology, and appoints AVFs and appointed ports for
the VLANs on each RB in the broadcast network.
•Appointed VLAN-x Forwarder (AVF) and appointed port—To avoid loops, TRILL requires all the
traffic of a VLAN on a broadcast network to enter and leave the TRILL network through the same
port of an RB. The RB is the AVF of the VLAN, and the port is the appointed port.
For more information about LSDB, LSPDU, and DIS, see Layer 3—IP Routing Configuration Guide.
TRILL frame formats
TRILL frames include control frames and data frames.
TRILL control frames include TRILL Hello, LSP, CSNP, PSNP, MTU-probe, and MTU-ack. These control
frames use 802.1Q encapsulation, and have a fixed destination multicast address 0180-C200-0041.
TRILL data frames have a specific format, as shown in Figure 1. A TRILL header and an outer Ethernet
header are added to the original Ethernet frame.

2
Figure 1 TRILL data frame format
Table 1 describes the fields in the TRILL header.
Table 1 TRILL header fields
Field Descri
p
tion
Ethertype The Ethertype is fixed to TRILL.
V Version number, which is 0. When an RB receives a TRILL frame, it checks the V
field and drops the frame if the Vfield is not 0.
R Reserved for future extension. An ingress RB sets the R field to 0when adding a
TRILL header. Transit RBs and egress RBs ignore the field.
M
Multi-destination attribute:
•0—Known unicast frame.
•1—Multicast, broadcast, or unknown unicast frame.
Op-Length Length of the Options field. 0indicates that the Options field does not exist.
Hop Count Hop count, which is used to avoid loops. An RB drops a TRILL frame whose hop
count is decremented to 0.
Egress RB Nickname Nickname of the egress RB.
Ingress RB Nickname Nickname of the ingress RB.
Options Options field. This field exists when the Op-Length field is non-zero.

3
How TRILL works
TRILL establishes and maintains adjacencies between RBs by periodically advertising Hello frames,
distributes LSPs among RB neighbors, and generates an LSDB for all RBs in the network. Based on the
LSDB, each RB uses the SPF algorithm to calculate forwarding entries destined to other RBs.
TRILL forwarding mechanisms
Different types of frames are forwarded using different forwarding mechanisms. The following sections
describe these mechanisms.
Unicast frame forwarding mechanism
As shown in Figure 2, a unicast frame is forwarded as follows:
1. When a unicast frame enters the TRILL network, the ingress RB encapsulates the original Ethernet
frame with a TRILL header (like an IP header) and an outer Ethernet header (like the Ethernet header
of a regular Ethernet frame).
2. RBs forward the frame hop by hop according to the egress RB nickname in the TRILL header to the
egress RB in the same way routers forward IP packets. Each hop replaces the outer Ethernet header
with an appropriate outer Ethernet header, and decrements the hop count in the TRILL header.
3. Upon receiving the TRILL frame, the egress RB de-encapsulates it to obtain the original Ethernet
frame, and sends the frame to the target device.
Figure 2 Unicast frame forwarding flow
The outer Ethernet header enables traditional Ethernet switches to forward TRILL frames and connect RBs.
Multi-destination frame forwarding mechanism
In a TRILL network, RBs do the following:
VLAN 10 VLAN 200 VLAN 300 VLAN 10
Ingress RB
RB 1
S1 S2
Ethernet frame TRILL frame TRILL frame Ethernet frame
Egress RB
RB 3
Transit RB
RB 2
Ingress RB = RB 1
Outer VLAN = 200
Egress RB = RB 3
Outer S-MAC = RB 1
Outer D-MAC = RB 2
Payload
Inner VLAN = 10
Inner S-MAC = S1
Inner D-MAC = S2
Ingress RB = RB 1
Outer VLAN = 300
Egress RB = RB 3
Outer S-MAC = RB 2
Outer D-MAC = RB 3
Payload
Inner VLAN = 10
Inner S-MAC = S1
Inner D-MAC = S2
Payload
Inner VLAN = 10
Inner S-MAC = S1
Inner D-MAC = S2
Payload
Inner VLAN = 10
Inner S-MAC = S1
Inner D-MAC = S2
Unicast frame

4
•Compute a TRILL distribution tree for each VLAN according to the LSDB.
•Use the TRILL distribution tree to guide the forwarding of multi-destination frames, which include
multicast, broadcast, and unknown unicast frames in the VLAN.
As shown in Figure 3,when a multicast frame from VLAN 10 enters the TRILL network, RB 1, which is an
ingress RB, encapsulates the multicast frame into a TRILL frame. In the frame, the egress RB is RB 2, the
root bridge of the TRILL distribution tree for VLAN 10. When the frame arrives at the root bridge, it is
distributed throughout the TRILL distribution tree. Then, the TRILL frame is de-encapsulated by RB 3 and
sent to the destination station S2. Because the network segment where RB 4 resides does not have a
receiver of this frame, RB 4 drops the frame.
Figure 3 Multicast frame forwarding flow
TRILL selects distribution trees for forwarding multicast, broadcast, and unknown unicast frames based on
the VLANs to which the frames belong. Because the topologies of TRILL distribution trees are different,
traffic can be load shared. However, equal-cost links are not used for load sharing.
When N equal-cost links exist in the network, each TRILL distribution tree selects the link with the largest
pseudonode ID for forwarding packets. As shown in Figure 4, two equal-cost links exist between RB 1
and RB 3. Assume the link directly connecting RB 1 to RB 3 has the largest pseudonode ID. Both the TRILL
distribution tree rooted at RB 3 and the TRILL distribution tree rooted at RB 4 select the link. For more
information about pseudonode IDs, see Layer 3—IP Routing Configuration Guide.
VLAN 10VLAN 10
S1 S2
VLAN 200
TRILL network
RB 1
Ethernet frame
Payload
Inner VLAN = 10
Inner S-MAC = S1
Inner D-MAC = Multi
TRILL frame
Ingress RB = RB 1
Outer VLAN = 200
Egress RB = RB 2
Outer S-MAC = RB 1
Outer D-MAC = All RBs
Payload
Inner VLAN = 10
Inner S-MAC = S1
Inner D-MAC = Multi
TRILL frame
Ingress RB = RB 1
Outer VLAN = 200
Egress RB = RB 2
Outer S-MAC = RB 2
Outer D-MAC = All RBs
Payload
Inner VLAN = 10
Inner S-MAC = S1
Inner D-MAC = Multi
RB 4
RB 3
Ethernet frame
Payload
Inner VLAN = 10
Inner S-MAC = S1
Inner D-MAC = Multi
RB 2
Multicast frame Distribution tree
of VLAN 10
Root bridge of
distribution tree
Leaf of
distribution tree

5
Figure 4 Multicast ECMP
TRILL distribution trees support Equal Cost Multiple Path (ECMP), also known as multicast ECMP. When
multicast ECMP is enabled, TRILL assigns equal-cost links to different TRILL distributions trees. This
improves the load sharing performance.
When N equal-cost links exist in the network, each TRILL distribution tree selects an equal-cost link for
forwarding packets through J mod N in root bridge priority order. J is the priority sequence number of a
TRILL distribution tree and starts from 0.
As shown in Figure 4:
•The link directly connecting RB 1 to RB 3 is assigned to the TRILL distribution tree rooted at RB 3.
•The link RB 1-RB 2-RB 3 is assigned to the TRILL distribution tree rooted at RB 4.
TRILL distribution trees support fast root switching. When an RB detects that the root of a distribution tree
is unreachable, the RB deletes the LSP of the root from its LSDB. This triggers recalculation of all
distribution trees in the TRILL network. Multicast, broadcast, and unknown unicast traffic is switched to
new distribution trees.
Protocols and standards
•RFC 6325: Routing Bridges (RBridges): Base Protocol Specification
•RFC 6326: Transparent Interconnection of Lots of Links (TRILL) Use of IS-IS
•RFC 6327: Routing Bridges (RBridges): Adjacency
•RFC 1195 : Use of OSI IS-IS for Routing in TCP/IP and Dual Environments
Configuration restrictions and guidelines
When you configure TRILL, follow these restrictions and guidelines:
•Configuration in Layer 2 Ethernet interface view takes effect on only the current port. Configuration
in Layer 2 aggregate interface view takes effect on the current interface and its member ports.
Configuration on a member port of an aggregate interface takes effect after the member port
leaves the aggregation group.
•To connect a spanning tree network to a TRILL network, make sure the following requirements are
met:
{The spanning tree protocol is disabled on the TRILL network.
{An edge port connects the spanning tree network to the TRILL network, and BPDU guard is
enabled on the edge port. This allows the port to transit to the forwarding state before DRB
election is finished and prevents multiple DRBs from being elected.
RB 1 RB 2
RB 3
RB 4
Cost=3
Cost = 1

6
For more information about spanning tree protocols, see Layer 2—LAN Switching Configuration
Guide.
•H3C recommends not enabling loop detection on TRILL ports, because TRILL networks prevent loops
from being generated. For more information about loopback detection, see Layer 2—LAN
Switching Configuration Guide.
•If IRF is used, retain the IRF bridge MAC address permanently. Otherwise, traffic interruption might
occur after an IRF split. For more information about IRF configuration, see IRF Configuration Guide.
•Do not configure the TPID for VLAN tags on RBs. For more information about TPIDs, see Layer
2—LAN Switching Configuration Guide.
•Do not connect multiple TRILL ports on an RB to the same link. Otherwise, these TRILL ports might be
elected as the AVFs of a VLAN at the same time because these TRILL ports cannot sense each other.
This will cause loops in the VLAN.
TRILL configuration task list
Tasks at a
g
lance
(Required.) Enabling TRILL
(Required.) Configuring the system ID and nickname for an RB
(Optional.) Configuring the link type of a TRILL port
(Optional.) Configuring the DRB priority of a TRILL port
(Optional.) Configuring the link cost for a TRILL port
(Optional.) Configuring the announcing VLANs and designated VLAN
(Optional.) Configuring TRILL timers
(Optional.) Adjusting LSP parameters
(Optional.) Adjusting the SPF algorithm parameters
(Optional.) Configuring the TRILL unicast equal-cost routes
(Optional.) Configuring TRILL distribution trees
(Optional.) Enabling logging of TRILL neighbor changes
(Optional.) Configuring SNMP for TRILL
(Optional.) Configuring TRILL GR
Enabling TRILL
After you enable TRILL on a port, TRILL can operate correctly by using default settings. A port with TRILL
enabled is called a "TRILL port."
Configuration restrictions and guidelines
When you enable TRILL, follow these guidelines:
•To enable TRILL on a port, first enable TRILL globally.

7
•Enable or disable TRILL on all ports in a VLAN, so that the ports in a VLAN have the same TRILL
status (enabled or disabled).
•Do not enable both TRILL and EVB on a port. The allowed VLAN list of a TRILL-enabled port cannot
overlap with that of an EVB-enabled port. For more information about EVB, see EVB Configuration
Guide.
•When you set up a TRILL network, avoid the case that multiple TRILL neighbors are established for
one RB port. When you plan a network, avoid the networks shown in Figure 5 and Figure 6.
{Figure 5 shows a typical network where two TRILL neighbors are established for the same port
of an RB.
{In Figure 6, because TRILL is not enabled on the port connecting RB 2 to RB 3, the port will
transparently transmit the TRILL Hello frames from RB 3. As a result, two TRILL neighbors are
established for the port connecting RB 1 to RB 2.
Figure 5 Two TRILL neighbors are established for a port (1)
Figure 6 Two TRILL neighbors are established for a port (2)
Configuration procedure
To enable TRILL:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enable TRILL globally
and enter TRILL view. trill By default, TRILL is disabled globally.
3. Return to system view. quit N/A
4. Enter Layer 2 Ethernet
or aggregate interface
view.
interface interface-type
interface-number N/A
Traditional Ethernet
switch
RB 1
RB 2 RB 3
TRILL enabled port

8
Step Command Remarks
5. Enable TRILL on the
port. trill enable By default, TRILL is disabled on a port.
Configuring the system ID and nickname for an RB
The system ID and nickname of an RB are identifiers of the RB in the TRILL network.
•System ID—Unique identifier of an RB in the TRILL network. The system ID can be automatically
assigned or manually configured.
•Nickname—Address of an RB in the TRILL network. The address can be automatically assigned or
manually configured. When multiple RBs in the TRILL network have the same nickname, the RB with
the highest priority uses the nickname. When RBs have the same priority, the RB with the highest
system ID uses the nickname. The system automatically assigns new nicknames to the other RBs.
If you set a new different system ID for an RB, the system resets the TRILL process.
To configure the system ID and nickname for an RB:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter TRILL view. trill N/A
3. Configure the system
ID for the RB. system-id system-id
By default, an RB automatically generates a
system ID according to its MAC address
upon startup.
4. Configure the
nickname for the RB.
nickname nickname [ priority
priority ]
By default, the system automatically assigns
nicknames to RBs, and the priority for a RB
to hold a nickname is 64.
Configuring the link type of a TRILL port
The following link types are available for a TRILL port:
•Access—Access ports include access ports without the alone attribute and access ports with the
alone attribute. Access ports with the alone attribute do not send or receive Hello frames and do not
participate in the DRB election or AVF negotiation. Access ports without the alone attribute can
process only local data frames and Hello frames.
•Hybrid—A hybrid port combines the attributes of an access port and a trunk port, and can process
local data frames and passing data frames.
•Trunk—A trunk port can process passing data frames and some of Layer 2 protocol frames (for
example, LLDP frames), but it cannot process local data frames.
To configure the link type of a TRILL port:
Step Command Remarks
1. Enter system view. system-view N/A

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Step Command Remarks
2. Enter Layer 2 Ethernet
or aggregate
interface view.
interface interface-type
interface-number N/A
3. Configure the link
type of a TRILL port.
trill link-type { access [ alone ] |
hybrid |trunk }
By default, the link type of a TRILL port is
access without the alone attribute.
Configuring the DRB priority of a TRILL port
On a broadcast network, TRILL must elect a DRB. An RB with a higher DRB priority is preferred. When two
RBs have the same DRB priority, the RB with a higher MAC address takes precedence.
To configure the DRB priority of a TRILL port:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter Layer 2 Ethernet or
aggregate interface
view.
interface interface-type
interface-number N/A
3. Configure the DRB
priority of a TRILL port. trill drb-priority priority By default, the DRB priority of a TRILL port is
64.
Configuring the link cost for a TRILL port
The link cost of a TRILL port can be automatically calculated by the system or manually configured:
•When a link cost is manually configured, the manually configured link cost takes effect regardless
of whether automatic link cost calculation is enabled.
•When a link cost is not manually configured and automatic link cost calculation is enabled, the
automatically calculated link cost takes effect.
•When a link cost is not manually configured and automatic link cost calculation is not enabled, the
default link cost 2000 is used.
The system automatically calculates the link cost of a TRILL port by using the following formula: link cost
= 20000000000000/interface baud rate.
To configure the link cost for a TRILL port:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter TRILL view. trill N/A
3. Enable automatic link cost
calculation for TRILL ports. auto-cost enable
By default, automatic link cost
calculation is enabled for TRILL
ports.
4. Return to system view. quit N/A

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5. Enter Layer 2 Ethernet
interface view or Layer 2
aggregate interface view.
interface interface-type
interface-number N/A
6. Configure the link cost for a
TRILL port. trill cost value The default setting is 2000.
Configuring the announcing VLANs and
designated VLAN
The concepts and symbols used to describe a VLAN on a port are as follows:
•Enabled VLAN—A VLAN enabled on the port.
•Forwarding VLAN—A VLAN for which the port is the appointed port.
•∩and ∪—Set operation symbols. ∩indicates set-theoretic intersection, and ∪indicates
set-theoretic union.
RBs use a VLAN set to forward Hello frames.
•A DRB uses the VLANs in this set to send Hello frames: enabled VLANs ∩(announcing VLANs ∪
designated VLAN).
•A non-DRB uses the VLANs in this set to send Hello frames: enabled VLANs ∩(designated VLAN
∪(announcing VLANs ∩forwarding VLANs)).
A TRILL port sends Hello frames in all VLANs in those VLAN sets. To prevent Hello frames from
overconsuming CPU resources, narrow down the VLAN sets by reducing the number of announcing
VLANs.
RBs use the designated VLAN to forward TRILL protocol frames (except Hello frames) and local data
frames. For RBs to establish adjacencies and forward TRILL data frames, make sure the designated VLAN
is an enabled VLAN.
To configure the announcing VLANs and designated VLAN:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter Layer 2 Ethernet
interface view or Layer 2
aggregate interface view.
interface interface-type
interface-number N/A
3. Configure announcing
VLANs. trill announcing-vlan { vlan-list | null }
By default, no announcing VLAN is
configured, and the announcing
VLANs are enabled VLANs.
4. Configure the designated
VLAN. trill designated-vlan vlan-id
By default, no designated VLAN is
configured. The system
automatically selects an enabled
VLAN as the designated VLAN.

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Configuring TRILL timers
You can configure the following TRILL timers:
•Hello interval and Hello multiplier—An RB advertises Hello frames at the Hello interval to maintain
a TRILL adjacency. The shorter the Hello interval, the faster the network convergence. However, a
shorter Hello interval consumes more system resources. The adjacency holding time is obtained by
multiplying the Hello interval by the Hello multiplier. The RB advertises the adjacency holding time
to neighbors through Hello frames. If a neighbor does not receive any Hello frame from the RB
before the adjacency holding time expires, it removes the TRILL adjacency with the RB.
•Inhibition time—An RB that acts as the AVF of a VLAN guarantees that frames from the VLAN have
only one incoming port or one outgoing port along a link. When other RBs receive frames from the
VLAN, they do not perform any processing. However, when the RB detects that a root bridge
change occurs on a link or that the AVF advertised by other RBs conflicts with the local AVF, the RB
inhibits the local AVF for a certain time to avoid loops. When the inhibition time expires, if the RB
is still the AVF of the VLAN, the RB restores the role of AVF.
•CSNP interval—On a broadcast network, the DRB advertises CSNPs at the CSNP interval to
perform network-wide LSDB synchronization. A CSNP records all LSP digests of the local LSDB.
When an RB receives a CSNP, the RB compares the CSNP against the local LSDB to verify whether
some LSPs are aged out or missing. If the CSNP has an LSP digest that the local LSDB does not have,
the RB sends a PSNP packet to request the LSP.
To configure TRILL timers:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter Layer 2 Ethernet
or aggregate interface
view.
interface interface-type
interface-number N/A
3. Configure the Hello
interval. trill timer hello interval
The default setting is 10 seconds.
This command sets the Hello interval for the
RB. The Hello interval of the DRB is 1/3 of the
Hello interval of the RB, so that the DRB
failures can be quickly detected.
4. Configure the Hello
multiplier.
trill timer holding-multiplier
count The default setting is 3.
5. Configure the inhibition
time. trill timer avf-inhibited time The default setting is 30 seconds.
6. Configure the CSNP
interval. trill timer csnp interval The default setting is 10 seconds.
Adjusting LSP parameters
You can modify the following LSP parameters:
•LSP maximum age—An LSP originated by an RB uses the maximum age as the remaining lifetime.
When the remaining lifetime of an LSP in the LSDB is 0 seconds, the RB removes the LSP's content,

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keeps the LSP's digest, and purges the LSP from the network by advertising the LSP that has the
remaining lifetime set to 0.
•LSP refresh interval—When the remaining lifetime of a locally originated LSP is no greater than
(maximum age – refresh interval), the LSP is refreshed even if no change occurs to it. This
mechanism avoids frequent LSP aging and ensures network stability.
•Maximum length of an LSP originated by an RB—The actual maximum LSP length is determined by
the smallest of following values:
{The configured value.
{The interface MTU.
{The maximum length of an LSP originated by an RB (which is carried in LSPs).
•Maximum length of an LSP that can be received by an RB—When the RB receives an LSP
exceeding the length, the RB drops the LSP.
•Overload bit of LSPs—When the Overload bit in the LSPs sent by an RB is set, the RB fails and
cannot correctly perform route selection and packet forwarding. When the RB cannot record the
complete LSDB because of insufficient memory, routing calculation errors occur. To make
troubleshooting easier, temporarily exclude the RB from the TRILL network by setting the Overload
bit for the LSPs sent by the failed RB.
•Minimum LSP interval and maximum number of LSPs transmitted per time—To avoid frequent LSP
aging in the network, RBs periodically advertise LSPs. The actual refresh interval of an LSP is
determined by both the minimum LSP interval and the maximum number of LSPs transmitted per time.
To prevent LSPs from being aged out accidentally, set the LSP maximum age and the LSP refresh
interval appropriately.
To adjust LSP-related parameters:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter TRILL view. trill N/A
3. Set the LSP maximum
age. timer lsp-max-age time The default setting is 1200 seconds.
4. Set the LSP refresh
interval. timer lsp-refresh time The default setting is 900 seconds.
5. Configure the
maximum length of an
LSP originated by an
RB.
lsp-length originate size
The default setting is 1458 bytes.
The maximum length of an LSP originated
by an RB cannot be greater than the
maximum length of an LSP that can be
received by an RB. Otherwise, the system
displays error messages.
6. Configure the
maximum length of an
LSP that can be
received by an RB.
lsp-length receive size
The default setting is 1492 bytes.
The maximum length of an LSP that can be
received by an RB cannot be smaller than
the maximum length of an LSP originated by
an RB. Otherwise, the system displays error
messages.