Port channel between Cisco & Non Cisco device

[raju]

Hello,

We have two Networks running in different platform and different Class IP address also , one Network with Cisco 6509 and other with 3com CB-3500 (Layer3 Switch). We made connectivity using Fast ethernet (100 Base FX ) , can able to ping and can use applications across both Networks . Due to heavy bandwidth requirement , we tried with two separate 100 Base FX ports and both are in same Vlan (without port channel ) on both the ends , we can't able to ping each other and it creates loop somewhere . We tried to use port channel on Cisco 6509 side (2 100 Bse FX ports ) and 3com side we created Trunk( I guess , it's similar to port channel on Cisco side ), but no use .Currently , we are using only one link (100 Base FX ) which works fine , but users feel slow when they use applications across two Network and the ports also showing high utilization on both the ends . Any suggestions to use more than one port or port channel ....

Regards,

Raju

[hbaerten]

An alternative, since the interconnection is used for routing (not bridging), is to run a dynamic routing protocol that supports equal-cost loadbalancing, like (E)IGRP or OSPF (if the 3com L3 switch supports it). Then just add interconnections using seperate subnets.

hth

Herbert

[rjackson]

The two links are the loop. Spanning tree will shut one of them down. Creating a channel makes one spanning tree entity for the group of ports so it wont shut the extra ones down. A trunk is a circuit that carries multiple vlans. A channel is a group of ports that can be one vlan or a trunk. Trunk is not what you want on the 3com. Research "channels" or "teaming" and see if they have such a feature. They should.

[raju]

Thanks very much Jackson . I did research on 3com side and it does not give useful info . As a fact matter of fact , we found an option called "Bridgeport " on 3com side , tried with same , did not work . My question is if we use separate links without port channel , it does not work , creates loop somewhere , can't able to ping each other .

[konigl]

To do Layer 1 redundant links, Cisco Catalyst does EtherChannel which is proprietary; 3Com CB3500 does IEEE 802.3ad link aggregation which is a standard. They are NOT compatible. I am not sure if the 6509 can do 802.3ad link aggregation; maybe you can, with a software upgrade. I will look into this and get back to you, unless someone else answers that question first.

To be able to benefit from multiple paths between these two switches, if you cannot get the 6509 to do 802.3ad as mentioned above, your best bet is to leverage the equal-cost path load-balancing that OSPF will get you. (The 3Com CB3500 cannot do EIGRP, that's also a Cisco-proprietary technology).

Basically, you create two subnets: one that is used exclusively on the first switch-to-switch connection, and the other that is exclusive to the second switch-to-switch connection. Then, enable OSPF at both ends of each connection. Two paths between the switches, same cost on each, so both should get used.

This will work for you if all the VLANs at the site with the 6509 are local to that site, while all the VLANs at the site with the CB3500 are contained there at that site. If you need to have access ports for a single VLAN at both sites, this solution will not help you. (If you have yet another pair of fiber strands available, though, you could connect that up and configure it to bridge that single VLAN between both sites. Then, you would have two gateways on that VLAN: the 6509 and the CB3500. You will have to decide which will be the default gateway, because Cisco's proprietary HSRP and 3Com's standard VRRP are not compatible, either.)

Hope this helps.

[raju]

Thanks . Awaiting for your reply about if 6509 will support 802.3ad with software upgrade . Currently , we are running RIP v2 on both 6509 & 3500 and we don't want to enable OSPF just for this purpose and we really don't know what will be impact on 6509 Network which has 3500 users by enabling OSPF on 6509 .

Again , whatever Vlan's we have on 6509 side are exclusively for 6509 Network users (local site) and Vlan's on 3500 are for exclusively other Network users (local site) . we have extra 2 pair of fiber strands free , have free fast ethernet ports (100 Base FX ) on 6509 and 3500 side as well .

I can do one thing . I can create one more Vlan on 3500 and 6509 side assign this Vlan for second connectivity port . But RIP will not do load Balancing .

[konigl]

Update:

I found information that shows Catalyst 6500 supports Link Aggregation Control Protocol (LACP) based VLANs -- that is, 802.3ad link aggregation -- with Catalyst OS version 7.1(1) and later, and IOS version 12.1(13)E and later. Which one you use depends on whether you're doing hybrid mode (Cat OS + Cisco IOS) or native mode (IOS only) on your 6509.

"Link Aggregation Control Protocol, (LACP) is defined in IEEE 802.3ad and allows Cisco switches to manage Ethernet channeling with devices that conform to the 802.3ad specification.

LACP is similar to Cisco's proprietary implementation of EtherChannel, Port Aggregation Protocol (PAgP) which allows ports with similar characteristics to form a channel through dynamic negotiation with a partner system."

Here's two links, search them for LACP to find the configuration information you need:

(802.3ad 6500 7.1) Configuring EtherChannel

http://www.cisco.com/en/US/products/hw/switches/ps708/products_configuration_guide_chapter09186a008007ec1c.html

(802.3ad 6500 12.1) Configuring Layer 3 and Layer 2 EtherChannel

http://www.cisco.com/en/US/products/hw/switches/ps708/products_configuration_guide_chapter09186a008007e6d3.html

It looks like there is also support on the 6500 series for Virtual Router Redundancy Protocol too, in case you find yourself in a situation where it might be useful to set up a fault-tolerant default gateway IP address for end users between your 6509 and the CB3500.

Hope this helps.

[amitavbanerjee]

Hi Raju,

This is Amitav, Network Consultant @ Bangalore. We had the saqme kind of problem at Toyota Kirloskar Motor - We wanted to create etherchannel between Cat 4507R and Nways IBM 8274. However as far as I feel, the thing that you are trying to do will not work as the other switch does not support 802.1Q. The moment you create a second connection, 6509 will identify that as a loop because of STP and put it on standby. You can try using IGRP as 3-Com will not support EIGRP over two links with the same cost.

Regards,

Amitav

tf_amitavb@tkm.co.in

[raju]

Thanks Amit . Currently , we feel that performance is ok with the single link and it does not exceed more than 15% utilization at any point of time (peak & off period ) for the port on 6509 (100 Base-FX )used for connectivity with CB-3500 . Anyway , we have a plan to replace 3com Switches with Cisco Switches and will have GBIC connectivity over single mode fiber between two Networks .

Thanks.

[ruwhite]

Or RIP--first, IGRP is being pulled from IOS, so it might be even be in the code on the 6500 (or if it is, it won't be there forever). Second, do 3com's support IGRP? I didn't think so...

But doing this is going to require redistribution into EIGRP, right?

Russ.W