H3C S12500-X User manual

H3C S12500-X & S12500X-AF Switch Series
TRILL Configuration Guide
Hangzhou H3C Technologies Co., Ltd.
http://www.h3c.com
Software version: Release 1135 and later
Document version: 6W101-20151130

Copyright ©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.
Trademarks
H3C, , H3CS, H3CIE, H3CNE, Aolynk, , H3Care, , IRF, NetPilot, Netflow,
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 S12500-X & S12500X-AF documentation set includes 17 configuration guides. These
guides describe the software features for the H3C S12500-X & S12500X-AF Switch Series running
Release 1135 and later, 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 application scenarios, fundamentals, and
configuration of TRILL.
This preface includes:
•Audience
•Conventions
•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 S12500-X & S12500X-AF series
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.
Represents an access controller, a unified wired-WLAN module, or the access
controller engine on a unified wired-WLAN switch.
Represents an access point.
Represents a mesh access point.
Represents omnidirectional signals.
Represents directional signals.
Represents a security product, such as a firewall, UTM, multiservice security gateway,
or load-balancing device.
Represents a security card, such as a firewall, load-balancing, NetStream, SSL VPN,
IPS, or ACG card.
Port numbering in examples
The port numbers in this document are for illustration only and might be unavailable on your device.
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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
[e-mail]
http://www.h3c.com
Documentation feedback
You can e-mail your comments about product documentation to [email protected].
We appreciate your comments.

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Contents
Configuring TRILL ············································································1
Overview··································································································································1
Basic concepts ···················································································································1
TRILL frame formats ············································································································1
How TRILL works ················································································································2
TRILL forwarding mechanisms ·······························································································3
Ping TRILL and tracert TRILL ································································································6
Protocols and standards ·······································································································8
Configuration restrictions and guidelines ·························································································8
TRILL configuration task list ·········································································································9
Enabling TRILL ·························································································································9
Configuring the system ID and nickname for an RB ········································································· 10
Configuring the link type of a TRILL port ······················································································· 11
Configuration procedure ····································································································· 11
Configuring the DRB priority of a TRILL port ·················································································· 12
Setting the link cost for a TRILL port ···························································································· 12
Configuring announcing VLANs and the designated VLAN································································ 13
Configuring TRILL timers ··········································································································· 13
Configuring TRILL LSP parameters and features ············································································ 14
Setting TRILL LSP parameters ····························································································· 14
Enabling TRILL LSP fast advertisement ················································································· 16
Enabling TRILL pseudonode bypass ····················································································· 16
Setting the SPF algorithm parameters ·························································································· 17
Configuring TRILL distribution trees ····························································································· 17
Setting basic distribution tree parameters ··············································································· 17
Enabling TRILL distribution tree multithread calculation ····························································· 18
Enabling load balancing over TRILL distribution trees ······························································· 18
Configuring TRILL equal-cost routes ···························································································· 19
Enabling incremental flush for TRILL multicast routing entries ··························································· 19
Configuring TRILL Layer 3 forwarding ·························································································· 20
Enabling logging of TRILL neighbor changes ················································································· 21
Configuring SNMP for TRILL ······································································································ 22
Configuring TRILL GR··············································································································· 22
Using ping TRILL and tracert TRILL to test network connectivity ························································ 23
Displaying and maintaining TRILL ······························································································· 23
TRILL configuration example ······································································································ 24
Network requirements ········································································································ 25
Configuration procedure ····································································································· 25
Verifying the configuration ··································································································· 28
TRILL configuration example ······································································································ 29
Network requirements ········································································································ 29
Configuration procedure ····································································································· 29
Verifying the configuration ··································································································· 31
Index ···························································································33

1
Configuring TRILL
TRansparent Interconnection of Lots of Links (TRILL) uses IS-IS to provide transparent Layer 2
forwarding.
TRILL requires a license to run on the device. 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 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 that contains RBs, as shown in Figure 3.
•System ID—Unique identifier of an RB in the TRILL network. The system ID is 6 bytes in
length.
•Nickname—Address of an RB in the TRILL network. The nickname is 2 bytes in length.
•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 a broadcast network. It helps simplify network topology, and assigns 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
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 VLAN's AVF, and the port is the VLAN's appointed port.
For more information about LSDB, LSPDU, and DIS, see Layer 3—IP Routing Configuration Guide.
TRILL frame formats
TRILL frames include protocol frames and data frames.
TRILL protocol frames include TRILL Hello, LSP, CSNP, PSNP, MTU-probe, and MTU-ack. These
protocol 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 Description
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
Multidestination attribute:
•0—Known unicast frame.
•1—Multidestination frame (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.
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.

3
TRILL forwarding mechanisms
TRILL uses different mechanisms to forward Layer 2 and Layer 3 traffic. The following sections
describe these mechanisms.
Layer 2 forwarding mechanisms
TRILL forwards the traffic within a VLAN by using the following mechanisms:
•Unicast frame forwarding mechanism.
As shown in Figure 2, a unicast frame is forwarded as follows:
a. When a unicast frame enters the TRILL network, the ingress RB encapsulates the original
Ethernet frame with the following headers:
−A TRILL header (similar to an IP header).
−An outer Ethernet header (similar to the Ethernet header of a regular Ethernet frame).
b. RBs forward the frame hop by hop according to the egress RB nickname in the TRILL
header 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.
c. 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 Layer 2 unicast frame forwarding flow
The outer Ethernet header enables traditional Ethernet switches to forward TRILL frames and
connect RBs.
•Multidestination frame forwarding mechanism.
In a TRILL network, RBs perform the following operations:
{Compute a TRILL distribution tree for each VLAN based on the LSDB.
{Guide the forwarding of multidestination frames in each VLAN by using its TRILL distribution
tree.
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
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 Layer 2 multicast frame forwarding flow
TRILL selects distribution trees for forwarding multidestination 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 2. Assume the link directly connecting RB 1 to RB 2 has the largest
pseudonode ID. Both the TRILL distribution tree rooted at RB 1 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 to improve 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 2 is assigned to the TRILL distribution tree rooted at
RB 1.
{The link RB 1-RB 3-RB 2 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. Multidestination traffic is switched to
new distribution trees.
Layer 3 forwarding mechanisms
IMPORTANT:
•TRILL Layer 3 forwarding is available in Release 1138P01 and later versions.
•TRILL Layer 3 forwarding is supported only on FE and FX cards.
•TRILL can perform Layer 3 forwarding only for IPv4 unicast traffic.
As shown in Figure 5, distribution layer device RB 1 is the gateway of a data center network. RB 1
forwards Layer 3 traffic between VLANs in the data center network and Layer 3 traffic between the
data center and external networks.

6
Figure 5 TRILL Layer 3 forwarding
When an access RB receives a unicast frame from a terminal device, the RB encapsulates the frame
into a TRILL frame and sends it to the gateway RB. The gateway RB then de-encapsulates the
TRILL frame for Layer 3 forwarding.
A gateway RB uses the IP addresses of VLAN interfaces to provide gateway services for terminal
devices in different VLANs.
For terminal devices to learn the MAC address of a gateway, enable periodic sending of gratuitous
ARP packets on the VLAN interface that acts as the gateway. For information about gratuitous ARP,
see Layer 3—IP Services Configuration Guide.
Ping TRILL and tracert TRILL
IMPORTANT:
Ping TRILL and tracert TRILL are available in Release 1138P01 and later versions.
You can use ping TRILL and tracert TRILL to test TRILL network connectivity when network failure
occurs or new RBs are added to the network.
Ping TRILL and tracert TRILL are implemented through the TRILL Operation, Administration, and
Maintenance (OAM) protocol.
Ping TRILL
Use ping TRILL to determine if an RB is reachable.
As shown in Figure 6, the source RB sends OAM echo requests to ping the destination RB. Upon
receiving the requests, the destination RB responds to the source RB with OAM echo replies. The
source RB outputs statistics about the ping TRILL operation, including the number of sent echo
requests, the number of received echo replies, and the round-trip time. You can measure the
network performance by analyzing the statistics.
Access
IP network
RB 1
（Gateway）RB 2
RB 3 RB 4 RB 5 RB 6
Distribution
TRILL network
VLAN 100 VLAN 100 VLAN 200 VLAN 200

7
Figure 6 Ping TRILL packet forwarding
Tracert TRILL
Tracert TRILL enables retrieval of the nicknames of RBs in the path to a destination RB. In the event
of network failure, use tracert TRILL to test network connectivity and identify failed nodes.
Tracert TRILL operates as shown in Figure 7.
1. RB 1 sends RB 3 an OAM echo request with a hop count value of 0.
2. The first hop RB 2 responds by sending a hop count error notification to the source RB because
the hop count of the request is 0. The notification uses the nickname of RB 2 as the ingress RB.
In this way, RB 1 can get the nickname of the first hop RB.
3. RB 1 sends RB 3 an OAM echo request with a hop count value of 1.
4. RB 2 forwards the request to RB 3 according to the TRILL unicast routing table and decrements
the hop count value by 1.
5. The second hop RB 3 responds to the source RB with a hop count error notification. The
notification uses the nickname of RB 3 as the ingress RB.
6. RB 2 forwards the hop count error notification to RB 1. RB 1 gets the nickname of the second
hop RB 3.

8
Figure 7 Tracert TRILL packet forwarding
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
•RBridges: TRILL RBridge Channel Support
•RBridges: Operations, Administration, and Maintenance (OAM) Support
Configuration restrictions and guidelines
When you configure TRILL, follow these restrictions and guidelines:
•Configuration in Layer 2 Ethernet interface view takes effect only on 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.

9
{An edge port is used to connect the spanning tree network to the TRILL network. The edge
port can transit to the forwarding state before DRB election is finished. This prevents
multiple DRBs from being elected.
For more information about spanning tree protocols, see Layer 2—LAN Switching
Configuration Guide.
•As a best practice, do not enable loop detection on TRILL ports, because TRILL avoids loops.
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.
TRILL configuration task list
Tasks at a glance
(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.) Setting the link cost for a TRILL port
(Optional.) Configuring announcing VLANs and the designated VLAN
(Optional.) Configuring TRILL timers
(Optional.) Configuring TRILL LSP parameters and features
(Optional.) Setting the SPF algorithm parameters
(Optional.) Configuring TRILL distribution trees
(Optional.) Configuring TRILL equal-cost routes
(Optional.) Enabling incremental flush for TRILL multicast routing entries
(Optional.) Configuring TRILL Layer 3 forwarding
(Optional.) Enabling logging of TRILL neighbor changes
(Optional.) Configuring SNMP for TRILL
(Optional.) Configuring TRILL GR
(Optional.) Using ping TRILL and tracert TRILL to test network connectivity
Enabling TRILL
Before you enable TRILL on a port, first enable TRILL globally.
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).
To avoid loops, use the following procedure to enable TRILL on a port:
1. Shut down the port by using the shutdown command.
2. Enable TRILL and assign the port to VLANs.
3. Bring up the port by using the undo shutdown command.

10
When you set up a TRILL network, avoid the case that multiple TRILL neighbors are established for
one TRILL port, for example, the networks in Figure 8 and Figure 9.
Figure 8 shows a typical network where two TRILL neighbors are established for the same port of an
RB. In Figure 9, because TRILL is disabled 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 8 Two TRILL neighbors are established for a port (1)
Figure 9 Two TRILL neighbors are established for a port (2)
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.
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
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.
Traditional Ethernet
switch
RB 1
RB 2 RB 3
TRILL enabled port

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•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 the RBs also have the
same priority, the RB with the highest system ID uses the nickname. The system automatically
assigns new nicknames to the other RBs.
The system resets the TRILL process when the RB's system ID changes.
To configure the system ID and nickname for the 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, the RB automatically generates
a system ID based on its MAC address
upon startup.
4. Configure the
nickname for the RB. nickname nickname [ priority
priority ]
By default, TRILL 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 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.
Configuration procedure
To configure the link type 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 link
type of the TRILL
port.
trill link-type { access [ alone ] |
hybrid |trunk } By default, the link type of a TRILL port
is access without the alone attribute.

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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 in
DRB election. 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 the TRILL
port. trill drb-priority priority By default, the DRB priority of a TRILL port
is 64.
Setting the link cost for a TRILL port
The link cost for a TRILL port can be automatically calculated by the system or manually set.
•A manually set link cost takes precedence over a calculated link cost.
•If no link cost is set and automatic link cost calculation is enabled, the calculated link cost takes
effect.
•If no link cost is set and automatic link cost calculation is disabled, the default link cost of 2000
is used.
If you manually set the link cost for a TRILL port, make sure its peer TRILL port uses the same link
cost.
The system automatically calculates the link cost of a TRILL port by using the following formula: link
cost = 20000000000000/interface baud rate.
To set 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
5. Enter Layer 2 Ethernet
interface view or Layer 2
aggregate interface view.
interface interface-type
interface-number N/A
6. Set the link cost for the TRILL
port. trill cost cost-value The default setting is 2000.

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Configuring announcing VLANs and the
designated VLAN
The concepts and symbols used to describe a VLAN on 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 send Hello frames in a set of VLANs. The VLAN set is calculated as follows:
•DRB—Enabled VLANs ∩(announcing VLANs ∪designated VLAN).
•Non-DRB—Enabled VLANs ∩(designated VLAN ∪(announcing VLANs ∩forwarding
VLANs)).
To prevent Hello frames from consuming excessive CPU resources, reduce 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 announcing VLANs and the 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 VLANs
are configured, and 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.
Configuring TRILL timers
You can configure the following TRILL timers:
•Hello interval and Hello multiplier—The 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 within the adjacency holding time, it removes the TRILL adjacency with
the RB.
•AVF inhibition time—As the AVF of a VLAN, the RB guarantees that frames of the VLAN enter
and leave a broadcast network through the same port. Other RBs on the broadcast network do
not process frames from the VLAN.
To avoid loops, the RB suppresses its AVF role during the inhibition time when one of the
following conditions exists:

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{The RB detects a root bridge change on the broadcast network.
{Other RBs advertise a different AVF for the VLAN.
When the inhibition time expires, the RB restores its AVF role if it is still the AVF of the VLAN.
•CSNP interval—On a broadcast network, the RB advertises CSNPs at the CSNP interval to
perform network-wide LSDB synchronization if it is elected as the DRB. A CSNP records all
LSP digests of the RB's local LSDB. A remote RB compares a received CSNP against its 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 remote 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 an
RB. The Hello interval of a DRB is 1/3 of the
Hello interval of an RB. This allows for DRB
failures to be quickly detected.
4. Configure the Hello
multiplier. trill timer holding-multiplier
count The default setting is 3.
5. Configure the AVF
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.
Configuring TRILL LSP parameters and features
Setting TRILL LSP parameters
You can set the following LSP parameters:
•LSP maximum age—The RB uses the LSP maximum age as the remaining lifetime of the
LSPs that it originates. When the RB detects that the remaining lifetime of an LSP reaches 0
seconds in the LSDB, the RB performs the following operations:
{Removes the LSP's content.
{Keeps the LSP's digest.
{Sets the LSP's remaining lifetime to 0 and purges the LSP from the network by advertising
the LSP to other RBs.
•LSP refresh interval—A locally originated LSP is forcibly refreshed when its remaining lifetime
is no greater than n: n = LSP maximum age – LSP refresh interval. This mechanism avoids
frequent LSP aging and ensures network stability.
•LSP generation timer parameters—By adjusting the TRILL LSP generation timer parameters,
you can prevent frequent network changes from consuming excessive bandwidth and device
resources.
When the network is stable, the LSP generation timer is set to the minimum interval for each
LSP generation. When the network is unstable, the LSP generation timer is added by the
incremental interval for each LSP generation until the maximum interval is reached.