Virtual Trunking Support On Bpx And Igx In Release 9.2; Virtual Trunking Interactions With Other Features; Table 25-12 Networking Channel Capacities For Virtual Trunks - Cisco BPX-BXM-155-8DX Installation And Configuration Manual

Compatibility Between Cards in Virtual Trunks
Nodes running Release 9.2 software can interoperate with nodes running 9.1 or 8.5, but you cannot add
UXM and BXM virtual trunks into a network of mixed software releases. This is because the
networking messages are different among the software releases, specifically the virtual trunk number
and the cell format on virtual trunks.
You configure the BXM and UXM cards similarly as in releases previous to Release 9.2; that is, you
use similar card, line, port and connection commands for configuration.

Virtual Trunking Support on BPX and IGX in Release 9.2

Channel Capacities
In releases previous to Release 9.2, for UXM and BXM cards, networking channels are pre-allocated
when the first trunk is upped; that is, 270 channels are allocated for each trunk on that card.
For example, if the card had four trunks enabled on it, trunk 1 would have channels 0 through 270
allocated, trunk 2 would have channels 271 through 540; trunk 3 would have channels 541 through 810,
and trunk 4 would have channels 811 through 960 allocated.
Network channels are no longer pre-allocated. Networking channels will be allocated for each trunk
when the trunk is upped. For each trunk that is upped, 270 channels will be dynamically allocated for
networking.
For legacy UXM/BXM cards, approximately 270 networking channels are allocated for each virtual
trunk. For example, UXM cards will allocate 4320 channels if all 16 virtual trunks are upped on a single
card. BXM cards will allocate 8640 channels if all 32 virtual trunks are upped. See Table 25-11 for
networking channel capacities for virtual trunks.

Table 25-12 Networking Channel Capacities for Virtual Trunks

#VT
1 VTs
2 VT s
3 VTs
16 VTs
32 VTs
This implies that UXM legacy cards upping all 15 virtual trunks would consume 4320 gateway
channels for networking, leaving none for user traffic. For this reason, you will need to limit the
number of virtual trunks that you up on a legacy UXM card. You can use the
the number of trunks upped on a UXM card.

Virtual Trunking Interactions with Other Features

The fundamental architecture of the virtual trunking feature inthis release is similar to that of the BNI
virtual trunk implementation in previous switch software releases. The standard UNI/NNI cell headers
are used across the virtual trunks, and two-stage queueing as defined by the VI interface.
This section discusses some features that interact with virtual trunking, including:
•
•
Cisco BPX 8600 Series Installation and Configuration
25-24
. In Release 9.2, networking channels are pre-allocated only for AutoRoute trunks.
# Networking Channels for Legacy Cards # Networking Channels for Enhanced Cards
270 chans
540 chans
810 chans
4320 chans
8640 chans
trunks and ports on the same card
VSI resource partitioning
Chapter 25 Configuring BXM Virtual Trunks
270 chans
270 chans
270 chans
270 chans
270 chans
cnfport
Release 9.3.0, Part Number 78-10674-01 Rev. D0, July 2001
command to control