Hewlett Packard Enterprise 5920 Series User manual

HPE 5920 & 5900 Switch Series
TRILL Configuration Guide
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art number: 5200-4558
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Document version: 6W100-20171115

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i
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····················································································································5
Protocols and standards ····························································································································7
Configuration restrictions and guidelines···········································································································7
TRILL configuration task list·······························································································································8
Enabling TRILL ··················································································································································9
Configuration restrictions and guidelines···································································································9
Configuration procedure···························································································································10
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 ···································································································11
Setting the link cost for a TRILL port················································································································11
Configuring announcing VLANs and the designated VLAN·············································································12
Configuring TRILL timers·································································································································13
Configuring TRILL LSP parameters and features····························································································14
Setting TRILL LSP parameters················································································································14
Enabling TRILL LSP fast advertisement··································································································15
Enabling TRILL pseudonode bypass·······································································································15
Setting the SPF algorithm parameters·············································································································16
Configuring TRILL distribution trees ················································································································16
Setting basic distribution tree parameters································································································16
Enabling TRILL distribution tree multithread calculation··········································································17
Enabling load balancing over TRILL distribution trees·············································································17
Configuring TRILL ECMP routes ·····················································································································18
Enabling incremental flush for TRILL multicast routing entries········································································18
Enabling logging of TRILL neighbor changes··································································································19
Configuring SNMP for TRILL ···························································································································19
Enabling TRILL to forward traffic from EVB S-channels··················································································20
Configuring TRILL GR ·····································································································································20
Associating a TRILL port with a track entry ·····································································································21
Using ping TRILL and tracert TRILL to test network connectivity····································································21
Displaying and maintaining TRILL ···················································································································22
TRILL configuration example···························································································································22
Network requirements······························································································································22
Configuration procedure···························································································································23
Verifying the configuration························································································································25
Document conventions and icons·································································27
Conventions·····················································································································································27
Network topology icons····································································································································28
Support and other resources ········································································29
Accessing Hewlett Packard Enterprise Support ······························································································29
Accessing updates···········································································································································29
Websites ··················································································································································30
Customer self repair·································································································································30
Remote support········································································································································30
Documentation feedback ·························································································································30
Index·············································································································32

1
Configuring TRILL
TRansparent Interconnection of Lots of Links (TRILL) uses IS-IS to provide transparent Layer 2
forwarding.
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 TRILLnetwork
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 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 0x22F3.
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.
Options
Outer Destination MAC Address
0 32
Outer Source MAC Address
Ethertype = 802.1Q Outer VLAN Tag Information
Ethertype = TRILL
New FCS
16
V
Inner Destination MAC Address
Inner Source MAC Address
Ethertype = 802.1Q Inner VLAN Tag Information
Outer
Ethernet
header
Egress RB Nickname Ingress RB Nickname
R M Op-Length Hop Count
TRILL
header
Inner
Ethernet
header
Original Ethernet Payload
Ethertype of Original Ethernet Payload
Payload

3
TRILL forwarding mechanisms
Different types of frames are forwarded by 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 the following headers:
2. A TRILL header (similar to an IP header).
3. An outer Ethernet header (similar to the Ethernet header of a regular Ethernet frame).
4. 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.
5. 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.
Multidestination frame forwarding mechanism
In a TRILL network, RBs perform the following tasks:
•
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.
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 TRILLframe. In the frame, the egress RB is
RB 2, the root bridge of the TRILL distribution tree for VLAN 10, and the destination MAC address is
multicast address 0180-C200-0040. 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
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
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 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 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 10
VLAN 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 multiple 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 TRILLdistribution tree rooted at RB
3.
•
The link RB 1-RB 2-RB 3 is assigned to the TRILL distribution tree rooted at RB 4.
TRILLdistribution 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.
Ping TRILL and tracert TRILL
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 5, 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.
Cost = 3
Cost = 2
Cost = 1
RB 1
RB 2 RB 3 RB 4

6
Figure 5 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 6.
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.
RB 1 RB 2 RB 3
ECHO-REQUEST
ECHO-REQUEST
ECHO-REPLY
ECHO-REPLY
Ingress RB = RB 1
Egress RB = RB 3
Hop Count = 63
Sequence number = 1 Ingress RB = RB 1
Egress RB = RB 3
Hop Count = 62
Sequence number = 1
Ingress RB = RB 3
Egress RB = RB 1
Hop Count = 63
Sequence number = 1
Ingress RB = RB 3
Egress RB = RB 1
Hop Count = 62
Sequence number = 1

7
Figure 6 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
•
RFC 7978, Transparent Interconnection of Lots of Links (TRILL): RBridge Channel Header
Extension
•
RFC 6905, Requirements for Operations, Administration, and Maintenance (OAM) in
Transparent Interconnection of Lots of Links (TRILL)
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 the member port of an aggregate interface takes effect after
the member port leaves the aggregation group.
RB 1 RB 2 RB 3
ECHO-REQUEST
Ingress RB = RB 1
Egress RB = RB 3
Hop Count = 0
Hop Count = 0 error notification
Ingress RB = RB 2
Egress RB = RB 1
Hop Count = Default
ECHO-REQUEST
Ingress RB = RB 1
Egress RB = RB 3
Hop Count = 1
Hop Count = 0 error notification
Ingress RB = RB 3
Egress RB = RB 1
Hop Count = Default-1
ECHO-REQUEST
Ingress RB = RB 1
Egress RB = RB 3
Hop Count = 0
Hop Count = 0 error notification
Ingress RB = RB 3
Egress RB = RB 1
Hop Count = Default

8
•
To connect a spanning tree network to a TRILL network, make sure the following requirements
are met:
The spanning tree protocol is disabled on TRILL ports.
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.
•
Do not configure the TPID for VLAN tags on RBs. For more information about TPIDs, see Layer
2—LAN Switching Configuration Guide.
•
To avoid loops, do not connect multiple TRILL ports of an RB to a broadcast network, because
TRILL ports cannot detect each other when they are on a broadcast network. If there are
multiple TRILL ports, they might be elected as the appointed ports of a VLAN at the same time
and result in loops.
•
For the TRILL network to forward Layer 3 multidestination traffic correctly, make sure the
following requirements are met:
The IGMP/MLD snooping version must be the same on all RBs.
IGMP or MLD must be enabled on the access-facing VLAN interfaces on gateway RBs to
prevent topology changes from interrupting traffic.
•
Enabling PIM-DM or IPv6 PIM-DM on core layer and distribution layer devices might cause
multicast traffic duplication. As a best practice, use other Layer 3 multicast protocols.
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 ECMP routes
(Optional.) Enabling incremental flush for TRILL multicast routing entries
(Optional.) Enabling logging of TRILL neighbor changes
(Optional.) Configuring SNMP for TRILL

9
Tasks at a glance
(Optional.) Enabling TRILL to forward traffic from EVB S-channels
(Optional.) Configuring TRILL GR
(Optional.) Associating a TRILL port with a track entry
(Optional.) Using ping TRILL and tracert TRILL to test network connectivity
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.
•
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. If the trill evb-support command is not executed
on an EVB-enabled port, make sure the allowed VLANs of the port do not overlap with those of
a TRILL-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 7
and Figure 8.
Figure 7 shows a typical network where two TRILL neighbors are established for the same
port of an RB.
In Figure 8, 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 7 Two TRILL neighbors are established for a port (1)
Traditional Ethernet
switch
RB 1
RB 2 RB 3
TRILL enabled port

10
Figure 8 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
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 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.
RB 1 RB 2 RB 3
TRILL enabled port TRILL disabled port

11
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—Atrunk 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.
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 of a TRILL port can be automatically calculated by the system or manually configured.
•
A manually configured link cost takes precedence over a calculated link cost.
•
If no configured link cost exists and automatic link cost calculation is enabled, the calculated link
cost takes effect.
•
If no configured link cost exists and automatic link cost calculation is disabled, the default link
cost of 2000 is used.

12
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 value The default setting is 2000.
Configuring announcing VLANs and the
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 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 an excessive amount of 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 VLAN
is 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

13
Step
Command
Remarks
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 TRILLadjacency 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:
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. ACSNP records all LSP
digests of the RB's local LSDB. Aremote 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.

14
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 tasks:
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—Alocally 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 TRILLLSP generation timer parameters,
you can prevent frequent network changes from consuming an excessive amount of 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.
•
Maximum length of originated LSPs—The RB selects the smallest value from the following
values as the actual maximum length of LSPs to be sent to a neighbor:
The configured maximum length of originated LSPs.
The interface MTU.
The maximum originated LSP length carried in the LSPs sent by the neighbor.
•
Maximum length of received LSPs—When the RB receives an LSP that exceeds the length,
the RB drops the LSP.
•
Overload bit of LSPs—The RB sets the Overload bit in LSPs if 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 RB.
•
Minimum LSP interval and maximum number of LSPs transmitted per interval—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 interval. To prevent LSPs from being aged out accidentally, set the LSP
maximum age and the LSP refresh interval appropriately.
To set TRILL LSP 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. Set the TRILL LSP
generation timer
timer lsp-generation
maximum-interval
By default, the maximum LSP generation
interval is 2 seconds, the minimum interval

15
Step
Command
Remarks
parameters.
[ minimum-interval
[ incremental-interval ] ]
is 10 milliseconds, and the incremental
interval is 20 milliseconds.
6. Configure the
maximum length of
originated LSPs. lsp-length originate size
The default setting is 1458 bytes.
To prevent the system from generating
error messages, do not set the maximum
length of originated LSPs to be greater
than the maximum length of received
LSPs.
7. Configure the
maximum length of
received LSPs. lsp-length receive size
The default setting is 1492 bytes.
To prevent the system from generating
error messages, do not set the maximum
length of originated LSPs to be greater
than the maximum length of received
LSPs.
8. Set the Overload bit of
LSPs and set the
lifetime for the set
Overload bit. set overload [ timeout ]
By default, the Overload bit is not set.
Do not perform this task on the root RB of
a TRILL distribution tree. The root RB
cannot forward traffic when the Overload
bit of LSPs is set on the RB.
9. Return to system view.
quit N/A
10. Enter Layer 2 Ethernet
or aggregate interface
view. interface interface-type
interface-number N/A
11. Configure the
minimum LSP interval
and the maximum
number of LSPs
transmitted per
interval.
trill timer lsp interval [ count
count ]
By default, the minimum LSP interval is 10
milliseconds, and the maximum number of
LSPs transmitted per interval is 5.
Enabling TRILL LSP fast advertisement
LSP fast advertisement enables TRILL to immediately advertise the specified number of LSPs that
invoke SPF calculation. This mechanism improves network convergence time.
To enable TRILL LSP fast advertisement:
Step
Command
Remarks
1. Enter system view. system-view N/A
2. Enter TRILL view.
trill
N/A
3. Enable TRILL LSP fast
advertisement.
flash-flood [ flood-count
flooding-count |
max-timer-interval
flooding-interval ] *
By default, TRILL LSP fast
advertisement is disabled.
Enabling TRILL pseudonode bypass
This feature disables a DRB from generating LSPs for the pseudonode when the DRB has only one
neighbor on a broadcast network. This reduces the number of LSPs in the network.
To enable the pseudonode bypass feature:

16
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. Enable the pseudonode
bypass feature. trill bypass-pseudonode enable By default, the pseudonode
bypass feature is disabled.
Setting the SPF algorithm parameters
The RB uses the SPF algorithm to calculate a shortest path tree with itself as the root based on the
LSDB. The RB uses the shortest path tree to determine the next hop to a destination network. By
adjusting the SPF calculation intervals, you can prevent resource overconsumption when the
network is unstable.
When the network is stable, the SPF calculation interval for continuous calculations is reduced to
minimum-interval. When the network is unstable, the SPF calculation interval is added by
incremental-interval × 2n-2 (n is the number of continuous SPF calculation times) for each SPF
calculation until the maximum interval is reached.
To set the SPF algorithm parameters:
Step
Command
Remarks
1. Enter system view.
system-view
N/A
2. Enter TRILL view. trill N/A
3. Set the SPF
calculation interval for
TRILL.
timer spf maximum-interval
[ minimum-interval
[ incremental-interval ] ]
By default, the maximum SPF calculation
interval is 10 seconds, the minimum SPF
calculation interval is 10 milliseconds, and
the SPF calculation incremental interval is
20 milliseconds.
Configuring TRILL distribution trees
Setting basic distribution tree parameters
In a TRILL network, RBs perform the following tasks:
•
Compute TRILL distribution trees according to the LSDB.
•
Use the TRILL distribution trees to guide the forwarding of multidestination frames.
An RB with a higher priority is selected as the root bridge of a TRILL distribution tree.
An LSP sent by an RB carries the following TRILL distribution tree information:
•
The number of TRILL distribution trees that the RB wants all RBs to compute.
•
The maximum number of TRILL distribution trees that the RB can compute (this number is fixed
at 15).
•
The number of TRILL distribution trees that the RB has computed.
Each RB can compute a maximum of mTRILL distribution trees. An RB determines the number of
TRILL distribution trees to compute (n) by selecting the lower value from the following two values:
•
The number of TRILL distribution trees that the highest-priority RB wants all RBs to compute.

17
•
The smallest mvalue across the TRILL network.
The RB selects the first nnicknames from the nickname list advertised by the highest-priority RB.
The RB uses the selected nicknames as the root nicknames for computing distribution trees.
To set basic TRILL distribution tree parameters:
Step
Command
Remarks
1. Enter system view. system-view N/A
2. Enter TRILL view.
trill
N/A
3. Set a priority for the RB.
tree-root
priority
priority The default setting is 32768.
4. Configure the number of
TRILL distribution trees that
the RB wants all RBs to
compute. trees calculate count The default setting is 1.
Enabling TRILL distribution tree multithread calculation
This feature enables a multicore CPU device to improve TRILL distribution tree calculation efficiency
by using each thread to calculate a distribution tree.
To enable TRILL distribution tree multithread calculation:
Step
Command
Remarks
1. Enter system view. system-view N/A
2. Enter TRILL view. trill N/A
3. Enable TRILL distribution
tree multithread calculation. multicast multi-thread enable By default, this feature is disabled.
Enabling load balancing over TRILL distribution trees
By default, ingress traffic is not load balanced over TRILL distribution trees after a forwarding VLAN
is deleted on the RB. To load balance ingress traffic of the remaining forwarding VLANs over the
existing distribution trees, you can enable load balancing over TRILL distribution trees.
Ingress traffic is load balanced in any of the following conditions, regardless of whether load
balancing is enabled or not:
•
A forwarding VLAN is added.
•
A distribution tree is added or deleted.
When a distribution tree is added, the RB switches ingress traffic to the new tree to implement load
balancing. However, the RB cannot use the new distribution tree to forward traffic before other RBs
are ready to use the new tree. In this case, you can set a delay timer for the RB to switch ingress
traffic to the new distribution tree.
If traffic is not evenly distributed over distribution trees, you can also perform one-time load balancing
over TRILL distribution trees.
To enable load balancing over TRILL distribution trees:
Step
Command
Remarks
1. Enter system view. system-view N/A
2. Enter TRILL view. trill N/A