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New Member

SRB and TLB on the same TokenRing Interface?

Is it possible to configure (...and run) source-route and also transparent bridging on one TokenRing interface as the example will show in the following? (I've tried this configuration and it seems to work, but i'm not shure which problem could occur?)

!

source-bridge ring-group 100

dlsw local-peer peer-id 10.0.0.1

dlsw remote-peer 0 tcp 10.0.0.2

dlsw bridge-group 1

!

interface TokenRing5/0/2

ip address 10.0.0.1 255.255.255.0

ring-speed 16

bridge-group 1

source-bridge 1 1 100

source-bridge spanning

!

bridge 1 protocol dec

bridge 1 hello-time 10

1 ACCEPTED SOLUTION

Accepted Solutions
Silver

Re: SRB and TLB on the same TokenRing Interface?

Hi,

After working with the DLSw Development team, I am told that Cisco do not support SRB and TB on the same token ring interface for DLSw traffic.

I am not 100% understand your second question. Do you run SRT (i.e. SRB and TB) on the second router? Is the second router the backup peer as the local primary router?

If you only run SRB only on the second router, there is no problem. If you run TB on the second router, the second router has to be backup for the primary local router. (i.e. No two router can be active at the same time). If you do, you create a loop. SRB uses RIF to detect loops. Thus, it is OK to have loops in SRB network. However, TB does not allow loops. Spanning tree only run locally on the token ring. It does not detect a loop involving remote DLSw peer. (i.e. it cannot detect a loop like primary local peer->remote peer->secondary local peer).

10 REPLIES
Silver

Re: SRB and TLB on the same TokenRing Interface?

Yes, it is possible to configure SRB (source-route bridging) and TB (transparent bridging) on the same token ring interface. It is called SRT (source-route transparent bridging). If I am not mistaken, it is defined by IEEE 802.1D.

I have a question and a comment. Why do you want to send SRB and TB traffic to DLSw?

SRB bridges source-route traffic into DLSw; while TB bridges non-soure route traffic into DLSw. Most token ring stations are capable of sending source-route frames nowadays.

You may run into MTU problem. TB in IOS drops any packet whose size is greater than 1500 bytes. If DLSw picks up the TB path, IOS sets the LF (largest frame) bit in RIF header as 1500. However, not all token ring stations honor the LF bit. You may come up with a problem where TB drops a packet larger than 1500 bytes. As a result, DLSw/LLC2 circuits drop intermittently.

New Member

Re: SRB and TLB on the same TokenRing Interface?

Hi, first of all thanks for your detailed answer. i think this will help me! The reason for both (TB and SRB) is that the customer has placed a bridge in my TokenRing to connect his Ethernet Traffic, and at the moment it seems to be difficult to for tis bridge to "play" TB <-> SRG gateway. at the moment there is a TokenRing adapter of my 3745 directly connected to that ring (003) and the Ethernet clients connect "transparent" bridged to it.

so SRT is no my "favorite" solution, but maybe it has to be a "work around"

Silver

Re: SRB and TLB on the same TokenRing Interface?

Thanks for the additional information. Have you suggested you customer to use a Cisco router running SR/TLB? Maybe you have.

New Member

Re: SRB and TLB on the same TokenRing Interface?

is there a difference between bridging TB into DLSw by defining dlsw "bridge-group 1" or bridging it into the SRB by defining "source-bridge transparent ..."(?) concerning the WAN (DLSw) part?

Silver

Re: SRB and TLB on the same TokenRing Interface?

DLSw does not take traffic from SR/TLB. SR/TLB only bridge traffic between a local token ring and local ethernet interface.

New Member

Re: SRB and TLB on the same TokenRing Interface?

couple of things you need to do

1) make sure there is only one entry point into the ethernet domain. If youi have a "redundant path", your tlb will break

2) You forgot your pseudo ring for ethernet. You can not TLB without it.

command syntax is:

source-bridge ring-group 100

!you have this part, now we just need to set up translation bridging by the next command. Make sure your ethernet interface is in a bridge group as well. This example config factors bridge group 1

source-bridge transparent 100 30 1 1

!this creates a pseudo ring 30 and assosiates it to ethernet birdgegroup 1

This link will help you with any other Q's

http://www.cisco.com/en/US/tech/tk331/tk660/technologies_tech_note09186a00800947b2.shtml

Remember HSRP is still 2 entry points since you arp mac addresses. One entry point only.

And like what was said.. DLSW will not tlb, if you have ehternet and Token ring on the same lan talking, you need TLB.

New Member

Re: SRB and TLB on the same TokenRing Interface?

couple of things you need to do

1) make sure there is only one entry point into the ethernet domain. If youi have a "redundant path", your tlb will break

2) You forgot your pseudo ring for ethernet. You can not TLB without it.

command syntax is:

source-bridge ring-group 100

!you have this part, now we just need to set up translation bridging by the next command. Make sure your ethernet interface is in a bridge group as well. This example config factors bridge group 1

source-bridge transparent 100 30 1 1

!this creates a pseudo ring 30 and assosiates it to ethernet bridge group 1

This link will help you with any other Q's

http://www.cisco.com/en/US/tech/tk331/tk660/technologies_tech_note09186a00800947b2.shtml

Remember HSRP is still 2 entry points since you arp mac addresses. One entry point only.

And like what was said.. DLSW will not tlb, if you have ehternet and Token ring on the same lan talking, you need TLB.

New Member

Re: SRB and TLB on the same TokenRing Interface?

couple of things you need to do

1) make sure there is only one entry point into the ethernet domain. If youi have a "redundant path", your tlb will break

2) You forgot your pseudo ring for ethernet. You can not TLB without it.

command syntax is:

source-bridge ring-group 100

!you have this part, now we just need to set up translation bridging by the next command. Make sure your ethernet interface is in a bridge group as well. This example config factors bridge group 1

source-bridge transparent 100 30 1 1

!this creates a pseudo ring 30 and assosiates it to ethernet bridge group 1

This link will help you with any other Q's

http://www.cisco.com/en/US/tech/tk331/tk660/technologies_tech_note09186a00800947b2.shtml

Remember HSRP is still 2 entry points since you arp mac addresses. One entry point only.

And like what was said.. DLSW will not tlb, if you have ehternet and Token ring on the same lan talking, you need TLB.

New Member

Re: SRB and TLB on the same TokenRing Interface?

OK thanks for your answer, that means the transparent part of following example won't work with DLSw:

source-bridge ring-group 100

source-bridge transparent 100 30 1 1

dlsw local-peer peer-id 10.0.0.1

dlsw remote-peer 0 tcp 10.1.0.1

!

interface TokenRing 0

ip address ...

bridge-group 1

source-bridge 200 1 100

source-bridge spanning

!

bridge 1 protocol dec

so i've to define "dlsw bridge-group 1" instead of the "source-bridge transparent 100 30 1 1" statement.

I think it works (i've tried), but my main question still is, if this "bridging SRB and TB on thesame TokenRing Interface" is official supported by Cisco? ...and when it is, the second question would be: "what about a second local TokenRing Router for backup?"

regards

Frank

Silver

Re: SRB and TLB on the same TokenRing Interface?

Hi,

After working with the DLSw Development team, I am told that Cisco do not support SRB and TB on the same token ring interface for DLSw traffic.

I am not 100% understand your second question. Do you run SRT (i.e. SRB and TB) on the second router? Is the second router the backup peer as the local primary router?

If you only run SRB only on the second router, there is no problem. If you run TB on the second router, the second router has to be backup for the primary local router. (i.e. No two router can be active at the same time). If you do, you create a loop. SRB uses RIF to detect loops. Thus, it is OK to have loops in SRB network. However, TB does not allow loops. Spanning tree only run locally on the token ring. It does not detect a loop involving remote DLSw peer. (i.e. it cannot detect a loop like primary local peer->remote peer->secondary local peer).

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