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* the VLT unit-id is not identical.
NOTE: If you configure the VLT system MAC address or VLT unit-id on only one of the VLT peer switches, the link
between the VLT peer switches is not established. Each VLT peer switch must be correctly configured to establish
the link between the peers.
– If the link between the VLT peer switches is established, changing the VLT system MAC address or the VLT unit-id causes
the link between the VLT peer switches to become disabled. However, removing the VLT system MAC address or the VLT
unit-id may disable the VLT ports if you happen to configure the unit ID or system MAC address on only one VLT peer at any
time.
– If the link between VLT peer switches is established, any change to the VLT system MAC address or unit-id fails if the
changes made create a mismatch by causing the VLT unit-ID to be the same on both peers and/or the VLT system MAC
address does not match on both peers.
– If you replace a VLT peer node, preconfigure the switch with the VLT system MAC address, unit-id, and other VLT
parameters before connecting it to the existing VLT peer switch using the VLTi connection.
– If the size of the MTU for VLTi members is less than 1496 bytes, MAC addresses may not be synced. Dell Networking
recommends retaining the default MTU allocation (1554 bytes) for VLTi members.
•
VLT backup link
– In the backup link between peer switches, heartbeat messages are exchanged between the two chassis for health checks.
The default time interval between heartbeat messages over the backup link is 1 second. You can configure this interval. The
range is from 1 to 5 seconds. DSCP marking on heartbeat messages is CS6.
– In order that the chassis backup link does not share the same physical path as the interconnect trunk, Dell Networking
recommends using the management ports on the chassis and traverse an out-of-band management network. The backup
link can use user ports, but not the same ports the interconnect trunk uses.
– The chassis backup link does not carry control plane information or data traffic. Its use is restricted to health checks only.
•
Virtual link trunks (VLTs) between access devices and VLT peer switches
– To connect servers and access switches with VLT peer switches, you use a VLT port channel, as shown in
. Up to
48 port-channels are supported; up to 16 member links are supported in each port channel between the VLT domain and an
access device.
– The discovery protocol running between VLT peers automatically generates the ID number of the port channel that connects
an access device and a VLT switch. The discovery protocol uses LACP properties to identify connectivity to a common client
device and automatically generates a VLT number for port channels on VLT peers that connects to the device. The discovery
protocol requires that an attached device always runs LACP over the port-channel interface.
– VLT provides a loop-free topology for port channels with endpoints on different chassis in the VLT domain.
– VLT uses shortest path routing so that traffic destined to hosts via directly attached links on a chassis does not traverse the
chassis-interconnect link.
– VLT allows multiple active parallel paths from access switches to VLT chassis.
– VLT supports port-channel links with LACP between access switches and VLT peer switches. Dell Networking recommends
using static port channels on VLTi.
– If VLTi connectivity with a peer is lost but the VLT backup connectivity indicates that the peer is still alive, the VLT ports on
the Secondary peer are orphaned and are shut down.
* In one possible topology, a switch uses the BMP feature to receive its IP address, configuration files, and boot image from
a DHCP server that connects to the switch through the VLT domain. In the port-channel used by the switch to connect
to the VLT domain, configure the port interfaces on each VLT peer as hybrid ports before adding them to the port
channel (refer to
Connecting a VLT Domain to an Attached Access Device (Switch or Server)
). To configure a port in
Hybrid mode so that it can carry untagged, single-tagged, and double-tagged traffic, use the
portmode hybrid
command in Interface Configuration mode as described in
.
* For example, if the DHCP server is on the ToR and VLTi (ICL) is down (due to either an unavailable peer or a link failure),
whether you configured the VLT LAG as static or LACP, when a single VLT peer is rebooted in BMP mode, it cannot
reach the DHCP server, resulting in BMP failure.
•
Software features supported on VLT port-channels
– In a VLT domain, the following software features are supported on VLT port-channels: 802.1p, ingress and egress ACLs, BGP,
DHCP relay, IS-IS, OSPF, active-active PIM-SM, PIM-SSM, VRRP, Layer 3 VLANs, LLDP, flow control, port monitoring,
jumbo frames, IGMP snooping, sFlow, ingress and egress ACLs, and Layer 2 control protocols RSTP and PVST only.
Virtual Link Trunking (VLT)
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Содержание S4048-ON
Страница 1: ...Dell Configuration Guide for the S4048 ON System 9 9 0 0 ...
Страница 146: ...Figure 14 BFD Three Way Handshake State Changes 146 Bidirectional Forwarding Detection BFD ...
Страница 477: ...Figure 68 Inspecting Configuration of LAG 10 on ALPHA Link Aggregation Control Protocol LACP 477 ...
Страница 480: ...Figure 70 Inspecting a LAG Port on BRAVO Using the show interface Command 480 Link Aggregation Control Protocol LACP ...
Страница 481: ...Figure 71 Inspecting LAG 10 Using the show interfaces port channel Command Link Aggregation Control Protocol LACP 481 ...
Страница 522: ...Figure 87 Configuring Interfaces for MSDP 522 Multicast Source Discovery Protocol MSDP ...
Страница 523: ...Figure 88 Configuring OSPF and BGP for MSDP Multicast Source Discovery Protocol MSDP 523 ...
Страница 524: ...Figure 89 Configuring PIM in Multiple Routing Domains 524 Multicast Source Discovery Protocol MSDP ...
Страница 528: ...Figure 91 MSDP Default Peer Scenario 1 528 Multicast Source Discovery Protocol MSDP ...
Страница 529: ...Figure 92 MSDP Default Peer Scenario 2 Multicast Source Discovery Protocol MSDP 529 ...
Страница 530: ...Figure 93 MSDP Default Peer Scenario 3 530 Multicast Source Discovery Protocol MSDP ...
Страница 633: ...Policy based Routing PBR 633 ...
Страница 777: ...Figure 119 Single and Double Tag TPID Match Service Provider Bridging 777 ...
Страница 778: ...Figure 120 Single and Double Tag First byte TPID Match 778 Service Provider Bridging ...