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VSS Support & Feature

srikanth ath
Level 4
Level 4

Hello Expert,

we are planning to configure VSS on our Core switches.

1. Not sure whether present IOS or Supp supports this feature or not(Below Provided Output of version and module). If it doesnt support what to be upgraded with sup or IOS?

2. I heard like configuring VSS (issuing switch convert mode virtual in exec mode) on a switch needs to rebooted. I cannot reboot the switches as its my production. Currently these switches are running HSRP while loadbalancing on both the switches, where sw1 is active for odd vlans and sw2 is active for even vlans where as sw1 is standby.

3. Is this a best technology over HSRP for redundancy between my Core Switches. Can you defend with some usefull points?

isco Internetwork Operating System Software
IOS (tm) s72033_rp Software (s72033_rp-ENTSERVICESK9_WAN-M), Version 12.2(18)SXF12a, RELEASE SOFTWARE (fc1)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2008 by cisco Systems, Inc.
Compiled Thu 10-Jan-08 23:41 by kellythw
Image text-base: 0x40101040, data-base: 0x42DC5270

ROM: System Bootstrap, Version 12.2(17r)S4, RELEASE SOFTWARE (fc1)
BOOTLDR: s72033_rp Software (s72033_rp-ENTSERVICESK9_WAN-M), Version 12.2(18)SXF12a, RELEASE SOFTWARE (fc1)

SG-CORERouter2 uptime is 1 week, 2 days, 15 hours, 17 minutes
Time since SG-CORERouter2 switched to active is 1 week, 2 days, 15 hours, 16 minutes
System returned to ROM by  power cycle (SP by power on)
System image file is "sup-bootdisk:s72033-entservicesk9_wan-mz.122-18.SXF12a.bin"

cisco WS-C6509-E (R7000) processor (revision 1.3) with 458720K/65536K bytes of memory.
Processor board ID SMG1119NNN
SR71000 CPU at 600Mhz, Implementation 0x504, Rev 1.2, 512KB L2 Cache
Last reset from s/w reset
SuperLAT software (copyright 1990 by Meridian Technology Corp).
X.25 software, Version 3.0.0.
Bridging software.
TN3270 Emulation software.
52 Virtual Ethernet/IEEE 802.3 interfaces
100 Gigabit Ethernet/IEEE 802.3 interfaces
1917K bytes of non-volatile configuration memory.
8192K bytes of packet buffer memory.

65536K bytes of Flash internal SIMM (Sector size 512K).
Configuration register is 0x2102

XXXXXXX#sh module

Mod Ports Card Type                              Model              Serial No.

--- ----- -------------------------------------- ------------------ -----------

  1   48  CEF720 48 port 1000mb SFP              WS-X6748-SFP       SAL1117MHKU

  2   48  CEF720 48 port 1000mb SFP              WS-X6748-SFP       SAL1323RLU6

  5    2  Supervisor Engine 720 (Active)         WS-SUP720-3B       SAD111603V4

  6    2  Supervisor Engine 720 (Hot)            WS-SUP720-3B       SAL1115L7UT

5 Replies 5

Jon Marshall
Hall of Fame
Hall of Fame

Srikanth

You don't have either the right supervisors or IOS to run VSS ie. -

1) you need sup720-10G-3C or sup2T to run VSS

and

2) you need a minimum IOS 12.2(33)SXH1

In answer to your general questions -

1) yes you would need downtime to convert

2) VSS is, in my opinion, the way to go. It has a number of benefits -

a) no need for load balancing odd and even vlans from access switches. Because an etherchannel can be spread across both 6500 chassis with VSS you get the full uplink capacity for all vlans, Because of this STP is still run but it is not actually needed to block lins from the access layer switches

b) no need for HSRP. There is only one control plane for both switches and so you only need to configure the active switch. This simplifies configuration. Both switches still forward data.

c)  if one of the switches fails there is very little disruption in forwarding of L2/L3 traffic. With your current setup if a 6500 fails then you need STP reconvergence. HSRP failover etc.

In terms of etherchannel as already described the ability to spread it across multiple switches is called MEC (Multchassis Etherchannel) and this is not just supported with VSS it also supported by stacked switches and the Nexus switches.

This seems to be the way things are going and it is a good thing as it gives you more throughput, removes STP as an active participant in the network (although you should still run it) and allows you to have a larger L2 network that is more stable although it can also be used for L3 as well.

So there are advantages to using it but you need to decide if you need/want these or whether what you currently have sufficiently meets your needs.

Jon

Leo Laohoo
Hall of Fame
Hall of Fame

Be aware that the venerable 6500E has been in the market a long, long time (hint, hint).

If you plan to go down the VSS road, then I'd recommend you consider looking at replacing your chassis sooner.  You're going to replace your supervisor card.  You might as well replace the entire chassis.  There's still a healthy "after market" demand for the chassis and the supervisor card or you could ask Cisco if you can avail of the Technology Migration Program (TMP).

Thanks all for the Quickreplies.

Jon,

As you mentioned in Point 2 (b)

b) no need for HSRP. There is only one control plane for both switches and so you only need to configure the active switch. This simplifies configuration. Both switches still forward data.

Both Switches Still forward the data.?

Not sure, How it is as i went throught the configuration of VSS and it says one would be the active switch and other would be in standby. Can you explain me in details how these both switches forward data with real time scenario.

Thanks,

Srikanth

One switch is active and one is standby for the control plane.

The control plane is used to build the forwarding tables, both L2 and L3, to send an receive STP BPDU, to exchange routes with L3 peers etc.

The forwarding plane (or data plane) is used to actually forward the data.

Both switches are active when it comes to forwarding the actual data ie. each chassis can forward traffic independantly of the other.

Jon

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